effects from coupling capacitors in audio circuits
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- Опубліковано 7 лют 2025
- The video shows the "bandpass" from different capacitor values used as coupling capacitor in audio circuits (20 Hz - 20 KHz). The "sound" changes completely with different values, and 1 series capacitor in the audio signal line can be used as audio filter (though the characteristic is far from ideal, complete audio bands are shut off, so not very selective!).
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Be aware of that, I saw on the internet my circuits reproduced in a poor or even not proper way. I can not help that, sorry.
More audio in my book: "Schematics 2, audio amplifiers and loudspeaker boxes" ISBN 978-1-4475-7336-4. You can find it via the above mentioned link to LULU.
Please note: the capacitor value and its effects also depends on the input resistance from the electronic stage to which it is connected (4-pole-theory). This means that with a high-impedant input stage (like a tube grid or a FET gate), the effects will be (somewhat) else. In the showed demo the input resistance is approx. 3-4 K (bipolar transistor). This low impedance input gives damping. Updated 1 June 2019.
Kennith Hillis: I removed your question/comment, sorry for that. I was too much in a hurry. When you post it again I will react on your question. 13 May 2024.
very simple but clear demonstration. A lot of beginners in diy audio should watch this at least once. Thank You!
You are welcome, thanks.
Finally, a great demonstration on how a couplig capacitor can affect your sound.
LINKS TO VIDEOS WITH SCHEMATICS ON MEASUREMENT TECHNIQUES & TESTS
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Test from a 455 KHz IF filter (oscillator) ua-cam.com/video/5wuHmHNESoY/v-deo.html
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one of the best electronics vidios on youtube. never tire of watchiing it.
Great video! Helped me understand an important part of audio diy. Thank you!
You are welcome, good to hear that it was useful.
Brilliant video! Such a simple demonstration but so effective and informative. Thank you for sharing.
OK, thanks!
Simple idea to present the impact of coupling capacitor, but extremely usefull!! Thanks!!
You are welcome.
Nice of you to demonstrate the effect of different cap values, but remember the input impedance of the amplifier, in this case a single transistor is crucial to what cap value you need to couple the audiosignal. Maybe your input impedance in this case was 2K Ohm or something? then you maybe need 100 uF to make 20 Hz pass. If the amplifier was a tube input with 500K Ohm input impedance, you maybe need only 10nF to make 20 Hz pass etc.etc.
Thanks and yes the input and the output impedance in filter circuits matters. I payed a lot of attention to these matters in other YT video's and in my books. Go to the "looking glass" on my YT channel trailer (Radiofun232 on You Tube), search there with keywords regarding this subject. Also in my books about audio on the Lulu website (more info in the textbox) you can find much more info. The setup was (say) a pre-amplifier (with a BC 547 b, 20 Hertz to 20 KC, schematic on my YT channel ), after that this set of series capacitors, then the end amplifier/signal tracer. You can easily reproduce that setup and take your own conclusions, I am interested. Upload your test results to You Tube, to your You Tube channel, give the link and I will study that and I will comment on your experimental results. 24 may 2022.
Just discovered this. I built a passive speaker from parts of some other devices not in use. Searching UA-cam for more clues. Some mid range issue made it interesting. In a way it seems as we should use a component tailored for each speaker in the box we have/make.
Thank you for this very practical demonstration. I remembered this video from 7 years ago. I was building a amp kit from S-5 electronics. The input coupling capacitor was limiting low frequencies
at .22 microfarads. I'm in a remote location. I left out input capacitors. It made an huge difference in base response. I'm not looking for "thumping bass". Just a faithful reproduction of source material. Everything I do is on a hobby level. I'm putting together another kit. with 1 microfarad. caps so I don't ruin the pot.
Thanks, good to hear that. And yes, by changing the coupling capacitors to (say) the non polar types (no electrolytics) in the order of 1 uF-4 uF you can gain a lot. And also good: non polar capacitors don't leak DC current, so the first amplifier (say that it is a transistor or an audio chip) will never get out of its working point ("bias"), it means that audio amps can get a kind of "eternal" life. On audio chip datasheets you can often see that no electrolytics are used to send the/an audio signal in. 30 oct 2022.
@@radiofun232 Well the kit was a tube amp kit. from S-5 /Hearsay electronics. NOS JAN "86" tubes. While looking for a link to share I discovered they are no longer doing business.
