Looking for a little help troubleshooting an issue I’m having with a vintage Onkyo A7 amplifier my father gave me. I’m having an issue with the right channel. When I play music, the right speaker sounds very thin, like there is no low end. If I use the balance control on the amp and switch from full left to full right, it’s obvious I’m not getting full sounds out of the right speaker. The tweeter seems to be coming through fine though. When I swap the output wires, the issue follows, so I’ve ruled out the speaker being the issue. I’ve tried new rca cables that I know work and the issue is still there.
I tried pulling out the main-in and pre-out jumpers to bypass the volume knob on the amp and now there is no low end in both speakers. Plugging the jumpers back in gives the left speaker low end again. At this point I don’t know if there is anything else I can do to try and identify the problem. I did open the amp to inspect the caps and they all seem OK (no leaking or bulging), but I’m no electrical engineer so I don’t really know what I’m looking for. Any suggestions would be greatly appreciated.
Just in case this matters, I am running spotify from my tv to an smsl su8 via spdif, rca to amp, speaker wire to speakers. Any and all help would be appreciated. Thanks in advance!