Hey Perry,
I just came across your thread on the C1 , Fantastic work ! I am hoping you can help me in the right direction with a C1 we are tinkering with.
We had a functional and un modded C1 , we decided to do the basic Bill D mod.
The mods, as per the PDF are done with the exception of leaving all the original op amps in place ... We were gonna' see how it sounded before swapping the 4136 op amps. The C1 is currently paired with a WOPL 400 and sounds fantastic...
The issue is there is a "turn on thump, click".... As you power up the C1 , it will "bounce" the meters reasonably hard on the 400, and a few seconds after the protect relay closes a "click" is heard from both speakers. ( this didn't happen before the mods ) ... arg...
The Carver manual references this issue...
View attachment 43197
View attachment 43196
We have +13.v on pin 11, -13v on pin 7 of the OP amps and followed the test in "4.6".... Pin 10 of IC8 is + on power up and switches - in 8 ish seconds
Both fets test ok...
Volume setting, input selection, balance has no effect on the bouncy bouncy ....
If you were to turn the C1 on first and wait 10 seconds or so before lighting up the 400 you would never notice any issues at all....
Anything off the top of your head ?
Cheers !