. Tube Depot still sells the kits. This is not a plug. I'm sorry this company is no more. Their main focus was on electronics for hearing impaired. Someone on their team designed some beautiful tube amp designs. I still have a model 16Ls in the box. GE JAN spec 5670 pre and GE 6005 power. It's cool, building with 1986 tubes I just want he thing to last.
100k input impedance and 1 microfarad coupling capacitors should sound just fine while giving this amp a lifespan.
@@kreiglord Thanks for this valuable info.
I love UA-cam, thank you for what you do!
+Bo88y Beretta You are welcome, good to hear that.
thank you for an absolutely brilliant audio capacitor demonstration . subscribed :)
You are welcome, good to hear that. Much more video's about audio are on my channel, thanks.
Helped me fix my navigation unit. You are amazing buddy.
My capacitors got damaged while working on the unit, it sounded like your low nf settings.
Very screechy, and the frequencies were extensively reduced.
I replaced the capacitors on each line to the original 0.47uf 10v rating and it sounds perfect once again :) Lots of work since they used SMD capacitors but great help with your video to understand the effects of bad/leaking capacitors.
All the best
You are welcome. Good to hear that you could use this info so well.
This was the best capacitor Demo I have ever seen, Thank you
It is not only usable in a pre amplifier, also a tweeter-loudspeaker can be connected via a series capacitor to eliminate the low frequencies (approx 100 N-470 N). But (important!): your end-amplifier must always see an inductive or resistive element (=loudspeaker coil or resistor). Many audio amplifiers cannot handle a situation where a 100 N cap connected to a tweeter must be driven. But in a combi with another speaker it is possible, though the cap can effect the other speaker too.
@teflondon91 As far as I could see these capacitors are used as power supply capacitors, connected to the bridge rectifier. They are used to keep the hum level low without using a stabilizing circuit with a transistor.
@vibra64 It is transparent silicon kit, used to fix the capacitors to the borad. It has good properties for isolating electronic circuits.
thank you for this. i will build my own tool like this, but also with capacitor for sending to ground to see that effect
Thanks, good to hear that it was useful.
There is a difference between the output and the input of an amplifier. On the output (non electrostatic amp.) a current has to drive a low impedance load, let us say a 4-32 Ohm coil. This means a "heavy" current, this can only be supplied via a high value capacitor (1000 uF-10000 uF), capacitive reactance. On the input all audio frequencies are delivered to a 3-4K (bipolar transistor amp input) or 500K-1M (triode tube amp input) stage. The coupl. cap. can be less if so.
Ok, it depends. When it is in a ferquency dependent circuit (oscillator or so) keep it exactly 0,1 uF. When it decouples an amplifier stage (power supply lead to ground, often R-C) you can often go higher, let us say 0,22 uF. When it has to transport sound (audio) as a coupling capacitor (audio line) you can go higher too, but in tube circuits this can give problems. When it bypasses a switch or transformer keep the 0,1 uF. (uF=mF).
Interesting, but the filter effect totally depends on the CD output impedance and the preamp input impedance. In a valve/tube amp there are also large DC voltages across the coupling caps which has a huge effect on their properties and sound.
Of course, it all depends on the input and output impedance. But it shows the "basics". Where have you found that high DC voltages across the coupling capacitors have an effect on the sound in a valve amplifier?
Where have you found that high DC voltages across the coupling capacitors have an effect on the sound in a valve amplifier?
OK, glad to hear that you could use the info.
I just went at lulu.com! ...im gonna buy the books! thanks again Ko!
+jeff ‘jeffbwack’ wackenthal Thanks for buying my books. They form a good background for all my video's on YT.
I think based on my own experiment the quality of capacitors and the manufacturer vary a little but very significant for china made junk capacitors...so it's difficult to really determine which capacitors to use but it's a great idea though to narrow down the scope of research
Very nice demo!
Thanks, it is the easiest way to filter somewhat frequencies out.
That's a really nice demonstration
Very rarely do we use high pass filter, this DC blocking capacitor is one of them.
@Teknogod17 I use capacitor too. But what I meant is the use of LPF is much higier thatn HPF.
Every LM386 datasheet should have a link to this video.
Thank-you, a practical demonstration is worth a ton of theory.
you are welcome.
dont need a fuckin demonstration of frequency response
wat i care is sound difference of capacitor materials which doesnt even appear in theory
That is interesting, please explain & read my new comment. 6 feb. 2024.
