I completely agree with your assessment of passive preamps. I went though 2 different kinds (including one fairly expensive one) before going back to a real preamp which restored the dynamics and bass that I had been missing with the passives.
Excellent video, Paul and historically you’re right on the money. But I suggest times have changed a bit or should I say opportunities have changed a bit. Try mating a passive pre with a pair of 600 wpc mono-block amps. Not only does the potential exist for a far more musical presentation, but you should also hear far more realistic bass and dynamics. Those familiar with high-end audio are often times impressed with silly things like “jump factor” that really is nothing more than amplified electronic distortions and have little to do with reality. The amplified gain stage of an active pre-amp induces distortions as well as “in-your-face” dynamics. Combine this scenario (active pre-amp) with very high-powered amplifiers and you’ll find yourself jumping with the initial attack of perhaps every note. Almost like your ears are running up onto the soundstage to hear the notes’ initial attack and then your ears run back into the audience to hear the notes’ ensuing decays. Nothing real there. But when mating that same very high-powered amplification with a passive pre-amp and suddenly all of the music, including all the initial attacks remain up on the soundstage while your ears remain planted in the audience. Very realistic. Moreover, the dynamics will no longer suffer with a passive pre with very high-powered amplification. Instead you’ll hear dynamics upon the soundstage where they belong again while your ears remain planted firmly in the audience where they belong and always with a distance. Again, very realistic. And like Paul said, since virtually every electronic adds its own noise, a well-designed passive pre should also sound significantly more pristine and even delicate. Also very realistic. And potentially quite musical.
Those interested in passive preamps should check out Schiit's preamps, the Saga and the Freya. They can be passive or active, using tubes or solid state, feature relay stepped attenuation, and are remote controlled. I have the Saga and love it but I did get the replacement remote so that I would have an aluminum one rather than the original plastic credit card type.
To clarify - the Saga+ can only be either *passive* or *hybrid active* (solid buffer, tube gain). The Freya+ in comparison can be 3 states - passive, buffered solid, or hybrid active (solid state buffer, tube gain stage).
Hi from the UK. Great presentation Paul. Straightened out a couple of issues I had in the back of my mind. Personally, I love a good passive PreAmp. Many these days are switchable between passive and true active operation which allows for some interesting side by side comparisons.
Hi, Paul. I have a PS Audio IV-H that I bought new c.1983-4 and still love it. Had a service done once and recently had an issue with one of the two sets of outputs (just switched to the good one, but lost my subwoofer connection, which is OK). For a great product that is still working well after 39 years that is not bad! Don't really miss tone controls and use passive mode as much as possible, but my Magnepans are really power hungry. Before I bought this, I used to scour all the ads in Sterophile and TAS, but I alway seemed to be drawn to the IV-H. After reading reviews, when my local high-end dealer offered this to me at a really good price, I jumped on it and am so glad I did. Thanks for a great pre-amp.
I bought a 'passive' pre-amp with no volume control and itwas basically an input box and the the rca jacks output to the power-amp which controlled the volume, both were Pioneer brand, in the 80s, loved it until 15 years later when one of the channels began failing with crackling sound.
Paul, I followed your advice on not toeing in speakers to create a greater sweet-spot, well... It worked! the top end seemed better too! thanks for the tip!
I have always tried to move my speakers in many different postionins before there set just right to my Ear and half the time i do set them straight also, but ! Every once in Awhile. I 'LL buy a speaker, that sounds much better tilted in-out off axes, Some manufactors recommend this ,But hey if you love a wide soundstage ,then i think Paul was right about that for the majority of speakers but Speakers with Horn teeeters like a lil tow-in
This is true as long as space behind and to the outsides of the speakers is sufficient to allow correct sound diffusion in the room. If you do not have this, I have found that toeing in is necessary to achieve reasonably acceptable imaging. I feel that it is a trade-off between the two depending on the room in question.
It's all about source and load impedance matching. Source impedance should ideally be aways equal or lower than the device connected to it. A resistor in in this case in the form of a passive potentiometer will change this, especially at lower volume (giving increased resistance). A unity gain buffer, with a low output impedance when also having a higher input impedance than the maximum resistance of the passive potentiometer connected across the input, will restore a lower output impedance as presented to the device being driven, and drive that output device and connecting cables as expected. This is especially important when driving devices with reactive components such as series coupling capacitors before their first stage of amplication. These, driven by too high a source impedance would possiby contribute to the described bass loss given that they also increase the impededance at lower frequency too, adding to the total impedance presented to the first stage of amplification, at those frequencies. Then there are damping issues of any reactive circuit connected to source, including any capacitors in series with the source.
I was wondering why people would think it lacks bass. Perhaps it had capacitors in the signal path to cut out DC that were with too small capacitance yielding a high pass filtering reducing the bass or perhaps more likely, the perceived bass was less when the volume was 20dB lower as we naturally hear less bass when volume is lower?
The passive preamp assumes you have enough voltage from the Dac or whatever to drive a power amp directly. Common sense then says that the best preamp is no preamp. However, if you try it, or use a dac with a variable output to control the power amp at first it sounds great but after a while you miss the space, ease and dynamics of an active pre. Been there done that. It is a great way to evaluate how much colouration your active preamp is producing though..
The issue with resistive passive preamps is the high frequencies. At the 6db down point in the rotation of the pot, the output impedance is 1/4 the value of the pot. In most cases that will cause a loss of high frequencies due to the cable capacitance (plus any other shunt capacitance present). A transformer volume control (or autoformer volume control) gets around this issue while having issues of it's own.
I think the safest route is to use as little gain as you need. A bit is good. The gain can be easily changed in many preamps. Usually just a matter of changing a resistor or two.
Hi Paul, please enlighten me. I currently have a dac with a built in preamp. I want to upgrade to a dac without the preamp and use an external preamp. Because of cost I must do this in stages. Preamp first…I was told the internal preamp should be set to 94, to feed that out put through the external preamp.doing this until I can afford the new dac. I haven’t tried this, what can I hope for in sound quality? Thanks, mike
I saw a circuit in a HiFi magazine years ago that used a video amp IC for an audio buffer. It was supposed to have very wide bandwidth, low distortion, and put out enough current that it needed a good-sized heat sink. I have looked around since and never found it again.
