Yeah, appreciate Paul but he could have done better here. The reason one sees *negative numbers on a scale is because they are logarithms.* A logarithm of any number between 0 and 1 is negative by definition. And _decibel_ is properly a _deci-bel_ meaning one tenth of a bel (named after Alexander). This is a ratio, it is unit-less (so it is not a voltage). In audio the ratio is that of the signal to that of a reference level.
My own personal definition has always been this: At 0db, there is no gain put into the signal. All the negative numbers below that are just an attenuation of the signal. And I always set my other gains downstream based off the source being 0db. No gain, no attenuation.
@@StoneyRerootkitwell, the input pulses are amplified in higher voltage/current. So you could put a ratio number (dB) on that. If you mean the input signal, dbFS is used. Ratio between full scale (all 1’s or whatever bit combination is used), and the actual signal.
Origin goes back to telephony. The simplest way to understand the markings on a "volume attenuator" is that it is not indicating the gain being added, but the attenuation ratio related to max output of that device. It is marked to show how much below max output it is set to. (BTW, The number you were looking for was the Bell System standard of 1 mW across 600 ohms, or 0.7746 V RMS, usually rounded to .775 V. Ever notice that VU meters are *usually* marked as being in "dBm" or deci Bels related to 1 mW.)
There is a lot of history on where the Bel and deci-Bel (dB) come from. Some other comments have already covered bits of it. Some time spent googling the topic will yield loads of responses from Wikipedia and other sources. Have worked with dBs of various flavors for 45+ years and they're really great once you get the basic concept down. The bel was standardized in 1928 and while not part of the SI standard itself, its use is excepted with the SI and is abbreviated as 'B'. The standard unit prefixes apply and because the bel was too large for most uses, commonly the practice was to apply the SI prefix 'd' for deci, or 1 tenth, e.g. dB. Other SI units and their prefixes can be used with the dB as in dBμV for dB relative to a microvolt, and so on. The bel and decibel is simply just a way to express logarithmic ratio quantities. Divide two quantities and take the base 10 logarithm and you have the bel, multiply that by 10 and you have the decibel. For example 10 log10(40/4) = 10 dB. If you take 10 log10(40/40) you get 0 dB. When you start working with really large or very small numbers and multiplying and dividing them the results get unwieldy for most people to deal with, but are more manageable once converted to dB form. The next step is to apply the dB to some reference value to easily see how large or small something is compared to the reference. One common reference used in communications is the milliwatt, or 1/1000 of a watt. In dB form this would look like 0 dB(mW) because 10 log10(1 mW) = 0 dB referenced to 1 mW. Here I state it as 0 dB(mW) to make it clear that its referenced to a milliwatt, but commonly this is simplified to 0 dBm, which is a bit confusing sometimes if you're working with communications formulas that include ratios of both milliwatts and meters because 10 log10(342 mW/15 mW) = 13.6 dBm (in common notation) and 10 log10(659 m/82 m) = 80.4 dBm. But as this only impacts a handful of people and most of us are aware of the issue it's just a minor annoyance . . . :) There's a huge list of things to which the dB can be applied, volts, watts, sound pressure level, dollars, you name it. The important part is understanding the base reference and how it is treated when converted to and working with the dB form. Importantly, changes in power are expressed as 10 log10(the ratio), changes in voltage are expressed as 20 log10(the ratio). This makes sense when you work through the math but too much for an already long comment. But unless the volume knob is calibrated with an absolute unit, turning it is just adjusting the ratio of the output against some arbitrary value. Let's say you have a receiver or amplifier rated to output 100 W. At full power the 0 dB position would be allowing the unit to output the full 100 W (assuming some standard reference input signal), at the -10 dB position it would be outputting 10 W, at -13 dB it would be outputting 5 W.
I agree, good explanation. The only thing I would add is that the reason we use a logarithmic scale is because our hearing, like most of our senses, is fundamentally logarithmic every time you double the power we hear that as an equal increase in volume.
Sound levels are measured in the logarithmic units called Bels, a Bel is 1 order of magnitude of power. Usually meter scales are marked in decibels (1 dB = 0.1 Bel). One reference level is 0 dBm, 0 on that scale is 1 milliwatt of power into a 600 ohm load. The VU meters on many professional mixers are set to indicate 0 VU at a level of +4 dBm. The meters on an analog tape machine might be set to read 0 at a level of 185 nWb/m (nanowebers per meter) of magnetic flux. Digital audio meters are often calibrated to dBFS (decibels Full Scale), 0 being the loudest sound that can be represented, so everything else is negative.
If we're going to head into tape, then, for clarification: 185nWb/m is/was the Ampex standard (USA) vs. 370nWWb/m being the European standard (6dB hotter). Then MRL muddied the waters by stating that 355 nWb/m is +6dB relative to185nWb/m, when in fact, it's 5.5dB! Too much!!!!
The simple answer is because a fader or a pot etc. is an attenuator, that's all there is to it. It doesn’t add gain; it only reduces the amplitude of the signal passing through it.
Since dB is a logarithmic scale, defining dB from absolute quiet as 0dB would net any signal high than that complex infinity or undefined. So from a purely mathematical point of view it makes the most sense to define it from a point that easily recognizable, for instance the max amplitute of an amplifier.
Some very good technical answers/ comments here from many people, thank you. I see the simple answer is that it shows the reduction of attenuation as you turn the volume control up.
Excellent, the first decent answer I've read here. Thank you for this very comprehensible answer. "Reducing attenuation" as you said, has it all in a nutshell.
First time I came across this channel, and I'm afraid probably the last, because that is the most flawed description of dB I've ever encountered. The decibel is a logarithmic measure. It is dimensionless. It's not a voltage. One reason we use a logarithmic measure is because our visual and aural senses are able to sense intensities over many orders of magnitude (powers of 10), and the logarithm increases very slowly as its argument increases (so, for example, a doubling of sound intensity corresponds to an increase of about 3 dB). The decibel is usually defined as ten times the log (base 10) of the ratio of two powers or intensities, where the denominator of the ratio is a reference level. So 0 dB means the intensity is at the reference level, and negative dB means it's less (since the logarithm of 1 is 0, and the logarithm.of a number between 0 and 1 is negative).
For a preamp 0dB just means the gain is 1 (output voltage = input voltage). For every -6dB you cut the voltage gain in half. Thus -6dB is a gain of 0.5 and +6dB is a gain of 2 (possibly causing clipping).
@@ThinkingBetter yes, but since lots of loads are (at least pretended) to be linear resistances, current gain will be equal to voltage gain. Thus power gain is a doubling/halving every 3dB.
@ The amplifier doesn’t know the impedance curve of your speakers. If your speakers have a flat linear frequency response it’s still linear to the voltage and not power. A doubling of voltage is generally considered a 6dB sound level rise and this we also use when we say a CD 16 bit PCM dynamic range is 6x16=96dB as every bit represents a doubling of voltage.
@ Right. Doubling voltage quadruples power so we’re both right. The definition of dB Voltage and dB Power are different precisely this reason. It’s only confusing if you say “+6dB is a gain of 2” without specifying that you mean a “voltage gain of 2”. Everyone in my world would say, “power doubles every +3dB”.
About four minutes in I thought "just how long is this video!?" -- you were going so relaxed and so calm and had some pleasantries and then described history and meaning of something confusing -- and it made sense -- and I realized your secret to how you get so much done: You have a time distortion field that causes time to move at a different rate for you. Very neat trick.
1:03. The dB is most certainly not a unit. It is a ratio. It only becomes a unit if it is referenced to a unit such a dB(A) dB(SPL) etc. You can measure the height of trees in dB if you want to by defining a standard tree. All others being a ratio of that tree.
@@orbalicious20 Would work but small d please :-) And would also require a bracket for the H so dB(H). Now all we have to do is agree on a standard breast !!!!
@@sephina The confusion usually lies from not realizing in advance that there is a difference between a 'dB' and a 'dBm'. A dBm definitely IS a unit and many people don't know to look carefully for that little 'm'
Well that video and most of the comments so far probably confused the heck out of the person who asked the question. Sorry Paul/People. To understand volume and why the numbers are represented with negative numbers, you have to start with GAIN. More specifically, the difference between Volume and Gain. GAIN = Additive VOLUME = Subtractive You set the GAIN to set the 0dB goal post. Let’s say 50Watts Integrated amps often set this for you (hence why there are no GAIN adjustments. For simplicity, let’s say the integrated and Power Amps are both set to 50W output (this is the voltage that matters). If you turn the VOLUME to 100%, or 0dB you are literally subtracting 0 or NOTHING. So the OUTPUT of the 2 amps will be 50W When you turn down the volume from 100%/0dB you are SUBTRACTING MORE from 50W. The reason that the displays are in units and not specific numbers or percentages, is because the entire exercise is logarithmic. Both in voltage AND dB. So it would be MORE confusing if you turned it down to 50%, but the actual output was still around 66% You turn the volume down in a linear fashion, expecting linear results. The problem is that the results are NOT linear. For this reason you need to use logarithmic units when discussing or defining output values. HENCE: -15dB as a volume. You are simply subtracting -15dB output from 50W. What that number [50W@-15db] ends up being will depend entirely on your GAIN setting. In our example, the GAIN setting is 50W. You must use the dB as the unit, because dB is a logarithmic unit, defining a logarithmic scale. The numbers are represented with a negative, because it defines how much you are SUBTRACTING from the GAIN setting/Goal-Post. When you grasp the very misunderstood function of volume (subtractive value from the gain setting), the negative number makes sense. Turning the volume UP is simply (and clearly uninuitively) REDUCING the amount of subtraction. Except at 100%/0dB So when you turn the Volume UP the negative numbers get smaller (subtracting less), and the vice-versa happens when you turn the volume DOWN, the negative numbers INCREASE. Because you are subtracting more from the GAIN setting.
I have approximately 10,000 songs and of all those songs there is only 1 that I have that seems to be recorded past the 0 dB range which is really awkward. I’m assuming it’s an issue with the header of the file but it’s really odd. Everywhere I play it, it sounds distorted and I thought that they recorded it badly like that but to my surprise when I use a specific preamplifier software and I lower the volume of the preamplifier, the audio sounds completely clean! 😮
@@timothystockman7533 I understand music not Teck. I chose you to ask because you mentioned Clipping. Like most of us I could never play my sound system at anywhere near full volume that would be far too loud. My electrical 'Ring' is a high watt ex Heater ring. My DAC and Streamer are capable of 32 768 . I suspect that for the above reasons I could not force my sound system to clip even if I tried, but I have no way of knowing if I am right and if I am right which one if any of the above mentioned aspects is the one protecting me from clipping? PS I would not be surprised if my system could handle twice the volume I could.
If it is an MP3, someone may used Mp3gain to boost the volume, and then you can reduce it again. Decoding is usually done with a generous headroom, and the level can go over temporarily in the DSP. It's just numbers and you can mark them as "multiply by another big number". If you scan your library for ReplayGain, lossy encodings will often have greater than 1 peak level. HDCD with peak extension may also show it. Many recordings out of studios today come distorted because of the Loudness War.
This is the right answer.. Or at least how I think of it, the volume control attenuates the signal, without it the full signal would be fed into the amplifier, so the maximum volume is zero attenuation, so 0dB.
It's a stupid representation trying to look intelligent. They don't tell you what the amplifier gain is at 0 dB (no attenutation), and at what input voltage to the amplifier will maintain an acceptable distortion threshold for the amp at the output, in other terms, still output a linear, uncompressed signal. My $0.02.
