solid state vs tubes

When considering my latest amp purchase, I strongly considered an ARC SS amp in that I was very impressed with the sound of the sp16 pre-amp and I did not find it to sound overtly "tubey". HAving heard ARC tube gear but not SS, based on what I read doing research, my expectation was that the ARC SS amps would retain the basic house sound which I liked to a good degree. I ended up going Class D instead, mainly foe ergonomic reasons. If the BC refs didn't work out, going with a well received SS amp by a reknowned company like ARC would have likely been my next try. Their SS amp specs certainly indicate that in general they are designed to work with tube pre-amps well.

a hybrid amp--having a tube input stage and ss output stage which is both a tube and solid state amp, has a chance to sound very close to a pure ss or tube amp, by virtue of the ability to alter tube types, may be the answer.

having the versatility of varying tube manufacture could create a more tube like or ss like sound, perhaps creating a sound that is so close to either a pure tube or ss amp, that differences are barely detectable.

mapman, regarding your last point, there was a sss designer, a college professor who designed a ss amp with greater amounts of 2nd and 4th order harmonic distortion, mimicking the sound of a tube amp by creating the pscho acoustic affect of dempahzing treble response. i heard it several years ago at ces. when i can remember the brand name, i will divulge it.

i wrote about this amp, in my review of the ces show at that time.

my point is that like carver, a manufacturer who understands both tube and solid state design and performance could incorporate in a ss amp those features which could create the type of amp i am looking for.

i don't think designers deliberately wish to incorporate coloration, so i will agree that ss and tube amps, will reveal differences , as you have stated which will be recognizable.

personally, i may be willing to accept a solid state amp which can sound pleasant in the treble, yet incorporate greater extension and resolution, so long as it doesn't drive me out of the room. this condition is very subjective.

i would like to keep cost as low as possible and as i indicated would like to audition the odysssey khartago and vincent 331, which is a hybrid amp.

i compliment you on your reasonableness and realistic perspective regarding this issue.

its so basic in audio, that i suspect there is no definitive answer, rather one which one can generate confidence and principles to guide ones personal selection of a particular amp.

i have learned to give up some of my unrealistic desires regarding sound and adopt a more flexible approach.such an approach will allow me to expand my willingness to consider products which i would have not considered years ago.

my stereo system no longer evinces a dark and syrupy sound which i espoused in the past. i have learned to accept a certain level of detail, so long as frequency response is truly balanced.

So to sum up, bottom line to me is that it is possible to get two amps to sound the same or at least so close the differences are negligible, but this is not likely to be the case in practice, especially if one amp uses tubes and the other transistors.

MrT.,

yes, no doubt either might sound good with any good speaker design, not just electrostatic.

What I was wondering was do two different amps, much less a SS and a tube amp, ever sound the same. They can sound different and both good in different ways. That's different than sounding "the same".

If any two amps sound the same, then I suspect in most cases the speakers may be the limiting factors. I would expect most high end speakers to not sound the same with two different good amps, even if both were tube or SS, but even more so if one is tube and one is SS.

Unless of course Bob carver or equivalent designed the two to sound the same up front.

mapman:

i heard avalon ascent and eclipse sound quite good with rowland and audio research ss amps. i've also heard them sound great with tubes.

in my opinion, the issue of ss vs tubes is more critical when the speaker is an electrostatic, ribbon, or planar magnetic.

i have heard vandersteen 2s sound "good" with ss and tube amps.

there are probably other acoustic suspension designs that can perform well with amps of either type.

i have not heard a panel sound as well with a ss amp as with a good tube amp.

i am trying to go cheap and am considering the khartago (odyssey) and vincent hybrid 331. i would like to audition them before buying, if possible.

since both are under $1000, i might take a chance.

Harbeth seems to be as fasinable with SS as tubes, whereas my speakers are proabably 98% tube users.

Can anybody tell me a pair of speakers that sounds the same well with either tube or SS amplification?

I can think of different speaker/amp combos, some SS and some tube amps, that sound very similar, but I cannot cite a case where a tube and SS amp sounded the same with the same speakers. They will almost always sound different with different resulting sonic strengths and weaknesses, the the listener must decide which is better.

Unless you are Bob Carver and your goal is to emulate one amp with another. I do not know any vendor whose busines is based on that these days. Each quality vendor typically does their thing well, be it SS or tube amps or both. Choice of amp will determine choice of speakers or vice versa.

