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

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.

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?

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.

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.

@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.