@@shipsahoy1793 - Yeah, this should explained what gain is. That would have been helpful. But I wouldn't be too critical, keep the audience in mind, right?
This makes me think of tachometers in racing. In some cases, a tachometer is rotated in the instrument panel, to indicate the ideal RPM at which to shift. It is sometimes rotated so that that ideal shift RPM is found at exactly vertical position of the needle on the dial. This way, a driver can “see” the needle hit ideal RPM without really looking down. Using a bit of peripheral vision, it is easy to make out when a gauge needle is pointing straight up. In such a case, the perfectly vertical position is kind of like “0 db” You can rev lower than that point, and you can rev higher, too. But the “sweet spot” is given a special indication by way of the needle pointing straight up. In your decibel example, the “sweet spot” is at zero.
Decibels is a logarithmic scale, 0dB is 1 and every additional 10dB multiplies that value by 10. 10dB = 10, 20dB = 100, 30dB = 1000, and so on. Of course it then follows that for every -10dB you instead divide by 10. -10dB = 0.1, -20dB = 0.01, you get the idea. In the case of a volume control we use 1 (0dB) to represent maximum volume and 0 to represent no volume, so -10dB in this case means a tenth of the maximum volume, -20dB is a hundredth, etc. Curiously this means that you can't actually express 0 volume in decibels.
There is a problem with explanations like this because decibels are ALWAYS relative, Never Absolute. A reference level must be established before the dB number can mean anything. In many cases, the reference is not stated, so the context must be considered. Is it consumer audio, pro audio, telephone, or something else? The standard for line level in consumer equipment is not the same as for professional equipment. And manufacturers of consumer equipment use whatever method they like for labelling the volume level on the unit. We often see no useful numbers at all. If we are fortunate we May get equally spaced dots around the knob or arbitrary (0 to 99) digits in a window. The total lack of explanation in owners' manuals doesn't help, so even if one reads the book they don't know the whole story.
In this case, although not stated, there is a reference level. It is 0dBm, with the m standing for milliwatts. And the 0.775V mentioned at the beginning, is the voltage measured when 1mW is applied to 600 ohms.
decibels on home stereo equipment on the volume control (which is the purpose of the video) is always tied to middle-tier gear sounding fancy. Aka voltage indexing .
Excellent and easy explanation, having a universal voltage to dB reference, and you mentioned clipping, so then what is clipping? I understanding the basic concept but for clarity sake, how would you explain clipping? Thank you.
As others have said the fact that dB is a relative measurement would be helpful here. It’s not a unit in its own right but a ratio. In my world we deal in dBW or more commonly dBm for mW, i.e. relative to 1 W or 1 mW of power.
Some volume controls go below AND above 0dB. For example, my Denon AVR is calibrated with reference to standard cinema SPL (Sound Pressure Level). The volume level goes from -79.5dB to +18dB but can be optionally capped at 0dB for maximum volume level.
@@blairhoughton7918 There is no direct conversion between dBFS and dB. They belong to different realms. 0 dBFS can mean -80 dB or +10 dB. It all depends on your device's volume settings.
@@NotExpatJoe There is a standard that sets +18 dB (actually dBu) as corresponding to 0 dBFS. It's based on common broadcast audio equipment and intends to ensure that the recording you deliver plays at the right volume on that equipment. So, yeah, you could say "dBFS on this machine", but if you just say "dBFS" everyone else should be able to assume you mean the standard meaning.
I've been into stereo for around 50 years. I've had an Outlaw RR2160 Mkii receiver for about 3 years now and it was the first stereo component that I've seen this -db volume. I've sort of got accustomed to it but it is awkward. People simply don't think that way. As the volume gets higher so should the number on the screen or the dial. On a guitar amp I wouldn't go -db on the dial as I turned the volume up. Humans are not audio measuring and calibration equipment, but then again maybe some of us are.
@@mr.b4444 I get that you want them to be the same and want them to be simple. I also get that you want Gain to be volume. Or that you are mistaking them to be the same thing. The problem is that they are not the same. Your Outlaw RR2160 Mkii is an “Integrated Amp” and your guitar amp is a “Power Amp” The difference is that the Outlaw processes the signal, and as such, uses Volume to modulate the signal. It then projects that signal to a baked in Output Gain Level. Your guitar amp does the exact opposite. The guitar amp takes a 100% line level signal and applies an amplified gain setting. Both are amplifiers that amplify a voltage, they simply modulate the output voltage in opposite ways. The reason that this is important to understand is because sometimes you want separate devices controlling the signal and the output. Signal Modulation (volume) is the act of subtracting or retarding the signal level, so when it hits the power amplifier that is calibrated to output a set voltage equal to the speaker specs, in relation to a standard signal input voltage, you don’t overshoot and blow said speakers. This is why Paul is talking about 0.775 Volts and 1.5Volts when he speaks about VOLUME. 0.775V is standard and sometimes called “mic Level”, and 1.5V is called “line level”. These are standardized SIGNAL levels. Your guitar is going to adhere to the LINE level. Your Volume is modulated by how hard to hit the strings and how much those pick-ups detect. In relation to 1.5V So it matters A LOT. Volume is modulated (as a signal level) Gain is set (as an output level) Set your power amplifier gain to output the correct voltage for your speakers. Modulate the volume on your receiver to suit within the capabilities of the amplifier and speaker (as set by gain). NEVER use the knob on the power amplifier to modulate the output loudness. This is how you blow speakers and do expensive damage.
@@pitspeedtv I must defend mrb He is correct, and if I'm reading your second comment correctly, you have got it entirely wrong. To simplify: Gain is a term used for the control of an input and volume is a term always used for the control of output. The gain knob on a guitar controls the circuitry between the guitars electric pickups (input) and the volume knob.( output). (Understanding why electronic instruments have this function is another chapter). This labelling process is repeated on the amplifiers input and output Typically these sections are also labelled as gain, and volume. My AV amp has an input control but it labelled as trim. Usually the gain control when turned to zero will shut the signal off completely. This It will sometimes also be used to amplify the signals optimal strength by a magnitude by as much as +10db. A trim control differs because usually the range of control is limited to between -3db/ +3db. The practice of using gain controls can also be found on DJ mixers and other forms of mixing consoles, and those used in PA and recording studios. Some will also have an extra trim level for finer attenuation.
Good people, all I'm trying to say here is that the labeling throws people off. Not trying to get technical here as to what happens behind the scene, no need to dissect this down to atoms and quarks. As you turn the volume up the number on the label gets higher. You have a light dimmer switch as you brighten the room the switch labeling shows a higher number or corresponding symbol, you hit the gas pedal in your car the speedometer's number increase. Simple, that's how most people view things.
That explanation probably did not help many people... Decibels is a logarithmic scale where a negative number is gain less than one and positive number is gain greater than 1. The gain is then referring to some spcific unit like volt or watt. So -20dBV is same as 0.1V and 0dBV is 1V. If we write 0dBm we are talking about milliwatt and 0dBm is same as 1mW. For the question why it is negative numbers on the scale is because we want to know how far we are from the max which is usually around 0dB.
@@rehnmaak Close. The u stands for unloaded, and dBu is 0 at 0.775 volts across any load, though the 0.775 was chosen to match 1 mW in 600 ohms so that on a 600-ohm load 0 dBu and 0 dBm occur at the same time. On any other impedance load 0 dBu would correspond to some other dBm value because the voltage would still be 0.775 volts while the power would no longer be 1 mW. dBu is referenced to 0.775 volts and dBV is referenced to 1.0 volts regardless of impedance. They're just logarithmic expressions of a voltage ratio. Meanwhile, the U in VU does stand for Units and 0 VU is 4 dBu, and at every voltage the dBu meter will read 4 dB higher than the VU meter.
So it is similar to photography exposure, where true exposure has an EV (exposure value),of 0 (zero). Over exposure will a number of EV+ and under exposure EV-. Exposure measured in a computation of Shutter speed and Aperture opening.
This answer misses a whole lot of important information. Around 1900, when western science was starting to work with electronics and electronic systems, and there were no electronic calculators and even slide rules were uncommon, it was realized that a logarithmic unit of gain was much more useful to humans than a straight multiplier. Gain is the ratio of two power levels, usually between a things input and its output, but can also be used as a ratio of maximum and minimum power level. If a straight multiplier is used, a lot of digits are needed in many cases, and calculating the gain of two units in series requires a lot of long hand calculation, which is a tedious and error prone if you have to do it by long hand calculation. If gain is expressed as a logarithm, usually only 2 or 3 digits are needed, and the gain of two unit in series is the sum of their two gains, which can be calculated without even pencil and paper. The unit of logarithmic gain is called the Bell, in honour of Alexander Graham Bell, and it is the (base 10) logarithm of the ratio of two power values. Practically units of 1/10 of a Bell are more useful, called deciBells or dB (10 x the ratio of two power levels) dB are so practical they are still widely used today. A value of 0dB means that the two power levels are the same. A positive dB value means that second power levels is higher than the first, and a negative value means it is lower. 3dB means the power levels are 2:1 and 10dB means the ratios are 10:1. -3dB means the power levels are 1:2. Power is voltage squared, so a dB is the (base 10) logarithm of the ratio of two voltages squared, more easily calculated as 20 times the ratio of voltages. Now to the question asked The output power of the amplifier is given as the ratio of the actual power to its maximum rated power. So a value of 0dB means the power is at maximum, +3dB means the power is at twice rated power (you are probably damaging the amp) and a value of -3dB means you are at half rated power.
*@ericnepean* I've read several answers that have helped me, but now that I've read yours, I'm going to go check my amp right away, hoping it still works...
man, no one cares about db. I had a stereo that used db as their volume level, so 0 is "loud". From cassete, that is amplified, from line, that is switched, from cd, that is processed upon by a DSP. The question was "why is my volume displayed in db" and 99% of the time its voltage or gain.
It always made sense to me from the perspective of volume knobs regulating resistance. So 'all the way open' is no resistance, and below that it resists to a certain extent.
Paul, great explanation! I always assumed 0dB to be the noise floor, but did not know the historical significance in keeping it homogeneous throughout the industry. Very cool! I do have a question though, dB is an exponential unit, however many potentiometers are linear. As we approach 0dB, are we going to see a dramatic change in volume, e.g. from -30dB to -20dB to -10dB, etc.? I would think that going from -30dB to -10dB alone would be a change by a factor of 100x. Would this hold true here too? And, is the voltage source going up linearly while causing an exponential increase in volume? I never thought about it like this, but it would totally make sense (especially when considering that there’s an amplification stage that should respond this way). Please share some insight.
If I recall my Electrical Engineering classes, dB is the ratio of output over input and is on logarithmic scale.... 0 is the max I would crank my amplifier to, safely... Else clipping may happen.
The volume potentiometer acts as a voltage divider. When the slider is at the top, the attenuation is equal to one, wich in logarithmic scale is 0dB. Anything between the minimum position, that usually means the slider touches the terminal connected with the ground - and the maximum - will be an attenuation between 0 and 1 - which in log scale shall be a negative number.
You can have a plus 6V signal. I do on my Vivaldi DCS stack. It's true it can clip but it depends on how your equipment is designed. My VAC pre-amp is designed for the signal before the line of gain stage with the volume control.
