how close in sound can a tube and ss amp sound ?

i have observed threads requesting advice regarding tube sounding solid state amps, within a price point.

i wonder how to confirm such a request.

in addition to recommendations, what about comparing a particular ss amp to a particular tube amp using an experimental design where bias, or preconception has been eliminated ?

has anyone tested the hypothesis that he/she cannot detect the difference between a tube and a ss amp, within the same power range, price point and minimizing interaction problems, such as impedeance mismatches ?

on the other hand if someone is seeking a tube-like sound out of a solid state amp, i would assume that one would use a "classic" sounding tube amp, e.g., cj mv 45, cj 75, cj 100, or cj mv125 as the tube amp and try to find a ss amp that is indistinguishable from the sound of the classic tube amp.

i have found that many ss amps differ with respect to bass and treble response from many tube amps.

in my own case, i would love to find a 120 watt ss amp which sounds like my vtl tube amp. unfortunately, i am not optimistic.

in other threads, some people have stated that it is impossible to find a ss amp that is "tube-like", in the classic sense.

Well, I had a Sonic Frontiers Power 2 tube amp and while I liked how the amp sounded in my system it actualy did not sound tube compared to my former Quicksilver or Counterpoint amps. So in my case a tube amp does not always equate to 'tubey' sound.
I heard several B&K amps that leans towards tube like sound versus an older Aragon 2004 amp that I had many years back that was the completely opposite. Just my 2 cents :)
A ss amp that sounds like a tube one is an oxymoron. Never shall they sound alike.
"in my own case, i would love to find a 120 watt ss amp which sounds like my vtl tube amp. unfortunately, i am not optimistic."
I think you already have answered your question.
In my opinion and with my system the roland model 6 monoblocks I have come close to my audiovalve challanger 180 mono's but not the same in regards with the female vocals,jazz and even pink floyd when they visit.
I bet you will get a reply from Atmasphere and see what he thinks.

All you have to do is clip the amp and you will know the difference between tube and transistor. That's the tip of the iceberg and the rest is already well 'documented'.

You will find many transistor amps that are lauded as having 'tube-like' qualities. But so far no-one is acknowledged as having found a means of causing a transistor amp to actually sound like a tube amp.

The bottom line is quite simple: if you want the sound of transistors don't get a tube amp and if you want the sound of tubes don't get a transistor amp.

Much discussion could ensue but that will be the gist of it.
"But so far no-one is acknowledged as having found a means of causing a transistor amp to actually sound like a tube amp."

I agree for the most part, but see The Carver Challenge for an exception.

I believe Carver marketed an amp based on results of this challenge, but that seems to be the end of it.
Agreement. My Rowland Model 6's sounded, and my darTZeel sounds, quite similar to my VAC Renaissance amps, but not identical. There are strengths to each design.

I should also add that my darTZeel has not been retrofitted for the improved biasing circuit that is now available for it, so it's not being run optimally, and since we're doing comparisons, the Rowland, while excellent, is not the equal of the darTZeel.
I don't think it's commonly agreed what a tube amplifier sounds like anyway. To say that you want a solid state amplifier to sound like a tube amplifier, well, what kind of tube amplifier and in what way?

In broad generalizations, an OTL does not sound like a SET does not sound like a Push Pull. Same with EL-34 versus EL-84, or 45 versus 2A3 versus 300B versus 845. Tube amplifiers are variously described as being euphonic, transparent, warm, extended, rolled off.

In my (albeit) limited experience, "dimensionality" and especially "fatigue free" seem to be hallmarks of what a (very) good tube amplifier will do that most solid state implementations find challenging without some other compromise.

"Sounds like" or "sounds the same" are phrases often used interchangeably here, when in fact they are quite different. IME, the former is possible on very rare occasion while the latter is not, at least not yet.

I have owned many of the Class A Pass amps, both Aleph and X.5. From that perspective, on a few occasions when hearing a new system and not first looking at the components, I have been hard pressed to identify the type of amp playing.

I have heard very good SS and very good tube amps sound similar and pretty convincing. To answer the OP, I think they can sound fairly close, but not the same.
The issue is going to be the distortion structure. Tubes in general favor the lower orders and depending on the amplifier technology can make a lot or a little of the even orders, usually with not a lot above the 5th.

(This is a general statement, for example our amps are fully-differential so there is no even-ordered harmonic at all until you approach clipping.)

Transistors for the most part are absent the lower orders. Instead they favor the odd orders and higher ones at that, usually the 5th, 7th and 9th. Now they do this only in trace amounts, but many tube amps don't make them at all.

