Synchro-bias
New ClassA
V9 is working again after rebuild and bias adjustment.
Some little issues that are not too urgent, that dont affect overall amp and enjoyment
1. I dont use via tone much, very rarely, slight hum heard more if nothing attached on all inputs, louder if bass is turned up otherwise crystal clear with new tone opamp -OPA1642 (who knows might be the cause). Bipolars are now just Nichicon FG negatives twisted and positives to pcb
NO hum on straight dc, tone related - tone pcb i am thinking
2. 1mv setting only right channel increases in volume, left appears unchanged
I thought maybe the teeth in the selector is broken for 1mv left channel. Or possible continuity for phono2 left and right channel to earth, then, issue would expect to affect phono1 one so i think it could be normal
Resistors in the path for 1mv setting
Some little issues that are not too urgent, that dont affect overall amp and enjoyment
1. I dont use via tone much, very rarely, slight hum heard more if nothing attached on all inputs, louder if bass is turned up otherwise crystal clear with new tone opamp -OPA1642 (who knows might be the cause). Bipolars are now just Nichicon FG negatives twisted and positives to pcb
NO hum on straight dc, tone related - tone pcb i am thinking
2. 1mv setting only right channel increases in volume, left appears unchanged
I thought maybe the teeth in the selector is broken for 1mv left channel. Or possible continuity for phono2 left and right channel to earth, then, issue would expect to affect phono1 one so i think it could be normal
Resistors in the path for 1mv setting