Great video thanks 😊
Great video. Please make a demonstration of inductor and capacitor together that are in high quality speakers to separate signal for bass, medium, and tweeter speakers.
ua-cam.com/video/UV_FTKb0G1A/v-deo.html
Buy my book "Schematics 2, Audio Amplifiers and loudspeaker boxes" Link in the textbox.
And here ua-cam.com/video/piB1m05ZTqY/v-deo.html or here ua-cam.com/video/UQ3I0kLTsCI/v-deo.html
You are welcome. Good to hear that it was useful.
That capacitor bank is freaking awesome
OK, thanks.
This is brilliant, best video and explanation I have ever seen. Could I possibly ask a question? I have an old analogue scope Advance or Gould OS1000A there is a capacitor that measures -970vdc one side and +50vdc the other side which is the blanking side. I am stumped as to the reason for this I can only think it is to block dc at the cap just an old novice, thanks again for the videos, go safe.
Thanks. I think it is part of the High Voltage circuit of the Cathode Ray Tube. To supply the grids they sometimes need negative voltages.
Great demo video. Thank you very much.
Great video. Can you tell me what is that white looking gel on your breadboard?
Belle démonstration !
Bravo !
georges
+Georges MILLION Merci.
Interesting demonstration. Thank you.
OK, good to hear that.
thank you for filling my mind with these useful information sir
You are welcome, good to hear that it was useful.
Great practical tips once again.
This is so helpful, thank you!
Ok thanks.
The capacitor alone is not the filter. You need to incorporate the input and output impedances of the stages being coupled by the capacitor. These impedances are critical.
Yes, true, explained in +/- 40 or more other video's on my YT channel (about audio filters) + in my book "Schematics 2, audio amplifiers and loudspeaker boxes", available on the LULU website. By the way: there is always input and output impedance.
This is a coupling cap audio line in a tube circuit; in between the diver valve (12bh7a) the grill to the pre-signal valve (12ax7) the anodes. It has a Sprage orange drop cap, I'll probably upgrade to V cap cuTF.
SO If out put signal is different I suppose I couldnt use a cap inline before say a tweeter to illiminate all the low end and have only the high end (tweeter) sound values?? I am just curious if it works in this fashion or is this only pre amplification. Just asking as I am building this capacitor test strip you have (great idea)
THanks
You are welcome, audio is always interesting.
Excellent Tutorial!!!
thanks, good to hear that it was useful.
Nice demonstration! However it should be noted that changing the capacitor has a "high pass" effect on the audio, and not a "band pass" as stated. Nice was to illustrate it though.
Thanks for such a revealling video
This is a great explanation. Thanks :)
Thanks.
Very useful and informative thank you
You are welcome, thanks.
Now that WAS interesting. Finally I now know something about coupling caps. A direct quick comparison and I know that the minimum specified coupling cap should 0.47uf or above. My circuit is specified with a 10uf c cap, and here am I trying to out-think the designer by subbing a 6.8, or even a 2.2 because I have both, and a 10uf in a film cap is going to be quite large and expensive.
Ok, now I know more,...
You are welcome. In audio amps I nowadays avoid electrolytics because of their limited lifetime and leakage. In many cases a 1 uF or 0,47 uF non polar capacitor can do the job too, especially as coupling capacitor.
@@radiofun232 Yes, I'm not keen on an electrolytic for a cc, but that's whats in the kit. A Nichicon Muse, probably fake, BP capacitor. Not keen, I'd rather sub in a 6.8 film I have. I also have some Russian paper in oil I rather like, for the irony, if nothing else. I don't imagine the Soviets, when they were producing electronic parts for their war machine had any idea their empire would fail and they'd be left with warehouses full of stuff which the West would snap up for audio use....
Many thanks for your response...
but doesn't the full filtering effect also depend on the resistor value used with the capacitor
Yes, surely! The input and output impedance are key figures in this setup.
I'm inversigatin for the replacement a coupling cap rated 0.1mF 600v. I thought a good idea to replace it to a 0.22mF and a better quality one. I see the difference is small, but I prefere to keep 0.1mF in order to keep the coherence and balance after watching your video.
Excellent tutorial. Thank you.
Ok, good to hear that.
Thanks for the video, learnt a lot 👍🏻
OK, thanks, good to hear that it was useful.
