Solid state amplifiers and sound stage, especially front to back "depth"

Planning on upgrading the preamp after warranty is expired. 

@atmasphere  Thanks, Ralph. FYI, your tube amps are my aspirational goal down the road. Would you mind naming a couple solid state amps you have found to be capable of sound stage depth equal to tube amplifiers?

@rh67 My speaker placement is optimized. The issue here is that sound stage depth is varying despite the fact that speaker position is not changing.

@mahgister I agree about the importance of the room and have done a lot of work to optimize that. This is no longer a question about the room, only about the way gear performs in a given room. I

@arafiq I’ve done extensive room treatments including some fairly elaborate things to deal with reflections. These have helped create the depth I’m enjoying with my tube amps and why I feel that the difference in depth must be due to the only variable changing— the amplifier. 
@atmasphere Thanks for the reflection about how feedback may be at work in my solid state. I don’t think Frank publishes much about his process but if anyone sees what he does vis a vis feedback, please share.

@djones51 So far, the consensus is that amp type affects soundstage a lot. So far, if I'm paying attention, only the Sunfire 300 amp has been given props for an amazing soundstage.
The SET 400 is 225 wpc into 8 ohms.

@twoleftears Perhaps a different positioning for a different amp is called for — that’s why my question included "Or, perhaps, am I failing to do something -- such as re-position my speakers?" That said, I’ve done measurements regarding impulses (first reflection, distal reflection, further reflections) and I don’t see much of a measurement difference between them regarding the kinds of timing that contribute to sound stage. I suppose just moving the speakers around would be an easy experiment. Thanks for that idea!

@audioguy85 I did a lot of movement of my system and back wall distance proved very important, both for SPL and for imaging. My guess is that rooms are very different, and my 6.5 ft. ceilings are a factor which probably you (and Fremer) don’t share. Possible crucial difference.

@zlone Wow, that’s a very controlled experiment and interesting result. Yes, I use great test tracks and yes, I’m using a tube preamp in front of both amps. With NOS Valvo 12ATs in it.

@jjss49 I’ll look at the distortions discussion.

@atmasphere  Got it. Thanks. I don't know why McGowan does it, then. Maybe he's the only one who doesn't do his math homework!

@djones51 
https://www.audiocheck.net/audiotests_ledr.php
Thank you so much for this webpage. I'm going to make good use of this. Really looks great!

I've added photos to my system — which is still very much in "proto type" aesthetically and cord management-wise, but which is measuring and sounding quite good. https://systems.audiogon.com/systems/9064

@mapman @lowrider57  @parker65310 @pwerahera 
Agree that it's a combination of many factors, including how the recording is made, speakers setup, and room acoustics; yes, these *all* determine "exactly how those cues are rendered and imaging and soundstage actually produced." That is why I am comparing exactly the same *very, well done and rich sound-staged* recordings. (I'd have to be using good recordings otherwise what would be the point of trying to compare amps?)

Also, these are being played on the same streaming service, in the same room, with the same speakers, in the same position. The interconnects are all the same. The power conditions, the room, etc. are all the same. *The* thing changing is the amplifier. As a friendly reminder, I'm trying to frame a precise question with stable conditions in order to isolate a single factor and elicit information about just that factor.

The Bel Canto and Ohm combination sounds interesting. A similar Bel Canto would run, say, $6k right now? That's almost 3x the price of the AVA, but knowing that a SS (Class D) CAN produce such impressive soundstage says something about the original question. Mbl's are much more, I understand.

@aubreybobb obb The SS amps are not at 600 -800 hours yet. Maybe 100 hours, at the most. As for resonance and vibration, I've never heard that "tube amps are more resistant to this factor." I always thought they were LESS resistant, because of the glass tubes. That's a startling claim and I have never heard that before.