The success or failure of a passive “preamp” really depends on the output impedance of the source component (lower is better) and the input impedance of the power amp (higher is better) along with the length and impedance of the connecting cables.
Hi Paul, you're right, PS Audio did not have the first passive volume control. I don't know if it was the first but Dynaco made one around early 1960; model DSC.
I agree with you. Passive pre-amp tend to have thin bass. How do we explain it technically? In a system, I computed bass drop using the output coupling capacitor capacitance value and the resistance of the volume pot. The amount of drop is 0.7 dB at 20 Hz. It is quite small compared to variations by speaker and room. Why do I feel 0.7 dB at 20 Hz? Does it have to do with RF noise? More RF noise is passed to power amp with passive pre?
The problem with passive preamps is that output impedance depends on the position of the volume pot. So it´s not fixed, if you put cable capacitance (the ones running from the preamp out to the power amp) in parallel with the potentiometer you have a variable high cut filter, so you loose trebble as well. That´s why you need a buffer, the problem is that it has to be transparent. And that´s diffucult and expensive. That´s the reason why intgrated amps are so popular in the mid price range IMHO, there you don´t need a preamp. An the sound is "integrated" and predictable.
I didn't know I had one but I do. A line in selector with volume pot (to turn it down not up). Not any good on the power amp section so it is on aux so I can use the great volume control on my amp. So now I have two pre-amps. Passive little Chinese box and the one in the AU-317. It helps me turn down the input voltage of the line in, so I can use more than the first two clicks of my volume control.
Hi Paul - I love your videos but, with respect, I have to disagree with your comment that passive preamps sound "wimpy". Yes, they can do, but as you point out, it's all about the cables - actually, as I've found out, it's all about the length of the cables. I have a fantastic Rotel RCD991 CD player from the 90s (with a R2R ladder DAC inside it, not a Sigma Delta). It has balanced outputs, so I run 1 metre cables into my Khozmo Acoustic Passive Preamp, into a Class D amplifier into a pair of Neat Audio Iota Alphas. The bass is phenomenal, the mids are exciting and the highs sparkle like diamonds. - Richard in the UK.
If you stick with a sensible impedance for the volume controt pot, say 10k, a lot of power amps will not sound noticeably worse compared to being connected to a low output impedance pre-amp, but then of course the source output impedance becomes more important. Some power amps are more tolerant of the output impedance of the passive or active pre-amp. These are notably the jfet input types, like marantz used for instance. Many integrated amps are in fact a passive pre-amp combined with a power amp and many did not sound lacking in bass. I don’t think 1m of interconnect would have changed the bass. In the old days lots of source components had output impedance of 470 ohm and more. Not buffering tape record outputs was particularly an issue with passive pre-amps as the power amp could influence the level to the tape record signal, and the tape deck loaded and interfered with the record signal. Tone controls did not work very well with passive pre-amps either.
Is a passive pre-amp just a selector switch and pot or can it be it that plus a unity gain buffer? You have to at least transform current (convert impedance) or amplify voltage to call something an amplifier. But it was installed in front of the power amp and that is where the “pre” comes from I guess. You can also charge more for something that contained the term “amplifier”. What you made was a passive attenuator. A bufferes attenuator is probably the most cost effective transparent solution with modern source components with high enough voltage output. It can have high input impedance and low output impedance. For some reason a lot of people liked to see tone controls on pre-amps although they would feel robbed of music if the tone controls were not defeated. This is where CD players changed the pre-amp market. Sufficient level and less need for tone controls and no more need for tape loops. People like to see lots of knobs on a pre-amp and lots of functions, the passive pre-amp selling price is difficult to justify by casual audiophiles. There are a number of good passive pre-amps, some use tapped signal transformers.
Couldn't you also use a transformer to step up the signal voltage? That would be expensive, but theoretically, assuming the power amp is of high enough input impedance, you could do this to boost low signal levels to line level without plugging it in at all.
I use 2004 OBH12 passive (dont use powered remote) with line level and sounds great. Never found bass to be an issue. Was running using nordost solar wind cables, NAD cd, marantz 50th anniversary monoblocks, mission m74i towers. Curently building jfet monoblocks with standalone power box. Experimenting using fine silver circuits. Will only keep OBH12 and cables from old system. Looking to drop cd player in favour of digital storage player, so a seperate jfet preamp planned to boost to line level...again using fine silver circuits.
i dont get it. i can see the use of passive EQ controls, but passive preamp? so it really is just to turn down volume if its too high coming from the source?
The criticism is always that the source component would not have enough juice to drive an amp directly. I've been using passive preamps for decades, love them. and the only condition being that your interconnects to and from the passive box should be 1 meter - or not much more. I never missed any dynamics (another criticism) or bass response except when I used plastic contact "pots." Use carbon contact pots (cheap) or stepped attenuators with metal film resistors (expensive). PS Just remembered, they won't work well with tube amps. Impedance issues. Use a 10K pot with a solid state amp.
I'd skip the tone control unless you have a special use for it. Since leaving commercial audio gear for the high end components I've never missed tone controls. I'd think it would compromise the purity of a passive box and perhaps cause impedance problems, but try before you buy.
Yes, totally agree on that point. I have Audio Pro active speakers for work (laptop) setup that are kind of heavy on bass while mids and highs are where it should be. I already purchased Loki (with passive controls & a bypass option) and it work like a charm with those speakers. Again, this is not a high end setup - just a desktop one and it does compensate very well for otherwise very good active bookshelf speakers. Tone controls on a high-end setup - Maybe a bit of "help" on some bad recordings but otherwise not much of a reason why to have them in a first place. Thanks again for a cable tip!
PalJoey1957 Agree with you except on the tube amp part Been using a Reference Line Perfectionist Attenuator passive preamp with my Quicksilver mono 8417 tube amps (via custom 0.7m RCAs) and it works fine, exactly as you describe it. Maybe because of the no now 100K impedance input? Anyway, love it over my active tube preamp
I love passive preamp and I am aware of the “whimpy bass” issue inherited with such preamp. Which is why I added a Burson Cable+ Pro (which has a built-in driver). This solves it.
