Egnater Rebel 20 bias test voltage too low

manolonte

New member
Hi,

I'm new to this forum, thank for all the valuable information I can find here. My problem (or not) is the following:

I bought a second hand Rebel 20 and it arrived yesterday. I have tested just at home at low volume, so I am not sure about how it sounds at its best. Up to now, the sound seems to be glorious.
I opened it to check the biasing (I have some knowledge in electronics, have fixed some amplifiers and made and modified many pedals), and to my surprise, I could not reach the recommended voltages on the test points. Only as much as 34mV on EL84 test point and 24mV on 6V6 aprox. It came adjusted with 19mV and 8mV, and rising the voltages made the sound worse, so I left it as it was. I think EL84 tubes are not original, they are JJ.

Should I worry about this? Does my amp have a problem? Do the tubes need a replacement?

Thanks a lot in advance,
Manuel
 
Last edited:
Hi again,

I have made some more exact measurements and adjusted the bias again with a good sound:
EL84: max: 27.4mV min: 1.5mV
6V6: max: 40mV min:3.2mV
Adjustment: EL84: 23.3mV 6V6: 33.3mV

Now it has a hotter but pleasat tone, better than before I think.
But still don't know if it is normal not to be able to get recommended settings.

One observation: one of the JJ EL84 tubes has almost no red glow in the upper end of the tube, much less than the others tubes.
 
Back
Top