The saying goes… _”A dB is a dB is a dB”_ …which means… • dB is *unitless* • dB is a *ratio,* expressed on a logarithmic scale • a dB could be the ratio of two POWER levels • a dB could be the ratio of two VOLTAGE levels
In pro audio channel sliders (have 0 aka UNITY) go plus db? But you mentioned going over zero on a consumer audio amp,. To me 0 is just the limit of the amp. So, why no unity mark on amps? I run the audio at unity into an amp but the amp is at a low volume to give it head room from clipping.
Thanks for informative video. I have recently bought a used hi-fi system from the 90's. Its the first time I've seen a db level indicator, linked to the volume control. I really thought the preamp was faulty, as when the volume is turned up, the db number goes down. All make sense now.
Should I go up to the next scale when doing room correction calibration if the needle goes above 0 (mid scale) say 70 to 80 db.max output 2v.87db target.
dB sound levels are a relative scale, so you can set 0 dB where you guess is the better absolute value to start measuring. Audio amplifiers set 0 dB at theyr maximum power output and then all others output levels are negative, once they are lower than maximum. Besides this, sound amplifiers set a positive margin of measure to deal with acidental peaks of power output, usually +3 dB. This is about twice maximum output at 0 dB, because 3 dB are 0,3 B and logarithm of 2 is 0,301... If maximum is 1 Volt x10^0 (0 B or dB), so 2 Volts are 1 x 10^0 × 2 or 10^0 × 10^0,301 = 10^0,301 = 2 or +0,3 B or +3 dB...
dB is a relative unit, so when something is specified in dB the question is "relative to what?". For something like radio transmitter power (for example on WiFi devices) it's relative to 1mW (also written dBm) or 1W (written dBW). 0dBm means 1mW and so on. For magnetic tape recorders it's relative to some magnetic flux level like 320nWb/m, over time the reference level has changed. For sound level (like when noise in a room is measured etc) it's the human threshold of hearing. For an amplifier it's most likely relative to its maximum output, so 0dB is "full volume" and anything lower means that much lower than the maximum. Studios use different voltage levels as 0dB, like 0.775V (1mW into a 600ohm load) or something else, but that would not really apply to a home amplifier, since the input is fixed level (whatever the source outputs) and output to the speakers is higher than 0.775V, unless the amplifier is for headphones). So, the 0dB on the volume knob means the maximum gain the amplifier has, depending on the source, it may not be enough for full output power or it may drive the amplifier into clipping.
Does that mean that if I wanted to listen at the volume level that the mix was mastered at, that I would need to listen at 0db? Because im certain that if I did my ears would bleed! My Klipsch RF7III will literally cause me pain if I go above -15db with my Yamaha and Emotiva amp.
No, because the mix was mastered using a completely different audio setup than yours. This is all relative to your equipment and you should always do whatever sounds best on your own gear. Mastering generally targets what your standard line level equipment will handle without clipping the signal, plus a bit of extra headroom. That way, people who want it loud can play it loud without distortion, and people who don't can always just turn it down.
Except it's useful as a reference. Have you ever punched in a tape monitor button or switched into a live input without checking the volume first? Can be quite shocking! And could damage equipment if you switch from a lower level source to one that's much higher in output. And having zero as the highest point prevents companies from playing numbers games with volume or other settings, thus confusing the consumers. (Look, my volume goes all the way up to 100!)
Useful in HT when you properly calibrate your system to reference level. You know exactly how far from reference you are and can even estimate current power output and potential headroom
This answer only leads to more questions. Why not express it in volts then? What has this to do with volume? It also doesn’t explain why the baseline isn’t set to some positive number (say 100), and where 0dB is actually zero volts (or no sound).
I got a quick question Paul. Why do PA audio companies list power ratings pumped up not RMS..WHY?..Why can't they all use RMS ratings so there's no cheating in power watts ..If they lie, why would I buy?
Short answer, because it makes a power amp look like it outputs more than it does. For the record, I'm not accusing PS Audio of doing this. The most aggregious are the car stereo manufacturers.
dB is a unit to logarithmically express signal gain (typically measured as the ratio of output voltage magnitude squared and input voltage matnitude squared, meaning this ratio is always greater than or equal to zero). So if this ratio is one, then nothing changes. Log(1) = 0. If ratio is greater than one, then signal is amplified. Log(something>1) yields a positive number. Conversely, if the ratio is fractional, then signal is attenuated. Log(something
Shorter: Isn't it just 0dB is maximum power, -10dB is 10dB quieter than maximum power? The absolute difference in speaker power is not what we hear, we hear non-linear (logarithmic) difference in speaker power, thus vol=10*log(P/Pmax). As the fraction part is always less than 1, the result is always negative. Now confusing part is whether we take the speaker power, or signal voltage. Because it's 10 in the formula for power, and 20 for voltage (vol=20*log(V/Vmax)). My guess is we use power decibels for power, like in amplifiers. But when setting an input level we use voltage decibels. But I might be wrong here. I just remember that half voltage is 6dB less, and half power is 3dB less.
Actually, dB is a ratio of powers. 10 log P1/P2. That's it. If you're measuring voltage, then it's 20 log V1/V2, assuming the same impedance on both sides. That's because if you're increasing voltage on a load you are also increasing current. I used to work in telecom, where levels were measured in dBm, where 0 dBm is 1 mW, usually on a 600 ohm load or 0.775V. If you don't have some reference, such as the m in dBm, then all you have is a ratio and the value is meaningless beyond that.
Thank you. I have some experience but not much and helping set up I thought the minus would be way too low but it isn’t so I was baffled. History is why.
Max amplifier power is when it is turned all the way up and is assigned the "0dB" value. No one listens with the volume all the way up for many reasons (distortion, neighbors, wife, etc.). That is why the volume display readout is negative. You are listening at less than the max output. That is also why the volume knob is sometimes referred to as an attenuator.
Decibel being a logarithmic scale relative to in this case the standard, and negative numbers being the signal divided down by some quantity. I guess human hearing really is kinda logarithmic.
Decibels can be calculated relative to any positive level, if the control has maximum as 0 then everything less is negative and no output is negative infinity. If a preamp has 20 dB of gain max., then -20 on the control is unity gain for the preamp overall*. At 0 setting, the maximum input level to clipping is the minimum level to allow full volume, quite a bit below "standard". Note some preamps have unity gain labelled as 0 instead, so the maximum gives you some information about the capabilities of the unit. *Note this is subtracting/adding but gain is actually dividing/multiplying. Magic of logarithms. Don't mix them up.
My Integrated amplifier has A and B for speakers with volume display in db, but the loudness of A and B is so clearly different when switching, although the db is kept at same level. Is this due to the speaker sensitivity or impedance?
Most certainly due to difference in sensitivity. For instance, if system B sensitivity is 3dB SPL less than that of system A, you'll need twice as much power to produce the same sound pressure (volume).
The one thing I wish you had added is that the negative values indicate attenuation from the maximum or “unity gain” meaning no gain in signal hence “0 dB of gain”
0 dBV = 1 Vrms, whereas 0 dBu = 0,775 Vrms, and +4 dBu = 1,23 Vrms which historically corresponds with 0 VU. +4 dBu is considered line level in pro-audio where contemporary devices have input and output voltage ranges up to +21 dBu which equals about 9 Vrms (or 24Vpp) and more. Whereas in consumer audio -10 dBV which equals 0,316 Vrms is considered line level.
dB is a unit of power within the entire electromagnetic spectrum, and so a unit their powers are expressed in, because a photon can be at different levels of power, and why all photonic. An Elecron though is slightly different, but in the same family of particles of photons. dB's are not linear either, but exponential, where V are a linear unit of measure of energy potential only within the range of electricity on the electromagnetic spectrum, but dB also covers light, so the radio wave, and even gamma ray, ranges of the spectrum too. So as you go up in the bandwidths the power levels increase as in colors of light, microwaves, X-rays then gamma rays, and why those will fry you if you were directly exposed to a more concentrated beam, as a Laser too is just light, but it's concentrated so the more concentrated (more photons hitting you at the same time), the more it will mess you up, and why people can, and have been injured, even badly working on a mistakenly thought harmless radio tower, due to close proximity which diminishes in dB/inch and so a 5W antenna my burn you at a 5 inch distance, and just feel slightly warm, 10 inches, and totally harmless a few feet away, although exposure time is a factor, but again that too is no longer a factor, as we get way more radiation and at many bandwidths in only a few hours of sunlight exposure than we can accumulate in a lifetime from cell towers and the like!! It also is a very good reason to not fall for any of the BS on cell phones frying or influencing your brain (way too week) or 5G being our demise, or used by the man to control us, (we have no indirect way of mind control, and just because we can measure, and influence the brain already, as to thought or behavior control, other than when hooked up, we are so far away, to do that, and already know that it would be prohibitively difficult to even go there and silly! and such absurd claims. If what they said was true, you would vaporize the instant you stepped out of your house into the suns light! They obviously are clueless about quantities, conversion the math and quantification, most, if not all of it, and experiencing the Dunning Kruger effect, which is psychological, not physics. Hence why turning up let's say your guitar amplifier by 1dB at a time gets much louder going up in each increment, than the last one, so lets say at 10, or 11 if you have an old Marshall (one louder according to Nigel Tuffnel of spinal tap) they are not twice as loud as 5, but more like 5X louder depending on the conversion factor between the two units. Now take voltage and current (A for Amperes {Amps for short}) both linear, multiply one with the other, and you get Watts also a linear unit of the combination thereof and a unit of power. They all can be converted to each other, but there are reasons to use them where best applicable. Hope that helps.
0dB is nominal volume also known as line or unity. You can consider this to be full volume. Audio processing is generally done at full volume via a pre-amplifier. So to turn it down you then negate from that in your post amplifier, hence -dB. Adjusting away from unity is called trim when negating and gain when additive. So the volume control is actually your amplifier trim/gain control. Some amplifiers have positive gain. Mixers normally have a single control from trim to unity and then unity to gain. Typically that is visualized as green for trimmed, orange is unity and red is gain (overdrive) Sorry. I just felt like the answer in the video was long winded and confusing.
Finally found some good answers to this question. But thanks to PS Audio for recognising it's importance so the question could be fielded out and thereby attain a good wholesome answer. I have been looking for a good answer to dB levels for so long🙏 Why does the optimum dB level for any music audio source into my NAD receiver always seem to be -20 dB except for HDMI streaming sources split off into an S/pdif audio signal. This source always needs to be turned UP to -10 or louder. 🤔
I always envisioned it this way: An amp has a maximum output, which of course is maximum volume. The volume control is basically a resistor, to *reduce* the output sent to the amp. At full volume (0 dB), the output to the amp is maximum, which is essentially “no resistance” in the signal going to the amp. At any volume other than full volume, the source signal is being reduced going into the amp, hence it is a negative number - the larger the negative number, the greater the resistance, and hence the lower the volume. This may not be technically correct, but it’s one way to visualize it. 🤷🏻♂️
We often confuse the -dB scale with guitar or other musical instrument volume knobs. They start at 0 and go up to 10 (unless you're a _Spinal Tap_ fan where they go up to 11🤣). It's natural for laypersons to assume audio and home theater amps should do the same.