@teflondon91 I saw today it was a test for supply capacitors, that is why he used the resistor. So far so good.
@teflondon91 cannot find the link to a mosfet circuit on this website.
Sir why we can use directly to the amplifier?
It is about coupling capacitors. A small value coupling capacitor limits the passage of low frequencies in the audio spectrum.
Hi. I have a question. I love vintage hifi from 80’s-90’s. I buy many old equipment and I noticed that they sound much less clearer (much less treble) than what they were sounding when they were new. What’s getting old in them? Is it the old capacitors acting as filter? What’s the reason they sound much less clearer? THX
I really don't know. It could be that the loudspeakers age. In the 1970's and 1980's they often used cones of (by the way: special) paper. They get soft on the long term due to the vibrations, losing their stiffness. But I think, when you measure the frequency characteristic of the amplifier itself (oscilloscope, sine wave generator) it will be constant during the whole lifetime. In those days also carbon potentiometers were overall used. Their contacts age (erode) on the long term during usage, that means that (say) a frequency control potmeter (e.g. in the high audio spectrum) does it job not so well after 20 years. When a carbon layer completely erodes you hear strange sounds and (a part of) the frequency band falls away.
it's really interesting to hear the difference, I have a question, what is the slope that we are hearing? Is it 6db/octave ? it sounds like it's more to me but I'm not sure.
I cannot give you an answer, sorry for that. I don't have the measurement devices to test it. Of course you can do these tests/measurements and show them on your YT channel, I am very interested.
@@radiofun232 I would be totally unable to do that kind of measurement to be honest. I mix a lot so I was more relying on my ears but it's almost pointless through youtube.
Anyway thanks for your video it's great inspiration !
@@leonardtristan6873 OK, the frequency bandwidth for audio on YT is in general quite good. But perhaps you can make this setup with a sine wave oscillator, a scope, an amplifier etc. when you want to do serious measurements. I derived my reaction from your comment when you talked aboud dB (decibel values) and frequency slopes.
What about on the input side of the amplifier? Its often .1uf to .01uf on the tube amp circuit ive been looking at. How does that effect the frequency range?
Thanks and that is a good (say difficult) question. In general this is real: when we send a signal (say: the complete audio spectrum from 20 Hertz to 19 KHz) from electronic device "A" (pre amp or filter unit) into electronic device "B" (the same or an end-amplifier) via a coupling capacitor, the output impedance of the source device and the input impedance of the receiving device play an important role in how good the complete spectrum (say: sine waves, same amplitude) is transfered. The input grid of a tube has a very high impedance (mega-ohms range), that means that with a (relatively) small capacitor value (say 100 N = 0,1 uF) this job can be done. Many bipolar transistor circuits have a low input impedance (kilo ohms range), that means that the capacitor needed to transport the complete audio spectrum (including the low frequencies, say from 50 Hertz to 1000 Hertz) must be higher (often 10 uF, sometimes 1 uF). Field Effect Transistors have a high input impedance. Much more info in many video's on my YT Channel. When you go to my channel trailer (Radiofun232 on UA-cam) and search via the "looking glass" with keywords like "audio" or "audio filter" or FET there is more (practical) information.
So would you please explain what different voltage ratings do...and is there any difference in the sound when using different voltage ratings..thanks very nice videos..
As far as I can hear the isolation material between the plates (dielectricum) does have a tiny influence on the sound, especially above 12 KHz. But there are many materials used as dielectricum. On higher voltages the dielectricum is, in general, from a thicker material or material with extremely good isolation properties (specialized plastics).
thank you, this was very helpful
OK, good to hear that.
Are you dutch? becouse i am.. i can hear it on the way you talk..
Joshua he is dutch as fuck3d😁😁😁
Good👍 job sir
its called High pass filter ! :)
or low pass and bandpass as you said !
Sure, also lower frequencies pass with adequate non polar caps.
Interesting video thanks for posting
Great video, thx a lot. I have 2 questions. I checked some speakers with just a capacitor as crossover for the tweeter and they all have different capacitor values between 1.5-4.7 µF. Is this because the manufacturer wants different sound or the tweeters are different or the amplifier is different ? How do I choose the right capacitor for a tweeter ?