Kopi I want to tone down the bass a bit from my JC1 mono blocks driving rather sensitive Kef R 900 speakers. Do you think a passive preamp would work well for my system?
Thanks Paul. You got me wondering: My bridged stereo amps have a second switched input each. This means I could bypass my active preamp. If I use a tube buffer and passive pre, which should go on the output of the CD player : pot or buffer? Thanks in advance :-)
No phono input, no headphone jack, no possibility to adjust the treble and bass, when some songs are badly recorded. I have tried all sorts of passive preamps, LDRs, switched resistor models, the best potentiometers, (Alps, Eizz, Khozmo, Goldpoint) and even DACs with digital volume control (RME ADI-2FS) attacking power amps directly. I could never find the sound I was looking for, it's too harsh, it lacks airiness, it sounds a bit confusing. For me, nothing beats a quality preamp, like Class A, or even better with tubes.
I'm interested to know what peoples thoughts on using home theater pre amps in high end audio. I currently use my Marantz pre pro, with Emotiva power amps but find that my $300 parasound pre amp sounds better than the Marantz, at least with 2 channel stereo listening, hooked up to the same power amps. I've always wanted to get a nice integrated amp with a home theater bypass feature although I find it is better to separate the home theater components from stereo listening system...
Paul is right. Passive preamps are a bit whimpy in the bass regions, thus giving the overall presentation a lack of depth, warmth, fullness, dynamics, balance, etc. to an otherwise potentially more musical, pristine and dare I say delicate playback presentation. But that was way back when. Try a passive pre-amp with some of today's very high-powered amps and the problem is solved. Not only solved, but if you care about the quality of music in a playback presentation, and the chances are quite good you'll never go back to an active gain stage again. Other beneifts of a sufficient passive pre-amp is that the electronics-induced jump factor disappears or is minimized and all the music falls back onto the soundstage where it belongs while your ears remain planted in the audience where they below. IOW, no more in-your-face music that is so typical of today's "hi-fi" playback systems. Just sayin' .
What if I make a phono preamp with a feed direct from the pot to the mid/treble power amp (passive) and a feed from a line buffer to the bass power amp (active)?
I used a quality passive preamp for a couple of years, but eventually I tried a BAT tube preamp instead and was blown away by the improvement in sound stage and presence as well as frequency response. I would advise NEVER to use a passive preamp.
The answer is simple: because they are not pre-amplifiers, they are volume controls. That's the first reason. The second reason is that, in order to buy a good one - despite it being just a volume control - you need to spend a lot. If all you are after is potentiometer, then it's back to reason one: it's not a pre-amplifier.
I have JC1 mono blocks driving Kef R900 speakers and the lower volume bass is a bit too much, so a passive (technically non) preamp might be just what I need. I want "whimper bass" haha! I am interested in anyone's knowledgeable opinions before I spend the time, money and effort building one.
Capable of being an iconoclast when I find something that works.... As a "buffer," I use s BBE Sonic Maximizer along with a passive preamp. Only use the BBE for its linear dynamic bass adjustment. High definition audio. I found all the regular preamps I have tried censors the music. Tried tubes... solid state.. Nice effects in a way. But, all censored the music. BTW.. my system consists of a PSA S300 and Schiit Yggdrasil DAC... Not shabby. Using at the moment only a simple passive with a blue ALPS running in balanced mode. Eye opener in a nearfield set up. (update) After saying all that? Found a very good tube balanced preamp.... I repent. That, is better than the passive.
Depending upon your speakers and where they are located in the room. Just keep adding some "lo Contour" until it sounds "just right." I only use phase coherent speakers.. I also make sure that I can move the speakers horizontally, vertically, angle, and distance.. precisely. Makes for a surprisingly great sounding "miniature stage" of performers at your desk top. After all, when you are sitting at a concert the performers are really miniature from your point of viewing. That's how I like listening as well. BBE also makes compact Maximizers for desktop use now. I have both their balanced configuration and single ended. I will not listen without one. Try Googling ' BBE 282i ' The only thing I found with them to be a problem was that its wall wart needs to be turned upside down in the socket. Intuitively, you would leave its wire hanging down in a three prong socket having its round ground situated on the bottom. The AC polarity needs to be reversed, having its wire pointing upward. REALLY makes an excellent difference. Just do not use the process function unless your tweeters are dull. Today most tweeters will not need it.
BBE now makes compact units (balanced and one for unbalanced) for desktop use.. You do not set it to any particular level other than listening and setting it by ear. It all depends on your room and speakers. Makes UA-cam videos sound fantastic. BBE's wall warts need to be inverted in the socket to get the right AC polarity. Really helps the sound for the better! So? When looking at the AC socket, with the round ground situated under the neutral and hot..... plug the WW in upside down, rather than having the cord hanging down. Its a secret of extracting the best sound from the desktop units. Found out it uses a proprietary chip made by the same company that manufactures the famous audiophile Muses 01 op-amps.
I do not believe I have ever heard of a passive pre amp. I do have some electronic design experience, and occasionally design and build specific purpose circuits. In all of my experience, "Passive" as far as electronic circuits go, has always meant that the circuit did not have any power supply, batteries, or related. Because of this video, i just checked out "Passive pre amps", and found one that is just an attenuator, but much to my surprise, it is available with either 120 vac, or 240 vac power. I have also found passive pre amps, that are pre amps like I understand, multiple switched input, but again, switchable 120 to 240 vac, and further more, software to download and install. I guess the meaning of a "Passive" circuit must have changed considerable, or, I have missed some major aspect in my electronics study and experience. Could you please enlighten me on the aspects of how both of these passive pre amps that I have found are passive when they both require power from the mains? Thanks ahead of time :)
A lot of passive devices have a power supply to drive a motorized pot or stepped attenuator for remote operation, or a display showing input and volume setting. The power is not actually part of the circuit.