I listen to music at 75% volume, 4 notches from the top out of my portable speaker. On my stereo system for vinyl which is in storage I go to -15 +1 notch up whatever that is idk how many notches there are it blew out my speaker before I got to 0
I listen mostly to Hendrix and Stevie Ray Vaughan and blues rock Clapton and Albert King and I want the truest tone possible since I’m a guitar player myself
there are different stages of audio processing from recording to playback to the SPL of the room you are in the sound level exists where audio content is played in air, it measures air presure level, yes there are different bias scheme to simulate human hearing response akin to pink noise vs white noise the digital recording level (also in dB scale) shows how close a signal is closing in to the ceiling of the pre-defined limit defined as 0dB, the numbers are stored in the recording file the volume knob indicator (usually on a preamp) shows how much the source level is attenuated before it is amplified, therefore controlling preamp output level keep in mind the dB is a ratio value, -14dBu and 0dBu differs by 14dB, -2dBV and 0dBV and differs by 2dB, because they are different units of measurement, it is irresponsible to say -14dBu and 0dBV differs by 14dB, just like 0F and -18C are actually equivalent air temperature for daily life purposes the "u", "V", "m" letter(s) and case behind the notation is important, it tells you how their base 0dB is defined (same as common log uses base 10, natural log uses the e value, dBu is based on sqrt(0.6)~=0.775V volt, dBV is based on 1Volt, dBm is based on 1mWatt) for this reason dB value of different unit of measurement cannot be directly compared, getting thre unit wrong can be a disaster, don't believe me? just lookup "gimli glider"
The decibel scale is always the result of a comparison with a certain standard level. - Paul here is using dB while comparing *voltage* levels to a standard of 1 V (he doesnt know the exact level) That is probaly standard in the audio amplifier business. - Other professional fields would use the dB scale to compare *Power* levels. [Watt] (the dBm scale for example, which compares a certain electrical power level with a standard electrical power. (usually in [mW] ) The above two both have a reference level in the electrical domain. (They are related and can be converted into eachother. Provided that you know the standard levels that are used and the resistance that the power is dissipated in) - I think your 90dB level is referencing *sound pressure* levels, (acoustic pressure level), in units or Pascal. In most those cases, the standard is 20uPa (micro-Pascal, the minimum threshold of what an average (heatlthy) humans ear can hear) A sound pressure level of about 1Pa is then about 90dB Amplifiers CANNOT be calibrated in this dB scale, because they drive electrical power.
That's sound, this is electricity. The electricity will be put into a highly inefficient loudspeaker (1% or so) and then spread across the auditorium, bouncing in all directions off various shapes and materials. And a lot of what you're hearing is noise made by the audience. So there isn't a standard way to map the knob on the mixing console to what you will actually hear. But, in general, turning it up will still make it louder or more distorted.
Oh my God! Another mystery of the universe has been solved. Even my Masters level professor of Noise and Vibration could not answer that, albeit 20 years ago
dB was originally measured as the loss over a certain distance of standard telegraph wire, set by Alexander Graham Bell, a Scotsman! Measured logarithmically, which was invented by John Napier in the 1500’s, a Scotsman! Just saying? :-)
An easy way to think of it is the greater the value without respecting sign (the negative symbol - and obviously not considering positive values too, purposefully for this example), the greater the attenuation is. Attenuation is the key word here. I suspect many will understand more deeply after considering this. Rock on.
Compared to the source input, everything above 0 is a gain, everything below 0 is a reduction. It’s really that simple. Some systems use a volume level, it could go 0-50 (such as common consumer car audio) or it could be a volume percentage, from 0-100%, such as computers/smartphones/etc, but somewhere in that range is the source input (for example it could be 40 on a scale of 0-50, or 80%) but if it isn’t measured in dB you will never know, so it’s actually the ideal scale to measure volume.
The definition I remember for electrical dB is 0dB = 1 milliwatt into 600 ohms load. I did the arithmetic once and it worked out to 1.0 v + a little. 1.25 volts = 0 dB sounds about correct.
@carterwilliamhumphrey3373 Which is not true. Re-read what I posted since I've been doing pro sound since 1985. The standards haven't changed from that perspective.
@@capfam2018He's right. 20 log (.316V/1V) is -10 dBV. 20 log(.316V/.775V) would be -7.8 dBu. Why does consumer gear specify it that way? Dunno. Maybe tired of people calling and complaining their voltmeter says their new toy doesn't match the spec because they assumed 1 V instead of .775 V.
So if I got this right, the dB is for recording or broadcast level to ensure uniformity. It has nothing to do with the dB used in sound measurements where 70 dB is normal talking.
Yes and no. A decibel is a ratio. As to a ratio of what? Well, it could be a voltage, wattage, data, or sound pressure, just to name a few measurements used in audio. In modern recording and broadcast, the professional analog scale is dBu. For digital, dBFS. Acoustic measurements, like what you're referring to is dB-SPL. Oh and then there peak vs. RMS...
70 dB is everyone talking loudly at once. Conversation is closer to 40 dB. 0 dB SPL is the sound power at 20 micropascal pressure amplitude, in case you're wondering.
This is confusing if you're coming from a wikipedia article saying "loudness of the blast heard 160 km from Krakatoa was 180 dB" or "Rainfall is around 50 dB". In that case, there's no electricity/amps/volts anywhere near. Do those decibels have anything to do with the decibels on the audio equipment? I guess not. So I guess it's always a "relative" ratio of sorts rather than a "unit". Kind of like Hz is just a "frequency" (of various kinds of things). In case of audio equipment, it's how far it is from reference power throughput (or something), but in case of rainfall, it's ratio of "air pressure" during rain vs "air pressure" during some reference situation. Did I get this right?
Sound pressure (acoustical measurement): 0dB-SPL= 20µPA (micropascals). It's a pressure reference. Paul is referring a professional analog signal (voltage), where 0dBu≈1.228v. But in fact, the scale on the volume knob, aka 0dB=unity gain. Anything below that will be a negative number.
@@carterwilliamhumphrey3373 Thank you for your reply. So if my music is playing at around the loudness of "rainfall" (~50 dB-SPL) and I walk up to the amp and dial the knob down "5 dB" (e.g. from -10 to -15), and then "measure" the air pressure back where I was standing, it's not gonna be ~45 db-SPL, right? The dBu difference is equipment specific and maps to a different "air pressure change" from amp to amp. (Which, I understand, is a weird way to put it, but it's just to make clear another way that these 2 different kinds of "decibels" are mostly unrelated)
@@sergueifilimonov2706 Um, maybe. This is potentially more complex than that as we step into "gain vs. power", "acoustical loudness vs. acoustical power", and even just the acoustical listening environment you're are in. In an anaecoic environment, I'd suspect that a 5dB change on the volume pot would yield a 5dB-SPL change.
It brothers me the low bass hum in the video. A hi-fi audio manufacture / recording studio needs to have better audio on the videos .. FYI. Davinchi Resolve can clean up the audio with the press of a button
I don't know he's saying the opposite hes saying why does my amplifier go - DB when I turn it up, he would have said it why does my minus DB increase when I turned it up but that's not what he said. if he's listening maybe you can clear it up.
Oh damn, no I did not understand that. I thought at 0.0 db, your receiver was putting out "maximum signal" and that anything above (positive) would definitely entail clipping. But my god after he said that, there's no limit to the amplitude of a signal when we're talking analog!! So yeah it might be the "most" your receiver wants to put out but if you hook up an amp that can exceed, that, well, I guess it can easily. Did not expect to learn something from this video lol...although will say I measured 20 volts at 0.0 db at 8 ohms (~50 watts) with my old DCM26 towers (supposedly 90 dB sens.--in theory put me at 105 dB at 1 meter) on my Yamaha RX-A2A with external stereo amp (at stereo with loud music--my wife quickly told me to turn it down after my measurement).
Depends on the unit: 0 dBv is 1 volt, 0 dBu (or dBm) is 0.775 volt. dB alone is not an absolute unit, just a relative unit between different signal measurements or levels.
Yeah, appreciate Paul but he could have done better here. The reason one sees *negative numbers on a scale is because they are logarithms.* A logarithm of any number between 0 and 1 is negative by definition. And _decibel_ is properly a _deci-bel_ meaning one tenth of a bel (named after Alexander). This is a ratio, it is unit-less (so it is not a voltage). In audio the ratio is that of the signal to that of a reference level.
You’ve confused me , what number is between 0 and 1 ?
@@uncleb8181 infinite amount of numbers. For example .5
❤Let's Talk About Class D Amplification🎉😊💜💫💢🐓🕵👀🎩
My own personal definition has always been this:
At 0db, there is no gain put into the signal. All the negative numbers below that are just an attenuation of the signal. And I always set my other gains downstream based off the source being 0db. No gain, no attenuation.
@@StoneyRerootkitwell, the input pulses are amplified in higher voltage/current. So you could put a ratio number (dB) on that. If you mean the input signal, dbFS is used. Ratio between full scale (all 1’s or whatever bit combination is used), and the actual signal.
Origin goes back to telephony. The simplest way to understand the markings on a "volume attenuator" is that it is not indicating the gain being added, but the attenuation ratio related to max output of that device. It is marked to show how much below max output it is set to.
(BTW, The number you were looking for was the Bell System standard of 1 mW across 600 ohms, or 0.7746 V RMS, usually rounded to .775 V. Ever notice that VU meters are *usually* marked as being in "dBm" or deci Bels related to 1 mW.)
Thanks for a much needed clarification
Yeah, the dBm vs. dBu business. Don't forget the obsoleted dBv there, as well as dBV! I teach this to novices and it's quite the alphabet soup.
Great answer, thanks!
In radio, 0dBm is 1mW into 50 Ohms. And there's dBμV as well.
dB's are a lot of fun! 😁
Bell as in Alexander Graham Bell
There is a lot of history on where the Bel and deci-Bel (dB) come from. Some other comments have already covered bits of it. Some time spent googling the topic will yield loads of responses from Wikipedia and other sources. Have worked with dBs of various flavors for 45+ years and they're really great once you get the basic concept down.
The bel was standardized in 1928 and while not part of the SI standard itself, its use is excepted with the SI and is abbreviated as 'B'. The standard unit prefixes apply and because the bel was too large for most uses, commonly the practice was to apply the SI prefix 'd' for deci, or 1 tenth, e.g. dB. Other SI units and their prefixes can be used with the dB as in dBμV for dB relative to a microvolt, and so on.
The bel and decibel is simply just a way to express logarithmic ratio quantities. Divide two quantities and take the base 10 logarithm and you have the bel, multiply that by 10 and you have the decibel. For example 10 log10(40/4) = 10 dB. If you take 10 log10(40/40) you get 0 dB. When you start working with really large or very small numbers and multiplying and dividing them the results get unwieldy for most people to deal with, but are more manageable once converted to dB form.
The next step is to apply the dB to some reference value to easily see how large or small something is compared to the reference. One common reference used in communications is the milliwatt, or 1/1000 of a watt. In dB form this would look like 0 dB(mW) because 10 log10(1 mW) = 0 dB referenced to 1 mW. Here I state it as 0 dB(mW) to make it clear that its referenced to a milliwatt, but commonly this is simplified to 0 dBm, which is a bit confusing sometimes if you're working with communications formulas that include ratios of both milliwatts and meters because 10 log10(342 mW/15 mW) = 13.6 dBm (in common notation) and 10 log10(659 m/82 m) = 80.4 dBm. But as this only impacts a handful of people and most of us are aware of the issue it's just a minor annoyance . . . :)
There's a huge list of things to which the dB can be applied, volts, watts, sound pressure level, dollars, you name it. The important part is understanding the base reference and how it is treated when converted to and working with the dB form.
