Revisiting "Psychoacoustics and amps" thread from '02/'03-Ken Kantor, are you there?

[Guest postjob62]

I've been searching (to some extent in vain) for information as to which, if any vintage Marantz SS receiver might do a better job than my current Pioneer SX-750 in powering my 2ax's. The Pioneer does a great job, but my Marantz 2230 sounds *so* good with my 4x's that I just thought there might also be a magical Marantz out there for my 2ax's.

In so doing, I came across the above referenced thread in which Ken Kantor basically put forth that which he considers irrefutable, to quote:

"If two solid state amps of comparible power sound different, then one or both of the amps is broken. Properly functioning amps do not sound appreciably different from one another, at least different enough to change the sound quality in a system to any real degree."

I continued to read the thread, and if I'm correctly interpreting Ken's scholarly statement, a solid state watt is a solid state watt, just that and no more; further, if two completely different amps of exactly the same power output are run through the identically same speakers under identical circumstances, then the results are sonically indistinguishable one from the other, at least to the human ear.

Say what?

Now Ken is obviously a brilliant engineer and I'm an electrical unsophisticate, so unlike others I'm not here to refute his point(I couldn't) but rather to ask Ken and any others to amplify (no pun intended) and clarify, perhaps in more layman-like terms. I would have to assume that whatever the chosen power level, it would have to remain constant for whatever impedance the speaker presented to the amp. Obviously you couldn't use two different amps producing 100 wpc at 8 ohms with 3a's if one of the amps folded up with a 4 ohm load. But beyond that, am I to understand that *nothing* else about the amp matters? Output coupling, power supply, transformer size, damping factor, subjective "voicing", and all the things that make up a SS amp's architecture-none of these things matter, just the number of watts produced?? So the perceived "warmth" of an early Marantz, the smoothness of the HKx30 series, the brightness and articulation of '70's Pioneers- all this is simply that, just subjective perceptions based on, well, perceptions?

I've always held forth that perceptions are more important than reality, and in fact often become reality. So maybe this is my just desserts. But honestly, I just had a deja vue recollection to the exact day I found out there was no Santa Claus. And I'm 56!

Admittedly, I'm of a mindset to want to believe this. I recently read Peter Aczel's "10 Biggest Lies" article, and frankly, a lot of what he said made sense to me. But I need some help with this one. Ken, if you're there, please make sure I understand this correctly. It will save me a lot of agonizing over non-existent details, and will free up some time to concentrate on what I know does matter- the wonderful sound of these old AR speakers.

As an addendum, Ken, how do you and others weigh in on the Aczel "tube superiority is a myth" proposition?

Regards,

Ed

[Guest postjob62]

Ok, after sleeping on this (fitfully) maybe I can give myself a partial answer. Not having access to the "previous article" referenced by Ken and not knowing all that was spoken before, perhaps I'm allowing myself to be confused by terms. Perhaps some of the things that have been routinely thought to impact sound coloration are considered preamp functions, which obviously are single-unit housed within the receivers I mention. And presumably, these preamp functions would fall outside Ken's definition of a solid state amplifier.

Still, where do things like damping factor and capacitance coupling vs. direct coupling fall- inside Ken's amplifier functions, outside as part of preamp functions or in the case of a receiver, in between?

Inquiring (but simpler) minds want to know.

Ed

[Steve F]

This is a subject rife with emotion, strongly-held positions, passion, and misconceptions, and we certainly won’t sway the opinions of most people in this discussion. Nor are we trying—this is just a good exchange of thoughts and ideas.

Many well-respected industry stalwarts with impeccable engineering and listening credentials, such as Julian Hirsch and Tom Nosaine, echo Ken’s sentiments. In fact, Mr. Nosaine conducted a series of very tightly-controlled blind A-B listening tests in Stereo Review a few years ago where he compared an “audiophile” system with fancy amplifier, super-duper CD player and exotic cables to a system using a 1970’s-era Heathkit amp, a garden-variety CD player and lampcord. There were absolutely no statistically-significant correlations to the preference of either system from among the group of golden-ears assembled for the testing. None. Zero. Zilch. Nada. Zippo.

