EL34 Hickok 439B setup

[Bruce_weiland]

Hi Guys and Gals,

I recently bought a very nice pair VTL MB-225T.

I have some new Svetlana, and used Tesla EL34's

My tube roll chart (spring 1972) in my Roger Kennedy modified and calibrated Hickok 439B does not have the EL34 listed.

It does have the KT88, and the KT66. I "think" the KT66 is somewhat close to and EL34 electrically, so I am using those settings for testing.

But, I know those are not the correct settings.

I don't suppose anyone out there in cyberland could give me the correct settings, could you?


Thanks for any reply.

Bruce

 

[kevinkr]

See if the 6CA7 is listed which is the U.S. equivalent for the EL34.. Is that actually a 539B, if so I might be able to provide the proper settings at some point..

 

[Bruce_weiland]

Kevin, thanks. 🙂

That was simple. The only setting difference was a bias increase from 3.0 to 5.5.

Yes, it is a Hickok 439B, with SS regulation, and digital meters.

Kevin, and others. I have two other questions, OK three.

1) Which is more important to match on output tubes, Gm, or DC plate current?

2) When a tube "fails" is it likely it will take another tube with it?

3) Does anyone know, in a VTL/Manley 8 output tube monoblock, are the four tubes to one side (left), one phase, and the four on the opposite side (right) the other phase of a push pull.

Thanks again to all who have more knowledge and experience than I.

Bruce