How to Measure Amplifier Sound Stage Capability?

[avanti1960]

All else in a system being equal, sound stage length, width, depth and volume has varied greatly among different amplifiers.
Listening to my Rogue Audio Cronus Magnum ii and then plugging in my NAD c356bee you notice a startingly collapsed sound stage, a wall sized aquarium shrink to the size of a small picture window.
The yamaha amp had a soundstage someplace in between.
Are there any electrical characteristics that can be measured and linked to sound stage dimensions?

 

[MakeMineVinyl]

Are there any electrical characteristics that can be measured and linked to sound stage dimensions?

No, there are no such measurements. Any audible differences in soundstaging would have to show up as pretty large differences between channels of the amplifier, like huge phase differences (channels out of polarity for instance), gross frequency response differences between channels, or one channel having gross distortion compared to the other (several percent). Short of a downright defective amplifier, these are not going to happen.

This is assuming that you are in the identical position during each listening session.

There are undoubtedly other things going on; for instance in my case, my system sounds different to me in the morning just after I get up than it does in the evening (it sounds better in the evening). This is probably due to my mental state (or lack of it ) at different times of the day.

 

[solderdude]

First I would try to test it not knowing which amp is playing.
Stereo separation and frequency response may have a relation.
Soundstage is something the brain recreates.
As soon as the brain + eyes + knowledgde (what is in the chain) are involved all bets are off.

 

[Observer]

Soundstage is maybe the most interesting part in stereo listening. I also notice that with different amps I got different soundstage with same speakers. Between all amps I had, old Musical Fidelity A2 (A Class amp) produce to me best and most precise soundstage in my room(5.4mx4 m). I don’t claim that with AB class amps you don’t get good soundstage, but it looks that single ended, A class amps got the edge. (some N.Pass designs, tube single ended amps).
Is this because amps operating in class A conduct over the entire input cycle, so transistor never turns “OFF” ?
I can’t say.

Correct speaker placement is a must before start to play with different amps, front end, cables...etc.
Distance from back wall is needed for depth of field, but If speakers high frequency driver (tweeter) are to close to side walls, first reflections would mess with direct sound and ruin the whole thing.
This is because our brain need at least 6 msec of difference/delay between direct sound from speaker and reflected sound to be able to “cancel” reflected sound.
To achieve this, sound of a first reflection has to travel 1.7 m (5.6 ft) more than the direct sound of the source, then it should not have influence on stereo soundstage perception.
If that is not possible (small room), then difusor or absorption panels on the wall could help (pic. below).
Also, you can try moving listening position closer, and maybe some speaker “toe in”.

Closing eyes when listen help to minimize distractions, therefore maybe hi fi systems sound best at night .
We capture sound by ears, but in the end we always listen with brain.

 

[phoenixdogfan]

Soundstaging is a function of interaural timing differences (IATDs) and should receive no contribution from the amplification device. If an amp seems to be enhancing "soundstaging" that means it's doing something wrong.

 

[avanti1960]

Soundstaging is a function of interaural timing differences (IATDs) and should receive no contribution from the amplification device. If an amp seems to be enhancing "soundstaging" that means it's doing something wrong.

but which is "right"? the voluminous or the collapsed sound stage?
if the former is wrong I don't want to be right....

 

[avanti1960]

First I would try to test it not knowing which amp is playing.
Stereo separation and frequency response may have a relation.
Soundstage is something the brain recreates.
As soon as the brain + eyes + knowledgde (what is in the chain) are involved all bets are off.

even with ABX testing? my results are consistent amp to amp and my imagination is not powerful enough to fake a large or small sound stage.

 

[avanti1960]

No, there are no such measurements. Any audible differences in soundstaging would have to show up as pretty large differences between channels of the amplifier, like huge phase differences (channels out of polarity for instance), gross frequency response differences between channels, or one channel having gross distortion compared to the other (several percent). Short of a downright defective amplifier, these are not going to happen.

This is assuming that you are in the identical position during each listening session.

There are undoubtedly other things going on; for instance in my case, my system sounds different to me in the morning just after I get up than it does in the evening (it sounds better in the evening). This is probably due to my mental state (or lack of it ) at different times of the day.

no offense but the results are consistent and repeatable throughout my years of listening. amp "A" has a collapsed sound stage regardless of time of day or whether i have had my coffee yet !
peace !

 

[Mnyb]

Simply as others says , normally amps don't do "soundstage" or lifted veils or blackness or (insert any audiopress jargon ).

If your experiment says it does the experiment is wrong . even if you ABX things can get wrong . even if one chooses the right method failure is always an option even consistent failure over many years.

Do they have different power capabilities ? the amps .
Driven outside thier spec into clipping or other kinds of distress ? this will sound different , can the extra distortion create or remove soundstage ? who knows .

But its not normally a trait of an amplifier , it amplifies electrical signals and gross fr or phase varitions is not common these days .

Another fun fact did not these old Musicalfidelity amps actually had gross crossover distorsion anyway even if they where partly class-A ? the very thing they tried to avoid ? Their old products where pretty horrible , they have since got much better , new products from mf measures quite well.

The "Rogue Audio Cronus Magnum ii" mentioned in op is not that some kind of tube amp ? such audiophile contraptions may introduce "stuff".
I would take the NAD as correct if in good working condition.