There are real audible differences in the way amps overload, however, and this is not at all at odds with the “no audible difference between properly-operating amps” position. Some amplifiers exhibit more upper-order or odd-order THD than other amps, and that is more audibly-objectionable. So-called “chip” amps can really distort quite harshly when they run out of steam, with their scope output looking almost like a square wave. Amps that clip more gracefully, like solid-state amps with “soft-clipping” circuitry or many tube amps will sound different at overload than amps that behave more offensively.

Amps can also differ in their s/n ratio, and a subtle amount of low-level hiss injected into the signal can subjectively change the perceived quality of the sound, or at least make one amp sound “different” from another. Also, another article in Stereo Review about a decade ago (I believe written by Julian, but I’m not positive) showed that different speakers interacted with the same amplifiers differently, causing very subtle changes in frequency response over the 20-20kHz spectrum, on the order of +/- ½ to 1 dB. A gradually downward tilt compared to a gradual upward tilt of a dB-- that might very well be audible, but it’s not the amplifier itself, per se. It’s the interaction of the amp/speaker combo, not the “quality” of the power being produced like so many audiophiles might like to believe.

Remember also, that human hearing is pretty darned sensitive, and unless amplifier A-B testing is tightly controlled—really tightly controlled—an amp that is ever-so-slightly louder will invariably sound “better.”

All the above being said, I swear I’ve heard a difference in amplifiers in my systems when I’ve changed electronics and everything else—speakers, positioning, source units, cables, etc.—has stayed the same. I’ll be listening to a Miles Davis or Buddy Rich CD that I know really well, totally into the music, not listening to the ‘system,’ and all of a sudden, a subtle background detail will jump out at me that I never noticed before. Coincidence? Amplifier change? Difference in how my hearing or concentration was on that particular day? Who knows. But this is a hobby of never-ending fascination, isn’t it?

Steve F.

[soundminded]

If Ken said what I think he said and meant what I think he meant then I must disagree. I am not an audio fanatic and don't believe most of the current fads which audiophiles take as doctrine. But I do believe that different amplifiers sound differently. This is based on having had to re-equalize my sound system when I decided to replace my Dynaco Stereo 120 after a breakdown failure. IMO, the science of testing amplifier performance hasn't kept up with the technology of designing and building amplifiers. As a result, tests which were very valuable in showing us the meaningful differences and limitations fifty years ago are all but useless today because even the most modest amplifiers will often measure textbook perfect yet in actual use sound different from other amplifiers. One problem with our tests is that they are invariably made with a resistor for a load. Not only is a real world loudspeaker system highly reactive but it isn't even a passive load generating a reverse emf from the momentum in the moving assembly/voice coil combination applied backwards to the amplifier output stage. The size, regulation, and stability of the power supply can dampen this effect substantially or not. Another factor is very subtle differences in frequency response with real loads. These can cause amplifiers to sound different but I think can be externally equalized to compensate for these minor differences. Amplifiers out of adjustment can have substantial crossover notch distortion very apparant at low listening levels and more noticable with efficient speakers. This may explain why some amplifiers sound harsh the way many early solid state amplifiers did. IMO, the most critical factor of any amplifier is its power supply. No amplifier can be better than the limitations of its power supply. Differences in signal circuit topology as long as they are competently designed are much less significant. The current crop of high quality MOSFET amplifiers seem to perform very well and some of them are notable values. Were I to need to purchase a new amplifier, I'd look at Crown's CE-1000 very seriously. For a little over $400, you get an tremendous performer. Others here admire units from Adcom and I'm sure those are very fine too. The cost of high quality amplifiers today in dollars adjusted for inflation is a small fraction of what it was a generation or two ago and performance which was once considered remarkable is now rather ordinary.

