What is responsible for soundstage in a preamp design?

[user 125886]

I have recently been doing something I told myself that I would never do again. That is, record vocals through the onboard preamps of my audio interface. That interface being a fairly cheap Motu M4. I am not a professional recording engineer, just a musician / hobbyist. However, I really need some experienced advice on this.

Here is my dilemma. I have recorded through almost every kind of notable preamp (tube, discrete opamp, neve style, onboard IC opamps). The main difference I have noticed is not the color of the tone (warm vs cold) or (dark vs bright). All of that tone stuff seems to be covered in these modern times with new IC style opamps and even plugin emulations of hardware. The real difference I hear is (2D vs 3D). That is what it seems the newer interfaces and plugins can't replicate. I was wondering what the exact culprit to that issue is?

Let's just leave out tube and neve amps. Let's just compare the difference between a preamp with discreet opamps (2520), and one with IC small form factor things that are in every audio interface. They both have detail, warmth, and clarity. However, the discrete designs has depth with a 3D soundstage. Conversely, the IC opamp is like watching a 2 dimensional black and white cartoon. No depth, just flat.

So what is responsible for the depth and 3D soundstage? Is it the discrete form factor (2520), Or is it the transformers that are usually associated with the 2520 form factor?

 

[ccaudle]

However, the discrete designs has depth with a 3D soundstage.

You are talking about single channel preamps, mono, correct? The first thing to think about is that with a single channel signal you can have no inter-aural time or amplitude differences, so in the physiological sense there can be no (true) sense of depth or soundstage. A correctly reproduced mono signal should be a very narrow image between stereo speakers.

So any sense of depth must be because of an alteration to the mono signal the reminds your brain in some way of the sensation of a stereo or binaural signal that could convey true interaural differences that correspond to depth or position.
My only guess is some type of modulation of the signal, but there is no obvious reason a discrete amp would have any modulation compared to an IC. Usually you would use a discrete op-amp because you needed a higher supply voltage, or wanted beefy output transistors so you could drive a lot of current.

Transformer possibly if it was not the highest quality, but good transformers like Jensen do not typically have a lot of distortion or dynamic range compression.

So I guess the short answer is there is no obvious explanation for anything like what you describe.

 

[NOON]

I know what you mean but can't put it into the technical terms required for a technical site like this. The difference between a good mic and a great mic in my personal experience is a sense of '3D-ness'. There's nothing wrong with the good mic, but the great mic just has a sense of depth of detail. I have experienced it to a lesser degree with preamps, but among the best preamps I have heard have been modern chip preamps like the THAT Corp chips, when surrounded by properly designed inputs and outputs and fed from a good power supply. I suspect that '3D' sound from a single source is not any one measurable aspect but the sum of getting lots of little things right.

 

[scott2000]

All of these comparisons you speak of are using the exact setup with your adda..etc?

 

[k brown]

I'll go out on a limb and offer that what the OP is hearing is the difference between flat/accurate/clean circuits ,and ones with euphonic distortions/colorations that can often be percieved as having more 'depth' or 'roundness', even in mono.

 

[ccaudle]

The difference between a good mic and a great mic in my personal experience is a sense of '3D-ness'.

Don't be led astray by completely inapplicable phenomena. Microphones have to convert vibrations in 3D space to a 1D electrical signal. There are plenty of explanations around polar response (i.e. frequency response off axis) and frequency response variations (it is physically impossible for any microphone to have frequency response as flat as even a mediocre preamp) that can explain some of that behavior of microphones.

Preamps start with a 1D electrical signal at the input, so none of the behavior around converting from acoustic to electric domain applies at all, just put it out of your head as any kind of useful comparison.

I suspect that '3D' sound from a single source is not any one measurable aspect but the sum of getting lots of little things right.

I guess that depends on what your definition of "right" is. I would argue that "right" for a single channel preamp is to create a point source image, and then it is up to you to use either stereo microphone techniques to capture true depth and soundstage, or stereo effects such as delay and reverb to create an artificial sense of space.

what the OP is hearing is the difference between flat/accurate/clean circuits ,and ones with euphonic distortions/colorations

I think that can be taken as given based on my understanding of hearing physiology, so I guess the question is what exact colorations, so that it can be designed in intentionally when desired.

 

[Ricardus]

This gets into the kinds of discussions we have on various home hifi forums I'm on, and for starters I just never use the word "soundstage" ever because I don't think it's real. The mix engineer controls where that tracks sits in the L-R stereo spectrum, and then reverb can give a sense of depth, but home hi-fi users talk about "soundstage" with almost religious reverence.

Considering where you might have been listening, and the various room modes and interactions that can happen on the way to your ears, it simply might not be reproducible.

About 20 years ago I ate some locally grown sweet corn and I have yet to find corn as sweet as that no matter how hard I try.

Same phenomena.

