11-24-2015, 11:48 AM
Liquids is right on.
The feedback is only negative feedback if connected to the proper side of the transformer. otherwise its positive feedback, which is a good way to have an oscillator, but not helpful for a guitar amplifier.
your intuition that it "doesn't matter" what the polarity of the speaker is, is not unfounded, the ear won't hear a difference, but if you didn't hook up the feedback wire to the right side... then it does make a difference to your amp.
The feedback is only negative feedback if connected to the proper side of the transformer. otherwise its positive feedback, which is a good way to have an oscillator, but not helpful for a guitar amplifier.
your intuition that it "doesn't matter" what the polarity of the speaker is, is not unfounded, the ear won't hear a difference, but if you didn't hook up the feedback wire to the right side... then it does make a difference to your amp.
(11-23-2015, 09:10 AM)Liquids Wrote: Bummer man. A fairly amatuer suggestion here - did you try flipping the primary or secondary transformer leads around...? Or disconnect any negative feedback temporarily to see how that affects things? Keep a REAL careful eye on it for sure if you DO flip and fire it up. Ideally use some older tubes you care little about--or get some, for troubleshooting, if possible.
It sounds like oscillations or 'motorboating' of some kind develops, though the symptoms are a little weird for it to be just reversed transformer leads I think, despite my suggestion. So even if that doesn't fix it, you'll be more certain that the transformer is wired properly, if you give that a try, if nothing else. It seems logical to start with stuff surrounding the transformer given that it's what you replaced...rule it out or otherwise.
Steve/Hangman or others will likely have better input though.