I think this is the bottom line. Build your system to meet your needs. Use tubes or SS as desired, but do not expect touse either to the same effect with the same speakers.

Tvad, I had the Aleph 2,3,J and XA30.5 - I no longer have any of them, but three tube amps; I really did want to have an SS amp, so I tried some of the "best" - but with my speakers.....

Tmsorosk, I agree we want equipment to sound as much like real unamplified, acoustic instruments as possible (don't think amplified, electronic instruments have a real reference). Now if tubes happen (for arguments sake)to reproduce sound that has properties closer to unamplified, acoustic instruments in a real space compared to SS generally, then an SS that could be indistinguishable from a tube amps in those properties that make tube amps sound better, than I might very well want an SS amp like that, not becuase I care about the technology used, but all things being equal it does seem easier to own an SS amp, even if you have to give up the "joys" of tube rolling to alter the sonic signature of the amp - though even there, I tend to think a tube amp sounds like its circuit design far more than whatever tubes you happen to use. It seems that Nelson Pass, for one, has always tried to make SS amps that can perform like tube amps, which he decided not to make since he felt there were already alot of good tube amps out there and preferred the challenge of making good sounding SS (not that I know him, he sort of says things in his various amp manuals from the Aleph and XA.5 series). They certainly are excellent amps, are they indistinguisable from tube amps? Well, there are alot of Pass/First Watt owners out there that might be able to add their 2 cents on that....

Atmashere Sorry didn't mean to get off topic , it's an audiophile thing . I guess what I was trying to say , do we really want an amp or component thats trying to sound like another technology , or like real music ? MAx

Tmsorosk, this one was a little different as the OP wants a transistor amp that does what a tube amp does, without the hassle of tubes, if I read things right. There was a discussion of some differences between the technologies that you don't see in the usual debates.

I always chuckle when i here the great tube verses S.S. debate . The choice is simple , as long as you haven't made up your mind on one or the other . Bring home and try as many of both as you can , the one that sounds the best is the one . Its not the means its the results that are important to the true music lovers , I thought we all new that by now . MAX

Mapman, I agree, the problem is this: distortion, in the form of exaggerated 5th, 7th and 9th harmonics (compared to the original sound) **masquerades** as 'dynamics'.

A simple way to tell that a system is lacking this distortion is that you can't tell how loud it is, until you find that you are shouting to talk to someone sitting right beside you.

Oh, and FWIW, soft clipping does not reduce the loudness cues. Its just more likely to not distort them as much. However clipping in any form is to be avoided, so we are talking about how the loudness cues may or may not get distorted when the system is not clipping at all.

Atmas,

Darn, I thought I submitted you on this topic.

Oh well...

So another way to look at it then is the soft clipping approach distorts the loudness cues by reducing them to make them more digestible to human ears.

OK, but real sound in the real world is what it is. There is nothing there to process the loudness cues in a more digestible manner. Not to say that may not be desirable in an amp.

Distortion and dynamics might be used interchangeably in discussion, but they are clearly two different things albeit often related despite what people might say or think.

If you perceive the peaks as less loud because that is how people hear, that would seem to infer that the dynamic range is affected, at least as perceived, since the peaks do not seem as loud anymore, just as those nasty loudness cues due to negative feedback that you are focused on make you perceive things as louder as you describe.

Mapman, that is true but is not the same as real dynamic range. I don't think it is a good idea to promote a practice of intentionally distorting the loudness cues in order to make something sound louder than it really is. A lot of amps do that though, and is why they sound loud and shouty, as in: "Turn that !@#$%^ down!!"

IOW, if your system has the ability to sound loud, the loudness cues are being distorted. It is possible to build a stereo that does not seem to play loudly, so that even 105 or 110 db is comfortable. I'm a fan of being able to play the system to life-like levels, that is not possible if it also messes with the loudness cues!

IMO/IME in about 90% of the conversations that audiophiles have about dynamics, the word 'distortion' can safely be substituted without changing the meaning of the conversation. It is the reason I avoid using 'dynamics' except in for this context.

The m4.0t I had did very well with Magnepan mg1c speakers for years delivering a lot of tube-like attributes in the sound. Most notably, zero fatigue....the longer you listened, the longer you wanted to listen. I cannot go so far as to say the sound was indistinguishable from the tube amp it emulated since I never did that comparison. My perception was it did what it said it did pretty well and I'd leave it at that.