 

[JohnRoberts]

About 20 years ago I ate some locally grown sweet corn and I have yet to find corn as sweet as that no matter how hard I try.

Same phenomena.

I recall back in the 60's eating some sweet corn at a friends house. He owned a farm, and got his water pot boiling before he went out into the field and picked the corn... That was the best corn I recall. Reportedly the sugar in corn starts turning to starch immediately after the corn is picked so freshness is a factor.

===

Soundstage is a place not a sound characteristic. Stereo spatial phenomenon are mostly related to the multiple mics placement and mix levels.

JR

 

[ccaudle]

Stereo spatial phenomenon are mostly related to the multiple mics placement and mix levels.

Right, I don't really like the terminology used, but the OP started with that so I'm trying to bite my tongue about the whole thing.
That is why I wrote in an earlier post that if you think you want to use that term with a mono signal then the signal "reminds your brain in some way of the sensation of a stereo or binaural signal," since from a physiology standpoint there is not any way you can trigger the actual spatial hearing mechanisms with a mono signal presented at equal amplitude and time from stereo speakers or headphones.

 

[JohnRoberts]

Right, I don't really like the terminology used, but the OP started with that so I'm trying to bite my tongue about the whole thing.
That is why I wrote in an earlier post that if you think you want to use that term with a mono signal then the signal "reminds your brain in some way of the sensation of a stereo or binaural signal," since from a physiology standpoint there is not any way you can trigger the actual spatial hearing mechanisms with a mono signal presented at equal amplitude and time from stereo speakers or headphones.

Without blinding the OP with science, there are some delay (phase shift) based studio effects that can suggest spatial movement (like phasors/flangers).

This is not a typical mono path phenomenon.

JR

 

[emrr]

Without blinding the OP with science, there are some delay (phase shift) based studio effects that can suggest spatial movement (like phasors/flangers).

This is not a typical mono path phenomenon.

I have one transformer coupled device with various input and output load switches, option of loading for 'correct' transformer response in a bridging world, or de-select for other conditions. The most measurable difference is a couple degrees of phase above 10kHz. I have occasionally used the difference to make cymbals or tambourines move perceptually forward or back in a mix that can't be otherwise changed. Subtle but real.

 

[k brown]

'Soundstage' is a widely accepted term describing the spatially three-dimensional effect created by stereophony (the whole reason it exists). 'Imaging' is a better term, since 'soundstage', as John points out, already had a meaning before stereo existed. In this usage, it's impossible to achieve with a mono signal unless it is processed in some way, for reproduction over two or more speakers. This has nothing to do with audiophile silliness - it's pure physics, created by (either or both) Interaural Time Differences (ITD), and Interaural Level Differences (ILD) - the most realistic results are achieved with a combination of the two.

Which is why I'm assuming the OP is really talking about 'richness' and 'roundness' of the sound. Tube/transformer euphonic colorations are the usual path . . .

It would help if the OP would weigh-in and clarify.

 

[user 37518]

I have recently been doing something I told myself that I would never do again. That is, record vocals through the onboard preamps of my audio interface. That interface being a fairly cheap Motu M4. I am not a professional recording engineer, just a musician / hobbyist. However, I really need some experienced advice on this.

Here is my dilemma. I have recorded through almost every kind of notable preamp (tube, discrete opamp, neve style, onboard IC opamps). The main difference I have noticed is not the color of the tone (warm vs cold) or (dark vs bright). All of that tone stuff seems to be covered in these modern times with new IC style opamps and even plugin emulations of hardware. The real difference I hear is (2D vs 3D). That is what it seems the newer interfaces and plugins can't replicate. I was wondering what the exact culprit to that issue is?

Let's just leave out tube and neve amps. Let's just compare the difference between a preamp with discreet opamps (2520), and one with IC small form factor things that are in every audio interface. They both have detail, warmth, and clarity. However, the discrete designs has depth with a 3D soundstage. Conversely, the IC opamp is like watching a 2 dimensional black and white cartoon. No depth, just flat.

So what is responsible for the depth and 3D soundstage? Is it the discrete form factor (2520), Or is it the transformers that are usually associated with the 2520 form factor?

I understand what you are trying to say, but I am afraid I don't have an answer for you and I don't even think there is an answer for what you are asking, since your post and language is extremely subjective. I really don't know what 3D is or an electrical property related to it. I can only think in terms of frequency response, THD, and what not. There is really nothing wrong with an IC op-amp, in fact, in every conceivable aspect (aside from perhaps voltage swing), I bet you that the IC op-amp is superior spec-wise to the 2520 (it depends on the IC, you didn't mention). So what I can only say is that you happen to like something the 2520 has that the IC doesn't, or more likely, you prefer something about the 2520 design pre than the IC pre. Parts are not everything, design is many times more important than the part itself.

 

[user 37518]

Which is why I'm assuming the OP is really talking about 'richness' and 'roundness' of the sound. Tube/transformer euphonic colorations are the usual path . . .

