audio-talk

I doubt it !
Ps. the RMS voltage of the 7V transformer secondary is 7V
I don't think you need to invoke peak currents , it's just that the total load is at least 24VA on a 25VA toroid, if it's not in open air to cool, it will be stressed. 50% extra VA should be fine - in that case, given the poor regulation of toroids, you may be fine with 2x 6.3 secondaries.

To select the TX secondary voltage required I worked on a 4v regulation loss from the peak TX voltage, so for a 6.3v RMS secondary...

6.3 x 1.414 - 4 = 4.9 ... this would be right on the edge for a 300B requiring 5v, which is why I went with a 7v. I do have a Hammond 266M12 which would give 2x 6.3v @ 3A each which should be plenty current - but it would restrict the voltage to about 4.9ish ? Is it worth me trying this ?

so for the VA required I need 7 x 1.2 x 1.6 = 13.4VA minimum... I think... Is that right?

The transformer losses are usually made up for by underwindin the primary, so at it’s rated currentand “nominal” mains voltage spec you get 6.3v. Then the better transformers would additionally provide plus voltage and minus voltage tappings on the primary to accomodate variation from “nominal” supply voltage.

Of course. Rating 6.3v at 3A. At lower load the voltage will be a bit higher.

All working ok now, dare I ask?

Andrew wrote: ↑Sun Sep 29, 2019 6:12 pm All working ok now, dare I ask?

All stable and silent (unless I'm really determined to stick my ear next to the Lowthers). The sound is awesome. Many thanks. Definitely bring this to the next meet.

The transformers I have in now are ok but borderline. I plan to swap out next weekend.

Well doesn't time fly. Our new arrival is developing nicely and is already outshining its older PP sibling.

Very surprising - I only built this SE amp as a quick and easy rough build spare amp while I brought my PP up to the spec of Geoffs, and because I thought it was a shame to have the kit in a cupboard doing nothing.

I'm desperate to have more experienced ears have a listen. When's the next meet ?