Passive pre is just an attenuator. A potentiometer or resistor ladder. There is no reason they should cost much money. I use one between my Oppo DVD/CD player and power amp. The Oppo puts out a rather high voltage and there is signal aplenty to play with. Just a potentiometer in a nice case. But nice casework can be expensive. I’m sure a huge percentage of high end audio prices is for to the casework.
I use a case from a nice looking but dead Acurus preamp for my passive pre. It had electronic source switching and volume control in big multi pin chips prior. Now a rotary mechanical source select switch and a motorized potentiometer with remote replace the two rotary digital encoders.
I still have a PS Audio IVH preamp I bought in the early '80s with "active/passive" feature sitting in a box in my basement. Unfortunately, it developed noise in the phono stage. I contacted PS Audio a couple months ago and they said it couldn't be repaired. anyway... I did like the passive feature and used it.
If a preamp contaminates the sound of the source, why not add a preamp to the source with the sound you want and add a volume contol? Then add a selector switch to the power amp. This can save the consumer money on expensive cables and power conditioners depending on the brand and setup.
Dont listen to them. Ohms law is about how electronic products work and interact. You can search on it if you want to know more. You can not have good sound without products working according to the laws of physics.
And here is the engineer explanation. It's also fun. www.diyaudio.com/forums/analog-line-level/219342-help-choosing-potentiometer-passive-preamplifier.html
A passive preamp is terrible. It has a very narrow useful range compared to active electronics. It will rob the dynamics of the sound as it increases output impedance in a way that creates a filter. Impossible to maintain SNR with a passive device like this.
Yes it would need gain when it goes to the amplifier,suffix PRE- means before amplification,guitars typically have a volume control either for one pickup or two and a further tonepot coupled with a capacitor,its common for guitars to have tone control for both pick-ups,the impedance of the potentiometers are chosen for the pickups or in some cases for the actual tone you want, the pickups themselves are the voltage supplyed by the varying magnetic field cut with the string vibration.Active is getting more common these days but not always desired. Passive implies there is no active components before amplification,though the source is the voltage.
not a pre-amp the amp stands for amplifier no gain not an amp, its a passive amplitude reducer. these guys must have been laughung long and hard while cashing the checks. cheeky swine pot=amp, he knows better
Any engineer would call it a variable attenuator, but audio enthusiasts would call it a pre-amp because it takes the place of where a true pre-amp would usually go. It's a vestigial name. Like saying "LED light bulb" even though there's no longer a glass globe in them.
Yeah, I pretty much agree with you (fancy that, agreeing with somebody on UA-cam) and indeed there are a lot of examples like Mobile (cell) Phones still have "bad lines" when we have problems with a connection. Similarly, an amplifier that is not an amplifier is called an amplifier, and hence we have a "passive preamplifier" which is really an oxymoron. But being old-school and in audio for fifty years (yeah, I am getting old, but only in body) I kinda like getting things right in what is my chosen field. Hope you don't mind? :)
I would call the device a variable attenuator since this is what it does. It either passes the signal straight (volume turned all the way up) or attenuates it. However, I personally do not need such a device since all my amplifiers have volume controls. But then again, I built a tube device that I call a "power preamp", which is a preamp (input selector, tape monitor, volume, balance, mono switch, headphone output), but also has a ~2W SE output stage. It has a variable-level output to the power amp and when I switch the mode, it disconnects the speaker outputs (so I can connect it and the power amp in parallel, the power amp disconnects the speakers when the power is off) and connects the power to the power amp. The reason I built it like this is that I realized that most of the time I listen to music (or watch a movie) at a low sound level, so I do not need to turn on the power amp and its tubes if I do not want to turn the volume up. And I also get the SE triode sound with 2nd order harmonics.
"San-sewer"? Greasy comment's about other companies products in an effort to elevate yourself reveals the something of the true character behind your products. Unprofessional. I would not proudly display a PS Audio product after having heard that.
dunno!.. Passive preamps sounds like snake oil !..Much like Expensive interconnects or speaker cables..Guess audiophiles need to spend their money somewhow! Always like the Philosophy.. less is better!
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I completely agree with your assessment of passive preamps. I went though 2 different kinds (including one fairly expensive one) before going back to a real preamp which restored the dynamics and bass that I had been missing with the passives.
Townshend Allegri +
Yup. Weaker dynamics with passive. Tried it, now back to active.
Congrats!
Thanks for caring bout audio
&
thanks for the history.
Excellent video, Paul and historically you’re right on the money. But I suggest times have changed a bit or should I say opportunities have changed a bit. Try mating a passive pre with a pair of 600 wpc mono-block amps. Not only does the potential exist for a far more musical presentation, but you should also hear far more realistic bass and dynamics.
Those familiar with high-end audio are often times impressed with silly things like “jump factor” that really is nothing more than amplified electronic distortions and have little to do with reality. The amplified gain stage of an active pre-amp induces distortions as well as “in-your-face” dynamics. Combine this scenario (active pre-amp) with very high-powered amplifiers and you’ll find yourself jumping with the initial attack of perhaps every note. Almost like your ears are running up onto the soundstage to hear the notes’ initial attack and then your ears run back into the audience to hear the notes’ ensuing decays. Nothing real there.
But when mating that same very high-powered amplification with a passive pre-amp and suddenly all of the music, including all the initial attacks remain up on the soundstage while your ears remain planted in the audience. Very realistic. Moreover, the dynamics will no longer suffer with a passive pre with very high-powered amplification. Instead you’ll hear dynamics upon the soundstage where they belong again while your ears remain planted firmly in the audience where they belong and always with a distance. Again, very realistic.
And like Paul said, since virtually every electronic adds its own noise, a well-designed passive pre should also sound significantly more pristine and even delicate. Also very realistic. And potentially quite musical.
Those interested in passive preamps should check out Schiit's preamps, the Saga and the Freya. They can be passive or active, using tubes or solid state, feature relay stepped attenuation, and are remote controlled. I have the Saga and love it but I did get the replacement remote so that I would have an aluminum one rather than the original plastic credit card type.
To clarify - the Saga+ can only be either *passive* or *hybrid active* (solid buffer, tube gain).
The Freya+ in comparison can be 3 states - passive, buffered solid, or hybrid active (solid state buffer, tube gain stage).