[Guest Bret]

>If two solid state amps of comparible power sound different, then one or both of the amps is broken.<

If you can get-over the initial shock of this, you can see that it is absolutely true. Ken is telling the *absolute* truth.

Bob Carver offers current and voltage outputs on his amplifiers because they *sound* different under a reactive load. So one output is broken and the other isn't? No, of course not. They are both broken in different ways. Bob keeps his credibility and Ken's allowed to keep his.

I've had the chance to compare a "modern" Sunfire to a middle-generation SAE to an Adcom to a Threshold amplifier, same room, same speakers, same wire. They all sound different. Are they all broken? Of course they are. But all of those were less broken than a Pioneer receiver which was less broken than a Yamaha receiver of half the output which was less broken than a Sony of 2/3rds the power of the Yamaha. (I've settled on the Sunfire as being my preference in broken amplifiers).

I don't remember the thread, but somewhere on these pages Ken makes another absolute statement (in the form of a question if I remember correctly) and says something like, "Do you know how hard it is to make any two speakers sound alike?" Ken designs speakers. Do you suppose he designs broken speakers, or they just get built broken?

Brush all of that aside a minute and consider this: Experiments show (I saw it on TV, they were running an experiment on the viewers to prove their point and I didn't know it; yep, they got me) that our brains "saturate" and "select." We are bombarded by so much input that our biology can't handle it and we "filter" our realities involuntarily as well as voluntarily. If we were equally aware of everything we'd be truly aware of very little and it appears we are totally aware of nothing. It's all in the misdirection.

Psycho-babble?

I discovered this about myself by accident. I had a favorite listening spot in my living room. Over my left shoulder was a lamp and on the far side of that was another chair. I would listen in subdued lighting, but my wife would always want to read. I could start a piece of music and find the "sweet spot" and just be lost in the performance (in the dark) when my wife would come into the room and turn on the bright, reading lamp. She would then sit down to read. The apparent stereo balance would change! I thought it was her presence changing room modes in some subtle way, but it wasn't. She could leave and the balance did not correct. Over time I came to understand that it was the *light.* Being bright in one eye, it changed what I heard!

That's insane, right? I've told you the effect, but not which WAY the balance changes. I encourage you to try this for yourself and tell us - did the image move toward or away-from the light? Two out of three other people I have asked to try it also experienced the same neurotic effect I did. So it's probably not so much brain-damage in me as it appears to be brain-function in at least some of us.

Now, how does that apply to amplifiers? It applies to everything we all perceive. If our senses can be so easily tricked (Dickens knew it), how can we ever know anything for certain? How can we possibly experience "Good" "Better" and "Best" when we can't know what we are experiencing at all?

Could it be that ARs are said not to "Rock" because they play "too much" and our brains are so busy filtering we lose some of the mind-bending directness you get with an Altec A-7 with a big horn on top shaking your fillings loose--- even if they aren't really as seismic as the ARs? Think about the implication of that: A system that's not-playing some things in a recording might make us think it sounds "better" because our brains are having to work less-hard to filter-out things we don't want to hear.

Or, as I'm guessing from my own experience, can I hear what I'm paying attention-to and as Paul Simon might say, I "disregard the rest?"

I think that the golden-eared experiments must contain limitations that make people less able to tell the difference between a $250 Taiwanese receiver and a $15,000 Japanese amplifier. I simply do not believe that it isn't obvious. Sorry. I can imagine an experiment so arranged as to *induce* the listener not to be able to tell, but let the listener choose the volume and program material and keep everything upstream mid-fi or better and I can't imagine not being able to tell; provided the exposures weren't too far apart. I don't claim golden-ears, but I'd love to have someone show me how wrong I am; just because it would be interesting - and cheaper.

But having agreed with you that you CAN absolutely, without question, hear the difference in amplifiers, who would believe you can hear the same amplifier differently if the lighting is changed? Ken's right, you're right, and I'm right.

