Thanks for letting us watch (those who consider themselves students and spectators) Nice job Kevin!
One question.Can c12 and c13 be elecrtolytics if there is no Dc to keep them formed?
One comment however concerns data on the power amplifier page. You indicate that the screen tap percent for the A431 clone is 40%. Do you know this to be a fact? The reason I ask is that the screen percent of a bonafied A431 is in fact 33%. If the clone is not 33%, then that represents a substantial change for the clone, making it not a clone at all. On the other hand, it would be very easy to simply assume the taps were at 40%, since that seems to be the percent that all of today's transformer wizards think represents "UL". In reality of course, nothing could be further from the truth.
Dave
For this application then, the current rating of this device needs to be significantly upgraded from the existing 8 A rating, and for long life operation, provided with adequate heat sinking as well.
Agree with Dave on the bridge rectifier- I'd be looking for AT LEAST a 10-12 amp unit, and I'd be bolting it to one of the panels of the chassis, with a good thermal conductive grease between it and the chassis, if not it's own heat sink.
In the amplifier in this thread, with the waveform and flat response produced to 50 kHz, in a design using a transformer that is rated to 60 kHz, it indicates that the response of the active circuits is well matched to that of the transformer, and that good stability will be achieved.
Response can be actively increased or decreased relative to that of the transformer's, but stability will be compromised if going above it, and sonic presentation will generally be compromised either way you go -- either because of the effects of instability from a poor feedback amplifier (too high a response), or because the stability networks are affecting response down into the audible range (too low a response) -- all IMHO of course.
Maybe my first relevant question. On Dave's recommendation I'm reading Morgan Jones' valve amplifies. I wish I was absorbing as much as the stuff going over my head. I happened to have just finished chapter on power supplies.If I understood correctly if the larger rectifier were noisy (because its larger?). You might be better off using Schottky rectifiers to build the bridge. Did I misunderstand?