Importantly, changes in power are expressed as 10 log10(the ratio), changes in voltage are expressed as 20 log10(the ratio). This makes sense when you work through the math but too much for an already long comment.
But unless the volume knob is calibrated with an absolute unit, turning it is just adjusting the ratio of the output against some arbitrary value. Let's say you have a receiver or amplifier rated to output 100 W. At full power the 0 dB position would be allowing the unit to output the full 100 W (assuming some standard reference input signal), at the -10 dB position it would be outputting 10 W, at -13 dB it would be outputting 5 W.
Technically perfect and correct explanation.
I agree, good explanation. The only thing I would add is that the reason we use a logarithmic scale is because our hearing, like most of our senses, is fundamentally logarithmic every time you double the power we hear that as an equal increase in volume.
Sound levels are measured in the logarithmic units called Bels, a Bel is 1 order of magnitude of power. Usually meter scales are marked in decibels (1 dB = 0.1 Bel). One reference level is 0 dBm, 0 on that scale is 1 milliwatt of power into a 600 ohm load. The VU meters on many professional mixers are set to indicate 0 VU at a level of +4 dBm. The meters on an analog tape machine might be set to read 0 at a level of 185 nWb/m (nanowebers per meter) of magnetic flux. Digital audio meters are often calibrated to dBFS (decibels Full Scale), 0 being the loudest sound that can be represented, so everything else is negative.
If we're going to head into tape, then, for clarification: 185nWb/m is/was the Ampex standard (USA) vs. 370nWWb/m being the European standard (6dB hotter). Then MRL muddied the waters by stating that 355 nWb/m is +6dB relative to185nWb/m, when in fact, it's 5.5dB!
Too much!!!!
And in the digital age, any audio above 0 dBFS begins to clip.
Always clips @@bigsky1970
The simple answer is because a fader or a pot etc. is an attenuator, that's all there is to it. It doesn’t add gain; it only reduces the amplitude of the signal passing through it.
That's what I've always thought...
Since dB is a logarithmic scale, defining dB from absolute quiet as 0dB would net any signal high than that complex infinity or undefined. So from a purely mathematical point of view it makes the most sense to define it from a point that easily recognizable, for instance the max amplitute of an amplifier.
An excellent answer that I like the best. Forget about the logarithms and all that.
@@thomasayau9911 Audio pots are wound so they match our 'loudness' perception - logarithmically.
Thanks! No idea what he was talking about...
Some very good technical answers/ comments here from many people, thank you. I see the simple answer is that it shows the reduction of attenuation as you turn the volume control up.
This is the best “straight answer”. 👍
Good answer. If you want the full historical explanation read my comment
Excellent, the first decent answer I've read here. Thank you for this very comprehensible answer. "Reducing attenuation" as you said, has it all in a nutshell.
This the best answer
First time I came across this channel, and I'm afraid probably the last, because that is the most flawed description of dB I've ever encountered. The decibel is a logarithmic measure. It is dimensionless. It's not a voltage. One reason we use a logarithmic measure is because our visual and aural senses are able to sense intensities over many orders of magnitude (powers of 10), and the logarithm increases very slowly as its argument increases (so, for example, a doubling of sound intensity corresponds to an increase of about 3 dB). The decibel is usually defined as ten times the log (base 10) of the ratio of two powers or intensities, where the denominator of the ratio is a reference level. So 0 dB means the intensity is at the reference level, and negative dB means it's less (since the logarithm of 1 is 0, and the logarithm.of a number between 0 and 1 is negative).
Thanks so much for this Paul! I've been wondering about this for some time. Appreciate the great explanation.
For a preamp 0dB just means the gain is 1 (output voltage = input voltage). For every -6dB you cut the voltage gain in half. Thus -6dB is a gain of 0.5 and +6dB is a gain of 2 (possibly causing clipping).
Actually, every 3db is either a doubling or a half (depending is you are going up or down).
@@jimtincher7357 No, you are thinking of power and not voltage.
@@ThinkingBetter yes, but since lots of loads are (at least pretended) to be linear resistances, current gain will be equal to voltage gain. Thus power gain is a doubling/halving every 3dB.
@ The amplifier doesn’t know the impedance curve of your speakers. If your speakers have a flat linear frequency response it’s still linear to the voltage and not power. A doubling of voltage is generally considered a 6dB sound level rise and this we also use when we say a CD 16 bit PCM dynamic range is 6x16=96dB as every bit represents a doubling of voltage.
@ Right. Doubling voltage quadruples power so we’re both right.
The definition of dB Voltage and dB Power are different precisely this reason. It’s only confusing if you say “+6dB is a gain of 2” without specifying that you mean a “voltage gain of 2”. Everyone in my world would say, “power doubles every +3dB”.
About four minutes in I thought "just how long is this video!?" -- you were going so relaxed and so calm and had some pleasantries and then described history and meaning of something confusing -- and it made sense -- and I realized your secret to how you get so much done:
You have a time distortion field that causes time to move at a different rate for you. Very neat trick.
1:03. The dB is most certainly not a unit. It is a ratio. It only becomes a unit if it is referenced to a unit such a dB(A) dB(SPL) etc. You can measure the height of trees in dB if you want to by defining a standard tree. All others being a ratio of that tree.
Perhaps you’re thinking of DBH (diameter at breast height)😉
@@orbalicious20 Would work but small d please :-) And would also require a bracket for the H so dB(H). Now all we have to do is agree on a standard breast !!!!
A decibel is a logarithm of a ratio.
@@oml81mm Correct and hence not a unit just like 1/2 is not a unit but 1/2mm is.
@@sephina The confusion usually lies from not realizing in advance that there is a difference between a 'dB' and a 'dBm'.
A dBm definitely IS a unit and many people don't know to look carefully for that little 'm'
Well that video and most of the comments so far probably confused the heck out of the person who asked the question. Sorry Paul/People.
To understand volume and why the numbers are represented with negative numbers, you have to start with GAIN. More specifically, the difference between Volume and Gain.
GAIN = Additive
VOLUME = Subtractive
You set the GAIN to set the 0dB goal post. Let’s say 50Watts Integrated amps often set this for you (hence why there are no GAIN adjustments.
For simplicity, let’s say the integrated and Power Amps are both set to 50W output (this is the voltage that matters).
If you turn the VOLUME to 100%, or 0dB you are literally subtracting 0 or NOTHING. So the OUTPUT of the 2 amps will be 50W
When you turn down the volume from 100%/0dB you are SUBTRACTING MORE from 50W.
The reason that the displays are in units and not specific numbers or percentages, is because the entire exercise is logarithmic. Both in voltage AND dB.
So it would be MORE confusing if you turned it down to 50%, but the actual output was still around 66% You turn the volume down in a linear fashion, expecting linear results. The problem is that the results are NOT linear.
For this reason you need to use logarithmic units when discussing or defining output values.
HENCE: -15dB as a volume. You are simply subtracting -15dB output from 50W. What that number [50W@-15db] ends up being will depend entirely on your GAIN setting. In our example, the GAIN setting is 50W.
You must use the dB as the unit, because dB is a logarithmic unit, defining a logarithmic scale. The numbers are represented with a negative, because it defines how much you are SUBTRACTING from the GAIN setting/Goal-Post.
When you grasp the very misunderstood function of volume (subtractive value from the gain setting), the negative number makes sense.
Turning the volume UP is simply (and clearly uninuitively) REDUCING the amount of subtraction. Except at 100%/0dB
So when you turn the Volume UP the negative numbers get smaller (subtracting less), and the vice-versa happens when you turn the volume DOWN, the negative numbers INCREASE. Because you are subtracting more from the GAIN setting.
First explanation I read that makes sense! Thank you
I have approximately 10,000 songs and of all those songs there is only 1 that I have that seems to be recorded past the 0 dB range which is really awkward. I’m assuming it’s an issue with the header of the file but it’s really odd.
Everywhere I play it, it sounds distorted and I thought that they recorded it badly like that but to my surprise when I use a specific preamplifier software and I lower the volume of the preamplifier, the audio sounds completely clean! 😮
Depends on the format, MP3 and FLAC/WAV 32-bit float can represent greater than 0; CD, 16-bit and 24-bit formats will clip.
@@timothystockman7533 I understand music not Teck. I chose you to ask because you mentioned Clipping.
Like most of us I could never play my sound system at anywhere near full volume that would be far too loud. My electrical 'Ring' is a high watt ex Heater ring. My DAC and Streamer are capable of 32 768 .
I suspect that for the above reasons I could not force my sound system to clip even if I tried, but I have no way of knowing if I am right and if I am right which one if any of the above mentioned aspects is the one protecting me from clipping? PS I would not be surprised if my system could handle twice the volume I could.
If it is an MP3, someone may used Mp3gain to boost the volume, and then you can reduce it again. Decoding is usually done with a generous headroom, and the level can go over temporarily in the DSP. It's just numbers and you can mark them as "multiply by another big number". If you scan your library for ReplayGain, lossy encodings will often have greater than 1 peak level. HDCD with peak extension may also show it. Many recordings out of studios today come distorted because of the Loudness War.
It's also because you are using an attenuator to control volume level. So 0dB is zero attenuation.
This is the right answer.. Or at least how I think of it, the volume control attenuates the signal, without it the full signal would be fed into the amplifier, so the maximum volume is zero attenuation, so 0dB.
Yup.
Thank you. I have a question: If 0dB is zero attenuation, why we have +? What does that mean?
It's a stupid representation trying to look intelligent. They don't tell you what the amplifier gain is at 0 dB (no attenutation), and at what input voltage to the amplifier will maintain an acceptable distortion threshold for the amp at the output, in other terms, still output a linear, uncompressed signal. My $0.02.
@@shipsahoy1793 - Yeah, this should explained what gain is. That would have been helpful. But I wouldn't be too critical, keep the audience in mind, right?
This feels like college. I always understood everything until the test.
This makes me think of tachometers in racing. In some cases, a tachometer is rotated in the instrument panel, to indicate the ideal RPM at which to shift. It is sometimes rotated so that that ideal shift RPM is found at exactly vertical position of the needle on the dial.
This way, a driver can “see” the needle hit ideal RPM without really looking down. Using a bit of peripheral vision, it is easy to make out when a gauge needle is pointing straight up.
In such a case, the perfectly vertical position is kind of like “0 db”
You can rev lower than that point, and you can rev higher, too. But the “sweet spot” is given a special indication by way of the needle pointing straight up.
In your decibel example, the “sweet spot” is at zero.
Now the RPM analogy makes total sense to me now. Cars and guitars. Who knew. Thank you. I get it.
Decibels is a logarithmic scale, 0dB is 1 and every additional 10dB multiplies that value by 10. 10dB = 10, 20dB = 100, 30dB = 1000, and so on.
Of course it then follows that for every -10dB you instead divide by 10. -10dB = 0.1, -20dB = 0.01, you get the idea.
In the case of a volume control we use 1 (0dB) to represent maximum volume and 0 to represent no volume, so -10dB in this case means a tenth of the maximum volume, -20dB is a hundredth, etc.
Curiously this means that you can't actually express 0 volume in decibels.
Nice explanation! As a an audio engineer I also like to think of everything before the amplifier as operating in the
There should only be one volume, 11.
This
Our amps go to 11.
Thats too loud. Get off the lawn you kids with your rock and roll and Ford elantras.
But why didn't you just make 10 louder?
*But only if you're Spinal Tap...*
There is a problem with explanations like this because decibels are ALWAYS relative, Never Absolute.
A reference level must be established before the dB number can mean anything.
