Quote:
Originally Posted by Electronic M
Most feedback I've seen comes off the speaker windings. Given the resistances I suspect a higher impedance feedback winding to supply a higher feedback voltage. If you can determine the correct ratio it might be feasible to use a normal output xfmr and another small one to step the speaker winding back up to feedback level.
|
I think they used a separate winding not for a different voltage, but because the way the bass driver is connected it would prevent feedback from being connected normally. (look at the reversed green and black wires)
The higher resistance doesn't necessarily mean a different voltage ratio either, it could just mean finer wire (the feedback winding will pass very little current, so can be a much finer wire than the voice coil winding). Easiest way to find out is to apply some voltage to the primary of the good transformer, and measure what appears at the secondary and feedback windings.
There are a few ways to fix this amplifier, what it looks like to me is a somewhat semi ignorant copy of a clever design. I say so because the two tweeters are out of phase, and it seems like they went to a lot of work to order custom transformers which in such a cheap console probably weren't justified.