Sophia Electric Baby Amp

[Poultrygeist]

The Single Ended Triode is the simplest of all amp circuits and uses the least number of parts. The SET is one of the oldest amp designs dating back to the 1920's. Unlike most push pull tube amps SET's require no negative feedback. Negative feedback is used to lower distortion specs. Feedback creates time smear which results in two dimensional sound.

Since SET's only make a few watts one must have high efficiency speakers to benefit from their high detail and holographic magic. SET's aren't well known or popular as commercial speaker companies are inclined to produce low efficiency speakers with power robbing crossovers that can command higher price tags and require lots of wattage. Companies that make amps cotton to the demand for higher power amps to drive these inefficient speakers as these big amps can increase profits vs a simple flea amp SET.

The Chinese made Sophia is a push pull amp and sells under other names on ebay for a couple of hundred.

[RGA]

SET amps typically run into problems with difficult to drive speakers - many reviewers unfortunately will blame the amp as "sounding that way" when it is simply running into power capability issues. When pushed to hard the amp will compress and the bass becomes wooly and the treble rolled off (hence the tilted frequency extremes comments).

If you use quality speakers that can take advantage of SETs they won't distort they won't run into power issues.

SET isn't the only kind of amp that sounds good - and IME it takes a fair bit of coin to do it any real justice because it is so dependent on the quality of the transformers and few are out there make top quality ones.

Like many things in life the KISS method works best - Keep It Simple Stupid. A high quality SET amplifier is the simplest design and it sounds terrific - IME done right it has no equal. The rest add and add and add more garbage that gets in the way - rather than use high quality parts they use off the shelf cheap parts that get in the way of the original sound.

SS amps use Feedback is which is an error correction device but the amp itself is creating the errors that SET amps don't create. The ill-logic of it is mind boggling.

The big problem is that SE tube amps should sound like giant distortion generators - they should sound bloody TERRIBLE. The fact that they sound so vastly better - clearer, better bass, open extended no fatiguing etchy highs and yet the measured response is WORSE - then there is a serious problem with the measurements (probably created by marketing departments and blindly followed. The result or truth happens when the play button is pushed.

Peter Qvortrup (CEO Audio Note - arguably the top or right there maker of SET amplifiers in the world) explains in Layperson lingo starting at about 3 minutes in. Hyundai might have Stolen Toyota Corporate "Secrets" - Motor Trend The General Forum Forum

[Feanor]

...
The big problem is that SE tube amps should sound like giant distortion generators - they should sound bloody TERRIBLE. The fact that they sound so vastly better - clearer, better bass, open extended no fatiguing etchy highs and yet the measured response is WORSE - then there is a serious problem with the measurements (probably created by marketing departments and blindly followed. The result or truth happens when the play button is pushed.
...

You and I can agree that we don't have a definitive set of measurements that will define good sound. No amp is perfect -- if any were, presumably there would be no issue, right? So the objective ought to be which shortcomings are the least offensive and how to build an amp that has the least offensive shortcomings.

The anti-S/S argument goes that the necessary negative feedback produces a type (or types) of distortion that, while low, are psycho-acoustically very objectionable. These distortions are usually identified as high-order harmonic distortion and/or intermodular distortion.

The anti-tube argument goes that tubes typically produce relative large amounts of low-order harmonic distortion, and that while this low-order h/d is psycho-acoustically pleasant, it works against accurate, genuinely realist sound.

For one thing, I think it's dangerous to generalize. Audiophiles privileged to own quality, high-end equipment talk about "convergence" of tube and solid state designs, i.e. as the quality (and price) go up, the sound becomes more alike. Apparently this is because offending distortion in both cases can be mitigated with careful, thorough design and implementation.

The other big thing is personal preference. (And I think this comes into play in the case of lower- and middle-range equipment.) Do you want relatively more accuracy at the price of some edginess, or do you want smoothness and warm at the expense of accuracy?

For my part, I guess I favour the accuracy. Partly it's the type of music I listen to, (acoustic; Classical); partly maybe it's my ears, (I'm deaf above 10 kHz); partly it's just my taste.

[Ajani]

You and I can agree that we don't have a definitive set of measurements that will define good sound. No amp is perfect -- if any were, presumably there would be no issue, right? So the objective ought to be which shortcomings are the least offensive and how to build an amp that has the least offensive shortcomings.

The anti-S/S argument goes that the necessary negative feedback produces a type (or types) of distortion that, while low, are psycho-acoustically very objectionable. These distortions are usually identified as high-order harmonic distortion and/or intermodular distortion.

The anti-tube argument goes that tubes typically produce relative large amounts of low-order harmonic distortion, and that while this low-order h/d is psycho-acoustically pleasant, it works against accurate, genuinely realist sound.

