What is responsible for soundstage in a preamp design?
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The short answer is there is not a well known answer to that question. It is not even clear that multiple different listeners agree on the presence of the effect. If you really wanted to answer the question in a rigorous way the first thing to do would be to make sure you can identify the effect when you can't see the label on the component (i.e. identify the sound against a known clean preamp when you can't see which preamp is in the signal path), and assuming that you can then measure all of the technical parameters of the preamp both static and dynamic (e.g. there may be a change in performance at higher amplitude, or only at certain frequencies, or only if the amplitude is changing above a certain rate, etc.). Once you have all the technical performance measurements you could either make a circuit that lets you add any identified imperfections in controllable amounts, or make a digital simulation of the behavior that would let you apply the effect to a signal recorded from one of the pre-amps which does not produce the effect and see which parameter (or possibly combination of parameters) produces the effect you hear.
Yes, that would be a tremendous amount of work, which is why there is not a well known answer to your question.
It is the $1M question, everyone has ideas, clearly no one knows. And $1M ain't worth half of what it was in 1992.
As a studio owner dealing with endless client perception, there's as many opposing opinions about what sounds good and why. The brilliant 3D tone of today may be despised tomorrow. Really.
The magic of the idea of soundstage is that works in mono too. It's about suggestion.
There's the endless argument that attributing these things to magic within the tech insults the skill of the operator; that one's hard to argue with. Some people can create it with any tech they are presented with, yet they also better have good source talent to have a head start. We all know this. Some equipment just seems to make audio capture easier. It'd be awesome to not have so much money invested in esoteric equipment, but it makes my life easier, and a whole lot of people wouldn't have the slightest idea where to begin operating a lot of what I use. A lot capturing different genre of audio wouldn't want anything to do with what I use, which makes life easier in the genre I tend to work with. So......who knows.....I can work with all this weirdo analog, I can mix live music broadcast on a modern digital console in a great sounding theater with top notch musicians, both sound fine. You can argue the room and the musicians make the live broadcast, but the console's definitely not getting in the way. I know ancient grizzled engineers with long successful music careers who do not give 2 shits what any of the equipment is, so long as it works. Not even the mics really matter to them, so long as there are some.
Looks like we failed nurturing the OP's confirmation bias...
The reference to TapeOp as a source of (dis)information is a tell-tale.
Horizoneer
Active member
Just in defence of the OP, I think that depth - a sense of a recorded sound being closer or further away - is an experience lots of mixers have had. Indeed, when I mix it's one of the main things I'm aiming for. Stereo width has been talked about a fair amount in this thread but it's something different. It's the feeling that a single mono channel has depth to it, even though it's a solid mono source.
Two particularly clear examples of it that I've experienced:
Hearing a nicely multi-miked drum kit in a studio with excellent isolation between the live and control room. Listening live through the desk & a pair of full range ATC monitors to what the drummer was playing, you could close your eyes ad genuinely believe the drum kit was there in front of you. The cymbals had life, depth and apparent size beyond left-right.
Then we listened back to that same performance, recorded through an old MOTU interface (this was 2003). It had lost its depth, even though the same mix of microphones was coming back at us. Particularly in the cymbals, the sounds was now flat. Stereo, but flat with a much reduced illusion of depth.
The second example - recording guitar through a Neve 80-series console. The sound again had a sense of front-back depth; like the strings were there right between but a little behind the speakers.
I'm not going to say x preamp does this and y preamp does not, or hazard a guess as to why it does or doesn't happen. It'll be a number of factors working together. I will say that when I'm mixing, I find that compression and subtle harmonic distortion are good ways to control a track's depth and position in the mix relative to other tracks.
Two particularly clear examples of it that I've experienced:
Hearing a nicely multi-miked drum kit in a studio with excellent isolation between the live and control room. Listening live through the desk & a pair of full range ATC monitors to what the drummer was playing, you could close your eyes ad genuinely believe the drum kit was there in front of you. The cymbals had life, depth and apparent size beyond left-right.
Then we listened back to that same performance, recorded through an old MOTU interface (this was 2003). It had lost its depth, even though the same mix of microphones was coming back at us. Particularly in the cymbals, the sounds was now flat. Stereo, but flat with a much reduced illusion of depth.
The second example - recording guitar through a Neve 80-series console. The sound again had a sense of front-back depth; like the strings were there right between but a little behind the speakers.
I'm not going to say x preamp does this and y preamp does not, or hazard a guess as to why it does or doesn't happen. It'll be a number of factors working together. I will say that when I'm mixing, I find that compression and subtle harmonic distortion are good ways to control a track's depth and position in the mix relative to other tracks.
user 37518
Well-known member
I don't want to open another (old) can of worms, but I guess I will risk it. I can tell you my experiences and my conclusions:
When testing different QUALITY pres with the same mic on the same source AB-ing them, you can definitely hear a difference, there is no question about it; I've been in the room with different people and the majority notice a difference, however, notice the conditions in which this is conducted. It is almost a clinical experiment, with the same source, switching between each pre, etc... This is a completely unreal scenario, first, because the differences, even though noticeable, are very small. Second, the differences might not be very relevant. Third, with different more 'real' or practical conditions, it would be extremely hard to hear a relevant difference if the pre's are being used normally, that is, if I don't purposefully distort or overdrive a pre, etc. For example, if I ask you to determine which pre was used to record some random sources, and if you are not ab-ing the same source between pres, if I play you different sources with different pre's and those sources are never used with two or more pres, it would be practically impossible for most people to determine which pre was used on which source. Again, I am assuming that the pre's are both more or less in the same category, that is, it is not an old tube pre being saturated vs a transformless AD797 IC pre driven very gently.
