Cool Tubes....

[wkhanna]

I have some decent tubes in my Carver C-19 pre/phono-pre.
These NOS Mullards are precious to me, a gift from the maestro who did the mods as directed by another maestro, Bob C.

A while ago I read this article from Perkins Electro-Acoustic Research Labs (PEARL).

As with many components, heat is THE enemy.
Tubes were a crucial component of the technology that preceded today's IC chips.
Their importance in the technology that was advanced at a blinding rate was paramount during the 2nd World War.
Used in all radar & communications, they were the backbone of the military & their reliability was paramount.
As such, there was extensive research conducted.
This article relates some of the results of those investigations.

Figure #3 on page 6 is of great interest to me.
Seemingly minor reductions in tube temp can result in significant increases in tube life.

I just placed an order for 4 Pearl coolers to wrap the 6922's residing in my C-19.
There may be additional benefits from the damping effect (microphonics).
I will update with my impressions once they arrive & I have time to do some comparisons.

[Kevin P]

Interesting article.

I wonder if running the filaments at a (slightly) lower voltage does for tube life, hopefully without adversely affecting tube performance too much. It would be an interesting experiment.

I might have to get some coolers for the vintage tubes in my headphone amp, just so they'll last longer.

[wkhanna]

Too Cool....

Too cool can be a problem, also.

Generally, a minimum of 100 degrees Celsius is required to generate the thermionic emission process which releases the electrons from the heated cathode base metal.

[PewterTA]

I was just over at Bill's this evening and we put on the Tubesinks (trademarked by me! ha ha) on his tubes in the Carver C-19 pre-amp.

I'm not one for thinking they would do much for the sound....but amazingly enough they did... well something to the sound. It's a pleasurable something. The sound has more ambiance around the instruments, they seem to float in mid air (maybe less attached to the speakers) is what we noticed... They were more musical as well. Just a nice difference. The highs might have lost a little of the sparkle that they had, but at no point did we feel that we were missing something...it just seemed more neutral would be my best guess on it.

Bill did read something about grounding the headsinks to the chassis and it brings back the slight loss in the high end, if that's the case, then these are an AMAZING addition. If the highs shine as well as they did before (which again, might have been too bright to begin with), but if everything else stays the same and a little shimmer is added to the high end then I'm completely sold on these!

[wkhanna]

I am glad Dan was here when I put these in.
He heard exactly the same thing I did.

I have often read that dampers can (but not always) be effective at improving micro-dynamics, especially in in signal-level tubes.

I noticed the difference within the first 10 seconds of the reference track we often use.

It is an ephemeral change that is quite subtle but distinct.

Detail remains, but there is an overall softening, an integration of the music that changes the sound from one of each discrete instrument to an assembly of musicians making music.
The upper highs remain full & intact.
But an element of edginess is gone.
I guess more ‘tube’ like would be what some may call it.
But it is without any loss of dynamics or range with improved realism.

Needless to say, I am quite pleased.

The Carver C-29





The Coolers....





You can also see the Mu-Metal shielding I put around the transformer (whose significant effect I described in another thread) in some of the additional photos....

[PewterTA]

Great Pictures Bill!!!

Definitely it is all worthwhile. Really in my book anything under $100 mark that makes a difference is worth doing. Especially the Mu Metal where it makes a definite improvement in the sound in every single device I've done it to.

[Lex]

Well, I have definitely seen it all now. Tubes with heat sinks. Freaking awesome dudes.

[mjb]

Well, I have definitely seen it all now. Tubes with heat sinks. Freaking awesome dudes.

Well, if Bill had applied copious quantities of heat sink compound to the tubes first, THEN we would have seen it all :B

Here's a 3CX1500A, 1.5 kW power triode, used in radio transmitters. Now THAT's a cool tube!