Beacon output transformer with 9 secondary taps, what ones to use?

[flyingtele]

I have aquired an old valve amp chassis that uses three preamp tubes and two el84 output tubes, just a basic 10 watt amp. But, the output transformer is confusing.
it has a centre tapped primary, sweet as. but, the secondary has 9 taps! the only labeling on the taps are the numbers 1-9.

What pair of taps should i use for a given impedance? do i just see what sounds best, or do i try to find a pair that have a similar dc resistance to the total speaker load?

[Enzo]

The DC resistance of neither the transformer nor the speakers will tell you anything useful. Oh, I guess you could figure out the order of the taps that way, but not their impedances.

I would guess the old chassis is from a PA amplifier, and your taps are something like:
Common, 4, 8, 16, 25v, 70v.

Or it could be a straight 70v transformer and each tap represents a power level, like 10w, 5w, 2.5w, 1.25w, etc, and common.

Or some combination of these things. Are all 9 taps electrically connected? Sometimes the CV windings are separate.

Look up 70 volt speaker systems, or 70.7v speaker systems sometimes. They are also called constant voltage systems or CV. SO CV speakers. SOmewhere in the area of 70v, 70.7v, CV or constant voltage speaker systems you ought to find some introductory material online.