In many cases, the reference is not stated, so the context must be considered.
Is it consumer audio, pro audio, telephone, or something else?
The standard for line level in consumer equipment is not the same as for professional equipment.
And manufacturers of consumer equipment use whatever method they like for labelling the volume level on the unit.
We often see no useful numbers at all. If we are fortunate we May get equally spaced dots around the knob
or arbitrary (0 to 99) digits in a window.
The total lack of explanation in owners' manuals doesn't help, so even if one reads the book they don't know the whole story.
Exactly.. it's a measurement in logarithmic scale of ratio of output over input
In this case, although not stated, there is a reference level. It is 0dBm, with the m standing for milliwatts. And the 0.775V mentioned at the beginning, is the voltage measured when 1mW is applied to 600 ohms.
decibels on home stereo equipment on the volume control (which is the purpose of the video) is always tied to middle-tier gear sounding fancy. Aka voltage indexing
.
Excellent and easy explanation, having a universal voltage to dB reference, and you mentioned clipping, so then what is clipping? I understanding the basic concept but for clarity sake, how would you explain clipping? Thank you.
As others have said the fact that dB is a relative measurement would be helpful here. It’s not a unit in its own right but a ratio. In my world we deal in dBW or more commonly dBm for mW, i.e. relative to 1 W or 1 mW of power.
Some volume controls go below AND above 0dB. For example, my Denon AVR is calibrated with reference to standard cinema SPL (Sound Pressure Level). The volume level goes from -79.5dB to +18dB but can be optionally capped at 0dB for maximum volume level.
If you are looking at SPL did the Denon specify which speakers and the size of the room were used for the calibration?
+18 dB corresponds to 0 dBFS, the standard maximum for digital signals. Likewise traditional 0 dB is -18 dBFS.
@@blairhoughton7918 There is no direct conversion between dBFS and dB. They belong to different realms. 0 dBFS can mean -80 dB or +10 dB. It all depends on your device's volume settings.
@@NotExpatJoe There is a standard that sets +18 dB (actually dBu) as corresponding to 0 dBFS. It's based on common broadcast audio equipment and intends to ensure that the recording you deliver plays at the right volume on that equipment. So, yeah, you could say "dBFS on this machine", but if you just say "dBFS" everyone else should be able to assume you mean the standard meaning.
@blairhoughton7918 good answer. 😁
My Outlaw Audio 990 Preamp Processors goes from -60db to +10. I usually keep it around -12 to -5db.
I've been into stereo for around 50 years. I've had an Outlaw RR2160 Mkii receiver for about 3 years now and it was the first stereo component that I've seen this -db volume. I've sort of got accustomed to it but it is awkward. People simply don't think that way. As the volume gets higher so should the number on the screen or the dial. On a guitar amp I wouldn't go -db on the dial as I turned the volume up. Humans are not audio measuring and calibration equipment, but then again maybe some of us are.
Your guitar amp knob is GAIN. Not Volume.
GAIN = Additive
Volume = Subtractive (from the GAIN).
100% Volume = GAIN setting.
@@pitspeedtv Could be, it doesn't matter what it technically is, my dial says 1-10, 10 being the highest and loudest...plain and simple.
@@mr.b4444 I get that you want them to be the same and want them to be simple. I also get that you want Gain to be volume. Or that you are mistaking them to be the same thing. The problem is that they are not the same.
Your Outlaw RR2160 Mkii is an “Integrated Amp” and your guitar amp is a “Power Amp”
The difference is that the Outlaw processes the signal, and as such, uses Volume to modulate the signal. It then projects that signal to a baked in Output Gain Level. Your guitar amp does the exact opposite. The guitar amp takes a 100% line level signal and applies an amplified gain setting.
Both are amplifiers that amplify a voltage, they simply modulate the output voltage in opposite ways.
The reason that this is important to understand is because sometimes you want separate devices controlling the signal and the output.
Signal Modulation (volume) is the act of subtracting or retarding the signal level, so when it hits the power amplifier that is calibrated to output a set voltage equal to the speaker specs, in relation to a standard signal input voltage, you don’t overshoot and blow said speakers.
This is why Paul is talking about 0.775 Volts and 1.5Volts when he speaks about VOLUME. 0.775V is standard and sometimes called “mic Level”, and 1.5V is called “line level”. These are standardized SIGNAL levels.
Your guitar is going to adhere to the LINE level. Your Volume is modulated by how hard to hit the strings and how much those pick-ups detect. In relation to 1.5V
So it matters A LOT.
Volume is modulated (as a signal level)
Gain is set (as an output level)
Set your power amplifier gain to output the correct voltage for your speakers.
Modulate the volume on your receiver to suit within the capabilities of the amplifier and speaker (as set by gain).
NEVER use the knob on the power amplifier to modulate the output loudness. This is how you blow speakers and do expensive damage.
@@pitspeedtv I must defend mrb He is correct, and if I'm reading your second comment correctly, you have got it entirely wrong. To simplify: Gain is a term used for the control of an input and volume is a term always used for the control of output. The gain knob on a guitar controls the circuitry between the guitars electric pickups (input) and the volume knob.( output). (Understanding why electronic instruments have this function is another chapter). This labelling process is repeated on the amplifiers input and output Typically these sections are also labelled as gain, and volume. My AV amp has an input control but it labelled as trim. Usually the gain control when turned to zero will shut the signal off completely. This It will sometimes also be used to amplify the signals optimal strength by a magnitude by as much as +10db. A trim control differs because usually the range of control is limited to between -3db/ +3db. The practice of using gain controls can also be found on DJ mixers and other forms of mixing consoles, and those used in PA and recording studios. Some will also have an extra trim level for finer attenuation.
Good people, all I'm trying to say here is that the labeling throws people off. Not trying to get technical here as to what happens behind the scene, no need to dissect this down to atoms and quarks. As you turn the volume up the number on the label gets higher. You have a light dimmer switch as you brighten the room the switch labeling shows a higher number or corresponding symbol, you hit the gas pedal in your car the speedometer's number increase. Simple, that's how most people view things.
That explanation probably did not help many people...
Decibels is a logarithmic scale where a negative number is gain less than one and positive number is gain greater than 1. The gain is then referring to some spcific unit like volt or watt. So -20dBV is same as 0.1V and 0dBV is 1V. If we write 0dBm we are talking about milliwatt and 0dBm is same as 1mW.
For the question why it is negative numbers on the scale is because we want to know how far we are from the max which is usually around 0dB.
Now do dBu, which is the scale he was talking about.
@@blairhoughton7918 "u" stands for "unit" and is the voltage that drives 1mW into 600 ohm load or 0.775V... So 0dBu is 0.775V.
@@rehnmaak Close. The u stands for unloaded, and dBu is 0 at 0.775 volts across any load, though the 0.775 was chosen to match 1 mW in 600 ohms so that on a 600-ohm load 0 dBu and 0 dBm occur at the same time. On any other impedance load 0 dBu would correspond to some other dBm value because the voltage would still be 0.775 volts while the power would no longer be 1 mW. dBu is referenced to 0.775 volts and dBV is referenced to 1.0 volts regardless of impedance. They're just logarithmic expressions of a voltage ratio. Meanwhile, the U in VU does stand for Units and 0 VU is 4 dBu, and at every voltage the dBu meter will read 4 dB higher than the VU meter.
So it is similar to photography exposure, where true exposure has an EV (exposure value),of 0 (zero). Over exposure will a number of EV+ and under exposure EV-. Exposure measured in a computation of Shutter speed and Aperture opening.
This answer misses a whole lot of important information.
Around 1900, when western science was starting to work with electronics and electronic systems, and there were no electronic calculators and even slide rules were uncommon, it was realized that a logarithmic unit of gain was much more useful to humans than a straight multiplier.
Gain is the ratio of two power levels, usually between a things input and its output, but can also be used as a ratio of maximum and minimum power level.
If a straight multiplier is used, a lot of digits are needed in many cases, and calculating the gain of two units in series requires a lot of long hand calculation, which is a tedious and error prone if you have to do it by long hand calculation.
If gain is expressed as a logarithm, usually only 2 or 3 digits are needed, and the gain of two unit in series is the sum of their two gains, which can be calculated without even pencil and paper.
The unit of logarithmic gain is called the Bell, in honour of Alexander Graham Bell, and it is the (base 10) logarithm of the ratio of two power values. Practically units of 1/10 of a Bell are more useful, called deciBells or dB (10 x the ratio of two power levels) dB are so practical they are still widely used today.
A value of 0dB means that the two power levels are the same. A positive dB value means that second power levels is higher than the first, and a negative value means it is lower. 3dB means the power levels are 2:1 and 10dB means the ratios are 10:1. -3dB means the power levels are 1:2.
Power is voltage squared, so a dB is the (base 10) logarithm of the ratio of two voltages squared, more easily calculated as 20 times the ratio of voltages.
Now to the question asked
The output power of the amplifier is given as the ratio of the actual power to its maximum rated power. So a value of 0dB means the power is at maximum, +3dB means the power is at twice rated power (you are probably damaging the amp) and a value of -3dB means you are at half rated power.
You win my "Best Answer" award!
*@ericnepean* I've read several answers that have helped me, but now that I've read yours, I'm going to go check my amp right away, hoping it still works...
man, no one cares about db. I had a stereo that used db as their volume level, so 0 is "loud". From cassete, that is amplified, from line, that is switched, from cd, that is processed upon by a DSP. The question was "why is my volume displayed in db" and 99% of the time its voltage or gain.
It always made sense to me from the perspective of volume knobs regulating resistance. So 'all the way open' is no resistance, and below that it resists to a certain extent.
Paul, great explanation! I always assumed 0dB to be the noise floor, but did not know the historical significance in keeping it homogeneous throughout the industry. Very cool!
I do have a question though, dB is an exponential unit, however many potentiometers are linear. As we approach 0dB, are we going to see a dramatic change in volume, e.g. from -30dB to -20dB to -10dB, etc.? I would think that going from -30dB to -10dB alone would be a change by a factor of 100x. Would this hold true here too? And, is the voltage source going up linearly while causing an exponential increase in volume? I never thought about it like this, but it would totally make sense (especially when considering that there’s an amplification stage that should respond this way). Please share some insight.
If I recall my Electrical Engineering classes, dB is the ratio of output over input and is on logarithmic scale.... 0 is the max I would crank my amplifier to, safely... Else clipping may happen.
The volume potentiometer acts as a voltage divider. When the slider is at the top, the attenuation is equal to one, wich in logarithmic scale is 0dB. Anything between the minimum position, that usually means the slider touches the terminal connected with the ground - and the maximum - will be an attenuation between 0 and 1 - which in log scale shall be a negative number.
You can have a plus 6V signal. I do on my Vivaldi DCS stack. It's true it can clip but it depends on how your equipment is designed. My VAC pre-amp is designed for the signal before the line of gain stage with the volume control.
The saying goes…
_”A dB is a dB is a dB”_
…which means…
• dB is *unitless*
• dB is a *ratio,* expressed on a logarithmic scale
• a dB could be the ratio of two POWER levels
• a dB could be the ratio of two VOLTAGE levels
So if I have a 100 Watt power amplifier and a preamp connected showing 0 dB, is my amplifier putting out 100 Watts? Assume pink noise as signal.