@jjss49  I wish I had those other amps for comparison with the AVA. I know that Pass voices his amps, and Paul McGowan has spoken about this extensively. I don't know if he still believes this, but Van Alstine has said (14 Sep 2006)

"I have no clue about "voicing" an amplifier. It is NOT a musical instrument. It is not supposed to "sound good". The best it can do is to not screw up the information presented at its inputs and drive whatever load is connected to it without interacting with or being modified by the load….We will leave "voicing" to trumpets and tubas and such, and keep doing basic evaluation of circuit electronics…..We did not spend any time "voicing", only refining our engineering knowledge and the application of that." [Source: https://www.audiocircle.com/index.php?topic=76587.20 ]

That's a surprising thing to hear from someone who makes good gear. Surely he listens to what his customers say, he goes to shows, listens to gear, etc. He may have said this as some kind of retort to someone else's overly-mushy (from an engineer's standpoint) statements. But without that kind of charity for him, it betrays an unenviable bull-headedness.

@wolfie62 may be right when saying, "Amplifier design is critical for achieving, or not, really good imaging/soundstaging."

If it is the case that tube amps do this quite typically but solid state do not, it may NOT be attributable to the kind of device at work but results speak the loudest, I suppose. Maybe it is merely that fewer solid state designers focus or try to accomplish a sonic objective that tube designers do. That's an important difference for some, but probably not for the end user who wants a rich sound stage.

@atmasphere  I think I remember Paul McGowan saying they build the amp, then go play it in their IRS5 room and then go back to the bench to change it. In other words, they want they amp to "voice" in a way that they deem to be "musical," and those adjustments are not based on measurement but on listening. That's at least how I remember him explaining it. And that seems to be exactly what Frank was saying he doesn't do. But I remain confused. 

@atmasphere I appreciate the clarification. I suppose I should have just asked the question about what is meant by "voicing." I'm just a hobbyist and consumer; I listen and read, and I hear some engineers such as Paul McGowan talk about "voicing" an amp. I guess I don't really know what that term can mean or how to interpret his comments vis a vis others. I didn't mean disrespect to Frank.

@georgehifi I think I read that comment of yours from another thread a while back and have done all possible to eliminate height between speakers.

I will play with positioning as per the suggestion. That helps the practical problem. The page from @twoleftears from Pass may resolve the theoretical difference between voicing (McGowan) or no voicing (Van Alstine).

Viz., Pass: "Of course the concept of a sweet spot depends on having an idea what of what constitutes the best performance. It could be that you want the lowest measured distortion, a particular mix or phase of harmonics in the distortion waveform, the greatest efficiency, greatest power or simply the best subjective experience when you listen to it. The sweet spot is whatever you want – after all, you are the designer....If you have a distortion analyzer, you could simply run through the range of combination of values and select the result you like best. If you simply want good measurements, you might be able to stop there. If you are looking for better subjective performance, you might find this a good place to start your listening."

Thanks @wjob the DVA M225 sounds like a better fit. 

@parker65310  Thanks for your post and your nice comment. I wouldn't be a moderator in anything but a classroom. There, carrots and sticks exist. Here, in the West World of audio discussion, almost anything seems to go! I'd get too many cuts and bruises.

I do feel that if I start a thread, I need to try to keep responding to comments and try to summarize where things are at, unless it just takes off in a (happy or unhappy) tangential direction. And I'm happy to back off if what becomes a side discussion takes over. I've learned a lot from these threads. There are some masterclass level teachers here with a lot of experience. It pays to listen.

@jjss49 Nothing forcing me to read it. Others can decide if my point was fair. I didn't post in haste or anger. Annoyance, yes, but not in anger.

@decooney Good points. I’m curious about those.
@mahgister Rube Goldberg machine is not a put down. They work, after all. They are just very elaborate. Your system fits into this category and works because you've been patient and clever enough to stick with it.
Relax. I am not replying anymore to histrionics.

But without acoustic control of the room you cannot hope for the maximal manifestation of this quality in a room....In most of the case for sure...

From my OP:

the amp produces a sound stage that is nicely defined and articulate from left to right, but not as much from front to back.I know my room is capable of that sound stage because my tube amp accomplishes it.

See where I said, "my tube amp accomplishes it"? What does "it" mean? Well, that is precisely the point where I told everyone that the room has acoustic control over sound stage, including depth. This is why it is redundant and unnecessary to explain (again and again) why it is important to exercise acoustic control. Got that covered. In the OP. And in my comments. Again and again. Now I am really really done making this point.