I understand Ken's method. If the signal goes in like THUS and comes out like SO and SO is identical to THUS in every way but amplitude, then I have a perfect amplifier and anything that sounds different is broken or perhaps my imagination, or perhaps my filtration.

Bret

[soundminded]

"Psycho-babble?"

No, I'd say semantic babble.

If you define broken as:

broken = sounds different

then when two amplifiers sound different, at least one of them is broken. How do you know which one it is? How do you know which one to return to the manufacturer for repair so that it is no longer broken? Given the vast array of different designs, wouldn't it be surprising if some did not sound at least a little different?

Bob Carver once said, give him 24 hours and he could make any amplifier sound like any other amplifier. He said he'd accomplish that by adjusting its transfer function to match the other amplifier. And what is transfer function? It's the amplitude and phase response as a function of frequency. And as I said in my prior posting, with real world loads, there can be real audible if subtle differences.

So which one is not broken or the least broken? The one with the flattest frequency response, the most unshakable power supply, and the lowest output impedence so that it is not affected by the load. That's probably a Crown amplifier with a damping factor in excess of 20,000.

[rrcrain]

I think we are starting to split straws with this thread. My suspicion is that the word "broken" should have been "imperfect" in his analogy. No amp, (or anything else built by man is perfect for that matter), with each design and unit bringing to the table its own strengths and weaknesses. I own two amps of the same model and they have a very slight difference in tonal quality, one being just slightly warmer than the other. Which one is "right"? Since I bi-amp, its not an issue and if I didn't, I still wouldn't worry about it. Slight differences in component tollerances, drifting over time and the differences in one lot of transistors to another all add up do have an impact.

Simply put, perfect does not exist, but darn near perfect does and its in the ear of the beholder to decide which sound they think is best.

[Guest Bret]

>broken = sounds different<

Why does this topic always make everyone so edgy?

You are correct. I was saying that unbroken is perfect. Anything imperfect is therefore broken. That gets me around Ken's contention that if to amplifiers sound "different" one is broken. As you say, "which one?" Which is where all my other extended and revised remarks came from. I can't tell by listening which one is more broken, and that's why I waxed stupidly on about perception.

The only thing I dislike about the engineering-approach is that it assumes it knows everything it needs to measure to declare the experiment properly measured. That's a little arrogant.

Bret

[soundminded]

"The only thing I dislike about the engineering-approach is that it assumes it knows everything it needs to measure to declare the experiment properly measured. That's a little arrogant."

Engineers create a model or paradyme. They base their measurements against this idealized paradyme. To the extent that the paradyme is limited, the significance of the measurements are limited.

IMO, in the case of audio amplifiers, the paradyme is slightly flawed but could be tweaked to be far more useful.

In the case of loudspeakers, the paradyme is very seriously flawed and needs a major rethinking.

In the case of the goals of sound systems and sound reproduction as a whole the paradyme is virtually worthless and cannot be salvaged. The entire problem needs to be re-examined at its most basic assumptions and the solutions re-engineered from the ground up. In that case, much better sound systems which are substantially different from what we have today would emerge. At this moment there is no real interest and therefore no commercial advantage in such an broad undertaking.

[soundminded]

The flaw in your arguement Bret is that it is based on circular logic. By redefining the term broken to mean imperfect based on the criteria of an engineering paradyme, then if two amplifiers perform differently, at least one of them must be imperfect, hence broken. (Of course all definitions are based to a degree on circular logic since they are always defined by other words.) The ludicrous irony of this is that based on the measurements engineers customarily use to evaluate the performance of amplifiers, they often cannot explain why they perform differently. This shows the flawed limitation of both their measurements and their paradyme yet they have made few if any serious attempts over the last 40 or 50 years to improve them. Perhaps they feel that these flaws are trivial but this leaves us in a quandry as to how to make an intelligent choice among the many alternative models availabie. If someone has an answer, this engineer would like to hear it.