However, it failed miserably when I went to the big OHM 5S3 speakers I currently run. It was a high power 360w/ch amp but had relatively low damping factor and did not deliver much current. Bass was weak. It was never spectacular on the Maggies either, but I attribute that more to the speakers than the amp. The bass on the OHMs is rock solid now with a suitable high curren, high damping amp, the BelCanto ref100m Class D IcePower monoblocks I currently use.

10-05-10. Magfan: As near as I understand it.....Carver nulled the amps by somehow comparing thru a single speaker. When the speaker made NO sound....or some large value 'down', they amps were producing the SAME sound. The louder the speaker, the greater the difference between amps. This is the source of the 't-mod' which was part of my now ancient Carver Cube, the M-400t.

I don't remember the exact numbers, but just for example, when the speaker being used was say......nulled to -60db, you could say they were the 'same' to 1 part in 10,000 or some such.

ONE possible flaw in this ointment is that of the speaker used. If it was a highly reactive load, the tube amp would not be at its 'best' while a speaker of the single driver/full range persuasion may put the SS at a disadvantage. I doubt there is an 'easy' or even 'best' answer here.

You make an excellent point IMO, Magfan. A perfect or near perfect null with one set of speakers, or even a variety of speakers that represent relatively easy loads, would not be meaningful with speakers that are highly reactive, or that have impedance dips that demand more current than the amp's power supply can provide.

As you probably realize, the target amplifier whose transfer function the M400t attempted to duplicate was the Mark Levinson ML2, a pure Class A solid state amp, which although low powered (due to voltage swing limitations) could provide enormous amounts of current into low impedance loads. That effort preceded by a couple of years or so the Stereophile "challenge" where the target was a C-J tube amp, and was performed for and reported by Peter Aczel in "The Audio Critic." That was well before Mr. Aczel's later unfortunate conversion to the belief that all amplifiers meeting certain basic criteria sound the same.

The technique actually involved three speakers. One speaker was connected to amplifier A in the usual manner, except through long cables that allowed the speaker to be placed at an inaudible location. Another identical speaker was connected to amplifier B in a similar manner, and placed at an inaudible location. A third speaker, as well as measuring instruments, were connected between the red terminals of the two amps. It was reported that a 74 db null was achieved, with a variety of music, with the monitor speaker remaining dead silent except for a small ground loop hum. Which is pretty remarkable.

According to a follow-up article in "The Audio Critic" a few years later (Issue 10, in 1987), while the Stereophile challenge initially resulted in a 70db null between the prototype Carver 1.0t and the C-J amp, a later test of that same C-J amp and a production 1.0t resulted in only a 28db null. Unfortunately it wasn't determined if that was because the production 1.0t didn't match the prototype, or because of tube aging or other changes in the C-J, even though Carver had returned the original prototype to Stereophile to enable that determination.

I too used to use an M400t, which I still have although I haven't used it in several years. I found it's sound, with easy to drive speakers, to be quite respectable, but to me far less preferable than the sound of several tube amps I've had. The main differences being that it projected a considerably smaller image (that surprised me, and I have no idea why it would be so), and, not surprisingly, it lacked what I would refer to as the harmonic richness of the tube amps.

Best regards,
-- Al

This thread is one of those no-win threads.
Like a 'what is best' thread. No single answer.
I'll probably never own a system better than I've got now, unless I win the lottery or somebody tosses me the key and alarm codes to the local fantasy land.
Just trying inject some levity.....the opposite of gravity. It was getting too serious.
And seriously, don't you think I've got a reasonable viewpoint?

Enjoy!

Magfan, You might appreciate this advise:
http://www.youtube.com/watch?v=bpTyG60zvcI&feature=related

LOL Magfan, Just how many shots did you do between those last two paragraphs?

I suspect, but don't know that the differences between current source and voltage source amps....and the speakers they go BEST with would preclude a single system with 'plug in the amp' testing possible....at the highest level.

As near as I understand it.....Carver nulled the amps by somehow comparing thru a single speaker. When the speaker made NO sound....or some large value 'down', they amps were producing the SAME sound. The louder the speaker, the greater the difference between amps. This is the source of the 't-mod' which was part of my now ancient Carver Cube, the M-400t.

I don't remember the exact numbers, but just for example, when the speaker being used was say......nulled to -60db, you could say they were the 'same' to 1 part in 10,000 or some such.

ONE possible flaw in this ointment is that of the speaker used. If it was a highly reactive load, the tube amp would not be at its 'best' while a speaker of the single driver/full range persuasion may put the SS at a disadvantage. I doubt there is an 'easy' or even 'best' answer here.

