Is there a Solid State amp that can satisfy a SET guy?

@scothurwitz I purchased a Pass XA25 a couple of months ago and i agree there is some magic (voodoo) going on. Once they get past their burn in time the XA25 took 120 hours there is some magic to be had. When i bought mine it had a ten day trial where i could have sent it back and i almost did a couple of times but once it got beyond the 120 hours it has settled down and has been near perfect and this is coming from a SET guy. The Pass is the best SS amp that i have heard and i have tried many including the latest D amps.

@david_ten My best advise is to forget about specs just go listen to the equipment your interested in first. Let your ears be your guide, knowing specs before hand can influence the brain and what you think your hearing.

I have decades of 211-845 amp use, Audio Note Ongako and Kagura 211 amps, Sophia Electric 845 Mono Blocks and LM 845 amps. If you went by specs alone you would never listen to these amps, sound wise they are some of the best sounding bar none. My personal preference are the 211 tubed amps.

Hi everyone

Pass Labs class ‘A’ amps, to my ears, are magic. I have owned the xa30.8 and I just love it. My speakers are extremely inefficient (83db) and it not only drives them effortlessly but it always remains so musical. I have a tube preamp for that tonal color and accurate timbre. 

To all the other Pass Labs amp owners out here, leave it on always. I have noticed that every time I have to unplug it from the wall, it takes exactly 3 full days until it sounds right again. There are subtle temporal cues that you can hear when it’s been fully warmed up that just aren’t 100% right when it’s just been turned back on. I leave mine on all the time and it always sounds amazing!

Scot

@atmasphere  Thank you for the insight. I will look into it.

This has been educational and helpful. Much appreciated. 

Sound-stage is based on volume (not phase dependent), ear to ear timing cues (also not phase dependent as long as shift is same for both speakers). That also primarily happens much less than 20KHz.


I don't think I have ever read any experiment that shows the ability to differentiate anything but quite significant phase shifts.

@roberttdid

This is all true. However there is a reason that wide bandwidth is a sought-after thing going well back (Stewart Hegeman, designer of the original H/K Citation series, felt wide bandwidth to be quite important). That reason is simply while the ear is insensitive to phase in sine waves, triangle waves and the like, it does use phase information for echo location and so does respond to phase information when a spectrum of frequencies are involved. It also interprets phase shift as a tonal coloration; a change in FR one or two octaves outside of the audio passband can be heard as a tonality in the audio band, with little regard for the loudspeakers involved. I had this demonstrated to me in spades about 30 years ago when I was sorting out an MFA Magus preamp in my shop; the complaint was brightness in the phono. It turned out to have an extra timing constant that set the phono EQ to flat at 50KHz. This was clearly audible as a brightness. By simply removing the components responsible in the EQ network, the RIAA slope was restored (at 50KHz) and the brightness removed. When the RIAA curve was tested using an inverse RIAA network, it was perfectly flat up to 20KHz before and **after** the change. I passed this information back to MFA and they incorporated it into their later production of that preamp.


In high end audio we are always concerned about the nth degree; if you really want to get soundstage right, you need wide bandwidth in the electronics even though the speakers won't reproduce it. And we also want the tonality to be correct; especially in an amplifier with a higher output impedance like an SET its going to have FR errors; it will do it no good if it sounds dark on top due to a rolloff above 20KHz.


Alternatively you can employ enough feedback so that the amplifier can compensate for phase shift in the audio passband. But to do that you need north of 60dB of open loop with good Gain Bandwidth Product and good phase margins, since you'll need to blow off 35dB of that gain (if we are talking about a power amp) with feedback.  This is next to impossible with tube amps and very difficult with traditional solid state designs (to my knowledge the Benchmark is one of the very few to do this). The most common amps that employ this much feedback are self-oscillating class D amps (mostly designed by Bruno Putzeys).

For example, one ’higher power output single tube’ amp has Bandwidth listed as 10Hz through 60kHz.

@david_ten 

Almost any power tube has bandwidth from DC to several MHz at least. We have 40MHz bandwidth in the output section of our amps- we intentionally limit the bandwidth in the voltage amplifier. The real issue is the bandwidth of the output transformer (which we haven't got).


The power bandwidth and the low power bandwidth are two different things BTW. I'm of the opinion that they should be nearly the same. But in many amps they are not- its common for the 1 watt bandwidth to be much wider than the full power bandwidth. So it might be a good idea to get some clarity about what is meant by

Bandwidth listed as 10Hz through 60kHz.

