EL84 Amp Design...Why Such High B+ Voltages?

[g1]

My point was that sometimes we have measurement problems. Less often with DC. You thought the zeners were not doing anything, but the DC shows they are making a difference. Now you can adjust the zener value to get to your desired DC B+ level.

[MZOONY]

Makes sense, I was anticipating I should see a difference on the AC

And was expecting to see some AC difference like 300-0-300 or something
From what I see is this technique ends up doing is giving you some negative DC to the ground chassis and as a result one gets lower DC voltage across the board like B+
Thanks I will take full DC measurements and compare them to what I am supposed to get per the schematic

[Dave H]

Adding a diode in series with the PT centre tap should reduce the DC voltage on the first filter cap by the zener voltage. If it doesn't the zener is reversed. To measure the AC voltage at the transformer you need to use a scope as the zener in series with the centre tap will cause the waveform to have a flat top making a meter AC voltage reading inaccurate.

[MZOONY]

Thanks Dave

[gui_tarzan]

The answer in my mind is to the statement on the first page: "I dunno...it just seems like when it comes to guitar gear, tone dominates over all while reliability gets thrown right out the window. Still don't understand the logic behind it."

The answer is simple; no one cares about an amp that's long-lived but short on tone. Why would one sacrifice tone for the life of a tube? The magic happens in the tone and you can't get that tone by playing it safe. Ask a race car driver if they'd prefer having a perfectly running engine and finishing in tenth or an engine that blows up just past the finish line when they won.

[g1]

And what about the answer from the guy who's engine blew just before the finish line?

[gui_tarzan]

He'd say "that's racin'"