if you become totally desperate, you will need to know the output requirements of the transformer (and how many outputs the transformer needs.. but could be split between two if the voltage is right and each circuit sucks up the voltage without allowing one of the inputs to take the full blunt force of the extra voltage.. *a totally dangerous gamble if you know that it will sometimes but not constantly*)
i have seen quite a few transformers for sale.
they sell 'em for hobbys and do it yourselfers.
just look up torroidal coil and see the different websites offerings.
hard to imagine that one torroidal coil of the same voltage output makes the amp sound different? no.. not really impractical thought here.
since the magnet can have its own noise in the signal.
some amps refuse to work with the noise, and it will sound bad until it dies.
hell.. it might even sound better until it dies.
the point is, if it is the wrong choice of noise or no noise at all.
since the noise can specifically excite the circuit in a way that was intended.. you can get better audio quality with the noise.
so if the noise doesnt match.. maybe you are missing the extra sound clarity.
and maybe the noise is needed to keep the amp from self-destructing, since that noise was fully intended to be there.. to say that the amplifier EXPECTS the noise to be there.
same can be true for amp circuits that dont want the noise.
knowing the noise for what it is from the replacement torroidal coil (or transformer) and knowing whether or not the amp requires the noise.. it could still be a question as to what specific noise is required.
why did the coil die in the first place?
did the copper get too hot over time and lost its characteristics?
maybe re-wrap the magnets.
was there a special liquid or material on the copper that has become ruined from time and age?
because that stuff would be way over my head since i am not a chemist.. maybe a dielectric or maybe a conducting gel.
not something easy to suggest.
maybe it would appear that there was no coating on the copper, and that is why it failed.
maybe the magnets are aged and lost their characteristics.
perhaps enough to know, but not enough to test.. and even if you could test, that doesnt mean you have the power of knowing what it was when it was new.
the bad thing about electrical repair..
sometimes those people replace pieces without knowing why they are replacing them.
meaning, they have no idea why that piece is special.
so if you went to one and asked them to fix it, they might use a piece from the same brand name (maybe even the same model number)
it might work.. and it might be that the brand name has changed their design, so it isnt the recommended choice for the repair anymore.
hopefully sunfire can answer these questions and get you all squared away.