change the tubes

[chefg1]

I am running eight 6550 tubes in my bogen amp. But i would like to switch to el34 . What would i have to do? oh it is the same mo-200 that i have talked about in earlier post.:thmbsp:

 

[nashvillebill]

You'll have to rewire the sockets slightly--compare the tube datasheets and you wil see the difference.

Then rebias the new tubes.

Oh, and can the EL34 handle your plate voltage?

You may also want to change your screen voltage.

 

[chefg1]

thank you very kindly,sir:thmbsp:

 

[dgta]

The MO-200 came with 8417 originally. If you still have the same OPTs, check the data sheets and see if the OPT primary impedance is suitable for the EL34s.

You also might need more drive, the 8417s have huge transconductance and require lower input. EL34 has exactly half the gm of 8417.