[kkantor]

There would be a HUGE commercial benefit if it could be shown that amps had much, if any, impact on sound quality. Audio lovers desperately want to believe that they do, and both magazines and manufacturers have a vested interest in promoting differentiation. However, it just in not the case. Many types of studies have been conducted over the years, and the differences between even the best and worst amps are surprisingly small. This does not mean that they are never audible. It just means that the actual sonic difference between a 50W receiver from 1975, and a modern $5,000 "Class A" rave, is not at all what people have come to accept. Believe me, if real differences could be demonstrated, companies would be all over it.

Why is this? In essence it comes down to the difference between signal transmission and signal transduction. Devices which transmit a signal without changing its form... that is, from bits to bits, or electric current to electric current, have a very easily defined job. Devices which tranduce the signal... that is, from bits to electric current, or electric current to acoustic waves, are much trickier. So, in almost every audio chain, the weak links are the mics, or speakers or D/A converters... transducers. Preamps and amps are much, much more accurate, as a rule.

Having said this, vacuum tube amps typically impart much more error than solid state amps, for a number of reasons. Building a solid state amplifier that is sonically neutral up to its clipping point just isn't that difficult in this day and age. There is no general rule about what kind of parts (capacitor types, transformers, etc) are best. What matters is the final signal that is sent to the speakers, under real-world conditions. Any amp that can relay the audio signal with a reasonably flat spectrum and low distortion will sound like any other amp that does the same. Easy to prove, always disputed...

[kkantor]

You are completely correct that the loudspeaker paradigm and, to a lesser extent, the overall audio reproduction paradigm, is broken. That is the motivation behind the more enlightened efforts at "auralization."

It is worth noting, however, that many, many audio engineering decisions are validated by listening, not by measurement. The relative indistinguishability of amps, for example, is not proven by reading meters, it is proven by listeners consistently failing to identify amps with the lights off.

[Guest Bret]

> it is proven by listeners consistently failing to identify amps with the lights off.<

I wonder if this forum's members might be a little better at this than statistics would predict.

Bret

[kkantor]

I'd be happy to bet $1000 that they wouldn't. Nobody ever does.

Of course, it is an even safer than usual bet, since I have no time to arrange this kind of thing anymore. In my younger days, I counted on audiophiles with big egos and big wallets to pay my way through college...

(Just kidding here, though I honestly have won a few bets from golden-ears who were sure they had that extra something to hear what lesser mortals could not. I haven't lost even once.)

[Guest bocoogto]

As some of you have suggested, amplifiers are much closer to being "perfect" than loudspeakers. Most medium to high quality amplifiers perform with less than 0.1% distortion (harmonic and IM). Amplifiers are the most accurate component in nearly every audio system. Very few parameters of loudspeakers are accurate within 1%--distortion, transient response, etc.

I agree with Ken Kantor about amplifiers sounding the same. I have not heard of even one blind listening test where the panel was able to, with any consistency, identify any specific amplifier when driving the same speaker(s). Those of you who don't believe that can test it for yourself. Use the same signal source for the two amps being tested. Use a DPDT switch to switch between two amplifiers driving the same loudspeaker. Carefully adjust the level of each amplifier to be equal and be sure there are no equalizers or tone controls active. If they are decent amplifiers, you will not be able to pick which one you're listening to once you lose track of which one is switched on.

It would be refreshing to hear some feedback from those of you who have tried this. Anything else is just talk.

[Pete B]

I agree with Ken here.

Bret, do you actually think that those doing the research have not thought of trained or golden ear listeners? The golden ears claim is a very common come back from those who think audio listening is comparable to wine tasting. Some say that Dyslexics have more acute hearing, are you Dyslexic? Not that better hearing would make a difference with good amplifiers.

Many try to offend the technical types claiming they do not have good ears.

It's interesting that I've worked in super computer design, radar and communications systems, digital design and more, and there is never some magic unknown "thing" that causes problems. These areas are all significanly more complex and more difficult than audio amplifier design.

