Date: Sat, 20 Sep 1997 15:55:05 +0300
From: Roman Efimov 

Hi Andrea!

>Is true that the lifetime of 6C33C-B is 700 hours only; a shop in
>Rome yesterday told me that He have received a fax with this
>I have 4 tubes now !! and it is a very short lifetime !!

Lifetime of 700 hours is followed for extremal conditions
of expluatation. Under real "home" conditions it may be much more -
up to 10000 hours. For examlple, I have about 40 6C33C's; some 
of them, manufactured in 1966,  were used in  military equipment 
for a long time - but it work fine now in my 10 watt SE amp with 
same bias as for a new one! If you want I could mail you 
a 6C33C's specification note from the manufacturer.              
By the way, the price of 6C33C's in our local flea market only 
for 1-2 $ per each for NOS and used... 

PS How much is the output power of your amp?

Roman Efimov

Odessa, Ukraine