[Nick3092]

I finally got around to wiring up a 3.5mm jack using 2-100 ohm resistors to tie L and R together, and then coupled it using a .1uf film cap to the high side volume pot and another .1uf to chassis ground. I disconnected the audio feed from the 2nd IF from the high side of the pot as well. I had the original radio speaker hooked up.

I queued up the same song (Sing, Sing, Sing by Benny Goodman) on both my ipod and my SSTRAN. First I played the ipod. I had the volume control all the way up on the iPod, and adjusted it via the volume pot on the radio. I rotated through all 3 tone settings with no notable distortion out of the speaker. The tone controls affected the sound exactly as they should.

I then disconnect the jack and put the line from the 2nd IF back on the high side of the pot and played back the same song via my SSTRAN. I got the distortion again on med and high bass settings.

So, I think that means I can say for sure the audio stage, tone controls, and speaker are not causing the issue. So now I'm left trying to figure out what in the earlier stages is causing some kind of distortion that is being filtered out on the "no bass" setting, but comes through on the other 2 settings.

This type of problem is new territory to me, so I'm wide open to suggestions.