I am looking for some debugging advice to help me narrow down something that has been bothering me. My right monoblock is not as loud as my left one. I've been using the gain on my sp14 to compensate (about 4 clicks), but I want to figure out why it is softer. My conclusions so far:
- it's not just room acoustics - at low volume listening a foot from the speakers the right output is obviously softer
- it is not the speaker or speaker cable - I swapped them and it follows the monoblock
- it's not the input - I switched the rca cables
- it is not the output tubes - swapped all 4 KT-88s between monoblocks
- it is not the driver tubes - swapped them
- voltages at all 8 pins on the 4 output tubes are all within published range.
I don't hear any audio artifacts. They both sound great to my ears, it is only a volume difference. But I want to isolate what is different and am asking for advice on how to do that. Are there measurements I should be taking at the speaker binding posts? Could a bad soldering job there cause this? Could it be a wrong/bad component on the board?