Buy / run / listen to, whatever floats your boat. Play safe, eat slowly and chew well. don't stay out late and respect your elders.

Interesting Mrtennis. It makes me wonder: Do you think there a single set of speakers and components that are capable of revealing everything that the finest examples of each design have to offer?

hi magfan:

you make an interesting point regarding differences in sound between "the best of the best" ss and tube amps. i agree with you, but i suspect that such differences will probably be detectable in most cases.

i think it would be interesting for a designer to try to duplicate what bob carver did years ago, when he "fooled" a panel of stereophile's "golden-ears", when he designed a ss amp that could not be distinguished from a cj tube amp by that panel ?

obviously, a particular tube amp would be selected as a bench mark and a ss amp would be designed to sound like the hypothetical tube amp.

can anyone do what bob carver did, again ?

Compare the 'best' with the 'best' and see....and not just the amp, but an entire system.
Source, pre/amp and speakers.

I'll bet the BEST of each when properly matched have much more in common than differences. Some of these esoteric differences which I see bandied about, may be unheard in a 'best' system.

Even the best tube amps will fall flat with highly reactive loads of huge impedance swings, while SS has its own limits, maybe when dealing with single driver / full range speakers.

"It is true that the soft clipping of tubes means you will get less of the odd-ordered harmonics, but this has nothing to do with dynamic range."

Less loudness cues perhaps then. If you perceive the peaks as less loud because that is how people hear, that would seem to infer that the dynamic range is affected, at least as perceived, since the peaks do not seem as loud anymore, just as those nasty loudness cues due to negative feedback that you are focused on make you perceive things as louder as you describe. Two different things causing perhaps opposite effects in regards to how loudness cues are "perceived"? Only one is adding and one is subtracting. I suppose the truth lies somewhere in the middle then when negative feedback is applied appropriately to not produce the undesired side effects.

Soft clipping means that dynamic range is restricted to some extent as I understand. That means loudness cues are reduced relatively, all other things aside, as well, right?

What I was talking about is the types of distortions made by tubes and transistors, VS how the ear hears. It is true that the soft clipping of tubes means you will get less of the odd-ordered harmonics, but this has nothing to do with dynamic range. That is a completely different issue!

Minorl, I do take exception to one comment you made about
"well engineered/designed tube or solid state amps", which is the issue of the human ear. If the equipment is "well engineered" to look good on paper, how "well engineered" is it to obey the rules of human hearing? In my book, it is thus not well engineered to the task that it was built for, since the bench specs have very little to do with how human hearing rules.

Have you seen this link? IMO this is one of the more serious stumbling blocks MrT has to face in his quest, and why I commented earlier on the particular SS amps that I did.

http://www.atma-sphere.com/papers/paradigm_paper2.html

Hifi,

Yes, I think each person has their own goals and motivations that determine the right solution for them. Each approach has its own strengths and weaknesses with considerable overlap possible.

In my case, my speakers are the determining factor. My OHM speakers are the key ingredient in my system that cannot be easily replaced by other designs cost effectively. In lieu of using a separate sub perhaps, these speakers require SS amps to get everything they are capable of out of them. That dictates my course. The results satisfy me when I compare them with the best reference systems I have heard, which includes various systems run off tube amps.

So its worth r-iterating again that it is hard to focus on switching just one component (a tube for SS amp) and delivering similar or better results. USually a major change like this will have ripple effects that require other changes to go along with it to achieve the desired results. You should be prepared for that if you make a major change to a system you already like, regardless of teh technologies applied. If you are not ready to potentially have to start all over again, then stay put.

All of the tech talk aside,what it all boils down to is,you need to have a tube amp at home,in your own system.If possible,it would be nice if you also could have the solid state amp at home available to change between the two, and spend a good amount of time with each.The more time you live with each one,the more of a chance you have to find out what each has to offer.Being in this hobby for several decades, and many different amps,plus other types of components in and out of my system,I find that tube amps do offer a natural sound about them that solid state never has offered me.That aside,I do use solid state also,but mostly for convenience.I am not saying solid state amps are bad.They just can't do the same.People say tubes can't either,mostly in the bass resign.Ever since solid state came out(over fifty years plus ago),they have been trying to give the consumer what they noticed is missing,since their introduction.After all those past years of them (the designers),trying to achieve this,it hasn't changed much,if any.I don't think the tube amp builders are feeling any loss to the serious listener,that has spent a lot a time with both.On the other subject about Bob Carver,that got him taken as being a serious designer in the audio world.He himself stated that the Transfer Function is not going to take place of tubes.He finds that he could be satisfied with solid state.If they did that test at the reviewers home,in their own systems,I imagine the outcome would have been totally different,and would have been more fair.With all of this said,you need to compare the two in your own system,for some time.How long depends on you.I don't think there are any rules in general for the time it may take for someone to notice the plus and minus of each amp type.If they took my amps away,and gave me a choice of one tube amp,or one solid state amp,I think I myself would settle for the tube amp.

