Tubes question.... (preamp/poweramp/biasing/etc)

[Joeytpg]

Ok, I know the Vh4 can take different types of tubes, so a few questions come to mind:

1) can I mix two EL34 and two 6L6s?

2) If I change preamp tubes, do I need to rebias the amp ?

3) can I take out two tubes and run the vh4 as a 50watter? (is it safe?)


thanks guys

 

[steve_k]

Ok, I know the Vh4 can take different types of tubes, so a few questions come to mind:

1) can I mix two EL34 and two 6L6s?

2) If I change preamp tubes, do I need to rebias the amp ?

3) can I take out two tubes and run the vh4 as a 50watter? (is it safe?)


thanks guys

1) why would you want to mix the two tubes? if you run the 6L6 tubes at the same plate voltage as the 34's, they will be running way too much hot. this is why the VH4 has the 6L6/EL34 switch on the chassis. since you cannot control the individual pots, i wouldn't bother. the 6L6's won't last long.

2) no. preamp tubes have nothing to do with bias.

3) yes, you can remove 2 power tubes. there is nothing unsafe about it.


steve

 

[Ampaddict]

the impedance (ohms)will change when you take out 2 tubes.

 

[Joeytpg]

Nice! thanks steve!

 

[steve_k]

no problem mate. yes, when you pull the two tubes (on the vh4 you can pull the fuses instead if you want as this will keep the pots clean from crud) you will half the output impedance. so, whatever ohm cab you are running, use half value.

steve