Speaker suggestion (and ohmage) for a Silvertone 1432

[Jonny toetags]

I'm working on a Silvertone 1432 with original speaker and it's deteriorating by touch.
What would be a suitable replacement and what how many ohms?

[Bruce / Mission Amps]

I think those use 4 ohm 12" speaker.
Disconnect your speaker leads from the speaker and use your low ohm setting on your DVMM...
around 3 ohms is a 4 ohm speaker, 6-7 ohms is an 8 ohm speaker... etc.

I'd go look at a Weber VST Signature 12" AlNiCo or ceramic. Or 10" speaker if it is that model.

[gimme some tone]

The 1432 sometimes has a multitap output transformer. I presume the unused tap on a 4 ohm rig is an 8 ohm tap.

[Bruce / Mission Amps]

In this instance I don't know because there might not be a dual secondary OT in it.
But, you might be wrong in presuming that if so, it would be 8 ohms....
the unconnected wire in those old 2x12 Silvertone amps is frequently 2 ohms...

[gimme some tone]

Re: speaker impedance - The 1432 schematic indicates 3.2 ohm impedance for the speaker. Weber will make a replacement 3.2 ohm replacement on request.

Re: using the "unused" output transformer tap - I connected an 8 ohm speaker to it, played through it for 10 minutes and it sounded fine.

Re: deducing the output impedance of the output transformer - Is there a characteristic of the transformer I can measure and compare the two taps and then deduce the other tap's impedance?

[g1]

Is there a characteristic of the transformer I can measure and compare the two taps and then deduce the other tap's impedance?

If you have a sensitive enough meter, a resistance check (with speaker disconnected) may show whether the unused tap is lower or higher in resistance. Try several times and look for consistent results as the difference will be slight and it may take the meter awhile to get a stable reading.
So, for example, if the 4ohm tap to ground reads .3 ohms and the unused tap to ground measures .5 ohms, you can deduce it is an 8 ohm tap. If the unused tap measured .2 ohms you would deduce it was a 2 ohm tap.
If the resistance check doesn't show a difference, you would need to measure power output with a dummy load and a scope. You would get maximum power transfer when the load impedance matches the tap.

[gimme some tone]

If you have a sensitive enough meter, a resistance check (with speaker disconnected) may show whether the unused tap is lower or higher in resistance. Try several times and look for consistent results as the difference will be slight and it may take the meter awhile to get a stable reading.
So, for example, if the 4ohm tap to ground reads .3 ohms and the unused tap to ground measures .5 ohms, you can deduce it is an 8 ohm tap. If the unused tap measured .2 ohms you would deduce it was a 2 ohm tap.

Thanks - those are some hard to get measurements.
I measured .5 to .6 ohms resistance on the 4 ohm tap and .3 ohms resistance on the unused tap. That result strongly suggests it is a 2 ohm tap.

Is there any harm in using an 8 ohm impedance speaker on the 4 ohm tap?