Thanks. Each tweeter has a specific frequency range, though always between (say) 14 KHz and (say) 21 KHZ. And not every tweeter can handle the same power. And there are also piezo tweeters (ceramic element drives the cone). That is the reason why you see different capacitors. In general the manufacturer chooses the capacitor in such a way that there is an "overlap" with the mid-tone loudspeaker. Or the frequency chacteristic is matched with 1 loudspeaker that does the low and the mid-tones. How to choose one? Best thing is to listen till you hear the sound that you like most. That is individual/subjective.
Can you explain why expensive or studio grade hardware like equalizer and compressor generally have this decupler enable audio signal
Equalizers have often typical bandbass filters for specific audio bands in the range 20 Hertz up to 20 KHz, say bass, medium, treble. This video shows only the effect of the capacitor value when you take it into an audio signal line.
@@radiofun232 that's perfectly fine but please make this piece of information on another level👌👍and i am waiting for learn
@@gurindersingh7933 I don't know what you mean, sorry. Wat is a "decupler enable audio signal"?
@@radiofun232 means pro audio input and out is decuppled Or dc cuppled
@@gurindersingh7933 Sometimes direct coupling (DC, so not via a decoupling capacitor) can "upset" the (audio) input of the next amplifier, so cause a (small) negative or positive voltage/current on the earth rail. That can lead to a ground loop = hum and many other strange audio effects.
Thank you for the demo. Why has many schematics, especially tube schematic, almost always 0.1 or even 0.022 uf values? is there something negative about having 0.47 uf or larger values? thanks again!
Tube amplifier circuits have an extremely high impedance on the tube grid, that is the electrode where the audio or radio signal is "sent in" to be amplified. That is the reason why transporting a big frequency (audio) band into these grids can be realised with (relatively) small capacitors, compared to transistor amplifiers, where the signal is sent into a low impedant input, often the base of a transistor, thanks.
Very interesting sir!!
+jeff ‘jeffbwack’ wackenthal Thanks, good to hear that.
I type this with the utmost respect, but both the video, video description and comment section are full of misinformation and/or oversimplification. Please be aware that this video should not be taken as a base for knowledge on the subject. The input impedance (not resistance!) of tubes and the effect of the absence of coupling capacitors to name just two examples.
+Thijs de Bont: please explain your objections better, then we can communicate about it.
+radiofun232 Perhaps I’m nitpicking on some points (other points are just plain wrong), but I truly believe that forming a proper knowledge base at this level will greatly help later on. Unlearning misinformation is a lot harder.
First, I think it should be made more clear, that all that is happening is a frequency shift in a first order high pass filter. No change in volume (although perceived, I get that) or other type of filtering?
Video:
0:14 In line-level stages, electrolytic capacitors are very rarely used. Foil, PIO of other non-polar caps are the norm.
2:52 The term is ‘reactance’. A capacitor will only fully block DC. The specific frequency at which attenuation occurs in a typical CR filter is further determent by the input impedance of a following stage.
3:40 The value of the coupling capacitor at the input of any amplifier is entirely dependent on the amplifier’s input impedance. There’s is no set minimum value.
Description:
- “The video shows the "bandpass”…: This is not ‘bandpass”, but “highpass”
- “…(though the characteristic is far from ideal,…: Why? The -6dB per octave RC- or CR-filter can be ideal for either low- or highpass filters, depending on the application. And this is exactly how most amplifiers set their usable frequency range.
- “…also depends on the input resistance…”: It’s ‘input impedance’, not resistance. Resistance only applies to DC.
- …high-impedant…: -> high-impedance
- “…(like a tube grid or a FET gate)…”: The input impedance of, let’s say, a typical class A common cathode, cathode biased, tube stage is not determined by the tube’s grid, but by it’s grid-leak resistor. Although high values are commonly used, you can just as easily use just a 1k resistor. Also, if negative feedback is applied at the grid, the impedance will be lower as well.
- “This low impedance input gives damping”: damping is the term used for effects on oscillation, attenuation for the effect of a CR type or other filter
Comments:
- “+BaneStrix In general these are good values, because the input impedance from the tube is high. You can try a 1 uF but perhaps it will overload the input grid with the AC sound energy.”: This is completely false. First, it’s impossible to give an answer without knowing the input’s gridleak value. Second, “overload the input grid with the AC sound energy” doesn’t make any sense, at all! That’s not how tubes work!
