"Phil Allison" wrote in message
...

Gareth Magennis wrote:



The EH tubes were actually branded "Watford Valves Cryo" - Watford Valves
put these things into liquid nitrogen to make them work better.
Apparently.
Cough.


Interestingly, I had another (non Cryo) Electro Harmonix ECC83 which
didn't
bug out at the reduced voltage, so perhaps this was a dodgy quad of ECC83,
of perhaps something to do with the Cryogenic process?



** I doubt they put the valves directly in liquid N2 - as it would destroy
them instantly by cracking the glass. Even if done some other and safer way,
the whole idea is completely nuts.

One of the design issues with valves is the vacuum tight seal between the
pins and the glass base - cos steel and glass do not have the same tempco of
expansion. Typically, steel has a higher tempco so the fit get tighter as
the glass envelope heats - conversely it gets looser at very low temps.

Prolonged exposure at very low temps could let air ( or N2) into the vacuum
and spoil the operation.


..... Phil







My bad, their website makes no mention of N2. Maybe they just stick them in
the freezer and call it Cryo.
Interesting info though.

Anyway, any thoughts on 5.1v heater voltage as a viable propostion?


Cheers,



Gareth.