For one thing, I think it's dangerous to generalize. Audiophiles privileged to own quality, high-end equipment talk about "convergence" of tube and solid state designs, i.e. as the quality (and price) go up, the sound becomes more alike. Apparently this is because offending distortion in both cases can be mitigated with careful, thorough design and implementation.

The other big thing is personal preference. (And I think this comes into play in the case of lower- and middle-range equipment.) Do you want relatively more accuracy at the price of some edginess, or do you want smoothness and warm at the expense of accuracy?

For my part, I guess I favour the accuracy. Partly it's the type of music I listen to, (acoustic; Classical); partly maybe it's my ears, (I'm deaf above 10 kHz); partly it's just my taste.

I think personal preference (and the opportunity to experience different technologies) is the key to audiophile choices.

Even the definition of accuracy in relation to HiFi can come down to personal preference. Which is more accurate: A speaker with a wild frequency response curve but good timbre or a speaker with only fair timbre but a flat frequency response? So at the end of the day it comes down to minimizing the compromises to develop a product at a price point.

I think a lot (possibly even most) audiophiles make the mistake of assuming that their personal preference is the RIGHT way. Hence anyone else with a different opinion is brainwashed, deaf or corrupt.

[RGA]

Feanor - but you have to consider where the distortion resides - in a SET it ONLY resides at high level when the amp is pushed hard - it is NOT THERE at low level. You can get around the amp power via speaker efficiency. You can't get around it with SS because it is ALWAYS there no matter what volume level. And it is why SO MANY people always yammer about needing more and more power - because they have to CRANK IT UP to make things out clearly and why so many systems are deemed to sound better louder. WIth SS based gear I am always wanting to reach for the volume knob to bring it to life. It is a reason that virtually all SET owners rave and rave about transient attack. It's faster and cleaner sounding.

Distortion means the sound should be AUDIBLY distorted no? It should not be able to pick and choose what part is distorted - it should ALL be distorted.

That means the voice should literally warble, the bass should be flabby, the treble should sound fuzzy or lacking sparkle. It should sound thick - the midrange should be overshadowed by the bass line because the woofer is not being driven properly. And yet that is not the case - it is the case when and ONLY when the amp is running beyond it's capability. And in a SS amp you know when that happens because the sound is truly atrocious but in a SET amp you can't quite tell because it never sounds bad the same way a SS sounds bad. It sounds mushy and compressed - but I have, to be blunt, excellent hearing and I know when something sounds veiled or wishy washy - and I HATE THAT. I hate it less than SS clipping but mud is mud.

And virtually all SET owners are classical music lovers. I am one of the very very very very very rare SE tube owners that is not "exclusively" a classical music listener. Art Dudley is probably THE classical music listener at Stereophile. Constanine Soo at dagogo is a huge classical music guy. Enjoythemusic - they go one better - the reviewer there who owns a complete AN SET system reviews classical music for a living and is also a classical music composer who is actually played. So if the guy composing and conducting at the Philharmonic doesn't know what it's supposed to sound like no one does!

Mike and Nelli of audiofederation who also sell Soundlabs which is arguably the TOP panel maker for sound quality listen mostly to classical music and play it at shows. Peter Q is a classical first guy with one of the best collections in the world on both CD and LP formats. He is a founding member of an organization that gives scholarships to classical musicians and is also a judge because no one knows as much as he does about classical music.

The vast majority of people on boards under 50 started out with SS amps - the ones who go to SET usually don't go back - and pointing to the one guy here or there is not convincing - the overwhelming majority of them don't go back and it has nothing to do with preferring distortion characteristics - distortion doesn't explain why it sounds faster clearer crisper. There is nothing warm about Audio Note gear (it can be depending on the recording but there is a reason why in every review the word Transparency is a big key) I probably own the warmest and most veiled amp that they make. Partly because if I have to choose a slight stray from accuracy I'll take that than the fatigue inducement of most that sound bright which passes for accuracy and good ears know the difference between bright and accurate - most however think if it's brighter it must be more accurate. Which is what they bank on during the 10 minute auditions most people give them on the wall-o-amps board at the big chains - the amp that stands out must be better - same for speakers.

The convergence argument I sort of agree with but I would not really parrot things on forums without first hand experience. I want to read the specific SS amp to the specific SET amp. And in fact I never read anyone use specifics when they make those comments. It's about as dumb as posters who say they can make a SS sound like a SET by putting a resister in the chain - the people who have never once auditioned a SET amp. SET amps don't all sound alike so how you can put a resister in a speaker chain and make it sound like two different sounding amps is the height of ill logic.