- “In general it means a shortcut and no sound or whatever. But there are amplifiers (BTL=bridge type load or old directly coupled amplifiers) that can drive an electromagnetic loudspeaker (coil in a magnetic field) directly.”: Oversimplification. If the coupling capacitor is omitted (short-circuited as you state), it’s completely dependent on the coupled stages what will happen. The DC points of both the preceding and following stage can come into play. One can upset or damage the other. If the DC points are at 0V or compatible in another way, you just loose the first order high pass filter characteristic.
- “For higher frequencies (8-10 Khz - 20 KHz) ceramic caps work well for audio circuits up to 20 KHz and more.”: Ceramics for audio filtering?? Ouch. They will add distortion for various reasons. Piezo electric effect being one of them. Any proper foil cap, polystyrene, polyester, polypropylene, etc. will have both excellent low- and high-frequency characteristics, many times greater than the audible spectrum.
- “…when I don't know how the low pass filter is connected to the speaker(s) and the amplifier output. The reason is that an extra capacitor can/will influence the low pass filter. “ The 30Hz-200Hz filter is not a low-pass, but a band-pass filter. And the comment is concerning a possible high-pass filter.
-“+Valvuleckter Ok, it depends. When it is in a frequency dependent circuit (oscillator or so) keep it exactly 0,1 uF. When it decouples an amplifier stage (power supply lead to ground, often R-C) you can often go higher, let us say 0,22 uF. When it has to transport sound (audio) as a coupling capacitor (audio line) you can go higher too, but in tube circuits this can give problems. When it bypasses a switch or transformer keep the 0,1 uF. (uF=mF).”: Any circuit where capacitance, inductance and resistance comes into play is a frequency dependent circuit. Not just oscillators and the likes. Also I’d like to point out that although the difference might seem small (0.1uF vs. .22uF), it will lower the high-pas filter’s frequency response by half! And what kind of problems do you refer to with tubes??
- “+Todd Littleton It is not only usable in a pre amplifier, also a tweeter-loudspeaker can be connected via a series capacitor to eliminate the low frequencies (approx 100 N-470 N).”: Given the low impedance of a typical tweeter or high frequency driver, 8ohm for example, a 100n to 470n will kill the frequency response. f100n = 1/2piXlC -> f100n = 0.2MHz(mega!).
+Thijs de Bont Thanks for your comments. I can agree for some of them. My You Tube channel is ment for people interested in electronics and a "broad" public. I have written "bandpass" between quotes, for the reason that you mention. I only wanted to show the effects from such a series capacitor, that is why I have chosen this title for the video. My aim is to show electronic circuits without mathematics and complicated explanations, my aim is to show the fun of hobby electronics, that is why my channel is called radiofun. All my work is purely experimental. And: I am no Hi-Fi purist, so the only aim from my audio circuits is to show circuits with which hobbyists can create their "own" sound in a living room the sound character that they like ("feelgood" circuits). Technical: 1) I don't talk about the norm of coupling capacitors in audio circuits, I only say that both electrolytics and non polar caps are used (they were and are). I am fully aware of the issues when electrolytics are used as coupling capacitors, in other video's this is explained (also in my book), also a comment.. 2) I am fully aware of the fact that the input impedance from a transistor or tube is extremely important for the damping from the filter, but I cannot explain the four pole theory for a broad public (my channel is a hobby channel) 3) 3.40 regarding the input impedance we can discriminate tube circuits (input to the grid, high impedance), FET circuits and bipolar transistor circuits. In hobby terms you can tell something about the audio effects that you can expect when you add an audio signal from a filter or tone control to these 3 different input stages. Without calculation and mathematics the sound character (bandpass or higpass) that you can expect can be foreseen, due to the expected impedance at the output from the filter. And: the bandpass/highpass from a capacitor is frequency dependent, so is not competely dependent on the amplifiers input impedance. Comments: A: Banestricks: "overloading a tube with AC sound energy", this is possible. The negative grid voltage only sets the amplifier tube to a certain working point, overmodulation leads to distortion and saturation from the anode current, the tube is taken out of its linear amplification. B: ceramic capacitors work fine in audio filters. I have made many filter circuits with them. You can use them to create experimentally the sound that you like in your audio circuit, interchange them with foil caps, listen again, etc. Interesting to develop an audio filter or tone control this way. In most cases it is not necessary that capacitors have properties far greater then the audio spectrum (a common misunderstanding) C: replacing a capacitor by a wire will surely have an effect...D: I cannot comment on circuits without a schematic,the only thing in general that I can say is that an extra capacitor can/will influence the filter and that is what I did E: Read my book "Schematics 2, audio amplifiers and loudspeaker boxes"" for more information about my (experimental) approach from audio circuits (I am active in electronics for 49 years with 30 years audio experience, hundreds of circuits) E: Valvucheker: I have given a few standard applications from capacitors and a rule of thumb value for bypass capacitors in power supplies (parallel to the electrolytic), there are standard values for decoupling capacitors related to the frequency band where the amplifier works (Audio or HF) F: Advice: test how a tweeter works when it is connected via a small capacitor (100N) to the output of an audio amplifier (classic PNP-NPN end stage). Of course first make a circuit where enough decoupling is present, such a circuit surely does not kill the frequency response but adds a fine transparant high to the sound.
