I have picked up an output transformer in which the secondary appears to have been made with 4 independent 4 ohm windings. If the transformer is to be used to drive an 8 ohm speaker then should I join all of the windings in series then tap it across 2 of the windings, or should I just join 2 of the windings to make 8 ohms and ignore the other 2 windings? Also, when joining windings, do I have to make sure they are in phase with each other, and if so, how?
Four independent '1 ohm' windings is more likely. This is how Sowter often do their transformer secondaries.
All in parallel give 1 ohm.
Two parallel pairs, then connected in series, give 4 ohms.
Two in parallel, connected in series to the other two, give 9 ohms.
All in series gives 16 ohms.
Using windings in parallel reduces resistance for the lower impedance options.
Correct phasing must be used - colour coding is the usual option, or use an AC meter.
For 8 ohms you can use either the 4 ohm or 9 ohm setting.
All in parallel give 1 ohm.
Two parallel pairs, then connected in series, give 4 ohms.
Two in parallel, connected in series to the other two, give 9 ohms.
All in series gives 16 ohms.
Using windings in parallel reduces resistance for the lower impedance options.
Correct phasing must be used - colour coding is the usual option, or use an AC meter.
For 8 ohms you can use either the 4 ohm or 9 ohm setting.
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