Question about tubes?

[Ski Bum]

It is a fact that as sound propagates through air, low order distortion increases over distance.

I assume that you are referring to large distances (relative to the wavelength) and high intensities--like in the throat of a horn loudspeaker--to be significant/audible, right?

Chris

No. Well, yes, large distances relative to wavelength.

For an example, take your lion and park him on the goal line. Put microphones on the 5 yard, 50 yard, and opposing goal line. Make the lion roar somehow, and compare what your get at each mic. What will the measurements reveal? What, besides diminished spl, that is?

[Ski Bum]

Only inside a horn waveguide, or at high (145 dB+) SPLs, and long distances. Concert sound system arrays are most affected by this issue.

Emphasis added.

This harmonic content shift of sound over large distances happens to be oddly similar to the distortion pastiche which single ended circuits impose on the sound, which may account for their ability to create the depth-of-auditory-field they're renouned for. Better sonics through higher distortion and perception trickery.

Of course, I could be completely wrong...it happens frequently, much to my chagrin. At least when you're wrong, it's a chance to actually learn something.

MDeneen, that's an insightful post. I would like to think that with more encompasing knowledge that the two approaches will eventually converge. Until then, the Klipsch forum is about the only place where you can discuss odd amps without either incurring the wrath of the objectivists, or drowning in the woo from the other side. I'm just glad that our Klipsch allow us to play with such toys in the first place.

[Chris A]

This harmonic content shift of sound over large distances happens to be oddly similar to the distortion pastiche which single ended circuits impose on the sound, which may account for their ability to create the depth-of-auditory-field they're renouned for.

Here is a much more convincing explanation (IMHO): http://forums.klipsch.com/forums/p/150846/1567490.aspx#1567490 - see the comment on Carver's explanation of tube amp reverb from a fairly recent video interview. I believe it is the high output impedance of the tube design that provides a room reverb effect, i.e., "spaciousness". I think that a DJ reverb unit spliced in a processor loop on the preamp would essentially do the same thing.

BTW: I don't prefer reverb units...that I can't turn off...

Chris

EDIT: I also prefer to not have a "built-in Aphex Aural Exciter" that injects level-specific harmonic distortion. I can certainly add that one in a processor loop if I feel the need for that.

[Ski Bum]

Here is a much more convincing explanation (IMHO): http://forums.klipsch.com/forums/p/150846/1567490.aspx#1567490 - see the comment on Carver's explanation of tube amp reverb from a fairly recent video interview. I believe it is the high output impedance of the tube design that provides a room reverb effect, i.e., "spaciousness".

Yeah, that sounds more reasonable than my hare-brained theory. Cool thread and link, thanks! Bob is always interesting.

I think you and Mr. Carver are absolutely correct. High output impedance does allow the speakers to pick up room response and add it back into the signal. As a quick test, I unhooked the source completely from my left channel SET amp and played music on the other channel at moderately loud levels (~85db). Sure enough, on the side disconnected from the source I could faintly hear the music. It was very low level, competing with power supply hum, only distinctly audible with ears pressed against the speakers, but it was there. I don't have a pp amp handy to try this with, but I imagine the room-reverb would be even more subtle, given their slightly lower output impedances. There is no sound from the disconnected channel at all when I tried this with ss amps. This goes a long way to explain how tube amps make musical notes seem to hang in the air a bit longer, and how the sense of acoustic space is subjectively enhanced. Pretty cool effect. It also helps explain why processors never quite accomplish the same trick as tube amps driving speakers.

I think that a DJ reverb unit spliced in a processor loop on the preamp would essentially do the same thing.

I could never achieve that, but I did waste a tremendous amount of time trying. Well, 'waste' may not express how fun it was.

What I noted above was much more subtle than the reverb units I tried, which were comparably heavy handed and artificial sounding even at the lowest possible settings. Also, the tube amp / room interaction results in aberrations specific to the listening room, where the processor's settings are arbitrary, so the results may be similar, but will never be exactly the same. The processor does to the signal just what you tell it to, but the high output impedance amp actually 'plays your room'. I personally find the amp/room method much more enjoyable.

BTW: I don't prefer reverb units...that I can't turn off...

Chris

A compelling argument.

When I want to turn it off, I have to swap amps. However, I often can't get the tubes back in the chain fast enough. The best policy is to have both, I suppose. One can never have too many amps.

[captmobley]

Absurd, you say! I resemble that remark! Very wrong-I am, quite often, I'm told. Perhaps I should have personalized my remarks-you guys are technically way over my head.

What I should have said, is that tube amp watts sound better to me than solid state watts.

If it sounds good to you, it is good.