+radiofun232 And I applaud your effort of making these videos! Basic electronics are a lot of fun to tinker with. But we already know that ;). My comments below:
2) You’ve mentioned 4 pole theory a few times. But as far as I can see (and hear), you’re only using a single CR filter (1-pole, first order) and not a 24dB/octave arrangement. Can you elaborate? Or do you refer to the 4 angles of phase shift that can occur within a circuit?
3) It is BOTH the capacitor value and the following input impedance that determine the -3dB filter point for either a high- or lowpass filter. They are both equally important.
A) Overmodulation, saturation or however you call it is a property of amplitude, not frequency. When the amplitude stays within the designed parameters, it will happily amplify frequencies of 1Hz and below.
B1) Just listening doesn’t cut it. There are so many factors that influence the perceived sound. Our brains being one of them. Measurements tell the whole story.
B2) You state polyester cap (foil) works well up to 8kHz, and then using ceramics for the higher regions. That’s just wrong to make such an unfounded statement.
C) Absolutely it will make a difference, but please read the comments again. You start with ‘shortcut’ and ‘no sound’. That’s either extremely oversimplified or not true and a contradiction.
D) Lets agree to disagree
E1) Claiming superior knowledge by amount of years in the business doesn’t cut it. The ability to relay correct information does.
E2) In you original comment you don’t point to power supplies, but to the per-stage decoupling of the power rail. Power supply bypass capacitors (parallel to the main filter caps) is a completely different matter.
F) I don’t quit get the remark “first make a circuit where enough decoupling is present”. Because if you refer to another, bigger cap in series for DC protection, the entire point about the 100nF is mute. The bigger cap (let’s assume 100uF for +/- 200Hz highpass filter) will swamp any effect of the added 100nF cap.
+Thijs de Bont, thanks for your comments.
2. This circuit with 1 series capacitor (with an input and an output impedance) to which an audio signal (20 Hz-20 KHz) is applied can be considered as a 4-pole;
3. I don't say that only the capacitor value or only the resistor value is important, on the contrary, when you read my comment well;
A. I don't say that overmodulation is a property of frequency, when you read my comment well. This must be clear from my remark that the amplifier tube is taken out of its linear working point by a too strong audio signal on the grid; I cannot see why an amplifier tube must amplify frequencies from 1 Hz and below (if a tube is able to reach these low frequencies);
B1. Listening tests are (in my opinion) decisive. Only an opinion, no offense. Measurements don't tell the whole story. An amplier with good test results can sound bad;
B2.My remark about polyester caps and ceramic caps is made on the basis of hundreds of audio experiments, audio filters, etc. I don't say that foil caps cannot be used above 8 Khz. It depends completely on the circuit and the kind of sound that you want to create in an audio amplifier (in the whole chain, from -say- CD player to loudspeaker boxes);
E1: I don't claim superior knowledge. I only claim that I know what I am talking about on the basis of my experience and many experiments with sound.
E2: There are standard values for decoupling capacitors for AF and Hf circuits (e.g. in the Dutch "Elektronisch Jaarboekje") from the 1960's.
F: How to make a well balanced sound in a loudspeaker box or audio amplifier is explained in my book. By the way: the approach in this book is to show ways to create audio circuits and speakers with certain sound characters, the focus is not on typical Hi Fi or measuring results.
what value will you suggest for cutting off bass 200hz and below. i have 2 satellite speakers small ones and a woofer, i want to cut off the bass on the small speakers. I already have a low pass filter 30hz to 200hz.