Minorl, all good points, but, I do agree with Atmasphere on the point that in many instances one technology will work better than the other, and visa versa. In such instances, one or the other can not be swapped in and out and be expected to work at their best in such varied systems.
Obviously, this often compromises direct comparison, and one has to ultimately decide what pro and cons of the total system, best suit the individual consumer.

The discussion here is equally facinating and confounding. Because the arguments are great. But, lets remember that original post was about whether in direct comparison between tube and solid state amps the difference was non discernable. Atmasphere as usual presents a well thought out technical discussion regarding the benefits of tube amplification and some drawbacks for solid state. As I pointed out, with well engineered/designed tube or solid state amps, I'll take either because a correct well engineered design is just that, regardless of whether it is tube or solid state. Most of the arguments (not all) against solid state really stems from the mass produced stuff produced in the 70s and 80s. It wasn't really terrible, it was just not really good enough for serious listening, but background music. I have several systems in my home that are used specifically for background music when I'm not doing serious listening. However, Bob Carver was correct in that if you give a good engineer enough time and money, they can make an amp sound like the best made. Just copy the transfer function of the best. But, solid state distortions vs tube distortions, come down to how hard the engineer wants to work to eliminate the worst kind of distortion and leave only distortions that aren't bad. Both in tube or solid state. Nelson Pass has an excellent article on his DIY Pass Labs site about this very topic. Wonderful reading. Compromises abound in this industry. How much time and money does the engineer have to work with? If unlimited, you will have a solid state amp that no tube amp can touch and the same can be said for a tube amp. I have heard some not so great tube amps and some not so great solid state amps. I have also heard some wonderful tube amps and some wonderful solid state amps. sooner or later I'm going to hear some Atmasphere tube amps and I bet they are absolutely great and I would be faced with the decision to go broke again for a short time or not. But, even when I'm sitting worrying about how much money I just spent, I ultimately end up smiling when I realize that the music is absolutely wonderful and life is good. First thing first. I know good music when I hear it and I can tell a bad recording or simply bad music when I hear it. I played classical violin (first chair), oboe, sax, and many other instruments. I know Jazz, R&B, rock, classical, etc. I know live unamplified music and have heard very good amplified music. So, I know what a real symbol sounds like. So, my point is when you sit in front of that special system and listen to music, does the singer come out on stage? can you see the stage? where is the piano?, drummer, etc? can you see it? how deep is the stage? If you can't see this, then 1) either something is wrong with your system, 2) something is wrong with the recording or a combination of both. but, you absolutely should know that something is wrong. I am a advocate of making friends with a very good stereo equipment shop and on occasion go in and listen to their best system (that you know is good) and reacquant yourself with what a great system should sound like, so you will know what is wrong with yours and work slowly in fixing (a piece at a time) yours. It takes years, unless you have a lot of money now. Enjoy the music. Life is short. Equipment come and go and does slowly improve over time. But, don't marry the equipment, marry the music. I really enjoy reading your threads.

enjoy

Hmm, not sure I see a consensus that use of negative feedback is always categorically a negative. It seems to be debatable at best.

The soft clipping characteristics of tube amps in general seems to be pretty widely accepted. Soft clipping means that dynamic range is restricted to some extent as I understand. That means loudness cues are reduced relatively, all other things aside, as well, right?

Mapman, I am **not** talking about clipping, although it is true that in clipping, tube amps generally make less odd ordered harmonics than transistors do.

What I am talking about is the fact that when you use feedback to control distortion, the price of the feedback is distortion of the loudness cues (5th, 7th and 9th harmonics). Not by much, but as I mentioned before, 1/100th of a percent is audible. It seems crazy to think that the ear is that sensitive, but after all, it has to be sensitive to *something* and this is the mechanism that we use to determine the volume of a sound! So when you see amps with very low THD, its likely that this mechanism has been interfered with.