The odd orders are heard as brightness and also makes the presentation seem louder.

The lower orders are heard as warmth, bloom, that sort of thing.

So either way you look at it, distortion is what we are trying to get rid of and as far as the tubes/transistor thing goes, its two ways of doing that with a different price. Fortunately topology plays a role too, so its not cut and dried- IMO the variations we see are what make the high end part of the industry so interesting.

About this close:

Tubes(you are here)______________(you are here)Solid State
i appreciate the wisdom and experience imparted in the above posts, especially ralph's technical explanation as to why ss and tube amps should sound different.

human hearing is imperfect, so i ask the question again:

has anyone been unable to detect differences between a specific ss amp and a specific tube amp?

if so, what tube amp and what ss amp and under what (experimental) conditions ?
That is a very specific gross generalization. Good one.
I answer again - read my prior response.
Mrtennis, Human hearing is all there is in audio. It is what is perfect, it is the audio equipment that is not.

IOW, the ear/brain system has certain rules it follows. The closer the audio equipment comes to following those rules, the more it will sound like music rather than electronics.

Now in the case of odd ordered harmonics, which as at the crux or our discussion, the ear happens to be very sensitive. In fact, this is one of the things that the ear is *most* sensitive to. So its to your advantage to not distort the odd ordered harmonics- the result will be a harder, brighter sound if you do. Now to emphasize the point: the ear is *so* sensitive in this area that modern distortion instruments have trouble measuring the area that is important- often the distortions are buried in the noise on the test bench.

It happens though that tubes tend to make less of these distortions overall, although a **lot** depends on the topology of the amplifier, and so if a designer knows what he is doing, he can do it with transistors too- its just a lot harder. To avoid this distortion, you have to keep the circuit as linear as possible, without loop feedback.

This is a difficult task, but you can see that if you really want to be about it, pentodes and transistors will have more in common than triodes and transistors will. Certain semiconductors are quite linear- approaching that of triodes, and to make the best use of them the circuit will have no feedback and will be class A. There are not many transistor amps like that. Those that are are either very expensive (+$100,000) or very low power (Nelson Pass First Watt).

Now its a lot easier to design the odd ordered distortion out of the amplifier if you work with triodes. I am not saying that they are superior, I am saying they are easier. But the fact of the matter is that there is a lot more experience in the field working with triodes in this way, so you might want to consider going the other way (towards triodes, away from transistors) if you are looking for the best performance with your Quads.
In some cases very close . But who wants that . I went from solid state to tubes and back to solid state . Both have advantages and disadvantages , one is clearly not better than the other . Buying upscale equipment usually fixes the weaknesses of both .
thanks again for the explanations, especially the problem of odd order harmonics and the advantage of some tube products which are , allegedly, designed to minimize odd order distortion.

am i to assume that the relationship between magnitudes of even to odd order distortion is manifested by the effects of clipping.

that is, an set amp which is operating beyond is ability to play beyond certain spls, may produce distortion from clipping which is perceived as plesant, whereas, some ss amps , when clipping may be perceived to sound unplesant ?

it would seem that one of the salient factors distinguishing the sound of some tube amps compared to some ss amps is their performance when operating in a clipping mode.
Do you want to judge an amp on how it sounds when its clipping . If it clips at the levels your using it at , you bought to low powered an amp .
>>12-29-10: Mrtennis
it would seem that one of the salient factors distinguishing the sound of some tube amps compared to some ss amps is their performance when operating in a clipping mode<<


It's irrelevant.
Audiofeil, in this case Mr. Tennis is right in some circumstances. If the amplifier is being clipped only on peaks, its behavior with that clipping will have a lot to do with its sound.

If you have a transistor amplifier and a tube amplifier of equal power and gain, such that either is clipped on peaks only, what you will find is that if the tube amplifier is built right, instead of outright distortion or excessive brightness, it will simply seem to compress right before audible distortion onset.

If for example the speaker is 90 db, and the amplifier 50 watts, this clipping behavior can be pretty important as there can be plenty of opportunity to clip the amp. It is situations like this that have led to the idea that tube amplifier power is often thought to be greater than that of transistors.
why do some ss amps seem to perform poorly in the range 1000 hz to 5000 hz ?

they often sound like there exists a peak somewhere in the above mentioned region.

whereas, many tube amps, sound more pleasing in the aforementioned range.

could it be that some tube amps are subtractive ? , even though both ss and tube amps may measure well.
Very few people compare amplifers based on clipping.