It is difficult to say when there is no schematic and when I don't know how the low pass filter is connected to the speaker(s) and the amplifier output. The reason is that an extra capacitor can/will influence the low pass filter.
go to google and type in high pass filter. if you are not familiar with electronics, it'll show you how to calculate cut off frequency etc...
Hey really great experiment!
What capacitor should I use for bolder and warmer sound ?
The complete audio spectrum (20 Hz-20 KHz) in a pass-through (line) capacitor can be transported with a capacitor of minimum 470 N (0,47 uF) or higher. Non polar types are preferred.
Thanks sir, nice and clear video and .... accent by the way ;-)
OK, thanks, could be, I am from the Netherlands. More info on my Channel Trailer called "Radiofun232 on UA-cam".
I would like to know if putting a 50 volt cap in place of a 16 volt cap change anything..it is in a vintage transistor radio..the UF will be the same..
That is no problem. It is even better, especially on the longer term (aging goes slower).
awesome video +++
How do I connect a Electrolytic capacitor ,a polar capacitor to cut the frequency of a speaker? In which way do I connect the capacitor to the speaker terminals? Thank you in advance
The negative from the cap must be connected to ground, in cases that the ground is negative (most cases).
How about connecting the polar capacitor in-line (serial, not paraller). Which way will the plus go? This is seen in rc filter configuration where there is a capacitor in line and then a resistor between V and grnd
Sorry if I make no sense (or such situation is not possible)
On a polar capacitor it is usually the negative terminal that is indicated, and this must go to the negative side of your circuit or rail.
Thanks for the video
Thanks, good to hear that you liked it.
what would happen if you don't use the capacitor at all?
In general it means a shortcut and no sound or whatever. But there are amplifiers (BTL=bridge type load or -old- directly coupled amplifiers) that can drive an electromagnetic loudspeaker (coil in a magnetic field) directly.
excellent video! I have to questions. Whats the difference between using capacitors or coils to roll of the frequencies? In audio circuits, why use tantalum capacitors and film capacitors over electrolytics, apart from the size and values? Can I use an electrolytic capacitor instead of a tantalum capacitor, with the same specifications? Thanks
Capacitors and coils have opposite electric/electronic properties when it comes to L-C filters. Electrolytics have polarity (+ and -) and may not be reversed. Tantalum capacitors have no wet or moist electrolytic. I cannot advise you regarding tantalum-electrolytic because I don't know where you want to use it in the schematic. Perhaps more info is on the www.
radiofun232 thank you!
WHat is audio capacitor brand would you recommend for restore my vintage stereo in future?
I dont have a brand but polysterene caps and polyester caps work good in audio filters, from 50 Hz up to 8 KHz. For higher frequencies (8-10 Khz - 20 KHz) ceramic caps work well for audio circuits up to 20 KHz and more.
Can you recommend which is best brand of capacitor for audio amp based on your experience...I used the ordinary cap sound quite hmmm....very bad.
I don't know brands, but polystyrene capacitors (and "plastic" capacitors) in general work good in audio circuits.
radiofun232 thx
hot glue is our friend❤️
Sir... please explain capacitor values for speaker (8 ohms) in full range, midrange ,midbass and high frequency
ua-cam.com/video/piB1m05ZTqY/v-deo.html and watch also the second video. It is more or less impossible to give an advice without knowing the situation.
I use 10uf as a norm. To much, but it works well.
Interesting... Thank you
You are welcome, good to hear that it was useful.
Very helpful, thanks.
NIce work...thanks...
Sean Connery?
Good video
Thank you
OK thanks.
Awesome...
How would you locate coupling caps on an amplifier? is electrolytic or film caps better?
+jon123423 In the past I always used electrolytics, but today I always use film caps between 500 N (0,5 uF) and 3 uF, non polar. The reason is that electrolytics always (start to) leak current, this influences the work-point from the transistor stage.
+radiofun232 But how would you locate coupling caps on an amplifier?
what kind of amplifier?
Solid state integrated amplifier.
Is it a chip amplifier, what is the type number?
i paralled 1.0 uf/50V Nichichon Fine Gold with the 1000 uf/50 V el cheapo power cap of my no name tuner and low and behold sound fantastick..i couldnt squeeze in the large obbligato cap i initially intend to bypass it so i went for small nichichon caps
great vid. thanks!!!
Mucha sabiduría gracias ☝🏼
very interesting!