Those talking as if they're authorities on amplifier design or the "sound of amplifiers" thinking there is more to it than loaded transfer function, nonlinearities of all types, and freedom from oscillation and current limiting ought to become versed in the work of Baxandall, the Hafler null test, and more. Tube and single ended amps sound different because they often have highish output impedance, and/or high levels of distortion.

I discuss the Hafler null test here, I'm PB2:

http://www.diyaudio.com/forums/showthread.php?threadid=48873

and also here, note that there's much I do not agree with in this thread:

http://www.diyaudio.com/forums/showthread....10&pagenumber=5

This was my definition of a not broken amplifier stated in 1996:

A good amp has high and invariant input impedance, low and invariant

output impedance, has as much dynamic headroom as possible,

high current drive, recovers cleanly from overload, behaves well in

overload, doesn't oscillate at any frequency and under any conditions,

is thermally stable, doesn't require maintenance and of course has flat frequency response, and low distortion of all kinds. Did I forget anything?

Pete B.

>> it is proven by listeners consistently failing to identify

>amps with the lights off.<

>

>I wonder if this forum's members might be a little better at

>this than statistics would predict.

>

>Bret

[kkantor]

It's a wonderful feeling to be liberated from the chains of oppressive Audio OCD!!!

http://www.classicspeakerpages.net/dc/user_files/543.jpg

http://www.classicspeakerpages.net/dc/user_files/544.jpg

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[Guest Bret]

>It's a wonderful feeling to be liberated from the chains of oppressive Audio OCD!!!<

Great!!

Does this make you a free radical?

Bret

[kkantor]

Yes. The FBI better keep an ion me.

>Great!!

>

>Does this make you a free radical?

>

>Bret

[rrcrain]

I have listened to a Krell versus a Rogue versus my ancient beasts all driving a set of Canton speakers and there is a rather stark difference. The Krell sounded wonderful, clear, crisp and well defined,,, and then my ears started to hurt. The shop was trying to sell the amp on consignment and wound up having to use some extremely expensive and exotic interconect wire just to get the amp to sound right; which I'll add they did not like doing. The Krell amp apparently has an extreme slew rate and can become harsh on an open ported speaker design like the Cantons.

The Rogue being a tube amp, was much more fluid in its presentation. Perhaps not technically as exact as the Krell, but absolutely a pleasure to listen to without listener fatigue.

My ancient beasts (solid state)tend to take on the coloration and presentation of the pre amp, or whatever else is driving them.

I have had the pleasure of having listened to quite a few different types, sizes, designs and manufacturers in amps and there "can" be quite a difference. I really can't tell the difference between a Grommes or Rogue as both sound very good, but there are subtle differences if for no other reason than the power ratings. Rogue versus Krell though is night and day.

[soundminded]

When I had to replace my Dynaco Stereo 120, I chose a Klaus Peterson design called the Mosfet 120, I think a kind of lineal decendant of the stereo 120. I had to re-equalize the system rather radically to get the sound back to where it sounded right. Once it was, I doubt anyone would have been able to tell the difference.

Defining the word broken the way it was, is a bad use of the term. When something is broken, it doesn't perform the way the designer or builder intended. Can two things perform identically yet one is broken while the other insn't? A simple example is two identical sounding FM receivers. Tune in any FM station and they are indistinguishable but one is broken and the other isn't. Why? Because the broken one was designed to be a stereo receiver and its multiplexer being broken never switches over. I agree that most audio amplifiers sound similar to the degree that under most condistions, it is difficult or impossible to tell the difference. BTW, Krell has a very widely know reputation for sounding thin, harsh, even tinny. Is the flaw with the amplifier or does it show up inferior speakers in ways lesser amplifiers don't. Anyway, I think engineers should revisit the measurements they make and test amplifiers under real world conditions, not under the fanatasy conditions of an 8 ohm resistor for a load.