The result: the SS/tubes controversy since SS amps usually use a lot more feedback than tubes do (which can be built with no feedback at all)- IOW tubes more closely mimic the rules of human hearing, and so make much less of these particular harmonics, even though they often make more of the lower harmonics (which the ear finds less objectionable, though they are often credited with the 'tube sound').

Its not so much that I prefer tubes, what I really prefer is amps that don't violate human hearing rules. So that is an amp without feedback, more than it is tube or transistor.

Now, without feedback, it might be better to have either a higher impedance in the speaker and/or a flatter impedance curve, but if that is the price to be paid it seems small if it is the difference between something sounding like a stereo and something sounding like real music.

As a corollary, here are a few factors that might push one into the stereotypical (no pun intended) soft clipping/tube amp camp rather than the stereotypical SS one.

1) recordings must be played too loudly in order to hear subtle details (increasingly common these days compared to past with many modern loudness wars recordings)

2) hearing/ears not what they could or used to be (typical as we grow older)

3) too much background noise to discern the low level details that might be heard otherwise

Please not that I do believe that, as Bob Carver seemingly demonstrated, SS amps can tweaked to sound like a tube amp if you have a way t accurately measure the differences and you have tthe knowledge to know what amp parameters or characteristics need to be changed to accomplish the goal.

As a consumer, the trick then is to do you homework and find a SS amp that plays better in this scenario than most S amps, and more like typical tube amps.

There is a technique in image processing called contrast stretching. Essentially it means if you clip off the extreme bright and dark extents of the image or picture, you can then stretch out what remains and often show subtle contrast details that are otherwise not apparent. Seems to me soft clipping as found with many tube amps and even some SS, operates similarly. Peaks are clipped in a softer manner that is more digestible to the ear. That allows volume to increase to higher levels than otherwise. Now more subtle variations can be heard in the rest also.

Now take clipping out of the picture by using an amp/speaker combo capable of achieving this at realistic listening volumes. Peaks go louder sooner (though are not cliped or distorted necessarily) and, ouch loud things can hurt now perhaps sooner rather than later because, hey those peaks are loud as they should be. But you now may need a really good ss amp with excellent resolution and detail in order to actually hear the subtle details because, hey things are not louder overall now so subtle differences in teh sound are harder to discern, especially if you do not have good ears and or a very quiet listening environment where what is played can be clearly heard.

Am I off somewhere in describing things this way?

Swamp,

It seems much of the argument revolves around how amps distort, in particular how they distort when clipping occurs.

My understanding is that no amp should normally be run in a manner where clipping occurs. If it does occur, then a different and better suited amp for teh application is needed.

What happens when clipping is effectively taken out of the equation with SS? It seems to me that most issues I detect with GOOD SS amps sounding harsh or distorted can be attributed to clipping occurring or some other abnormal operating scenario that perhaps affects transient response, not a normal one.

Mapman- I won't speak for Ralph but I think you are missing something important here. We are not talking about an amp that is filtering or transforming anything. The issue here is that, supposedly, we perceive certain kinds of distortion (can't remember if its odd or even harmonics) as more harsh or objectionable than others. So, (to make up an example) 0.10% distortion of those harmonics sounds "worse/louder" than 1% distortion of those to which our "ears" (actually brains, I think) are less sensitive. Remember the numbers are made up and I also believe that even within the odd vs. even harmonic dichotomy, there are certain specific harmonics to which our ears are more sensitive.

I only say "supposedly" because I don't have any independent knowledge of the science nor am I an auditory physiologist or experimental psychologist. However, this explanation is consistent with what I remember from my long ago undergrad days about differential response to various kinds of stimuli. This also jibes with what I have heard w my own ears; that ss amps that measure 1X% THD do not, in many cases, sound as good as tube amps that measure 10X% THD.

If your hypothesis is that minimizing THD is an important design goal for an audio amplifier, then many would say that, based on their listening tests, your hypothesis cannot be experimentally verified. That statement does not deny that minimizing distortion is not an important design goal, just that minimizing THD (which is measured in a very specific way) cannot be shown to be an important design goal.

Another way to think of this is that it may be a case of "if your measurements don't match up your experience, maybe you're measuring the wrong thing." In this case, measuring THD may not be the right thing. I think Ralph would suggest a weighted measurement that assigns the most "weight" to those harmonics to which we are most sensitive. Call it WHD (Weighted harmonic distortion) or what have you. The relative weight assigned to each harmonic would have to be determined experimentally, in order for this concept to be applied in practice. When you think about it, THD is actually a specific type of WHD, in which the weight is "1" for each harmonic.