Weird audiophile products can do weird stuff not normally expected by the gentlemen on this forum.

it require further investigation is the rogue weird enough to make audible contributions ?
ABX the NAD to another well designed SS amp of similar power ?

 

[Vini darko]

Everything sounds identical , this hobby is pointless , might as well collect Ants

 

[JW001]

Everything sounds identical , this hobby is pointless , might as well collect Ants

Engineers don't deal with amplifier sounstage, period. The components that have anything to do with the perceived soundstage are speakers. So to answer the OP question: get ANY competently designed amplifier and speakers with wide dispersion. If you want to pursue this further, get a DAW software and learn how to introduce acoustic effects which make the perceived soundstage wider. Or, get The Soundstage Activator

 

[scrubb]

What about channel crosstalk? If the left and right channels are bleeding into each other would this not collapse the soundstage? Or do I not understand crosstalk?

 

[Vini darko]

I often wonder if harmonic distortion plays a role in perceived soundstage. Kinda like a reverb effect. Especially with tube amps wich have a big old spray of them.

 

[SIY]

What about channel crosstalk? If the left and right channels are bleeding into each other would this not collapse the soundstage? Or do I not understand crosstalk?

It takes a LOT to be audible. Think of the separation in phono cartridges- 25dB or so on a good day with the cartridge, disc, and stars all perfectly aligned.

99.9% of the time, amplifier effects on soundstage are purely imaginary.

 

[solderdude]

even with ABX testing? my results are consistent amp to amp and my imagination is not powerful enough to fake a large or small sound stage.

The trick here is to use a 3rd amp. Assuming the 3rd one is a good amp you can determine if A and C sound similar or B and C.
In that case you can find out which amp to dump or have checked out.

 

[Blumlein 88]

but which is "right"? the voluminous or the collapsed sound stage?
if the former is wrong I don't want to be right....

I see one of your amps is a tube amp. Most likely the collapsed sound stage is accurate.

But first have someone help you do this blind. You might be surprised to find all of a sudden you can't hear a different sound stage. Lots of people get the cart before the horse and want an explanation without confirming the event being explained is confirmed as real or not.

Soundstage comes from a difference in the left and right signal. If an amp is fully accurate and not being over-driven the differences will be purely in the signal for each channel in the recording. If an amp has more "soundstage", it must be creating a larger difference in the left and right signal than is in the recording. In essence it would be an additive soundstage coloration. How can that happen?

If the amp is being driven to audible distortion at times, then one channel will be more distorted than the other in a dynamic sense as one channel will always be requiring more or less power as music signals ebb and flow. This creates an additional difference which might be heard as some sort of extra depth or space. If frequency response were variable with output level, that too might have such an effect. Some tube units can have slightly variable response at various output levels. The more heavily driven channel has less extended response than the more lightly driven channel and again dynamically as the music signal varies that might create additional differences between the channels than is in the music signal itself. I suppose it is also possible that with some speakers a tube amp may have variable damping with different signal levels which creates another additive difference between channels.

So it wouldn't be surprising a clean, powerful amp that isn't bothered by any signal levels or speaker loads will have "less" soundstage.

And to repeat once at least, until you get someone to help you do this blind your imagination as you put it might be more capable than you think it is.

 

[tmtomh]

Harmonic distortion, particularly low/2nd order harmonic distortion, can produce a euphonic (pleasant but not accurate) effect of slightly increased ambience from the additional frequencies produced (aka a 2kHz fundamental gets a 4kHz harmonic distortion product added to it). This effect can potentially impact perception of soundstage. Some tube amps are said to produce this, and some Class A amps do too - not because they're Class A, but rather that because some amp designers, including Nelson Pass, have a low-negative-feedback philosophy that results in them building amps with fairly high harmonic distortion (for its alleged "musicality"). So some Class A amps might produce euphonic ambience because of the design philosophy of the people who built them.

Beyond that, though, no sure what else to say. I've experienced soundstage differences that are quite noticeable and reproducible - from changing speaker placement, changing rooms, and changing acoustic treatments at the first reflection points (and to a lesser extent on the front wall between the speakers). Amps, though, no.

 

[MakeMineVinyl]

What about channel crosstalk? If the left and right channels are bleeding into each other would this not collapse the soundstage? Or do I not understand crosstalk?

Crosstalk would have to be pretty gross to influence soundstage. Vinyl has a crosstalk of 25dB on a good day and the soundstage is just fine. Amplifiers would have to be horrible if they had anything worse than 40dB separation.

 

[MakeMineVinyl]

I've experienced soundstage differences that are quite noticeable and reproducible - from changing speaker placement, changing rooms, and changing acoustic treatments at the first reflection points (and to a lesser extent on the front wall between the speakers). Amps, though, no.

Agreed; the room and the speakers make up 99.999% of 'soundstage' or lack of it. If the speakers are anything other than relatively far out into the room and away from side walls, soundstage will suffer, especially in 'depth' perception. If the room is bad acoustically and not symmetrical, great imaging is pretty much impossible.

 

[avanti1960]

It takes a LOT to be audible. Think of the separation in phono cartridges- 25dB or so on a good day with the cartridge, disc, and stars all perfectly aligned.

99.9% of the time, amplifier effects on soundstage are purely imaginary.

no disrespect, this is flat out not correct. if you were here in person i am confident that you would hear the difference.