Short answer - yes
In pro audio channel sliders (have 0 aka UNITY) go plus db? But you mentioned going over zero on a consumer audio amp,. To me 0 is just the limit of the amp. So, why no unity mark on amps? I run the audio at unity into an amp but the amp is at a low volume to give it head room from clipping.
please do a video on your time management that would be really interesting!
Fully agreed
Thanks for informative video. I have recently bought a used hi-fi system from the 90's. Its the first time I've seen a db level indicator, linked to the volume control. I really thought the preamp was faulty, as when the volume is turned up, the db number goes down. All make sense now.
Should I go up to the next scale when doing room correction calibration if the needle goes above 0 (mid scale) say 70 to 80 db.max output 2v.87db target.
dB sound levels are a relative scale, so you can set 0 dB where you guess is the better absolute value to start measuring. Audio amplifiers set 0 dB at theyr maximum power output and then all others output levels are negative, once they are lower than maximum. Besides this, sound amplifiers set a positive margin of measure to deal with acidental peaks of power output, usually +3 dB. This is about twice maximum output at 0 dB, because 3 dB are 0,3 B and logarithm of 2 is 0,301... If maximum is 1 Volt x10^0 (0 B or dB), so 2 Volts are 1 x 10^0 × 2 or 10^0 × 10^0,301 = 10^0,301 = 2 or +0,3 B or +3 dB...
Dear Paul, which amplifier has the volume control that has zero dB printed at 12 O'clock. 😊
dB is a relative unit, so when something is specified in dB the question is "relative to what?".
For something like radio transmitter power (for example on WiFi devices) it's relative to 1mW (also written dBm) or 1W (written dBW). 0dBm means 1mW and so on.
For magnetic tape recorders it's relative to some magnetic flux level like 320nWb/m, over time the reference level has changed.
For sound level (like when noise in a room is measured etc) it's the human threshold of hearing.
For an amplifier it's most likely relative to its maximum output, so 0dB is "full volume" and anything lower means that much lower than the maximum.
Studios use different voltage levels as 0dB, like 0.775V (1mW into a 600ohm load) or something else, but that would not really apply to a home amplifier, since the input is fixed level (whatever the source outputs) and output to the speakers is higher than 0.775V, unless the amplifier is for headphones). So, the 0dB on the volume knob means the maximum gain the amplifier has, depending on the source, it may not be enough for full output power or it may drive the amplifier into clipping.
My preamp goes by percent. When I increase the volume, the percentage rises. So I suppose measuring in percentage is the inverse, yes?
Who knows. Depends on the taper of the attenuator.
A dB is a ratio not a unit.
After listening to this I'm left wondering my in car audio I strive to find 4V output?
How would they have arrived at 1.23V?
Does that mean that if I wanted to listen at the volume level that the mix was mastered at, that I would need to listen at 0db? Because im certain that if I did my ears would bleed! My Klipsch RF7III will literally cause me pain if I go above -15db with my Yamaha and Emotiva amp.
No, because the mix was mastered using a completely different audio setup than yours. This is all relative to your equipment and you should always do whatever sounds best on your own gear. Mastering generally targets what your standard line level equipment will handle without clipping the signal, plus a bit of extra headroom. That way, people who want it loud can play it loud without distortion, and people who don't can always just turn it down.
Paul's explanation makes perfect sense but, companies who use this to display volume on a consumer product are just pretentious jackasses
I'm with you. No one wants to crank it to -10. When engineers are put in charge of fun.
Good point. Like putting giant VU meters on the front of the amp. Look at me I'm the very definition of high tech.
Except it's useful as a reference. Have you ever punched in a tape monitor button or switched into a live input without checking the volume first? Can be quite shocking! And could damage equipment if you switch from a lower level source to one that's much higher in output. And having zero as the highest point prevents companies from playing numbers games with volume or other settings, thus confusing the consumers. (Look, my volume goes all the way up to 100!)
What else would they display?
Useful in HT when you properly calibrate your system to reference level. You know exactly how far from reference you are and can even estimate current power output and potential headroom
This answer only leads to more questions. Why not express it in volts then? What has this to do with volume? It also doesn’t explain why the baseline isn’t set to some positive number (say 100), and where 0dB is actually zero volts (or no sound).
I can’t believe no one mentioned Spinal Tap 😢and turning it up to 11.🎉
Now you're that guy.....
I just did 🤣.
"But this one has one more. It goes to eleven. It's higher." --Nigel
Couldn’t help thinking of Spinal Tap all the while listening to his explanation.
I got a quick question Paul. Why do PA audio companies list power ratings pumped up not RMS..WHY?..Why can't they all use RMS ratings so there's no cheating in power watts ..If they lie, why would I buy?
Short answer, because it makes a power amp look like it outputs more than it does. For the record, I'm not accusing PS Audio of doing this. The most aggregious are the car stereo manufacturers.
@@carterwilliamhumphrey3373 Hi Carter..That sounds dishonest. I would but anything from a company like that
@@wtesoro It is dishonest.
Same issue when internet is advertised as Mbps vs MB/s - sounds FASTER!
dB is a unit to logarithmically express signal gain (typically measured as the ratio of output voltage magnitude squared and input voltage matnitude squared, meaning this ratio is always greater than or equal to zero). So if this ratio is one, then nothing changes. Log(1) = 0. If ratio is greater than one, then signal is amplified. Log(something>1) yields a positive number. Conversely, if the ratio is fractional, then signal is attenuated. Log(something
Shorter: Isn't it just 0dB is maximum power, -10dB is 10dB quieter than maximum power? The absolute difference in speaker power is not what we hear, we hear non-linear (logarithmic) difference in speaker power, thus vol=10*log(P/Pmax). As the fraction part is always less than 1, the result is always negative. Now confusing part is whether we take the speaker power, or signal voltage. Because it's 10 in the formula for power, and 20 for voltage (vol=20*log(V/Vmax)). My guess is we use power decibels for power, like in amplifiers. But when setting an input level we use voltage decibels. But I might be wrong here. I just remember that half voltage is 6dB less, and half power is 3dB less.
dBm's are pretty straight-forward: 0 + 0 = 3.
What's confusing about that?
Actually, dB is a ratio of powers. 10 log P1/P2. That's it. If you're measuring voltage, then it's 20 log V1/V2, assuming the same impedance on both sides. That's because if you're increasing voltage on a load you are also increasing current. I used to work in telecom, where levels were measured in dBm, where 0 dBm is 1 mW, usually on a 600 ohm load or 0.775V. If you don't have some reference, such as the m in dBm, then all you have is a ratio and the value is meaningless beyond that.
New here. Came for the video - stayed to find out the secret to more time. Eagerly waiting.
Thank you. I have some experience but not much and helping set up I thought the minus would be way too low but it isn’t so I was baffled. History is why.
Max amplifier power is when it is turned all the way up and is assigned the "0dB" value.
No one listens with the volume all the way up for many reasons (distortion, neighbors, wife, etc.).
That is why the volume display readout is negative.
You are listening at less than the max output.
That is also why the volume knob is sometimes referred to as an attenuator.
so 0.00db is maximum line voltage output?
No, it's a standard reference output.
Decibel being a logarithmic scale relative to in this case the standard, and negative numbers being the signal divided down by some quantity. I guess human hearing really is kinda logarithmic.
Decibels can be calculated relative to any positive level, if the control has maximum as 0 then everything less is negative and no output is negative infinity. If a preamp has 20 dB of gain max., then -20 on the control is unity gain for the preamp overall*. At 0 setting, the maximum input level to clipping is the minimum level to allow full volume, quite a bit below "standard". Note some preamps have unity gain labelled as 0 instead, so the maximum gives you some information about the capabilities of the unit.
*Note this is subtracting/adding but gain is actually dividing/multiplying. Magic of logarithms. Don't mix them up.
My Integrated amplifier has A and B for speakers with volume display in db, but the loudness of A and B is so clearly different when switching, although the db is kept at same level. Is this due to the speaker sensitivity or impedance?
Most certainly due to difference in sensitivity. For instance, if system B sensitivity is 3dB SPL less than that of system A, you'll need twice as much power to produce the same sound pressure (volume).
my devialet expert pro stereo amp goes from -97.5 to +30, what does that mean??
It wants you to think you got 1000 times more value for spending 10 times more than it cost to make your rig.
The one thing I wish you had added is that the negative values indicate attenuation from the maximum or “unity gain” meaning no gain in signal hence “0 dB of gain”
0 dBV = 1 Vrms, whereas 0 dBu = 0,775 Vrms, and +4 dBu = 1,23 Vrms which historically corresponds with 0 VU.
+4 dBu is considered line level in pro-audio where contemporary devices have input and output voltage ranges up to +21 dBu which equals about 9 Vrms (or 24Vpp) and more.
Whereas in consumer audio -10 dBV which equals 0,316 Vrms is considered line level.
dB is a unit of power within the entire electromagnetic spectrum, and so a unit their powers are expressed in, because a photon can be at different levels of power, and why all photonic. An Elecron though is slightly different, but in the same family of particles of photons. dB's are not linear either, but exponential, where V are a linear unit of measure of energy potential only within the range of electricity on the electromagnetic spectrum, but dB also covers light, so the radio wave, and even gamma ray, ranges of the spectrum too. So as you go up in the bandwidths the power levels increase as in colors of light, microwaves, X-rays then gamma rays, and why those will fry you if you were directly exposed to a more concentrated beam, as a Laser too is just light, but it's concentrated so the more concentrated (more photons hitting you at the same time), the more it will mess you up, and why people can, and have been injured, even badly working on a mistakenly thought harmless radio tower, due to close proximity which diminishes in dB/inch and so a 5W antenna my burn you at a 5 inch distance, and just feel slightly warm, 10 inches, and totally harmless a few feet away, although exposure time is a factor, but again that too is no longer a factor, as we get way more radiation and at many bandwidths in only a few hours of sunlight exposure than we can accumulate in a lifetime from cell towers and the like!!
It also is a very good reason to not fall for any of the BS on cell phones frying or influencing your brain (way too week) or 5G being our demise, or used by the man to control us, (we have no indirect way of mind control, and just because we can measure, and influence the brain already, as to thought or behavior control, other than when hooked up, we are so far away, to do that, and already know that it would be prohibitively difficult to even go there and silly! and such absurd claims. If what they said was true, you would vaporize the instant you stepped out of your house into the suns light! They obviously are clueless about quantities, conversion the math and quantification, most, if not all of it, and experiencing the Dunning Kruger effect, which is psychological, not physics.
Hence why turning up let's say your guitar amplifier by 1dB at a time gets much louder going up in each increment, than the last one, so lets say at 10, or 11 if you have an old Marshall (one louder according to Nigel Tuffnel of spinal tap) they are not twice as loud as 5, but more like 5X louder depending on the conversion factor between the two units. Now take voltage and current (A for Amperes {Amps for short}) both linear, multiply one with the other, and you get Watts also a linear unit of the combination thereof and a unit of power. They all can be converted to each other, but there are reasons to use them where best applicable.
Hope that helps.
0dB is nominal volume also known as line or unity.
You can consider this to be full volume.
Audio processing is generally done at full volume via a pre-amplifier.
So to turn it down you then negate from that in your post amplifier, hence -dB.
Adjusting away from unity is called trim when negating and gain when additive.
So the volume control is actually your amplifier trim/gain control.
Some amplifiers have positive gain. Mixers normally have a single control from trim to unity and then unity to gain.
Typically that is visualized as green for trimmed, orange is unity and red is gain (overdrive)
Sorry. I just felt like the answer in the video was long winded and confusing.
