DR build humming

[Randall]

I finally got a 100@100v bias cap, and yes it dropped the hum down by about 50%. Compared to the other amps I have on hand, it is now about the same. I re-routed some wires in another thread to stop some oscillation, so I think I am track. thanks so much for your kind help everyone. I still have to figure out the standby pop.

[leocella]

. I discovered by lifting the PI plate node at the 100K/82K junction the hum will reduce to about half to an acceptable level

Hello Randall, i´ve reading a lot fo this problema (hum problem on DR), i have the same problem in my DR diy, what do you mean with "lifting"?, thanks! regards from Argentina
Leo

[leocella]

I finally got a 100@100v bias cap, and yes it dropped the hum down by about 50%. Compared to the other amps I have on hand, it is now about the same. I re-routed some wires in another thread to stop some oscillation, so I think I am track. thanks so much for your kind help everyone. I still have to figure out the standby pop.

Randall, soo, to reduce hum i have to try this:
1- change bias cap (100@ 100v)
2- add a cap 22@ 63v in the bias, like RI schematic
3- "lifting" the PI plate node at the 100k/82k junction
right?
regards!