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Just a brief follow up on my PP amp ps. On that amp i have LCLC (inductor, capacitor, inductor, capacitor) filter supply which yields a 360vdc B+. I would like to get the B+ pass 400vdc so, I installed a Sprague VitaminQ 5uf x 600vdc in the Cl position. BUT, on the ground leg of the cap i put a hd toggle switch so that i put the cap in and out of circuit. With the cap in circuit the power supply now has a B+ of 440vdc with the cap out of circuit the B+ is 340vdc. With the 440vdc B+ the ps is used for a PP 6550 amp. With the C1 out of a circuit via the switch the PS is now LCLC and will be used for a SE KT88 amp.
I was worried that the additional capacitor may affect the sound quality but there doesn't seem to be any deleterious effect. On the other hand the 440 volts does make the pp 6550 much better. cheers, Dak
Follow Ups:
whether the switched capacitance has a negative effect on sound quality? You are using the same PS for two very different amplifiers that probably sound at least a little different inherently. Or have you used the PS both ways to power only one of your two audio circuits? Even in that case, the voltage difference (340 vs 440) would in itself affect sonics. Anyway, sounds like a good solution to your problem.
Wonderful.
I might try this on my RH test amp since the gas regulators for G2 seem to drop the overall B+ a bit.
I am contemplating such a mod myself and wonder what circuit you used or devised. I was thinking of following the one in the RCA receiving tube manual. It is in schematics at the back of the book under 60watt hifi amp.
It seems like a bit of work but i am already making a seperate power supply for the next amp and i figure i will just put in another B+ supply of around 400v to use on the G2.
I used schematics from the RCA tube manual.
Two 7 pin regulators stacked on top of each other and a current limiting resistor.
Bypass with a .1uF cap.
I didn't use a separate supply for G2, maybe next time.
The one i am considering uses a 6gf7 ? and an 0A2. Along with a pot so that you can adjust the voltage. It taps off the B+ but the seperate filament transformer is used because 6gf7 heater is biased up 150v. That reminds me i need to get some of those. cheers, Dak
I used a 20A x 125vac toggle switch that closely matched my on/off switch. Just remember that switching when the circuit is hot ist verboten!
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