34/6l6 switch on VH 4

[Little B]

On my 070836# vh4 head theres a switch in front of the power tubes for 34's or 6l6's...Doesthat mean only use 34's or 6l6's, or can you mix tube types( 2- 34's+2 6l6's), no matter where the switch is?..

 

[MourningEngine]

On my 070836# vh4 head theres a switch in front of the power tubes for 34's or 6l6's...Doesthat mean only use 34's or 6l6's, or can you mix tube types( 2- 34's+2 6l6's), no matter where the switch is?..

No tube mixing possible with the VH4.

 

[Little B]

Thanks, I wondered about that..Do all vh 4'S have the 34/6l6 switch?

 

[MourningEngine]

Thanks, I wondered about that..Do all vh 4'S have the 34/6l6 switch?

Yes, they do as far as I know.

 

[FourT6and2]

Why is there a switch to begin with? Does it just adjust the bias range of the trimmer? What happens when you want to use KT77, KT88, 6550 and etc.?

 

[steve_k]

The older VH4's don't have one. This doesn't mean you can only run 34's or 6L6's. It varies the voltage so that a matched set of the other tube type can be put in amp without re-biasing, if you wanted to swap. Next time you are changing tubes and have the chassis out. Take your voltmeter or whatever biasing meter you use and measure plate voltage on 34's then switch it to 6L6 then measure it and see the change. By default, this will also change the biasing range for a tube since the input voltage has changed and the bias requirement changed.

Steve

 

[bronz79]

What happens when you want to use KT77, KT88, 6550 and etc.?

-6550=switch on 6L6
-kt88= switch on EL34 *doubt
-kt77= switch on EL34

*Sorry if i've mistaken i'm very tired and i don't remember family tubes types.

 

[Little B]

Hey, thanks for the info!..Can we confirm where the switch needs to be for KT88's?.....

 

[Ventura]

PM Duolos or Papa to get the real facts Braddah...

V.