It's irrelevant.
Audiofeil, my point is that many people indeed *do* compare clipping behaviors, only thing is, they don't know that that is what they are doing. Clipping can occur without the amplifier being outright distorted. Tubes have a much more graceful clipping behavior, which accounts for the idea that we have all seen before that 'tube watts' seem to be more powerful than 'transistor watts'.

Mr. Tennis, the range that you are talking about is the realm of the odd-ordered harmonics that I mentioned earlier. It is very challenging to build a transistor amplifier that does not produce a coloration at these frequencies, due to the way our hearing perception works. On paper you will find almost any transistor amp compared to almost any tube amplifier to be perfectly flat in this region.

IOW, we hear distortion as tonal coloration. That is why two amps can measure flat and sound so different. Now there is another reason, read this:

Quads are a Power Paradigm technology, which means if you used a Voltage Paradigm technology (most transistors) on them, you will get a tonal anomaly, in this case brightness.
Most people compare amplifiers at average or normal SPL far before clipping occurs.

Therefore comparing amps at clipping levels is basically irrelevant.

If you disagree, so be it.
my comments regarding the problematic nature of ss amps in the range 1000 hz to 5000 hz is not a function of power rating, or speaker--power requirements.

i agree with ralph's explantion concerning odd order harmonics.

i wonder if it would be possible to design a ss amp which doesn't exhibit the behavior i mentioned.

atr there any examples ?
Audiofeil, my point is that during that comparison, no-one is thinking that they are comparing amps that are clipping. They don't know that that is what is happening. If you have a speaker that is 89 db and a 35 watt amp, depending on room size and listening habits, **inaudible** clipping could be going on a lot.

The effect of inaudible clipping could be a change in tonality before outright clipping is detected by the listener. Or it could be perceived as compression, perhaps a strained quality of the amplifier during complex passages. It depends on how the amp is built, how robust the power supplies are, that sort of thing.

Mr. Tennis, I did give one example earlier- the Nelson Pass First Watt. Another would be the Ridley Audio amplifier. Last I heard that one was over $100,000. I might have mentioned this before too- making a transistor amp that does not distort odd ordered harmonics is not easy.
Okay I get it now. If an amplifier clips in a forest and there's nobody around to hear it, audibly or inaudibly, is it still clipping?

Maybe you should write one of your white papers to make it easier for the those of us living in the forest to understand. How about:

"The inaudible effects of clipping when comparing 2 amplifiers that aren’t clipping but would if you pushed them to clipping levels and the resultant perceptions of the listeners who infrequently listen at clipping levels".

What do you think?
I wouldn't expect most people to have clipping on SS amps of say 100 watts or more, unless listening very loudly, inefficient speakers, etc. Admittedly, many tube amps and almost all SET amps are smaller than this. So, while tube amps may clip more gracefully than some SS amps, they are also more likely to clip. So I tend to think that whatever causes the different character of SS and tube amps, it isn't clipping behavior.

I'm especially confident as it relates to my own experience, because this difference is obvious at whisper levels and is similar at normal levels . . .
After reading all these posts I'm starting to think I'm the only one thats been buying the right sized amps . The only amp I can recall that clipped was 30 years ago , A very large Sansui receiver . I guess since then Iv'e been purchasing the right amp for the application .
Happy new year
I think it's true for most of us as well. However, a consideration - especially for a tube amp, where watts is not quite so cheap - is how badly do you need to avoid clipping?

If an amp clips very gracefully (i.e., it only gently compresses the loudest dynamics and sounds good in the process), then it might not make financial sense to buy an amp powerful enough to never clip.

My solid state amps are all large enough to easily stay in the linear range, but I do have a couple small tube amps that I probably drive into clipping on the very loudest peaks. Nevertheless, the nature of these amps is apparent even at very low volumes, so I don't think their clipping behavior explains the "tube sound".

If we were discussing guitar amps, the story would be very different, since distortion is intentional there.
Maybe you should write one of your white papers to make it easier for the those of us living in the forest to understand. How about:

"The inaudible effects of clipping when comparing 2 amplifiers that aren’t clipping but would if you pushed them to clipping levels and the resultant perceptions of the listeners who infrequently listen at clipping levels".

It would be more about the 'audible effects of inaudible clipping'. However many have beat me to the subject, some by decades. The earliest I have read about this comes from Norman Crowhurst in the 1950s.
Acutally I'm more interested in inaudible effects and ineffectual audibles.

