Cryo tubes

[Purpleplexi]

I was a bit unhappy with the power tubes in my lovely Carr Mercury. It was like after about 20 minutes of playing amp went dark sounding. I'd replaced the preamp tubes already so I got a pair of these -

6V6GT STR-TAD CRYO

The TAD 6V6GT STR Cryo is a special Cryo treated version of the TAD 6V6GT STR. TAD have based this 6V6GT design on the oval plate RCA and GE 6V6GT of the late 50s early 60s. The round anode plates have extensions on them which form heat wings that will help the plates dissipate more heat. TAD...

www.watfordvalves.com

Never bothered with cryo tubes before but I liked the idea that they stay bright when overdriven - I don't like it when the driven sound loses it's clarity. Anyway everything they say in the blurb is true - these sound great. Realised the old ones were date stamped 02 which was about 15 years before the amp was built so I guess whoever traded it in stuck some crappy old tubes in it before they sold it. Tsk.....

 

[PelliX]

Fresh valves will sound better if the old ones are worn. The cryo stuff is complete nonsense though. In a century of vacuum tube production including development for military use, there's never been a single indication that it's in any way beneficial. If cooling them that far had any effect (which is highly unlikely), the effect would likely be reversed once their heated again to the 700C+ they reach during operation.

 

[Ampeq]

I never knew these even existed. It seems like they may become more uniform and last longer?

I’m starting a new company we’re Play Boy bunny’s hold the tubes between their boobs for 20 minutes, rotating them at the half way point. It does nothing for the sound, but watching them being made will melt your heart.

Each set will come with a copy of your tubes being made….. $485 for a set of “fairly” matched tubes. (No pushing or shoving)

 

[PelliX]

Oh, oh... Can we call them Boob Toobs?

 

[Ampeq]

Oh, oh... Can we call them Boob Toobs?

My thoughts exactly, and although the tubes might not be matched the holders are perfect.

 

[PelliX]

Pick a matched pair ... from your favorite matched pair... (tm)

 

[Ampeq]

One thing I’m not sure of is, if Tatiana, (one of our… a…. technician's) makes a set, are they now considered Russian tubes? Very technical… I’ll get back to you.

 

[PelliX]

Gives a whole new meaning to saying a valve has a pair of double-D getters...

 

[67plexi]

From a service standpoint the JJ 6V6S hold up well as far as new production tube
but the RCA black plate will win as far as sound goes pre 1962 made

 

[PelliX]

While it may coincide with a perceived preference, the black coating on the plates was actually intended to enhance thermal properties (radiation in this case), not to improve frequency response or any other aspect of the valve's performance. They also experimented with the dark heaters which were intended to be more linear inspite of wild ambient temperature swings and - if I recall correctly - slightly varying filament voltages. Ultimately, the cathode coating would be the 'interesting' one of the bunch as it's the component emitting the electrons.

I would certainly agree that black plates look cooler, though. Pun not intended but I'll go with it.

 

[Purpleplexi]

Pick a matched pair ... from your favorite matched pair... (tm)

I prefer a matched pair. Not keen on the `one hung low` look.

 

[Purpleplexi]

Fresh valves will sound better if the old ones are worn. The cryo stuff is complete nonsense though. In a century of vacuum tube production including development for military use, there's never been a single indication that it's in any way beneficial. If cooling them that far had any effect (which is highly unlikely), the effect would likely be reversed once their heated again to the 700C+ they reach during operation.

Either way I've decided to call the amp `Walt`. Only other time I've encountered the cryo thing was in my Subaru tuning days. You could make so much torque with them that they would eat the second and third gears. The solution was to cryo treat the new gears before reassembly. I never did it but it was well regarded and pretty much `de riguer` if you were drag racing. I considered it and there's a company near here in Kimbolton who with pretty much cryo treat anythiing.

 

[PelliX]

This is why I don't have single ended amps. There's something disturbing to me about one big output valve and two little preamp ones. Prefer a pair of big bottles anyday.

 

[PelliX]

Either way I've decided to call the amp `Walt`.

Sorry, I feel I'm missing a reference here...?

The solution was to cryo treat the new gears before reassembly. I never did it but it was well regarded and pretty much `de riguer` if you were drag racing.

I've heard of this, too. I might well stand to reason that it can somehow reduce the likelihood of fracturing in such applications, but that relates to mechanical strength. A valve doesn't operate 'mechanically' in that sense and heat is not only a byproduct but a vital part of its operation. I could imagine that it might help to perform extreme heating on the cathode of the valve before applying the coating due to thermal expansion, but that's a guess at best. As for freezing them after they've been put together, de-gassed and sealed it seems pointless - in fact *if* these companies are really giving those valves the treatment (and that's nearly impossible to prove, ultimately... [wink]), it might have a negative effect on the plastic bases or the adhesive used in applicable types (6V6, EL34, KTxx, etc, etc). Hmmm, next time I snag a base off an old one, I might just try some liquid nitrogen... the last one involved a lot of hacking at bits of glue and broken glass before I could remove the wires...