I personally love my CH Precision M1.1 Amplifier. 

@atmasphere Ralph, thanks for your response to and explanation of my question. For example, one ’higher power output single tube’ amp has Bandwidth listed as 10Hz through 60kHz. Based on what you shared earlier, how much of an impact would you expect minimal phase shift ’issues’ to have on overall sound quality? I did make note of your recommended "best range being 2Hz through 80kHz."

I realize all amps will have trade offs based on design and choices made with respect their build.

Those who disagree with Ralph... are you saying the above is not something I should be concerned about with respect higher output single tube SET amps?

Thank you.

@rh67
That is helpful,  thank you!
In my context it seems the SIT3 might be the better choice. I'm assembling a 4-way active system and this amp would drive the midrange (300-1800Hz), so the added bass presence from the XA25 wouldn't be developing. Would you agree?
However I drive the amps directly from a SS DAC, so if a SET had enough power it would likely be the preference. 

Good food for thought.
Thank you!

There is really little to no evidence for this statement, and considering the lobotomy most speakers do to phase-shift, it is hard to justify some extra margin from the amplifier destroying sound-stage. Sound-stage is based on volume (not phase dependent), ear to ear timing cues (also not phase dependent as long as shift is same for both speakers). That also primarily happens much less than 20KHz.


I don't think I have ever read any experiment that shows the ability to differentiate anything but quite significant phase shifts.

If you really want to get the soundstage right, the amp needs to have minimal phase shift in the audio regions so it will need bandwidth past 80KHz. Most larger SETs simply can't do that!

@annika I`m excited to get the Supratek and pair it with the XA25.

@rh67. I look forward to the compare and contrast of the LTA and Supratek with the XA25 once you have it all settled. 

You are digging your self a big hole Ralph.

@lewinskih01 The difference between the XA25 and SIT-3 is very hard to put into words but in a nutshell the XA25 has more bass control and weight the overall presentation has a little more authority will a little more defined presentation of the soundstage and instruments. With the SIT-3 there is a sense of tube bloom, both amps have this but it`s more noticeable with the SIT-3. For me it was a give and take what i had always wished a SET could be better at the XA25 brings. Does the XA or SIT-3 sound like a SET amp? With 3D imaging yes but the tube bloom of lets say a 300B tube is not going to be there but you will have traces of that signature and the XA25 and SIT-3 maintain the realism that SET`s are famous for.

Pre-amps have a big impact on how the SIT-3 and XA25 present their sound currently i`m using a LTA as a pre and the combination works really well, i just placed an order with Supratek for a Chardonnay pre, i had heard one of these pre`s about ten years ago and i have never forgotten how great that pre sounded and now they have a gen3 that`s even better from what i have read.

What i listen too is all over the place, classic rock is at the top, then jazz, jam music, progressive rock Porcupine Tree for example then the classics Frank Sinatra ect. and others Sade, Nora Jones and so on.

Hope this helps somewhat.

Neither can Class-D because of it's switching frequency and associated output filter to get rid of it, that brings phase shift down into the audio band as this shows in red. https://ibb.co/sjNy1Fq

This statement is false in that it ignores entirely self-oscillating amplifiers which are able to correct for phase shift. All the class D amps designed by Bruno Putzeys can do this. Self oscillating amps have been around for over 15 years.

However, it still does not grab my subjective and emotional senses. Could SS be a more objective and intellectual exercise?

You are touching correctly on something about how audio interacts with the brain. The brain has tipping points- in the case of music, its normally processed in the limbic centers. If the brain picks up on something wrong, it will move the processing to the cerebral cortex! Suddenly the music is less involving. IMO/IME, if you want the emotional involvement (and since music is an art form as old as humans themselves, emotional involvement would seem pretty important) then at least for the time being, you're going to have to deal with tubes.

Wow, this is just so typical.
Here your correct, and we probably all agree.

If you really want to get the soundstage right, the amp needs to have minimal phase shift in the audio regions so it will need bandwidth past 80KHz. Most larger SETs simply can’t do that!

Neither can Class-D because of it’s switching frequency and associated output filter to get rid of it, that brings phase shift down into the audio band as this shows in red. https://ibb.co/sjNy1Fq
Over here https://forum.audiogon.com/discussions/gan-based-class-d-power-amps you say the opposite, because you have a Class-D coming out.