[Guest Bret]

>As an addendum, Ken, how do you and others weigh in on the Aczel "tube superiority is a myth" proposition?<

Being unfamiliar with the proposition in question, all I can say about tube superiority is that tubes DO have a sound in-circuit and DO have varying weaknesses.

The good thing about tubes is that you can change them easily and relatively inexpensively until you find one that's sound suits you. The bad thing about that is that you never know if you are suited because it is better, or just because you like it. (but does it philosophically matter after that point?)

I have "tube-rolled" a Jolida 100A CD player using a PT P1A-P3A (external DAC and re-clocker/jitter reducer) combination off the digital out as a point of reference. All three sets of tubes sounded different - substantially.

Ken told me not to change the capacitor type in my AR speakers or I would change the sound of them. He was right. If I have three capacitors, all within C-spec, and they all sound different not merely based on materials, then one would assume that something other than capacitance makes a difference. Ken, or someone on his team, spec-ed a mylar capacitor for the tweeter in the 303, for instance. One can only assume that didn't happen by accident; therefore saying that all capacitors sound the same would be false and would cause an argument.

Well, tubes are quite possibly worse.

It is this sort of thing that makes me go, "No. . . couldn't be," when we talk about all amplifiers sounding the same. Two parts of the same "spec" can have radically differing characteristics. The sum of those in an amplifier would seem as likely to change the "balance/voice/sound" of an amplifier nire than a single component would change a speaker's crossover. The contention that it doesn't, therefore, baffles me. The fact that the individuals who contend it are the ones contending it is a little unsettling.

Bret

[soundminded]

Neither tubes nor transistors have any inherent sound characteristic of their own. They have various degrees of non linear distortion which can be eliminated or substantially reduced with clever circuit topology. However, most vacuum tube amplifiers have an impedence matching output transformer with inherent nonlinearities which cannot be compensated for. These include hysterisis losses and eddy current losses. Even the best transformers have about a 2% to 5% loss. There is simply no getting around the fact that these transformers introduce audible distortion which cannot be eliminated. You will rarely if ever see a vacuum tube audio power amplifier with less than .5% harmonic and .5% IM distortion and they are usually much higher. Frequency response is rarely even close to flat even with purely resistive loads compared to solid state amplifiers and hum and noise is usually much higher too. The consequent high end rolloff and poor damping factor resulting from high output impedence may mitigate the the shrill thin sounding loudspeakers so popular today among audiophiles. This is not good engineering. Among the worst things you can do to the design of a vacuum tube amplifier is eliminate negative feedback which will cause its performance to drift endlessly, use directly heated cathodes, and operate them class A which severly limits power output and shortens their lifespan. Yet these are the things currently most popular with audiphiles who like tubes. Among the few vacuum tube amplifiers which had the clarity of a solid state unit I heard was the NY Audio Labs OTL based on the Julius Futterman design. But heaven help you if you own one of these and it needs service and you can't get it back to the manufacturer to adjust the bias voltages. For anyone but hi8m it is a virtual impossibility to get it right.

[rrcrain]

You aren't the only one with old equipment! It's old, I built it from a kit and it still sounds very good. I didn't notice the bass being messed up until I looked at the photo, it explains what I've been hearing lately.

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[Guest Bret]

>Neither tubes nor transistors have any inherent sound characteristic of their own.<

Blanket statements like that can be so misleading. Sure, you're right, the tube has no sound of its own the same way that an AR-3a has no sound of its own. It is merely a collection of "errors" (non-linearities) and, according to this thread, the speaker is much, much worse a distortion offender than any reasonable tube amplifier.

I can't think of a component that doesn't have its own collection of non-linearities.

But the reason I bothered to respond is that when you get X number of people who will say that XYZ tube has "more bass" than ABC tube, and you try them both, and in fact there is "more" bass with XYZ tube. . . well, I tend to think that the XYZ tube has a *sound* whether it is supposed to or not. Maybe you mean something else.

Bret