@decooney Exactly.

@ speakermaster

Solid state amps do not play depth in the recording unless the recording has depth information but when you play a good recording they will have a lot of depth especially if your speakers are two or more feet out from the wall behind them.

Sorry to repeat myself, both in the OP and in the follow up posts I did, but I have stated that my comparison is very carefully limited to those recordings with depth information as demonstrated by tube amps.

@mahgister I've already stated that I've paid a lot of attention to the room. You're dissertating on your favorite topic and celebrating your (apparently effective) Rube Goldberg inventions, at length, and hopefully someone benefits. It does nothing for the question at issue in my OP, but whatever. You want to write a long post about what you know and what you do and how inexpensive but effective it is? Have at it. 

@sbank  Glad you like the thread. Appreciate the amp suggestions and your point about "when mated with appropriate speakers also capable of recreating depth" is a crucial condition — and no, we're not investing in random! As Dana Carvey channeling GHWB said, "Nah gonnah do it."

I did play with the speakers and LP a bit to try to tease out sound stage (due an amp change) -- Didn't. Help. At. All. Put tubes back in -- sound stage was back.

I like your suggestion about trying tracks with an acoustic bass upstage.

@mahgister You've registered your displeasure with me in a public way. I've said I think you deserved it. Let's agree to disagree on this. You can DM me if you want, but at this point, we've both stated our positions. If not peace, at least détente.

@mammothguy54 It adds great value to the thread because you did exactly the same experiment that I did and had exactly the same result.

@sugabooger 

I did do tone frequency sweeps with both amplifiers. Not much difference at all. Nor with impulse responses.

@213runnin Thanks. Previous posts in this thread addressed all those things.

Thank you, @atmasphere 

I have returned the amp. I'm open to suggestions.

@niodari 

On the other hand, whenever positioning of each musician is regarded, in width or depth, I guess the type and quality of a particular recording is important.

This is a valid point. But if one uses the same exact recording and the only change in the entire setup is amplifier -- and then the positioning, width, and especially depth is affected -- then the only thing which can be responsible is the one variable which changed. In this case, it was the amplifier.

@ebm Thanks so much for the recommendation. I’ll check it out! (Just looked -- a review had it at £16,250.)

I'll take a look at the video. I just tried out a @2k amp so this would be a bit of a leap but if it's good, it's good.

@niodari Thanks for that. Being honest, I cannot say I've heard the "echoey" aspect of the tube sound stage. Then again, maybe I've yet to hear the right gear. May I ask what your solid state and class D gear are? Thanks.

Thanks to recent posters. 
@avanti1960  Speaker positioning cannot be the factor responsible, as previously explained. Thanks for other insights, though.

The most recent podcast from Darren and Duncan sheds some light on the issue of left right and depth soundstage, particularly the kinds of factors involved in the design responsible for enhancing or limiting them. Also some interesting comments about class D amps and soundstage. Look for the episode with the title mentioning sonic holography. 

Agree, Erik. 
Mahgister, helmholtz controls sound very interesting. Can you refer me to some threads where they're mentioned so I can read up on them? All the best,

@mahgister Thank you so much for the links. The Science Direct one looks very good. I will look at the others. 

I am willing to experiment and also alter my room, perhaps not as much as you. So, I hope there is some kind of solution here that does not require as much effort or complication as it seems. I cannot look for a "needle in a haystack" but I can take time to make improvements if there is a clear process that is incrementally better.

@tweak1  If all the factors are the same and the difference is only the amp and the depth disappears, I don't understand how your comment applies.

@luisma31 I love that story and hope you get back the gear you clearly deserve.

FYI, I have the Adcom 535 amp and it really does a lot for it's age and non-hi-end nature. In my opinion, it's way undervalued on the used market, because it's great in a pinch!

@tomic601 @jjss49 advised the same thing. On my watch list.

I don't have a turntable, so I cannot try "Test Record 1 - Depth of Image ( Opus 3 Disc # 79-00 )". Alas.

@jjss49 Thanks. Might spring for it.