Hi guys
So I finally have my Crack up and running. All the resistances and voltages check out a-okay, except the tip / ring voltage when powering up without headphones attached. The voltage spikes to around 25 (way over the expected 9V), but goes down to a few millivolts after a while.
After letting it sit for a few minutes (making sure that jack voltage stayed close to 0), I plugged in some cheapo headphones, and an old ipod as source. And it works! Super chuffed.
The other problem I've encountered is hum. There is no hum up until around 30% volume, then it increases with volume. With no source attached, the increase is constant. With a source attached, the increase is constant until 90% volume, thereafter the hum drops quickly until there is none audible at max volume. Weird. This occurred with the cheapo 'phones as well as HD650s.
Mine is the 240V version. Changes made:
Installed shielded signal wiring from RCAs to volume pot
Alps blue pot
Neutrik locking jack
Increased value of output capacitors for possible Grado usage later
Mullard 12AU7
GE 6080
Edit: Belton tube sockets
Sooo... any suggestions?