There is a reason I always use this forum review of the guy who owned SS and owned top of the line Bryston and PMC and decided to bring home a much less expensive AN system. Why do I bring it up? Simple because Bryston is about as Solid State sounding as solid state gets. It's all about accuracy (ahem) and PMC is a professional grade monitoring company(hey that's what PMC stands for after all) that makes studio speakers and active monitors. This guy had the best of both.

So he had the day to day listening of the supposed "supremely accurate" sound. Added in a Meridian which are the "best of the best" of the CD digital replay world (ahem). So you could safely say that this guy arguably had about as accurate a system as you could get from SS amplifiers and any boxed speaker can get.

I have heard the same combinations for decades as well. He isn't responding to warbly sound. He's responding to the fact that he hears proper time domain behavior, the fact that he can more of what is on the recordings because it isn't being looped internally a milllion times, and he's hearing clarity and each instrument as separate entities in space and he's hearing the wholeness of notes not a gritty minced meat compressed back together chicken McNugget version of prime breast meat.

His analogy is bang on perfect flourescent light irritation versus natural light reality. And even if you can't hear above 10khz it's very readily apparent if you have the speakers that won't give the amp fits. General Asylum: REVIEW: Audio Note Level 3 system Other by KevinF

[Feanor]

Richard, because you have responded at such length, I feel obliged to respond.

I don't see myself ever owning a SET amp, although of course one never knows. I'm very content with my Magneplanar speakers and I don't see myself going to a high-efficiency design necessary to match a SET. (If I tried to used a SET with the Maggies I'd get sound but it would be clipping a lot of the time.) It would be fun and instructive to live with a tube amp for a while, but I don't it could be a SET but instead some sort of push-pull or "ultralinear" design capable of 50-60 wpc or better

Whatever you say about the relative virtues of S/S vs. tube and esp. SET -- and whatever the truth of those assertions might be -- I don't have a universal problem with S/S sound such as you suggest exists. My current Class D Audio SDS-258 amp is the most transparent amp that I've own; (its near equal was another class D amp, a Bel Canto eVo2). If you argue that s/s veils the sound, then you are 'way off the mark. Granted, my current class d amp isn't "warm" sounding nor, (though the terminology is vague), does it have the "harmonic richness" that tube amps in general are said to deliver. However it does deliver instrument timbres more accurately than any amp I've owned.

Amps I've owned, BTW, include the Monarchy SM-70 Pro, an S/S amp but one well regarded by the pundits. It is a high-biased, zero global feedback design does, (according to the pundits and me), deliver some measure of that so-called "harmonic richness" associated with tubes. To my ear, the Monarchys are inferior to my Class D Audio amp in general and specifically in transparency and timbre rendition.

The Class D Audio SDS-258 driving my Magneplanars deliver impeccable sound to my ear. So much so I have no specific desire for improvement -- I find it hard to image even. This is playing my best recordings as judged by overall merit, including some hi-rez recordings. With my poorer recordings it is another matter: these can sound bright, edgy, and/or veiled, but the fact that the best sound great demonstrates that these deficiencies are on the recording, not being added by the amp

Something interesting is that when I went from the Bel Canto to the Monarchys, I felt that the Monarchys sounded better playing about 70% (not all) of my recordings. By curious coincidence, when I went from the Monarchys to the Class D Audio, again I felt the new amp sounded better than the old amp for about 70% of recordings. But what was the stand-out difference in these impressions? In the Bel Canto to Monarchy case, the 70% comprised my less-good recordings, whereas in the Monarchy to CDA case the 70% comprised my best recordings.

But let me speak of preference. I value transparency and timbrel accuracy about warm & smoothness -- this won't be everybody's choice. Finally I'll also make the point that records vary in quality and that recording practice leaves something to be desired. Too often recordings end up sounding too bright; I suppose this reflects the producers & engineers objectives and/or preference. (BTW, this goes for vinyl as well as digital recordings.) For my part, I choose to hear recordings the way the creators them: I don't expect or want my amp to "correct" their work.

[YBArcam]

There is a reason I always use this forum review of the guy who owned SS and owned top of the line Bryston and PMC and decided to bring home a much less expensive AN system. Why do I bring it up? Simple because Bryston is about as Solid State sounding as solid state gets. It's all about accuracy (ahem) and PMC is a professional grade monitoring company(hey that's what PMC stands for after all) that makes studio speakers and active monitors. This guy had the best of both.

Interesting thread. Just thought I'd point out something, that PMC does not make true active speakers. They make powered speakers, using a Bryston amp that feeds the signal into a crossover (passive) and then to the drivers. Many would not consider this to be an active speaker because it does not feature an active crossover.

I would certainly like to hear a SET amp running high efficiency speakers, and will likely purchase speakers from either Zu, Tekton, or Brines someday to do so. Open baffle (in the right room) is another thing I'd probably like to own one day.