I'll stop now before I dig myself in too deep.

Atmasphere,

Does what you say about loudness cues, our ears and how amps are designed apply mainly in regards to how amps distort?

Loudness cues conveyed by certain harmonics is a natural occurence, correct? What if say a SS amp conveys these cues accurately as they would be if heard live? That may not be as pleasant as them not being conveyed accurately say as a result of tube amplification, but that does not make it wrong, does it? If not clipping/distorting, what if a good amp just conveys what's there accurately, and measurements support that this is what is occurring?

If an amp is not clipping and is fast enough to deliver transient peaks accurately, some might perceive that as a good thing I would think rather than relying on the amp to filter or transform the sound in a manner that makes it more pleasant or digestible. That does not occur when listening to things live. The sound and the harmonics that comprise it are delivered without benefit of amplification or filtering devices to shape it into something more digestible to our ears, for better or for worse.

Minorl, not to put to fine a point on it but the idea of designing an amplifier to pass a signal without distortion is being heavily glossed over in your arguments, which, other than that, I find myself in agreement with.

The problem lies with the fact that our ears, regardless of the individual, use a set of common rules that govern our perceptions. Now really, that is not a problem except that the bench tests that are commonly used are for the most part not devised with these perceptual rules in mind. So as a result, a common experience is that an amplifier that measures well does not sound good, because **in the attempt to measure well, the human perceptual rules are being violated**.

So it is not true to say that the amplifier that has the 'lowest distortion' will be in fact the amplifier that actually *has* the lowest distortion; the two can be quite different! Often 'higher distortion' amplifiers (as measured on the bench) are lower distortion when subject to the reality of our ears.

In short, the bench measurements come off as an example of the Emperor's New Clothes. Our ears OTOH, are the real thing. Now it is a simple fact that tubes more closely obey these perceptual rules than transistors do, that is why it is so hard to find the transistor amps that really sound like music. However, and I point to Nelsen Pass as an excellent example, when you find such an amplifier it will be because the designer is also looking at how our ears work.

Thanks for the correction Mrtennis; However, what I was trying to say (among other things) is that unless the designer/engineer used the same specs, layout, parts, construction, wiring, grounding, etc. in designing the amps, it won't matter if they are solid state or tube, they will absolutely never sound the same. Apples to apples. Two different 50 WPC tube amps will never sound the same unless they are the same amps. Same for solid state equipment. You will always detect a difference in sound from different equipment, even if they have the same specs. The transfer functions (don't ask) of each piece of equipment are totally differnt. That means that gain, phase, etc. are different based on the design and circuitry. That is what some designers tried to do in the past. Copy transfer function responses of high end equipment in the designs of their own. So, if we are talking about amps, and not pre-amps. First, what speakers are we considering? What is their impedance characteristics over frequency and power? Knowing that, what amps can handle that? If the speakers loads are very difficult, then only a few amps can handle them correctly without oscillating or blowing up. It totally depends on what the engineers intended in the design of the amps. Input impedance, sensitivity, gain, output impedance, load handling characteristics, power, voltage, phase, price, efficiency, etc. All of these must be taken into consideration in the design and as I mentioned earlier, depending on the price point, compromises must be made. So, the short answer is no. No tube amp will sound like a particular solid state amp or visa versa. Even two tube amps don't sound the same. It will ultimately come down to what type of sound you want. Real, altered, bright, fast, etc. This is why the used market is so great. There will always be the next greatest and better piece of equipment coming and someone will absolutely have to have it and will sell their other equipment to make room. I know a person that sold their Mark Levinson 20.6s because he doesn't have room for his top of the line Boulder amps and his Audio Research 610s. So, even though the 20.6's are better still than just about anything out their, they had to go and if I had the inclination, I would grab them. Solid state or not. That is not to say that their aren't any tube amps that are just as good or better, but you are now in the upper ranges of high end. you want great sound? take a listen to be top of the line Boulder amp/pre-amp. I haven't heard a tube set up better. Close or just as good? maybe, but better? I don't know. enjoy the music. Enjoy the race.