Hi from the UK. Great presentation Paul. Straightened out a couple of issues I had in the back of my mind. Personally, I love a good passive PreAmp. Many these days are switchable between passive and true active operation which allows for some interesting side by side comparisons.
Hi, Paul. I have a PS Audio IV-H that I bought new c.1983-4 and still love it. Had a service done once and recently had an issue with one of the two sets of outputs (just switched to the good one, but lost my subwoofer connection, which is OK). For a great product that is still working well after 39 years that is not bad! Don't really miss tone controls and use passive mode as much as possible, but my Magnepans are really power hungry. Before I bought this, I used to scour all the ads in Sterophile and TAS, but I alway seemed to be drawn to the IV-H. After reading reviews, when my local high-end dealer offered this to me at a really good price, I jumped on it and am so glad I did. Thanks for a great pre-amp.
Thansk!
I bought a 'passive' pre-amp with no volume control and itwas basically an input box and the the rca jacks output to the power-amp which controlled the volume, both were Pioneer brand, in the 80s, loved it until 15 years later when one of the channels began failing with crackling sound.
Paul, I followed your advice on not toeing in speakers to create a greater sweet-spot, well... It worked! the top end seemed better too! thanks for the tip!
I have always tried to move my speakers in many different postionins before there set just right to my Ear and half the time i do set them straight also, but ! Every once in Awhile. I 'LL buy a speaker, that sounds much better tilted in-out off axes, Some manufactors recommend this ,But hey if you love a wide soundstage ,then i think Paul was right about that for the majority of speakers but Speakers with Horn teeeters like a lil tow-in
This is true as long as space behind and to the outsides of the speakers is sufficient to allow correct sound diffusion in the room. If you do not have this, I have found that toeing in is necessary to achieve reasonably acceptable imaging. I feel that it is a trade-off between the two depending on the room in question.
It's all about source and load impedance matching. Source impedance should ideally be aways equal or lower than the device connected to it. A resistor in in this case in the form of a passive potentiometer will change this, especially at lower volume (giving increased resistance). A unity gain buffer, with a low output impedance when also having a higher input impedance than the maximum resistance of the passive potentiometer connected across the input, will restore a lower output impedance as presented to the device being driven, and drive that output device and connecting cables as expected. This is especially important when driving devices with reactive components such as series coupling capacitors before their first stage of amplication. These, driven by too high a source impedance would possiby contribute to the described bass loss given that they also increase the impededance at lower frequency too, adding to the total impedance presented to the first stage of amplification, at those frequencies. Then there are damping issues of any reactive circuit connected to source, including any capacitors in series with the source.
I was wondering why people would think it lacks bass. Perhaps it had capacitors in the signal path to cut out DC that were with too small capacitance yielding a high pass filtering reducing the bass or perhaps more likely, the perceived bass was less when the volume was 20dB lower as we naturally hear less bass when volume is lower?
Fletcher-Munson would be the explanation since he mentioned that the diminished bass couldn't be *measured*.
The passive preamp assumes you have enough voltage from the Dac or whatever to drive a power amp directly. Common sense then says that the best preamp is no preamp. However, if you try it, or use a dac with a variable output to control the power amp at first it sounds great but after a while you miss the space, ease and dynamics of an active pre. Been there done that. It is a great way to evaluate how much colouration your active preamp is producing though..
Your first sentence hit the nail on the head.
Fun listening to your stories.. Gives products a texture.. thanks!
The issue with resistive passive preamps is the high frequencies. At the 6db down point in the rotation of the pot, the output impedance is 1/4 the value of the pot. In most cases that will cause a loss of high frequencies due to the cable capacitance (plus any other shunt capacitance present). A transformer volume control (or autoformer volume control) gets around this issue while having issues of it's own.
I think the safest route is to use as little gain as you need. A bit is good. The gain can be easily changed in many preamps. Usually just a matter of changing a resistor or two.
Hi Paul, please enlighten me. I currently have a dac with a built in preamp. I want to upgrade to a dac without the preamp and use an external preamp. Because of cost I must do this in stages. Preamp first…I was told the internal preamp should be set to 94, to feed that out put through the external preamp.doing this until I can afford the new dac. I haven’t tried this, what can I hope for in sound quality?
Thanks, mike
I saw a circuit in a HiFi magazine years ago that used a video amp IC for an audio buffer. It was supposed to have very wide bandwidth, low distortion, and put out enough current that it needed a good-sized heat sink. I have looked around since and never found it again.
The success or failure of a passive “preamp” really depends on the output impedance of the source component (lower is better) and the input impedance of the power amp (higher is better) along with the length and impedance of the connecting cables.
Hi Paul, you're right, PS Audio did not have the first passive volume control. I don't know if it was the first but Dynaco made one around early 1960; model DSC.
I agree with you. Passive pre-amp tend to have thin bass. How do we explain it technically? In a system, I computed bass drop using the output coupling capacitor capacitance value and the resistance of the volume pot. The amount of drop is 0.7 dB at 20 Hz. It is quite small compared to variations by speaker and room. Why do I feel 0.7 dB at 20 Hz?
Does it have to do with RF noise? More RF noise is passed to power amp with passive pre?
The problem with passive preamps is that output impedance depends on the position of the volume pot. So it´s not fixed, if you put cable capacitance (the ones running from the preamp out to the power amp) in parallel with the potentiometer you have a variable high cut filter, so you loose trebble as well. That´s why you need a buffer, the problem is that it has to be transparent. And that´s diffucult and expensive. That´s the reason why intgrated amps are so popular in the mid price range IMHO, there you don´t need a preamp. An the sound is "integrated" and predictable.
I didn't know I had one but I do. A line in selector with volume pot (to turn it down not up). Not any good on the power amp section so it is on aux so I can use the great volume control on my amp. So now I have two pre-amps. Passive little Chinese box and the one in the AU-317. It helps me turn down the input voltage of the line in, so I can use more than the first two clicks of my volume control.
Wait, so if I turn the volume down on my dac/amp what happens? Does it convert less or just provide less amplification?
