Tubes Do It -- Transistors Don't.

Hey you guys! How come I seem to be the only one who gets told that I must like the "euphonic" distortion of tube amps.

I read an extremely interesting article the other day on the web. The premise was, that single-ended triode amps sound as good as they do, because of system synergy with single driver speakers(primarily). It seems this guy did some distortion analysis of SETs, and speakers. The SET generated primarily second order harmonic distortion, which was the bulk of the total harmonic distortion measured, very little other. The speakers measured primarily second order harmonic distortion also, with very little other. These distortion characteristics mainly differed in phase relationship.

His hypothesis was that if, by way of chance, the 2nd order distortion of each item appeared at 180 degree phase angles apart, the distortion would be cancelled out, creating the "straight wire with gain" ideal. If they appeared at 0 phase angle(together), they would add, and distortion would double. Since either case was unlikely, his solution was to determine which side of the 90 degree phase angle the intersection was, and phase the speaker wiring to place the phase intersection of distortion closest to the 180 degree mark that you could. This way if it was at 30 degrees and adding, by reversing phase, you could put it at 210 by reversing phase and achieve a high level of distortion cancellation. If you leave it at a phase angle close to 0, then the distortion adds - bad. Since the majority of this occurs in the 2nd order on both items, once a certain percentage of this 2nd order cancellation occurs, the THD is dramatically lowered for both items as a package.

This is his reasoning for why SETs have the remarkable clarity they do, while measuring in distortion %, the way they do.

His finding was that by switching phase connections on your speakers, you could find out which way sounds better(reduces distortion) on your system. You don't have to use measuring equipment, just your ears. The goal is to have the amp distortion cancel the speaker distortion as much as possible with your equipment.

This is not possible with push-pull or SS amps, as their distortion characteristics are comprised of many orders of harmonic distortion, and are not coincident with the distortion characteristics of speakers.

The effect is somewhat lost on multi-driver speakers because of the phase changes induced between drivers by the crossover network.

So, while I cannot personally attest to the veracity of his findings, it sounds like a very interesting explanation for the apparent dichotomy of SETs measuring poorly and sounding great. The amp is not used to drive a measurement meter. It is used to drive a speaker, and as such may exhibit different behaviors when doing so, than some lab freak with a meter may even realize.

Maybe there is no "euphonic" distortion in SET amps, when you connect them to a speaker and listen to music. What a novel concept. I never really liked the sound of a meter anyway.

KarlS, you need to try listening to a Berning ZOTL. One reviewer, when he was asked about the ZOTL he reviewed, said that it was the best SS amp he had ever heard. Of course it was a tube amp, but the point he was making was, that it had the beauty of a tube amp with the speed and woofer control of a SS amp. The Bernings are remarkable amps.

Karl, I think that it could do it, with the feedback selector switch in the 2 ohm position. My experience with the low impedance on the Bernings is some of the "life" goes out of the music. I think that this limits the dynamic headroom capability of the amp. I did not notice any problems with reproducing the low frequencies with a 4 ohm impedance load. It was most noticeable to me in the midrange vocals, where some "life" left the sound. 6 ohms was just as "happy" as 8, so anything above 6 ohm nominal should not be noticeable. I found this when I was doing some speaker designing for my MicroZOTL which is a push-pull design much like the ZH270 except no feedback. By using some non-inductive load resistors in a series-parallel network across the speaker terminals, I could determine the sonic behavior of the amp at different loads during play. I could determine where it would "harden up", if you will. Now the ZH270 has some limited feedback switching which provides better behavior under some difficult conditions than my no-feedback design. But my output impedance was 1.8 ohms, which is the same as the 2 ohm setting on the ZH270, so I think it would be similar. So I expect it would sound good, but not as good as a 6 or 8 ohm load.

Tubegroover, see my last post above for my experiences at lower impedances with the Berning.

Personally, I think it is rather funny that some people think that "tube heads" are in it for the distortion. That cracks me up!

If ANYONE on this board REALLY thinks that I, or other tube aficionados here, are buying tube systems to get a certain type of "even order distortion" or euphonic sound out of this gear, then they are totally deluding themselves. This notion that the purpose of tube gear is to introduce some kind of "likable" distortion, is ludicrous. I cannot even believe that I am hearing that kind of stuff from people who are supposed to be knowledgable about audio. Do you really think so poorly of your fellow audiophiles to believe that they would spend large sums of money to "distortion-ize" their systems? Do you think that they have no idea what good sound is? I can understand that some people in the SS camp like the sound of their SS amps, and that is fine. Good SS amps can do some things very well. And good tube amps do some things very well also. Nothing does everything perfectly. So all of us have preferences. But the idea that some audiophiles think that the "tube guys" are purposely distorting their systems is outrageous. I find this very disturbing.

Now, I am the first to point out that all things have deficiencies and will try hard to promote my ideas of what better sound can be. But, I have never promoted the notion that people who use digital sources or high power SS amps, are doing it because they like to reduce the sound quality of their systems.

Just think what people would say to me, if I stated that they use CD players because they like the "synthetic,lifeless sound". Or they use SS amps because they prefer the grainy, sandy distortion that only SS can provide, with the euphonic odd-order distortion. Or that using some SS preamp with a tube amp can add just the right amount of "sand" that we love so much.

This is unbelievable. Why do you do this? Is it a lack of understanding that tube systems can provide very good lifelike sound? Have you been brainwashed by the audio writers that spew out this garbage? Do you believe that spec sheets tell all about tube amps, but tell nothing about SS amps? Just what is the purpose in all this?

I love tube amps and I promote their use. But you will never find one post by me on this forum that actually denigrated an SS amp in a correct application. And I have never stated that the owners of SS amps are enthralled by some kind of distortion in their systems that is inherent to SS designs.

Now we have people actually posting on these threads that if they just put a couple of tubes in the system, then that is enough to give the "even order distortion" that they want. Incredible! What is this world coming to?

Okay, I'm out of this thread. Go ahead and hug your measurements. The funny thing is that this argument was over and done with 20 years ago, and many of you haven't even caught on to that yet. I just hate to see people floundering around in the dark. Just in case you need an update, the news in 1980 was that specs don't tell the story. Nothing has changed about that since. I thought this was an audiophile site.

The more things change, the more they stay the same. What I am seeing here is simply a re-hashing of the old "measurements" argument that was totally de-bunked, and trashed over 20 years ago. The measurements do not reflect the sound of the equipment when it is used in real world applications. Yet people still cling to this dead horse. And it gives rise to these incorrect statements about tube colorations and distortion, in comparison to SS amps' colorations and distortions which are usually designed from the ground up to have great measured specs, but can't cut it as well in the listening room. Look, a cheap Yamaha reciever will measure out better than a Ongaku amp in the lab. Is there anyone who thinks that the Yamaha will sound better or be more truly accurate at reproducing music than the Ongaku? Puhleeeese. If measurements are your thing, then go out and buy a set of test instruments and hook your SS amp up to them and watch the meters move. If sound is your thing, then buy a good tube amp and hook it up to your speakers and enjoy music. If you think for one minute that those specification measurements are going to tell you anything about the real world capability of that amp, then you are sadly mistaken. Specs are a marketing scam, and that is all they are. I am very surprised that people on this board are still under the same misconceptions that were thrown out the window 20 years ago. The only spec I need to know is if the unit will turn on. The rest is done with the ears. By the way, the THD of this post was <.00000001%. Wanna buy it?