I'm playing around with a Nutone 2401b chassis that I picked up cheap. It uses a pair of 6AQ5 per channel. Because it supported having several sets of speakers going simultaneously, I assumed that the OTs would be a little off. But then I measured them ...
They've got a 100:1 turns ratio. 100Vms across the full primary yields 1Vrms on the secondary. That's a 10K:1 impedance ratio.
Obviously I can't use them for this. But what can I use them for? No power tubes I know of want 80k plate to plate. Hell, maybe push-pull 12AX7s?
They've got a 100:1 turns ratio. 100Vms across the full primary yields 1Vrms on the secondary. That's a 10K:1 impedance ratio.
Obviously I can't use them for this. But what can I use them for? No power tubes I know of want 80k plate to plate. Hell, maybe push-pull 12AX7s?
Maybe you could actually make a guitar amplifier that won’t get you evicted from an apartment. The usual complaint about practice amps is too much power, no matter how far down you dial it. This OT might get it down far enough for sane volumes. Maybe not AX7, but AU7 for sure. Or a pair of 3-watt video output pentodes run down at 100 volts.
See Rob Robinette's various micro amps - e.g. Blackvibe Micro EF80. The other hint is "it supported having several sets of speakers going simultaneously" you might do a quad box in parallel to get a 2 ohm load. Or even a 2ohm resistor in parallel with a single 16 ohm speaker to reduce the output power even further
And we're making it a guitar amp? So what if we use the transformer but it is "wrong"? We might like it anyway. Remember, you have heard recordings where the guitarist poked holes in his speaker with a pencil to get a sound he liked.