[Amps] Amps Digest, Vol 50, Issue 20

[K3vw at aol.com]

The problem with 3-500Z's was/ is caused by insufficient cooling of the  
tubes. Some amps even use a muffin fan on 3CX800 tube amps, which, according to  
Eimac's spec's are to be cooled by a blower, not a fan. Big difference !! A  
muffin fan can not build back pressure like a blower. A muffin fan will not move 
 any water in a manometer !! The manufactures, know what they are doing is 
wrong  but the heat related problems don't usually rear there ugly heads until 
years  down the road. Use chimney's with a blower when building an amp. It 
cost's more  initially, but pay me now or pay me later !! Willy  K3VW