It is interesting that most of the comments have to do with differences at clipping levels. To me, the biggest differences are at quite low volume levels. A lot of solid state gear sounds flat, dull and unengaging, compared to tube gear, at lower volume levels.
It seems to me that a lot of the attention on this thread about the differences between ss and tubes is referenced to how they differ in regard to how they clip, even if the clipping is inaudible(?!). I can understand that the clipping might be so minor that the distortion that certain low levels of clipping is generating, might not obviously sound like clipping, but manifest itself as some other perceived audible consequences. With all that said, it would seem apparent that the best recourse would be to avoid clipping all together. It would also seem apparent that the best way to do so would be with more power. While the speaker load, room volume, desired dB levels, and program source will determine what power requirements will actually be needed. Though not necessarily in all cases, it would seem that dollar for dollar it would be easier to accomplish that with ss.
so far no one has answered the central question:

has anyone heard a tube amp and a ss amp that are indistinguishable sonically ?
It's not obvious why you're asking. If you're just wondering if it can be done, it has been - read about the Carver challenge. If you have something more practical in mind, what is it exactly?

It's rare in my experience to hear ANY two amps that sound identical, regardless of technology.
the question is impossible to answer.

all ss amps do not sound alike.

all tube amps do not sound alike.

therefore, if one were to identify a particular tube amp that sounded like a particular ss amp, the answer would apply only to these two unique products.

the general question as posed would remain unanswered since there is no consistency among all ss amps and among all tube amps.
So far the closest I have heard a transistor amp to sound like a tube amp is one that sounded so neutral that it would be best to say it sounded like music the way a good tube amp sounds like music, without much in the way of artifact.

That amp is the Ridley Audio amplifier.
Just picked up a pair of TAD 125 Hibachi amps for my second system and am giving these a whirl. These seem to fit the bill as an attempt to emulate tube sound with a SS amp.

Too early to draw firm conclusions but I will say so far that these do have some similarities to "tube amp sound" that I have heard, probably more so than typical SS amps, and am thinking the comparison is a fair one.

We'll see....
It is a moot point if neither can be perceived as the "absolute sound", in other words live music. Isn't that the objective? No, not to everyone I'm sure.


I see your point in that neither technology has a lock on all aspects of the "absolute" sound of live music.

But both technologies do tend to have some unique strengths and weaknesses in general that tend to distinguish them so I think it is a fair question how close can they sound.

The best answer I can come up with is they can sound "very close", in fact probably so close that most would not be able to tell the difference reliably in practice.

Then of course, they are also quite capable of sounding quite distinct in ways that can often be clearly correlated to the technology used.

The gear I tend to like seems to have some common good attributes of both. Some of it is tube based and some not. I care more about the results than how they are achieved, but I also tend to be tube shy in that the extra work and expense required over time to keep things properly tuned and working does not appeal to me although I think tubes are way cool in general and I love to watch them glow.
Can we agree that it takes a 150 watt SS amp to duplicate a 75 watt tube amp?
The closest transistor amp i've heard to immulate tube was a Son of Ampzilla 2000.
"Can we agree that it takes a 150 watt SS amp to duplicate a 75 watt tube amp?"

In terms of listenable volume, often the case, but there are some soft clipping SS amps that might not fit this mold as much as most.

Also a 75 watt SS amp may be more likely to deliver more solid bass performance at moderate volume than a 75 watt tube amp with many speakers that are "difficult loads" and perform better in the bass normally with SS gear.
Mrtennis, It seems that between all the lines that there are answers. You have been answered by a wealth of experience and knowledge. The general consensus is, you can certainly find solid states that have some tube character and some tubes that have solid state character.
The Carver challenge has been mentioned, but I've tried his so called T amplifiers... I don't know what they heard in the original test, but the manufactured pieces are not tube like. As far as the clipping issue. One amp that I own is a very nicely modified Sumo Nine. Doubled filter capacitance, double bridge rectifier capacity, hard wired 10 gauge power cable, replaced a multitude of caps with great parts and all resistors. My particular amp is 78 watts to 8 & 152 watts to 4. This amp is pure Class A and I must say, when it clips, it does so with as much grace as anything that I have heard, but I'm not saying its just like tubes.
Orpheus10, no.
Every time I mention this "phenomenon", someone tells me that P = E X I. My 75 watt monoblocks never went to electronics school and they don't know that they are not supposed to kick the crap out of my 150 watt channel SS amp.
To sum it up, for me, the best tube amps I have heard are the ones that sound more like SS and the best SS amps are the ones that sound more like tubes.

Luckily there are some companies and products out there of both ilks that do a pretty good job of resolving this dilemma. And there are many others that almost do but manage to retain a unique bias to their sound that also has mass appeal.
Mapman, at last; something I can agree with.
Orpheus10, it depends on the load.
Unsound, could you elaborate. My 75 watt tube monoblocks and my 150 watt SS amp are simply interchanged and all else is the same.