changing valves

[dirtyplucker]

is it possible to change the power valves in a 65 twin reverb to 6v6's ? Im after reducing the volume of the amp .
cheers Dave.

[John_A]

I would imagine the voltage in a Twin is too high for 6V6's, but JJ's do have a higher than usual rating. Would definitely need a re-bias though.

Just my opinion, sure someone who knows will be along soon

[jpfamps]

I've seen some "gurus" advocating the use of 6V6s in a Fender Twin.

I personally would not advise this.

The anode, and more importantly the screen voltage, are too high for 6V6s.

If you really did want to do this, I would strongly advise increasing the value of the screen grid resistors to at least 1k, if not 1.5k.

You might be better off investigating an attenuator or a smaller amp.

[ICBM]

There's another thread about this somewhere, but I can't find it now.

To make it work you would need to mod the amp as jpfamps said, and also to alter the bias - and even then you'd need to use very robust 6V6s.

If you want to halve the power (which is what running 6V6s would do), just remove two of the 6L6s - either the inner or outer pair. No modification needed at all.

If you want less power than that, THD Yellowjackets - which run EL84s in place of 6L6s, and contain the necessary circuitry to reduce the voltages - would work, and also avoid modding the amp.