That is the problem with that kind of language, it means nothing, or it means something to you completely different than to me, what is roundness? I have no idea; 'richness' is perhaps harmonics? I mean, that is the problem with 3D, roundness, boldness, musical, and all that crap that means nothing, really. Once while teaching my students I asked them what "warm" meant, they all gave me different responses, many of them contradictory; some said: "It is a lack of highs", others said "it is a lot of highs" others said it meant distortion, others said it meant a lack of distortion. That is why audio companies abuse this in their ads, they just need to say "The amp is so forward and round that fits perfectly with my guitar", again, nothing. They could as well say "The amp is so dramatic and terse that fits perfectly with my guitar" or "The amp is so crescent and acquiesced that fits perfectly with my guitar", all mean the same to me

 

[k brown]

That is the problem with that kind of language, it means nothing, or it means something to you completely different than to me, what is roundness? I have no idea; 'richness' is perhaps harmonics? I mean, that is the problem with 3D, roundness, boldness, musical, and all that crap that means nothing, really. Once while teaching my students I asked them what "warm" meant, they all gave me different responses, many of them contradictory; some said: "It is a lack of highs", others said "it is a lot of highs" others said it meant distortion, others said it meant a lack of distortion. That is why audio companies abuse this in their ads, they just need to say "The amp is so forward and round that fits perfectly with my guitar", again, nothing. They could as well said "The amp is so dramatic and terse that fits perfectly with my guitar"

Indeed, which is why the OP needs to return to flesh out what was really meant. But as so often happens around here, they seem to have evaporated.

These filmy words mean something to the people using them, but require some 'splainin'.

 

[Ivan K.]

Re the OP thread...I used to be a location sound mixer in the movie biz. Almost all original dialog is recorded in mono and in post production, panned to match the performer's location on the screen by one of three mix engineers (dialog, music and effects). Any phasing or other effects are definitely unwelcome...BUT, what I'd call ambience is another story. We will almost always record " room tone" without anyone present, to add back into the dialog to make it sound more life-like. On location, we are always fighting signal to (ambient) noise and we try (unless it is for an effect), to obtain a clean & dry sound that gives the rerecording or dialog mixer, the best signal to play with. I believe that what OP is hearing is more or less ambience depending on how close the performers are to their mics. Phasing, reverb and other room effects are inevitable in some locations, even with highly directional mics and may even require the actor to re-record their dialog on a sound stage. In some situations, the Mono signal definitely seems to have depth and "spatiality".

 

[k brown]

Re the OP thread...I used to be a location sound mixer in the movie biz. Almost all original dialog is recorded in mono and in post production, panned to match the performer's location on the screen by one of three mix engineers (dialog, music and effects). Any phasing or other effects are definitely unwelcome...BUT, what I'd call ambience is another story. We will almost always record " room tone" without anyone present, to add back into the dialog to make it sound more life-like. On location, we are always fighting signal to (ambient) noise and we try (unless it is for an effect), to obtain a clean & dry sound that gives the rerecording or dialog mixer, the best signal to play with. I believe that what OP is hearing is more or less ambience depending on how close the performers are to their mics. Phasing, reverb and other room effects are inevitable in some locations, even with highly directional mics and may even require the actor to re-record their dialog on a sound stage. In some situations, the Mono signal definitely seems to have depth and "spatiality".

I'll be surprised if this is what the OP was asking about.

 

[Ricardus]

'Soundstage' is a widely accepted term describing the spatially three-dimensional effect created by stereophony

Yes. I am aware. And it's absurd. An instrument is placed in the L-R mix by the mix engineer and that's the end of it.

These home hi-fi people think their power cable changes the "soundstage" which is why I simply won't use the term. Imaging is better.

 

[ubxf]

May be it's completely of base but is it possible that OP impression is more about the signal being compressed/clipped (2D) vs full range (3D)

 

[user 125886]

I would like to apologize for my inaccurate use of terminology. I am truly sorry about that. I know there is no spec that measures a sense of psycho-acoustic perception. (Psycho meaning that it's all in your head). Sudo-depth, perceived depth, maybe I should have said something like that. But if this question is only met with pure technical theory, than you must inevitably ask the question of "Why even pay $600 a channel for an api or neve pre?". People don't buy those things based on spec measurements. They buy them for the psycho-acoustic effect it brings to the auditory sections of our brains. Of course, there is no actual 3D dimension because it's just a vibrating sine wave. I'm just asking "What aspect of the expensive outboard preamp is responsible for this psycho-acoustic interpretation of depth"

I have read countless reviews of various types of gear where the reviewer is describing said piece of gear as having "depth". Yes, depth is an actual perception when listening to electrolyzed vibrating sine waves being played through speakers and headphones. I could probably search the tap-op or sound on sound website review archives and find hundreds of times some random reviewer used the word "depth".

Ya know what. Nevermind. I never really get any valuable help from this forum anyway.