Fender Twin High Impedance Speakers

[J M Fahey]

1) use as much signal as needed to make amp clip, both peaks, then remeasure.

2) a scope is great to show things, but not as accurate measuring them, please drive amp to just visible clipping on both peaks, and remeasure VAC with a multimeter, if possible a true RMS one but even a cheap $10 one is acceptable.

Most probably it will not exactly match what scope says.

3)

I've verified the power tubes are good

"Good" as "hey!! ... they work! ... sort of" or "good" as "fresh just out of the box" ?... not the same thing.

Transistors work as good as new for ages or die a violent death; tubes lose emission every hour they are on, from just made to unusable, and degrading is linear ... meaning tubes with quite a few miles on the odometer may very well have lost 50% emission and still "work" .

Please try a fresh quad of tubes, even if momentarily borrowed from another amp.

[bobloblaws]

Please try a fresh quad of tubes, even if momentarily borrowed from another amp.

That is what I did, I grabbed four tubes from another Twin (which is putting out 80 watts). Same result.

I also tested the tubes in question with my trusty Eico tester.

[g1]

If you have access to that other Twin, I would compare the drive signal you have going to the power tube grids.

[bobloblaws]

If you have access to that other Twin, I would compare the drive signal you have going to the power tube grids.

Yep, as soon as the 1 Meg channel volume pots are in.

[J M Fahey]

*Maybe/hopefully* thatīs all there is

[Rhodesplyr]

Right! Rhodes "suitcase" amp has 4 x 32 ohm 12 inch speakers.

This was the first thing I thought, based on my screenname, when I read about 32Ω 12' speakers. They are, in fact, only used in the earlier 80W Peterson Rhodes Suitcase Pianos, not the later 100W models.

Edit: And they would have Fender labels on them.