Ok if I recap a 8uf bias cap with 47uf ? (Traynor YGM-3)

[Leo_Gnardo]

At this point the OP is probably banging his head on the workbench wondering what he did to cause all this. I liked my original answer. "It'll be fine"

To the OP the difference is an estimated 15s or a simulated 10s bias ramp up.

That's what I thought at first, without any math. Just make sure you let the amp warm up sufficiently before switching standby to 'GO' mode, and all will be well. Plus a reduction in background hum which is often a bugaboo with lightly filtered bias supplies.

[Helmholtz]

I found PSUD2 to be a convenient tool to simulate the bias ramp up. As expected I could fully confirm nickb's results.
(Also gave me reason to read up on Thevenin equivalents. Thanks again, Nick!)

[g1]

How many extra seconds for the 47uF compared to the 8uF? I think I'm mis-reading post #15.

[nickb]

How many extra seconds for the 47uF compared to the 8uF? I think I'm mis-reading post #15.

See post #12 for the answer. It depends on what you define as the measurement point 90% of final value, or 10% to 90%, or.... There's a graph so you can chose your points.

PS: The executive summary is that after 10 seconds they are pretty much the same.

[Helmholtz]

How many extra seconds for the 47uF compared to the 8uF? I think I'm mis-reading post #15.

From Nick's simulation in post #12 (green curves) it looks as if it takes less than twice as long with the 47µ to reach an intermediate voltage value as compared to 8µ.

E.g. -20V is reached after 5s with 8µ and after 9s with 47µ.

[g1]

Got it. Thanks guys.