The moral of the story is that good quality decent pre's (not a distorted tube pre vs a very clean IC pre), for all practical purposes, sound all the same when used in real conditions. And, if you add mixing, mastering, effects, etc... the majority of the differences will be masked or buried. That is the conclusion I arrived to years ago, but to each his own. Vocals can sometimes be an exception, because they are often times very loud in the mix, and the human voice is something we can relate very much and detect, so different pre's can really make a difference, not as much as different mics, but yeah.
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Hi! Could you post 2 records please? One with 'depth' feeling and one without.
Thanks by advance!
Funny you should say that @Horizoneer, I was just about to write up a very similar post. I agree with what a lot of other contributers to the discussion have already said, nevertheless I want to acknowledge that OP is right in saying that we have certain preferences when it comes to pres, and when this effect is exagerrated (i.e. same pres used on multiple sources) it is very easy to hear "substantial" (well... for a very critical listener anyway) differences in a blind test. I recently stumbled across this post Building low noise, euphonic, transformer balanced preamps as a beginner? , which contains a blind test between different pres (post#4) and immediately had a very clear preference.
Again, buliding on what others have said, I'm afraid the answer is much simpler than OP makes it to be - stuff that definitely makes a difference (frequency response, harmonic distortion, saturation, transient response and the big one COMPRESSION) is audible, and I would argue that especially the compression is something that feels more "immediate" to the average listener. There are tons of examples online where you can use a 1073 basically like a compressor, if you crank it.
In short - nothing esoteric about it, but many many different factors which in sum lead to different sounding pres, some more "immediate" sounding than others.
Again, buliding on what others have said, I'm afraid the answer is much simpler than OP makes it to be - stuff that definitely makes a difference (frequency response, harmonic distortion, saturation, transient response and the big one COMPRESSION) is audible, and I would argue that especially the compression is something that feels more "immediate" to the average listener. There are tons of examples online where you can use a 1073 basically like a compressor, if you crank it.
In short - nothing esoteric about it, but many many different factors which in sum lead to different sounding pres, some more "immediate" sounding than others.
That sounds more like a converter issue than the preamp aspect. Losing low level detail through the conversion(s) eg reverb tails.
My experience (FWIW) is that the amount of feedback in a design is responsible for the "holographic" presentation. This because the feedback is always lagging in time causing some smearing. The amount of feedback is key here as without it the distortion numbers are too high and also gain needs to be set mostly using some feedback. Now with opamps you have a huge amount of gain that needs to be reduced but in discrete devices this gain is moderate so is the feedback, in tube designs this even less so therefore these can "breathe" . The tight control of a high gain stage is good for low distortion numbers but luckily my ears can't read....
Oh no! The old TIM myth is still alive?
Myth or not, it easy to experiment with this and find out yourself, don't take my word for it.
No Feedback or low feedback circuits can sound different. But it's primarily distortion products rather than "time smearing".
True but distortion mainly effects the tonal quality not so much the imaging (actually the opposite, distortion kills the imaging). So here we have the dilemma, how much distortion is allowed...
Feedback works fine if the loop is very short but in case of complex amps it is usually not the case (global feedback vs local feedback).
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Got any measurements showing this time smear effect related to feedback ? How long do you reckon these global feedback related delays are ?
I recall testing some Sennheiser MKH105’s against some other omni SDC’s. They really sounded closest to an Oktava MK-012 omni in a voice test, and the primary difference was a greater sense of space/depth in the MKH with the Oktava being a less dimensional canvas. Absolutely nothing to back that up with!
Gavin Pursinger
Well-known member
Just pick something you like for the job you are doing...xformer hysteresis and power supply lag...rail voltages...an ic at 5vdc or tube at 250+vdc...time for audio signal to get thru the circuit could all apply...if it sounds great...use it...if it sounds like crap...don't
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user 37518
Well-known member
Feedback lagging? we are talking about audio frequencies, not Microwaves, there is no lagging to be concerned of, that is why 20 KHz is practically DC for radio engineers, such low frequencies are no problem at all for a feedback system in terms of lagging. I honestly don't understand how people can bash one of the greatest inventions of the 20th century without any solid arguments.
But perhaps you could elaborate on what type of experiments can you conduct and how did you determine that it is in fact feedback lagging causing the problem?
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I often say the idea of transient smearing due to feedback lagging is akin to the paradox of Zenon of Elea, which alleges that the archer's arrow cannot hit the turtle.
Sure, you can do that with compression, by changing the balance between direct sound and reverb tails, and you can do that with eq, by increasing or decreasing the presence region around a couple to a few kHz. I don't know that I would describe a source being statically moved slightly forward or slightly back as "3D," which speaks to the point of some of the earlier posts that the terminology is evocative, but not well defined. Whether the thought that the term evokes in my mind is the same as the thought in your mind, or the OP mind is difficult if not impossible to tell without some actual recordings to refer to.
I suppose it is possible that some preamp designs have some kind of amplitude compression or frequency response change that varies with time or signal level, but I don't have any that do, so I can only speculate that it might be possible in theory.
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