Audio and Video Talk > Valves / Vacuum Tubes

EF37 EF39 tubes

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darrylo:
Hi

My recently aquired pair of leaks have EF39 tubes installed. I'm no expert but they seem wrong for this application.

Are they ok to use or do I need to replace them with EF36-37's


Regards

Steerpike:
The EF39 is variable transconductance, intended to give automatic gain control in radio receivers. Vari-mu makes it not good for hi-fi audio - you'll get gain compression.
The EF37 is a lower noise than the EF36, otherwise they are very very similar.

darrylo:

--- Quote from: Steerpike on June 22, 2012, 07:17:29 PM ---The EF39 is variable transconductance, intended to give automatic gain control in radio receivers. Vari-mu makes it not good for hi-fi audio - you'll get gain compression.
The EF37 is a lower noise than the EF36, otherwise they are very very similar.

--- End quote ---

 :walled: Thats what happens when you trust people. He will get hes day

Ampdog:
Seems like somebody "rolled valves" again ....

Steerpike:
Some people might LIKE vari-mu's in audio pre-amps. I have a Hammerstein radiogram with EBF89s as the audio pre-amp - which is OK when it is in radio mode, but they run the phono and tape inputs throught the EBFs too!

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