Is there a device that doesn’t have a volume knob or a buffer? Literally just lets me toggle between different inputs and outputs?
Hi Paul - I love your videos but, with respect, I have to disagree with your comment that passive preamps sound "wimpy". Yes, they can do, but as you point out, it's all about the cables - actually, as I've found out, it's all about the length of the cables. I have a fantastic Rotel RCD991 CD player from the 90s (with a R2R ladder DAC inside it, not a Sigma Delta). It has balanced outputs, so I run 1 metre cables into my Khozmo Acoustic Passive Preamp, into a Class D amplifier into a pair of Neat Audio Iota Alphas. The bass is phenomenal, the mids are exciting and the highs sparkle like diamonds. - Richard in the UK.
If you stick with a sensible impedance for the volume controt pot, say 10k, a lot of power amps will not sound noticeably worse compared to being connected to a low output impedance pre-amp, but then of course the source output impedance becomes more important.
Some power amps are more tolerant of the output impedance of the passive or active pre-amp. These are notably the jfet input types, like marantz used for instance. Many integrated amps are in fact a passive pre-amp combined with a power amp and many did not sound lacking in bass. I don’t think 1m of interconnect would have changed the bass.
In the old days lots of source components had output impedance of 470 ohm and more.
Not buffering tape record outputs was particularly an issue with passive pre-amps as the power amp could influence the level to the tape record signal, and the tape deck loaded and interfered with the record signal. Tone controls did not work very well with passive pre-amps either.
Hey Paul!! Question...that switch on that passive preamp with the -20dB & 0 dB....could that switch be considered a quasi-pad?!?!
Is a passive pre-amp just a selector switch and pot or can it be it that plus a unity gain buffer? You have to at least transform current (convert impedance) or amplify voltage to call something an amplifier. But it was installed in front of the power amp and that is where the “pre” comes from I guess. You can also charge more for something that contained the term “amplifier”. What you made was a passive attenuator. A bufferes attenuator is probably the most cost effective transparent solution with modern source components with high enough voltage output. It can have high input impedance and low output impedance. For some reason a lot of people liked to see tone controls on pre-amps although they would feel robbed of music if the tone controls were not defeated. This is where CD players changed the pre-amp market. Sufficient level and less need for tone controls and no more need for tape loops.
People like to see lots of knobs on a pre-amp and lots of functions, the passive pre-amp selling price is difficult to justify by casual audiophiles.
There are a number of good passive pre-amps, some use tapped signal transformers.
Love the AU717, and its phono circuit.
Couldn't you also use a transformer to step up the signal voltage? That would be expensive, but theoretically, assuming the power amp is of high enough input impedance, you could do this to boost low signal levels to line level without plugging it in at all.
30 years ago…audible illusions tube preamp was Best Buy far…magic back then….
I use 2004 OBH12 passive (dont use powered remote) with line level and sounds great. Never found bass to be an issue. Was running using nordost solar wind cables, NAD cd, marantz 50th anniversary monoblocks, mission m74i towers.
Curently building jfet monoblocks with standalone power box. Experimenting using fine silver circuits. Will only keep OBH12 and cables from old system.
Looking to drop cd player in favour of digital storage player, so a seperate jfet preamp planned to boost to line level...again using fine silver circuits.
i dont get it. i can see the use of passive EQ controls, but passive preamp? so it really is just to turn down volume if its too high coming from the source?
This is one of your best talks I have heard.
The criticism is always that the source component would not have enough juice to drive an amp directly. I've been using passive preamps for decades, love them. and the only condition being that your interconnects to and from the passive box should be 1 meter - or not much more.
I never missed any dynamics (another criticism) or bass response except when I used plastic contact "pots." Use carbon contact pots (cheap) or stepped attenuators with metal film resistors (expensive).
PS Just remembered, they won't work well with tube amps. Impedance issues. Use a 10K pot with a solid state amp.
cca. 1m long or less?! That's good to know. I am looking into Schiit Audio Sys passive preamp and Loki tone control combo for my desktop... Thanks.
I'd skip the tone control unless you have a special use for it. Since leaving commercial audio gear for the high end components I've never missed tone controls. I'd think it would compromise the purity of a passive box and perhaps cause impedance problems, but try before you buy.
Yes, totally agree on that point. I have Audio Pro active speakers for work (laptop) setup that are kind of heavy on bass while mids and highs are where it should be. I already purchased Loki (with passive controls & a bypass option) and it work like a charm with those speakers. Again, this is not a high end setup - just a desktop one and it does compensate very well for otherwise very good active bookshelf speakers.
Tone controls on a high-end setup - Maybe a bit of "help" on some bad recordings but otherwise not much of a reason why to have them in a first place.
Thanks again for a cable tip!
I have never owned a system that didn't need gain as compared to the signal direct from the components.
PalJoey1957
Agree with you except on the tube amp part
Been using a Reference Line Perfectionist Attenuator passive preamp with my Quicksilver mono 8417 tube amps (via custom 0.7m RCAs) and it works fine, exactly as you describe it. Maybe because of the no now 100K impedance input?
Anyway, love it over my active tube preamp
I love passive preamp and I am aware of the “whimpy bass” issue inherited with such preamp. Which is why I added a Burson Cable+ Pro (which has a built-in driver). This solves it.
Kopi I want to tone down the bass a bit from my JC1 mono blocks driving rather sensitive Kef R 900 speakers. Do you think a passive preamp would work well for my system?
Thanks Paul.
You got me wondering:
My bridged stereo amps have a second switched input each.
This means I could bypass my active preamp.
If I use a tube buffer and passive pre, which should go on the output of the CD player : pot or buffer?
Thanks in advance :-)
I wonder how Schiit's SYS sounds. I was curious about it for one of their headphone amplifiers.
You invented the tone defeat! That's cool!
Not tone defeat, gain defeat.
No phono input, no headphone jack, no possibility to adjust the treble and bass, when some songs are badly recorded. I have tried all sorts of passive preamps, LDRs, switched resistor models, the best potentiometers, (Alps, Eizz, Khozmo, Goldpoint) and even DACs with digital volume control (RME ADI-2FS) attacking power amps directly. I could never find the sound I was looking for, it's too harsh, it lacks airiness, it sounds a bit confusing. For me, nothing beats a quality preamp, like Class A, or even better with tubes.
the Audio Research toggle switches are still the coolest things.