I think Nelson Pass chose SS because he felt there were already alot of really good sounding tube amps, the trick was to get SS to sound good and he wanted to take on the challenge - don't know whether his stuff sounds tubelike or not, though he often describes the ways in which his circuits are similar to tubes in their simplicity compared with other SS designs. Mrtennis, I have no idea if there will ever be a time when you can detect the difference between SS and tubes, too subjective (yours) to know, but it does seem that there are at least some audiophiles that would be hard pressed to detect the difference and know which was which.

minod, you present some lucid arguments but you neglect to discusss the central concern of this thread, nameley the posssibility that in a given stereo system, a tube and solid state amp produce a "sound", which makes it almost impossible to detect the difference between them ?

Wow! this thread will go on for ever because it is a subjective discussion/argument. Lets take away the tube and solid state fan boys that won't ever accept that the other can be as good or better. Some people are in a particular corner because that is what they believe period. People vote republican or democrate many times, not because the candidate is better than the other, but because they refuse to vote any other way. same is true for tube vs solid state arguments most times. Good Engineering is good engineering. If it is designed and constructed correctly, it will reproduce the electronic signal as it was designed to. Remember those words. as it was designed to. Does the engineer seek to reproduce the signal as accurately as possible or do they seek a particular sound? Many times it is the sound, not signal accuracy, and people develop a personal taste for what they like and totally throw out accuracy. I have compared top of the line tube equipment (apples to apples) with top of the line solid state and as with any piece of equipment designed by different people, there will be differences in sound output. But, I can say as an engineer and as a music lover that they both (excellent top of the line tube and solid state) sound wonderful and I would take either. As I have written many times, take your favorite well recorded music, sit in a room, listen to your music on a tubed amplifier, then remove that one and plug in a solid state amplifier and listen again. compare apples to apples. A $5000 tube amp with a $5000 solid state amp (just make sure they are in similar price and quality range). Designers have compromise points based on the budget and price range of products. That is why price, and quality ranges are so important in comparisons. You can't reasonably take a Audio Research REF 610 amp and compare it with a Yamaha $700 amp and think they would be even close. Don't play with cables or any other item. Just amp to amp and see (listen). It will come down to your personal preference. Don't allow your thinking to be biased by other's ideas or preferences. Listen for yourself. You will find that a good engineer/designer can do tube and solid state equally well. Do you honestly think that Nelson Pass can't design and build a top of the line tube amp? Same with Tube designers doing solid state. Listen to the music. Love the music. Does it sound real? If not, why? First is probably that it was recorded badly. Which is the case most times. Just a bad recording and certain equipment is very forgiving and will not reveal the inaccuracies. Or they are designed for a particular sound. Other equipment will reproduce the signal as it was recorded and will reveal terrible sound. But, it may not be the equipment, but the recording. There are many things going on, not just one thing. Talk to knowledgable friends, listen to equipment and music and have fun. Borrow equipment from people and stores and listen.

"I wish people would come out sometimes and say, "It sucks"."

I agree with you Bostonbean, but it's more easily said than done. I have friends and acquaintances that would receive criticism of their wife and kids more kindly than they would their audio systems. I think it's absolutely crazy, but I've seen one friendship cool substantially after the suggestion of a subwoofer; and I've seen another friendship actually end after a guy, who just couldn't take it anymore, asked the host if he could watch television.

BB, Good point. Perhaps I was being a bit melodramatic. I would like to see something more like: It does A, B, C. But it does not do X, Y, Z.

"I wish people would come out sometimes and say, "It sucks". That would make this hobby much more simple."

Well, there are quite a few vinyl advocates that say digital sucks so there is one example for you. Simpler now?

10-02-10: Koegz
Atmasphere; I owned the ZERO gold ic and sp's. They were ok. I was never really thrilled with them. You spend that kind of $'s, even second hand, you should be ecstatic. I never noticed the improvement you speak of. I am not saying it did not exsist. They are very well made, as they should be, but very very stiff. Tough to install and feel comfortable with their instalation.

Koegz, Atmasphere wasn't referring to cables. He was referring to Zero Autoformers, as linked to on the left side of this page.

Best regards,
-- Al

The best speaker you ever heard?
08-29-06: Hifisoundguy
Bose Acoustic Wave System series 2 !
Hifisoundguy (Reviews | Threads | Answers | This Thread)

10-02-10: Hifisoundguy
I think in the next 3 to 5 years Class D gear will over take tube gear (Sound Wise)
Hifisoundguy (Reviews | Threads | Answers | This Thread)

Yes with your Bose Acoustic Wave System series 2!!