I've never seen this addressed before but when calculating the voice coil impedance in order to find a matching output xformer, don't you need to also include the hum bucker coil impedance in series with the voice coil? I recently dismantled a speaker and the hum bucker was separate on the pole piece. It had a decent amount of wire in that coil, surely enough to affect the overall impedance! Thanks
Ron
Well...yes you do. However I think compared to the voice coil the humbucker which is a much thicker wire coil shouldn't amount to too large a percentage. In addition the voice coil impedance is larger than its mere DC resistance as there will be the inductive component.
Plus when you replace the transformer it will likely be a good enough match, not an exact one.
Thanks Mike. I've seen some speakers listed with impedances of an ohm or two. The hum bucker coil I saw had a fair amount of windings so I'm thinking it would account for a fair amount of the total including voice coil.
Ron
Better yet, early Philco speakers are fractions of Ohm.