Now I know why my vintage Onkyo Integra pre amp is labeled like this - thanks!
Finally found some good answers to this question. But thanks to PS Audio for recognising it's importance so the question could be fielded out and thereby attain a good wholesome answer. I have been looking for a good answer to dB levels for so long🙏 Why does the optimum dB level for any music audio source into my NAD receiver always seem to be -20 dB except for HDMI streaming sources split off into an S/pdif audio signal. This source always needs to be turned UP to -10 or louder. 🤔
Movie/TV stream audio always seems to be far quieter than everything else on any given system
@@SepticFuddy Yes, that's a good start...
It’s essentially a voltage benchmark where people figured out “this much energy” is what’s required to effectively utilize audio gear
I always envisioned it this way:
An amp has a maximum output, which of course is maximum volume.
The volume control is basically a resistor, to *reduce* the output sent to the amp.
At full volume (0 dB), the output to the amp is maximum, which is essentially “no resistance” in the signal going to the amp.
At any volume other than full volume, the source signal is being reduced going into the amp, hence it is a negative number - the larger the negative number, the greater the resistance, and hence the lower the volume.
This may not be technically correct, but it’s one way to visualize it. 🤷🏻♂️
We often confuse the -dB scale with guitar or other musical instrument volume knobs. They start at 0 and go up to 10 (unless you're a _Spinal Tap_ fan where they go up to 11🤣). It's natural for laypersons to assume audio and home theater amps should do the same.
They can, since most of the ones with digital displays can be configured to go 0-100 instead of negative dB.
@@blairhoughton7918 I didn't know that, Blair. My Denon HT amp is about 22 years old. It has no such setting. Thanks for the info👍.
I listen to music at 75% volume, 4 notches from the top out of my portable speaker. On my stereo system for vinyl which is in storage I go to -15 +1 notch up whatever that is idk how many notches there are it blew out my speaker before I got to 0
I listen mostly to Hendrix and Stevie Ray Vaughan and blues rock Clapton and Albert King and I want the truest tone possible since I’m a guitar player myself
So how does this relate to, say dB levels during a concert of around 90 dB? I don't understand the scaling.
there are different stages of audio processing from recording to playback to the SPL of the room you are in
the sound level exists where audio content is played in air, it measures air presure level, yes there are different bias scheme to simulate human hearing response akin to pink noise vs white noise
the digital recording level (also in dB scale) shows how close a signal is closing in to the ceiling of the pre-defined limit defined as 0dB, the numbers are stored in the recording file
the volume knob indicator (usually on a preamp) shows how much the source level is attenuated before it is amplified, therefore controlling preamp output level
keep in mind the dB is a ratio value, -14dBu and 0dBu differs by 14dB, -2dBV and 0dBV and differs by 2dB, because they are different units of measurement, it is irresponsible to say -14dBu and 0dBV differs by 14dB, just like 0F and -18C are actually equivalent air temperature for daily life purposes
the "u", "V", "m" letter(s) and case behind the notation is important, it tells you how their base 0dB is defined (same as common log uses base 10, natural log uses the e value, dBu is based on sqrt(0.6)~=0.775V volt, dBV is based on 1Volt, dBm is based on 1mWatt) for this reason dB value of different unit of measurement cannot be directly compared, getting thre unit wrong can be a disaster, don't believe me? just lookup "gimli glider"
The decibel scale is always the result of a comparison with a certain standard level.
- Paul here is using dB while comparing *voltage* levels to a standard of 1 V (he doesnt know the exact level) That is probaly standard in the audio amplifier business.
- Other professional fields would use the dB scale to compare *Power* levels. [Watt] (the dBm scale for example, which compares a certain electrical power level with a standard electrical power. (usually in [mW] )
The above two both have a reference level in the electrical domain. (They are related and can be converted into eachother. Provided that you know the standard levels that are used and the resistance that the power is dissipated in)
- I think your 90dB level is referencing *sound pressure* levels, (acoustic pressure level), in units or Pascal.
In most those cases, the standard is 20uPa (micro-Pascal, the minimum threshold of what an average (heatlthy) humans ear can hear)
A sound pressure level of about 1Pa is then about 90dB
Amplifiers CANNOT be calibrated in this dB scale, because they drive electrical power.
That's sound, this is electricity.
The electricity will be put into a highly inefficient loudspeaker (1% or so) and then spread across the auditorium, bouncing in all directions off various shapes and materials. And a lot of what you're hearing is noise made by the audience.
So there isn't a standard way to map the knob on the mixing console to what you will actually hear. But, in general, turning it up will still make it louder or more distorted.
Oh my God! Another mystery of the universe has been solved.
Even my Masters level professor of Noise and Vibration could not answer that, albeit 20 years ago
dB was originally measured as the loss over a certain distance of standard telegraph wire, set by Alexander Graham Bell, a Scotsman! Measured logarithmically, which was invented by John Napier in the 1500’s, a Scotsman! Just saying? :-)
An easy way to think of it is the greater the value without respecting sign (the negative symbol - and obviously not considering positive values too, purposefully for this example), the greater the attenuation is. Attenuation is the key word here. I suspect many will understand more deeply after considering this. Rock on.
Thank you, Mr. Paul, that was very interesting to know.
Compared to the source input, everything above 0 is a gain, everything below 0 is a reduction. It’s really that simple. Some systems use a volume level, it could go 0-50 (such as common consumer car audio) or it could be a volume percentage, from 0-100%, such as computers/smartphones/etc, but somewhere in that range is the source input (for example it could be 40 on a scale of 0-50, or 80%) but if it isn’t measured in dB you will never know, so it’s actually the ideal scale to measure volume.
The definition I remember for electrical dB is 0dB = 1 milliwatt into 600 ohms load. I did the arithmetic once and it worked out to 1.0 v + a little. 1.25 volts = 0 dB sounds about correct.
0 dbu is .775v. Consumer input is -10(.316v) and pro level is +4(1.228v).
I'll add to that -10dBV has a reference of 1 volt, +4dBu has a reference of .775 volts.
@carterwilliamhumphrey3373 Which is not true. Re-read what I posted since I've been doing pro sound since 1985. The standards haven't changed from that perspective.
@@capfam2018 I don't know what you're trying to argue here. We are on the same page. And yes, the analog standards haven't changed.
@@capfam2018He's right. 20 log (.316V/1V) is -10 dBV. 20 log(.316V/.775V) would be -7.8 dBu. Why does consumer gear specify it that way? Dunno. Maybe tired of people calling and complaining their voltmeter says their new toy doesn't match the spec because they assumed 1 V instead of .775 V.
So if I got this right, the dB is for recording or broadcast level to ensure uniformity. It has nothing to do with the dB used in sound measurements where 70 dB is normal talking.
Yes and no. A decibel is a ratio. As to a ratio of what? Well, it could be a voltage, wattage, data, or sound pressure, just to name a few measurements used in audio. In modern recording and broadcast, the professional analog scale is dBu. For digital, dBFS. Acoustic measurements, like what you're referring to is dB-SPL. Oh and then there peak vs. RMS...
70 dB is everyone talking loudly at once. Conversation is closer to 40 dB.
0 dB SPL is the sound power at 20 micropascal pressure amplitude, in case you're wondering.
We all like a bit of reference level 👍🏻
This is confusing if you're coming from a wikipedia article saying "loudness of the blast heard 160 km from Krakatoa was 180 dB" or "Rainfall is around 50 dB". In that case, there's no electricity/amps/volts anywhere near. Do those decibels have anything to do with the decibels on the audio equipment? I guess not. So I guess it's always a "relative" ratio of sorts rather than a "unit". Kind of like Hz is just a "frequency" (of various kinds of things). In case of audio equipment, it's how far it is from reference power throughput (or something), but in case of rainfall, it's ratio of "air pressure" during rain vs "air pressure" during some reference situation. Did I get this right?
Sound pressure (acoustical measurement): 0dB-SPL= 20µPA (micropascals). It's a pressure reference. Paul is referring a professional analog signal (voltage), where 0dBu≈1.228v. But in fact, the scale on the volume knob, aka 0dB=unity gain. Anything below that will be a negative number.
@@carterwilliamhumphrey3373 Thank you for your reply. So if my music is playing at around the loudness of "rainfall" (~50 dB-SPL) and I walk up to the amp and dial the knob down "5 dB" (e.g. from -10 to -15), and then "measure" the air pressure back where I was standing, it's not gonna be ~45 db-SPL, right? The dBu difference is equipment specific and maps to a different "air pressure change" from amp to amp. (Which, I understand, is a weird way to put it, but it's just to make clear another way that these 2 different kinds of "decibels" are mostly unrelated)
@@sergueifilimonov2706 Um, maybe. This is potentially more complex than that as we step into "gain vs. power", "acoustical loudness vs. acoustical power", and even just the acoustical listening environment you're are in. In an anaecoic environment, I'd suspect that a 5dB change on the volume pot would yield a 5dB-SPL change.
i was sure i could recollect one digital volume display that won from minus to 0 then to plus a few points, like a overdrive.....
My Yamaha 5/6.1 surround sound receiver usually sits at about -33 for normal TV and up to -15 for the big movie theater sound. 0 is way too loud.
Well that's because at 0db you're running it at almost it's maximum output volume. -33 is about half volume on mine.
@@RaymondReeves-db8dr, stating, not misunderstanding.
More simply, the volume knob reduces volume. All the way down is total reduction. All the way is no reduction.
This is why engineers want it to be 0db but not consumers
the attached story makes perfect sense to me now
When you mix sound for broadcast today, it is typical to normalize your audio to -3 db. Loud enough without clipping.
I wish UA-cam enforced that. It's getting better now but some stuff (CBS content is a frequent culprit) is unnecessarily loud.
It brothers me the low bass hum in the video. A hi-fi audio manufacture / recording studio needs to have better audio on the videos ..
FYI. Davinchi Resolve can clean up the audio with the press of a button
But you don't put voltage into something; voltage goes _across_ it, and then current goes into and through it.
Ahhh Unity Gain. Thats your answer. Important stuff when you produce or involved in live mixing even djing etc.
I don't know he's saying the opposite hes saying why does my amplifier go - DB when I turn it up, he would have said it why does my minus DB increase when I turned it up but that's not what he said. if he's listening maybe you can clear it up.
Oh damn, no I did not understand that. I thought at 0.0 db, your receiver was putting out "maximum signal" and that anything above (positive) would definitely entail clipping. But my god after he said that, there's no limit to the amplitude of a signal when we're talking analog!! So yeah it might be the "most" your receiver wants to put out but if you hook up an amp that can exceed, that, well, I guess it can easily.
Did not expect to learn something from this video lol...although will say I measured 20 volts at 0.0 db at 8 ohms (~50 watts) with my old DCM26 towers (supposedly 90 dB sens.--in theory put me at 105 dB at 1 meter) on my Yamaha RX-A2A with external stereo amp (at stereo with loud music--my wife quickly told me to turn it down after my measurement).
great video, i was asking myself this question forever XD
Clear as mud y’all.
His secret: money
For many years the zero level was 1 milliwatt into 600 ohms Many old voltmeters used this as the reference of .732 volts.
Depends on the unit: 0 dBv is 1 volt, 0 dBu (or dBm) is 0.775 volt. dB alone is not an absolute unit, just a relative unit between different signal measurements or levels.
For clarity: +4dBu is approximately 1.228v. The reference (0dBu) is .775v, which is also actually a round up of an infinite decimal.