I have grown frustrated lately with my system. Yes, it's the same old ss amp running into passive box speakers of average efficiency...similar to what 8 out of 10 audiophiles own. Though I think the amp is one of the better examples of ss design. Right now I've got a pair of PMC TB2i running, rather than the Castles showing in my sig (which I still own). I think I prefer the Castles though. They have won out over many other speakers I've tried. As they aren't worth a lot selling them makes little sense.

Both speakers are enjoyable. When I listen to either everything seems right...driver integration, frequency balance, clarity, dynamics, pace, rhythm, and timing, tone, openness (the latter two are done better with the TB2i). I can't really point to something and say, "that sounds wrong". Yet, something is missing as I'm not as engaged in the music as I know I could be. I could continue on the merry-go-round, trying other amps and speakers. At some point one realizes that buying the same kind of gear likely isn't going to change things drastically.

I have decided to go the active route by picking up a pair of Quad 12L actives. Unlike PMC they feature an active crossover. There are better active speakers (Focal makes a couple), but for the price on the used market the 12L is a great way to try actives. And it will be easier for me to try an active speaker as I can simply plop it right into my system using the Exposure's pre-outs, as opposed to buying a HE speaker and a SET amp (which would cost more money).

I think active speakers overcome some of what you guys overcome by running SET amps into HE speakers. It does away with the passive crossover (there are many articles online about the pitfalls of a passive crossover splitting a high level signal, and how using an active crossover on a low level signal all but eliminates these issues, not to mention biamping which is also a plus). In a nutshell, greater efficiency and reduced phase and timing issues, with better micro and macro dynamics.

I wish I knew what kind of amps Quad uses in the 12L. There is one thread on AA where someone had opened up the 12L and he said the amps are single ended. I have not been able to verify this elsewhere though. I'd love it if they were a single ended design with minimal feedback used. In any case, hopefully this is a positive change for me. Who knows, if it is then I might even try tubes by plunking a tube pre in front of the Quads.

[RGA]

I think personal preference (and the opportunity to experience different technologies) is the key to audiophile choices.

Even the definition of accuracy in relation to HiFi can come down to personal preference. Which is more accurate: A speaker with a wild frequency response curve but good timbre or a speaker with only fair timbre but a flat frequency response? So at the end of the day it comes down to minimizing the compromises to develop a product at a price point.

I think a lot (possibly even most) audiophiles make the mistake of assuming that their personal preference is the RIGHT way. Hence anyone else with a different opinion is brainwashed, deaf or corrupt.

Yes but that only applies to people who have actually bothered to listen to said technology. Most people hear SS all their lives - audiophiles in my general age group grew up on SS - most hi-fi stores in Canada carry only SS amplifiers. And that is likely true in the U.S. There are a few that will carry tubes like ARC or McIntosh but even here both of them sell SS amps.

How many people actually audition Tube amps? The number is greatly reduced. Tube hybrids don't count cause you don't know if the problem (if there is one) is generated from a mismatch in the technologies so it can hardly be blamed on the tube cd player or preamp - the fact that it wasn't there with a SS preamp or CD player isn't really deductive reasoning.

The fact is very few people audition tube amps - and very very few audition SET amps - and then which SET amps? There are may different types of them - some people don't like all that much.

The problem is most people who spout off on SETs have never ever heard one - and then even if they heard one - so what - It's like me saying I heard a Yamaha receiver so now I can OPINE on Monarchy and Pass Labs - because after all "I heard a solid state amp) or I auditioned a $100 DAC so I know what all DACs including the Benchmark Dacs sound like.

Listening to a Cary is not the same as listening to an Audio Note just as listening to a Copland is not the same a Mcintosh or ARC.

Indeed, I should try and refrain from lumping SS together - because it's not all the same. I am reviewing a $2k Roksan SS amp and I own $2kish Rotel system and they don't sound at all alike.

[LeRoy]

The Single Ended Triode is the simplest of all amp circuits and uses the least number of parts. The SET is one of the oldest amp designs dating back to the 1920's. Unlike most push pull tube amps SET's require no negative feedback. Negative feedback is used to lower distortion specs. Feedback creates time smear which results in two dimensional sound.

Since SET's only make a few watts one must have high efficiency speakers to benefit from their high detail and holographic magic. SET's aren't well known or popular as commercial speaker companies are inclined to produce low efficiency speakers with power robbing crossovers that can command higher price tags and require lots of wattage. Companies that make amps cotton to the demand for higher power amps to drive these inefficient speakers as these big amps can increase profits vs a simple flea amp SET.

The Chinese made Sophia is a push pull amp and sells under other names on ebay for a couple of hundred.

Thanks for the info on the Sophia alternatives and the SET background. So, what speakers are you using with your SET amp?