Thanks for the more easily understood, non technical explanation Ralph. One comment that pertains to my exact situation is that when I do crank the volume on my 300B SET it does start to sound loud! I have put in a First Watt M2 amp into my system. Through what I have come to understand and accept is that SS may be more intellectual and SET more visceral. But the detail, bass and overall impact are things to be appreciate and enjoy. However, it is also clear that I am an emotional man, especially when it comes to my hi fi and even the two channel home theater that it doubles. I am forcing myself to continue to listen to the M2 but I don’t know if I will be able to sacrifice the visceral. I believe I could get that with say one of your amps but 38, I think, tubes and very low WAF. Could I get this with a push pull tube amp? Then a BIG SS plus is getting an amp with a lot of power and a lot of head room. I imagine the effortless sound of tons of headroom my be very attractive. Intellectual? Now listening to a great recording of a Telemann chamber orchestra and hearing the inner detail makes it quite enjoyable. I can imagine how additional headroom would add a lot! However, it still does not grab my subjective and emotional senses. Could SS be a more objective and intellectual exercise?

The posts caught my attention as I am in the middle of choosing a 211 or 845 amp. You’ve allayed the concerns the posts raised.

@atmasphere Can you comment as well? Thanks.

@david_ten   The bigger the SET, the more issues you have with bandwidth. Some of this depends on design, for example the type of amp known as a 'parafeed' can have more bandwidth since DC is kept out of the core of the output transformer. This is why the 300b for the most part has described the upper limit of 'hifi' since getting more than about 7 or 8 watts means that the audio passband is compromised. If you really want to get the soundstage right, the amp needs to have minimal phase shift in the audio regions so it will need bandwidth past 80KHz. Most larger SETs simply can't do that!


Also if you want to get the bass right, you need bandwidth on the bottom end to prevent phase shift from robbing the amp of that impact. The general rule of thumb is 10x the cutoff frequency so to do 20Hz correctly you have to go to 2Hz. Again, most SETs can do that, many struggle to get down to 20Hz without rolling off!

IOW the larger SETs can be regarded as a tradeoff between bandwidth and power. Now as I've mentioned a fair amount, with SETs that do not run feedback (which is the vast majority of them) you really don't want to run them past about 20-25% of their full power rating in order to really be hearing what they do. This means that you really need an efficient speaker. Higher power SETs try to get around this limitation somehow, but IME this is a forlorn hope. So if you need more power, you are far better off getting a moderately powered push-pull amp. The distortion is lower overall, so you get a greater amount of 'usable' power. I put that in quotes because of course you can run an SET past that power limit I mentioned, what happens is you get more distortion and it starts to sound loud. But that is an interaction with the kind of distortion its making (higher ordered harmonics) and the way our ears perceive sound pressure (it uses higher ordered harmonics to gauge sound pressure). A push-pull amp is less likely to do this.

If you've ever read a comment about how 'dynamic' a certain SET is, that comment derived directly from running the amp on a speaker that was not efficient enough to prevent the user from running above that 20-25% power region. Dynamics are supposed to come from the recording, not the amp!! The word 'dynamics' as used by audiophiles usually means 'distortion' and the latter can replace the former in most audiophile conversation without changing the meaning of the sentence in which the change occurred.


Bottom line: I would think twice about a buying a higher powered SET, if getting the music to sound more real is your goal. OTOH no worries if you just want a nice sounding stereo that sounds loud.

@lewinskih01, I can’t comment on the sonic differences between the XA25 and SIT3 (I’m a very happy owner of an XA25, but I haven’t heard the SIT3). However a non-sonic difference that may be important in many applications is that the gain of the SIT3 is **very** low for a power amp (spec’d as 11.5 db; measured by Stereophile as 11.3 db). That would make it a non-starter for use in my system, for example, since the DEQX HDP-5 I use as my preamp provides little gain. In fact the 20 db gain of the XA25 (which is about 6 or 7 db less than typical for a power amp) approaches (but does not quite reach) the point of being marginal in my system when I'm playing LPs.

Best regards,
-- Al

@rh67 

Have used SET amps for the last four decades. A SET amp produces a 3d sound to each instrument and the stage which contributes to music sounding real. The SS amps that for me capture much of this is the Pass XA25 and FW SIT3, i was so impressed with the XA25 that i purchased one 2 months ago".

Very interested if you could ellaborate on diferences between XA25 and SIT3. How are they different between them and how do they differ from your SET experience? BTW, what kind of music do you listen to?

I'm designing an active system around SETs for midrange and treble, but SIT3 and XA25 often make it to the "what if". But haven't heard them.