I'm interested to know what peoples thoughts on using home theater pre amps in high end audio. I currently use my Marantz pre pro, with Emotiva power amps but find that my $300 parasound pre amp sounds better than the Marantz, at least with 2 channel stereo listening, hooked up to the same power amps. I've always wanted to get a nice integrated amp with a home theater bypass feature although I find it is better to separate the home theater components from stereo listening system...
Oh wow quick question. I just got a Marantz Pre-amp at a yard sale and i find the noise floor on it to be really high...is this a issue with yours?
Paul is right. Passive preamps are a bit whimpy in the bass regions, thus giving the overall presentation a lack of depth, warmth, fullness, dynamics, balance, etc. to an otherwise potentially more musical, pristine and dare I say delicate playback presentation.
But that was way back when. Try a passive pre-amp with some of today's very high-powered amps and the problem is solved. Not only solved, but if you care about the quality of music in a playback presentation, and the chances are quite good you'll never go back to an active gain stage again. Other beneifts of a sufficient passive pre-amp is that the electronics-induced jump factor disappears or is minimized and all the music falls back onto the soundstage where it belongs while your ears remain planted in the audience where they below. IOW, no more in-your-face music that is so typical of today's "hi-fi" playback systems.
Just sayin'
.
What if I make a phono preamp with a feed direct from the pot to the mid/treble power amp (passive) and a feed from a line buffer to the bass power amp (active)?
Would it be possible to have a power amp that is bias towards the base end of the audio spectrum and therefore custom-made for a passive preamplifier?
But then it wouldn't be a high fidelity amplifier, ie. something that takes the input and does absolutely nothing but make it bigger.
CI Audio makes some passive controllers. They are worth a listen.
I used a quality passive preamp for a couple of years, but eventually I tried a BAT tube preamp instead and was blown away by the improvement in sound stage and presence as well as frequency response. I would advise NEVER to use a passive preamp.
A "passive amplifier" is not an amplifier (with or without "pre").
I figured it was an April fools prank.
The answer is simple: because they are not pre-amplifiers, they are volume controls. That's the first reason. The second reason is that, in order to buy a good one - despite it being just a volume control - you need to spend a lot. If all you are after is potentiometer, then it's back to reason one: it's not a pre-amplifier.
Does anybody make such a device with buffering these days. I pretty much only run my CD player now
Amusingly the Linear Control Center obviously used logarithmic taper pots, as opposed to linear taper.
what is it used for?
I have JC1 mono blocks driving Kef R900 speakers and the lower volume bass is a bit too much, so a passive (technically non) preamp might be just what I need. I want "whimper bass" haha! I am interested in anyone's knowledgeable opinions before I spend the time, money and effort building one.
Capable of being an iconoclast when I find something that works.... As a "buffer," I use s BBE Sonic Maximizer along with a passive preamp. Only use the BBE for its linear dynamic bass adjustment. High definition audio. I found all the regular preamps I have tried censors the music. Tried tubes... solid state.. Nice effects in a way. But, all censored the music.
BTW.. my system consists of a PSA S300 and Schiit Yggdrasil DAC... Not shabby. Using at the moment only a simple passive with a blue ALPS running in balanced mode. Eye opener in a nearfield set up. (update) After saying all that? Found a very good tube balanced preamp.... I repent. That, is better than the passive.
A Sonic Maximizer? Interesting. I've used those in studios, but never for home audio. So you bypass process mode and set the lo contour to what?
Depending upon your speakers and where they are located in the room. Just keep adding some "lo Contour" until it sounds "just right." I only use phase coherent speakers.. I also make sure that I can move the speakers horizontally, vertically, angle, and distance.. precisely. Makes for a surprisingly great sounding "miniature stage" of performers at your desk top. After all, when you are sitting at a concert the performers are really miniature from your point of viewing. That's how I like listening as well.
BBE also makes compact Maximizers for desktop use now. I have both their balanced configuration and single ended. I will not listen without one. Try Googling ' BBE 282i ' The only thing I found with them to be a problem was that its wall wart needs to be turned upside down in the socket. Intuitively, you would leave its wire hanging down in a three prong socket having its round ground situated on the bottom. The AC polarity needs to be reversed, having its wire pointing upward. REALLY makes an excellent difference. Just do not use the process function unless your tweeters are dull. Today most tweeters will not need it.
BBE now makes compact units (balanced and one for unbalanced) for desktop use.. You do not set it to any particular level other than listening and setting it by ear. It all depends on your room and speakers. Makes UA-cam videos sound fantastic. BBE's wall warts need to be inverted in the socket to get the right AC polarity. Really helps the sound for the better! So? When looking at the AC socket, with the round ground situated under the neutral and hot..... plug the WW in upside down, rather than having the cord hanging down. Its a secret of extracting the best sound from the desktop units. Found out it uses a proprietary chip made by the same company that manufactures the famous audiophile Muses 01 op-amps.
2:56 “bless you”
I do not believe I have ever heard of a passive pre amp. I do have some electronic design experience, and occasionally design and build specific purpose circuits. In all of my experience, "Passive" as far as electronic circuits go, has always meant that the circuit did not have any power supply, batteries, or related. Because of this video, i just checked out "Passive pre amps", and found one that is just an attenuator, but much to my surprise, it is available with either 120 vac, or 240 vac power. I have also found passive pre amps, that are pre amps like I understand, multiple switched input, but again, switchable 120 to 240 vac, and further more, software to download and install. I guess the meaning of a "Passive" circuit must have changed considerable, or, I have missed some major aspect in my electronics study and experience. Could you please enlighten me on the aspects of how both of these passive pre amps that I have found are passive when they both require power from the mains? Thanks ahead of time :)
A lot of passive devices have a power supply to drive a motorized pot or stepped attenuator for remote operation, or a display showing input and volume setting. The power is not actually part of the circuit.
