Metropoulos Forum

Hi Guys,

My SED =C= EL34's started to go out last night, so I threw in a spare pair I had laying around. When checking the bias on the new tubes (using the 1ohm resistor method) I could get the normal reading on V4, but no reading at all on V5. I'm not sure what could be causing this. I measured the 1 ohm resistor to verify it didn't get corrupted somehow, and it's still measuring 1 ohm.

Judging by the sound of the amp, I'm not entirely sure if V5 is getting biased properly or not. The sound is full, but somewhat harsh, but this could just be the tubes (and old pair of Ruby EL34CZ). I guess it's easy for most new tubes to sound harsh coming off of Winged C's.

Does anyone have experience with this bias reading problem?

BTW, its been a while since I've posted here. Feels good to be back!

Swap the tubes around to see if it's the tube or the V5 socket. If the socket is the problem you may have a loose ground connection on the 1 ohm. Check for continuity between pin 8 and ground.

Thank you sir. Swapped in some JJ's and got a normal bias reading. They aren't kidding when they say JJ E34L's have more headroom. Luckily the new SED winged C came in today so I'm back to creamy crunchy goodness.