Yes there is only one : Robert Koda.
Better than Dartzeel.

It’s just as annoying as people, who use uptalk when they speak.
But, since it’s an audiophile forum, they can get away with this kinda stuff. After all, all we care about is how their equipment sounds, not how they talk :-)

""To indicate that their statement should be read with an uptalk intonation."
I do understand that, but it's written word, and should be written correctly. It's annoying.

Have used SET amps for the last four decades. A SET amp produces a 3d sound to each instrument and the stage which contributes to music sounding real. The SS amps that for me capture much of this is the Pass XA25 and FW SIT3, i was so impressed with the XA25 that i purchased one 2 months ago. They do take about 100-150 hours to sound their best and an initial one hour warm up.

To indicate that their statement should be read with an uptalk intonation

Why do some people use question marks after statements?

I would opt for the Aleph 5 (rather than the 3) if doing some HT.

Re the Bakoon 13R, be aware that the input impedance of its RCA input is only 10K, which will not be a good match for many and perhaps most tube-based components.

I believe the other input choice provided by the 13R, a "Satri Link," would only be usable if driven by a Bakoon component providing that kind of output.

Regards,
-- Al

It is kind of impossible to find an Aleph 3!
There are a couple of Aleph 5s but I think the 3 may be better?
An amp designer friend says that "the lower the power the better".
Don't know if that is necessarily true but may apply to SET amps?
Should I try the Aleph 5? Not sure if it is as sellable as a 3 if I don't like it.
Then there are the comments that there is NO SS amp that can satisfy a SET 300B guy. I don't know for sure if that is true.
Three amps I would now be interested in trying are:
Pass Aleph 3 (or 5?)
Bakoon 13R
Pass XA 25!

BTW-The ongoing thread for months now on its 214th page is @whitecamaross discussion and many videos all about SS amps (cables, et al). Not a tube amp considered at all... well maybe an AR or two.

@roberjerman Thank you.

@wig Thanks!

The short answer to the OP’s question is no.  
And for the OP to ask means he already knows.

A Parallel SET amp will have half the output impedance of a single-tube SET - all else being equal. That will have a positive result driving a typical speaker with a varying impedance curve!

I would second the recommendation of your friend regarding the Alephs being SS amps that are closest to tubes. They are "single ended transistor" designs. But to sound their best, your speakers need a nominal (not just recommended) impedance of better than 4 Ohms. And for HT, you would likely need close to 100W for a large to medium room. I’ve been using the Aleph 2 monos since the mid 90s. Used them for 2.1 audio and for HT and other setups. No harshness and there is a sweet midrange. They do get hot. But so do tubes.

Thank you, Al. 

I'm also curious about the comments on Parallel builds of the 211 /845 being superior to single tube 211/845 based amplification?

I can't shed any light on that, David.  Best,
-- Al

@almarg  Al, Yes indeed! Those price differentials!!! : )

I'm also curious about the comments on Parallel builds of the 211 /845 being superior to single tube 211/845 based amplification?

Hi again, David. I would add that it follows from what I said about output transformer quality (and various other factors as well) that generally speaking I would expect a 211 or 845 amp to cost a great deal more than a 300B amp providing comparable sonic quality.

Good luck in your search! Best,
-- Al

@almarg Thank you very much, Al. The posts caught my attention as I am in the middle of choosing a 211 or 845 amp. You’ve allayed the concerns the posts raised.

@atmasphere Can you comment as well? Thanks.

I’m open to hearing from all four members from my initial post, on the topic, should you have additional and/or other perspectives to share.

Thanks in advance.

Hi Al,
I am not technically oriented much.
Only subjectively judge according to what I hear.
I do trust my ears. For me, I believe I know and understand what music sounds like. What I hear in well designed 300B SETs is a sound that comes close to what I hear in real life. It is not only a response through my ears, it affects my nervous system. I am not easy with sound that strikes me as unnatural. When I listen to a nice recording of a beautiful human voice I relax. It is sublime.

@david_ten 

Yes, David, that is a correct interpretation.  Assuming, of course, that the effect Ralph has described is not overshadowed by other variables in the designs of the specific amps being compared.  For example, differences in the quality of the output transformers, since the high voltages at which 211s and 845s operate makes it harder (and more expensive) to produce transformers providing comparable performance to those used in 300B amps. 

Best,
-- Al
 

@almarg Thanks!

Can I therefore surmise that the 211 / 845 amps are more accurate and more honestly representing the recording, than say a 300B?