Passive pre is just an attenuator. A potentiometer or resistor ladder. There is no reason they should cost much money. I use one between my Oppo DVD/CD player and power amp. The Oppo puts out a rather high voltage and there is signal aplenty to play with. Just a potentiometer in a nice case. But nice casework can be expensive. I’m sure a huge percentage of high end audio prices is for to the casework.
Greg Olson Definitely. The passive attenuator I checked out above, I think was something like $1,600.00 for the cheaper one. I was absolutely shocked!
BiddieTube there’s a sucker born every minute right!
I use a case from a nice looking but dead Acurus preamp for my passive pre. It had electronic source switching and volume control in big multi pin chips prior. Now a rotary mechanical source select switch and a motorized potentiometer with remote replace the two rotary digital encoders.
Paul, can I buy one of those please? :)
Thanks.
I still have a PS Audio IVH preamp I bought in the early '80s with "active/passive" feature sitting in a box in my basement. Unfortunately, it developed noise in the phono stage. I contacted PS Audio a couple months ago and they said it couldn't be repaired. anyway... I did like the passive feature and used it.
If a preamp contaminates the sound of the source, why not add a preamp to the source with the sound you want and add a volume contol? Then add a selector switch to the power amp. This can save the consumer money on expensive cables and power conditioners depending on the brand and setup.
Some products do have those.
PS Audio's own Directstream DAC's have a built in preamp with volume control, as one example.
Unless you're using mono blocks I don't see any reason not to go intergrated.
I like my POT in the Box
I invented the Passive Power Amp. Noise is based solely on physical temperature. These are very very quiet and consume no power.
I had a passive pre-amp and it sounded anemic.
I've never heard an active pre amp sound better than any passive pre amp.
What is this "Ohm's Law" that Paul keeps talking about. Is it an RSS feed/Podcast or what?
It's an audio only version of the video on the PS Audio website.
Dont listen to them. Ohms law is about how electronic products work and interact. You can search on it if you want to know more. You can not have good sound without products working according to the laws of physics.
The term "passive preamp" is a contradiction in itself. Its a passive switchbox with a pot or a preamp. It cant be both at the same time.
And here is the engineer explanation. It's also fun. www.diyaudio.com/forums/analog-line-level/219342-help-choosing-potentiometer-passive-preamplifier.html
A passive preamp is terrible. It has a very narrow useful range compared to active electronics. It will rob the dynamics of the sound as it increases output impedance in a way that creates a filter. Impossible to maintain SNR with a passive device like this.
i thought passive tone controls were ridiculous enough. now it turns out i was wrong.
Passive preamp is a contradiction, because there is no amplification involved.
Sansewer? Fruedian slip.
Freudian
Riechian, maybe Jungien.
Not so much a slip, IMO.
Probably the electric guitar had one of the first passive pre amps.
Yes it would need gain when it goes to the amplifier,suffix PRE- means before amplification,guitars typically have a volume control either for one pickup or two and a further tonepot coupled with a capacitor,its common for guitars to have tone control for both pick-ups,the impedance of the potentiometers are chosen for the pickups or in some cases for the actual tone you want, the pickups themselves are the voltage supplyed by the varying magnetic field cut with the string vibration.Active is getting more common these days but not always desired.
Passive implies there is no active components before amplification,though the source is the voltage.
Dave Micolichek I'm not talking about the guitar amp,the guitar itself has a passive circuit, volume and tone it's the same simplified principal .
@Dave Micolichek The original "Pignose" 😋
Probably because they're not preamps, they're pre-attenuators.
Loading.
Oh that’s what a pot is!
not a pre-amp the amp stands for amplifier no gain not an amp, its a passive amplitude reducer. these guys must have been laughung long and hard while cashing the checks. cheeky swine pot=amp, he knows better
First like
Sansewer!
I know it's just a joke , but Sansui was a fantastic company.
@@danielesbordone1871 yeah fantastic..but somehow is dead...
@@danielesbordone1871 yup, decent sounding mid-fi for the time.... sound wise give it the nod over Pioneer albeit slightly lesser build quality.
Isn't "passive preamp" an oxymoron? lol
Well...it goes before the amp, right?
How, "pre" of something that does not exist? The correct term should be *Attenuator.*
Any engineer would call it a variable attenuator, but audio enthusiasts would call it a pre-amp because it takes the place of where a true pre-amp would usually go. It's a vestigial name. Like saying "LED light bulb" even though there's no longer a glass globe in them.
Yeah, I pretty much agree with you (fancy that, agreeing with somebody on UA-cam) and indeed there are a lot of examples like Mobile (cell) Phones still have "bad lines" when we have problems with a connection. Similarly, an amplifier that is not an amplifier is called an amplifier, and hence we have a "passive preamplifier" which is really an oxymoron. But being old-school and in audio for fifty years (yeah, I am getting old, but only in body) I kinda like getting things right in what is my chosen field. Hope you don't mind? :)
I would call the device a variable attenuator since this is what it does. It either passes the signal straight (volume turned all the way up) or attenuates it. However, I personally do not need such a device since all my amplifiers have volume controls.
But then again, I built a tube device that I call a "power preamp", which is a preamp (input selector, tape monitor, volume, balance, mono switch, headphone output), but also has a ~2W SE output stage. It has a variable-level output to the power amp and when I switch the mode, it disconnects the speaker outputs (so I can connect it and the power amp in parallel, the power amp disconnects the speakers when the power is off) and connects the power to the power amp.
The reason I built it like this is that I realized that most of the time I listen to music (or watch a movie) at a low sound level, so I do not need to turn on the power amp and its tubes if I do not want to turn the volume up. And I also get the SE triode sound with 2nd order harmonics.
"San-sewer"? Greasy comment's about other companies products in an effort to elevate yourself
reveals the something of the true character behind your products. Unprofessional. I would not proudly display a PS Audio product after having heard that.
dunno!.. Passive preamps sounds like snake oil !..Much like Expensive interconnects or speaker cables..Guess audiophiles need to spend their money somewhow! Always like the Philosophy.. less is better!
Honestly the difference is seriously slight been buying and selling for 20 years no need for pre amp unless you have more money then brains