tubes and analog

Reading this thread over the past several days has been entertaining, to say the least. I've learned a few things from all of the technical discussion...mostly that I know very little.

Like a previous poster stated, I'd look to the tubes in the AES unit first. Some tube rolling/upgrading/replacing might be a less expensive way to attack the issue. Some Herbie's Audio Labs tube dampers would be a great tweak to try...they will help with your "muddy" bass, as well as "clean up" the sound a bit allowing the low level detail to come through.

Maybe, as some have stated, the AES and the PrimaLuna will never play nice together.

Some Herbie's Audio Labs tube dampers would be a great tweak to try...they will help with your "muddy" bass, as well as "clean up" the sound a bit allowing the low level detail to come through.

Excellent suggestion, and a very quick and easy way to determine if overly microphonic tubes are to blame for the muddy bass.

Raulinruegas, I'm not insulting you, but your description of our product just happened to be something that has not been documented in nearly thirty years of business. I had to call you on it plain and simple.

Like anyone else in the business, sure we've had failures. But not 'blowing up' on account of a tube failure! which is the context of your statement. As an OTL manufacturer, we had to face the prior legacy of Futterman et.al. who had convinced the world at that time that OTLs were unreliable. We had created a way to make them pretty well bulletproof, so that a tube failure, speaker short, open input or total overload could not damage the amp.

I'm well-known for doing stunts with the amps at shows- pulling power tubes while the amps are playing, shorting out the output while the volume control is turned up to the limit and other things- things you would expect to damage an amp if you did them.

One time I had a tube arc when I had the speaker terminals shorted during just such a demonstration. No big deal- the amp was playing as if nothing happened when I removed the quarters I was using to short out the speaker terminals.

So you chose to describe the the one thing our amps *don't* do. So of course I had to call you on the carpet. In order for these forums to work you have to stick avoiding misleading comments.

I'm friends with a physicist named Earl Geddes who specializes in acoustics and psychoacoustics, has authored books and holds patents in the field, and who not long ago presented several papers to the Audio Engineering Society on the subject of distortion perception. Earl is NOT a tube-o-phile.

Earl's research confirmed that the ear is very sensitive to low levels of high order harmonic distortion (I don't recall whether he singled out odd-order distortion or not), but very tolerant of high levels of second harmonic distortion. He also found that the ear is very sensitive to a rise in distortion at very very low power levels.

After he had completed the study, Earl made this remark to me (as close as I can remember): "Duke, now I see why you and your friends like tubes so much". He also told me that his study indicates a negative correlation between THD and listener preference - in other words, listeners were more likely to prefer the device with the higher total harmonic distortion measurement! The reason is, the THD measurement does not correlate well at all with distortion perception. THE INDUSTRY IS MEASURING THE WRONG THINGS.

Earl Geddes and Lydia Lee have proposed a new distortion metric that correlates very well with subjective listening tests, but it has not been embraced by the industry.

Anyway, my point is that in general solid state devices have lower measured distortion, but the distortion characteristic of tube devices is more in harmony with the way our ears work.

Finally, as an Atma-Sphere dealer, I have never had a customer's Atma-Sphere amp or preamp "blow up". Tube failure is not an amp blowing up, and Ralph's amps are designed so that tube failure does not damage the amp at all. In several thousand hours of listening, I have had one case of output tube failure and one case of input tube failure in an Atma-Sphere amp, both of which were easily remedied by replacing the tubes with no damage to anything. Ralph has never had a case of a customer's amp "blowing up", so I think Raul overstated his experience a bit.

Duke

Dear Audiokinesis: The problem was " more " than a simple single tube: first one tube, few minutes latter a second one and finally damage the speaker.

Atmasphere is right the amp don't suffer a serious damage, but I'm talking of a whole sale tube technology problems when used on audio:

+++++ " You certainly know every single tube technology limitations: very high output impedance, tubes are a noisy device " per nature ", tubes designs have higher distortions level than SS or hybrids one, tubes have heavy problems to reproduce accurately both frequency extremes specially the low bass where ( beteen other things ) does not have control over the woofers like the SS topology, tubes are untrusty: time to time ( very short time ) blow-up, tubes are not performance consistent: almost every single day sound different ( many people don't take in count because every day are in touch with their systems ). Jh you know that we can go on speaking about but this is not the subject: you and me know that there is nothing perfect in tubes or SS electronics.

Jh, the subject is that the " very old myths " about SS designs, fortunately, dissapear. Today we have very good SS designs as we can find good tube designs. The best of all is that today the customers have several choices that in the past don't. " +++++

and I'm talking of those tube problems only because Mr. Atmasphere " thinks " that he lives in an " island " where only exist TUBES and where the other technologies are not " up to the task ".

This is totally untrue there are hybrid and SS designs ( tube designs too ) that not only are very good designs but that outperforms the Atmasphere gear.

Regards and enjoy the music.
Raul.