Thank you.

@david_ten

I have no experience with 211 or 845 amps, but I would speculate that in **some** cases an explanation of why **some** of those amps may sound "slow and boring" compared to 300B amps derives from something Ralph ( @atmasphere ) has pointed out in the past.

What he has pointed out (and it makes perfect sense to me) is that since the distortion produced by a 300B (or other low powered SET amp) rises dramatically as output power becomes a significant fraction of its capability, while also becoming vanishingly small at low power levels, and since our hearing mechanisms use certain harmonic distortion components as loudness cues, from a subjective standpoint such amps will tend to have a greater perceived contrast between high volume peaks and softer notes.

In other words, dynamics will seem to be enhanced relative to the presentation of many other kinds of amps.

While if everything else is equal (including speaker efficiency and listening volume) that effect will occur to a much smaller degree, if at all, with a more powerful 211 or 845 SET amp, since the amp will be operating at a relatively small fraction of its power capability even on high volume peaks.

Best,
-- Al

- Don’t go for single tube 211, 845 SETs, they sound slow and boring.
- Pani’s recommendations are dead-on and mimic my experiences exactly.
- I have been turned off by owning what should have been a really good sounding amp, the Viva Solista 845 based SET. Yes, it was boring compared to my 300B SET.
- I had the same experience with a De Havilland 845. It was a bore

@pani @eaglejo @mglik @roxy54

What do you attribute the above to? Would like to learn what might be going on with respect the amps you found behaving this way and (perhaps) speaker pairing, etc. synergy? Thanks.

I have a Supratek Cabernet 300B preamp.I was using that with a pair of Bakoon 5515M 50 watt monoblock amplifiers which were unfortunately not mine and had to be returned to the owner.That was a wonderful sounding combination .

Seriously considering getting a Bakoon 13R. It seems like the most different SS. Current drive instead of voltage drive. And I pretty much already know that it may be the ultimate headphone amp.
IME very linear and pure is best with headphones. SET sound is too rich. Believe I can get a demo 13R. Very curious about how it will handle my my big speakers. Still do think about a strong SS amp.
But it is absolutely true that 300B SET fans are a strong sub group in Audio. There are strong and real reasons why we are so devoted to our way of amplifying systems. However, I cannot discount the strong and real reasons why maybe the lion’s share are devoted to SS. I am certainly coming to well understand why this is. I will never forget the “realness” of that MGM lion’s roar! Speaking of lions...

@cal3713

It’s a Purity Audio Design Harmonia V2; you have a choice of 2A3 or 300B but I prefer a more dynamic sounding tube and chose the more linear sounding 2A3.

I considered the Supratek but that would take up more room on my rack and I wanted a Pre where the DHT were not influenced by other variants tubes, just the purity of the 2A3 by itself : )

www.responseaudiony.com/harmonia-mk2.html

Wig

mglik,
Interesting to hear about your experience with the Viva 845 amp. I had the same experience with a De Havilland 845. It was a bore and didn't work with any of the 4 speakers that I had at the time even though it was hyped to be very good.
Like you, I had a great experience with an 8 watt 300b SET. Much better and deeper bass than I later experienced with another good EL34 amp.

I have been turned off by owning what should have been a really good sounding amp, the Viva Solista 845 based SET. Yes, it was boring compared to my 300B SET. I sold it quickly and went back to the 300B. I also have owned a good parallel 300B amp. Also, not satisfied. It lost a lot of the “magic”.
The more I listen to my new Tetra 606s pushed by my 300B mono blocks the more I love it. I use them every morning for vinyl and every evening for 2 channel home theater. Last night It was a great submarine movie, “Hunter Killer”. All the explosions in the bass were thrilling as they should be. Was it the ultimate experience as with a high powered SS amp, no. Can I live with it, yes. Especially this morning as I delightfully listen to a gorgeous female voice singing Schubert lieder! Could ANY SS amp give me the same delight, no!

With efficient speakers (99db) my little Dennis Had Firebottle High Output SEP (pentode) has 12 to 17 watts available depending on the power tubes (will work with a lot of options from EL34s to KT150s)...with the 99db 8ohm speakers it never runs out of gas, and is far from "syrupy" or "euphonic" as some describe tubes...simply clean and clear with power and detail for days.

The Tom Evans amps might also be an option.  I'm using the Vibe/Pulse as my pre-amp into a Triode Labs 2a3 and then some Rethm speakers.