express clone: bias tooooo high!

[mac0611]

I finally got it all together , and fired up the power to make initial checks. I have a whopping -12.35 bias voltage! All values have been checked, and as per the franny pics, everything is hooked up right. Can anyone chime in with their thoughts? Thanks!

[Normster]

Just a shot in the dark here, but I ended up swapping out the 220k dropping resistor for a 150k to get my bias within range.

[Allynmey]

As normster did, many people had to change to 150K. For some crazy reason, I didn't have to. I had plenty of wiggle room there with the 220K....strange.

Allynmey

[mac0611]

Hi everyone,

my bad. voltage was too low. I have a 100K in there now, and I can get -31.5V, enough to flip the standby. Strange that I have to use a value more than double below 220K to get to the bare minimum. Anyway, I fired it up, and with my '57RI LP, I am absolutely stunned by this amp!! The crunch is tight and well defined, and the single note clarity is remarkable, given the huge amount of gain in this amp. I have to stay well away because of feedback, but otherwise, the amp is dead quiet. I churned out "working man" by Rush, and I couldn't believe the balls this monster has. I would like to post pics, but they aren't coming up. I am going to get someone to help me post sound clips for all to hear. Special thanks to Allyn, Dana, and Moose for all the help and parts.

[mac0611]

one more thing, tube complement is: Tungsram EL34's, a 7025 RCA in V1, and GE 12AX7's in V2 and V3. All new and tested.