AC voltage regulation

[ToneDeaf]

   This has nothing to do with BottleHead gear. Although I did just order a Mainline Headphone Amp.  My problem is fluctuations in my AC voltage. I built a 300B amp. When I built it I was going for about 360v-365v on the B+, with 3.5K output transformers. In the mornings my AC voltage is about 124V. That 4 volts bring my B+ up to almost 390V . In late afternoon to early evening it goes down to 120 volts and the B+ goes down to about 365V. This drives me nuts. I can't really hear a difference, but it drives me nuts. I was saving for a PS Audio P5  AC power re-generator but that got put aside for a Mainline amp (already ordered), and a pair of HD820's ( saving for).
     Is there any not to expensive ways to regulate my AC. I thank you all for listening. Any help would be greatly appreciated.

[Paul Birkeland]

Can you post some info on the design of your 300B amp?  There may be a way to clamp the B+ down a bit if it gets high.

-PB

[ToneDeaf]

  It's a tubelab amp design. It's the Tubelab Single End. If you look up tubelab you can see the schematic. I built mine with 300B's. There is a capacitor that I can  change to a lower the value, and bring down the B+.  It's just that I really don't feel like changing right now. And the problem is that even if I do that, my AC line voltage is still going fluctuate and raise and lower my B+ It probable doesn't matter, but it makes me nuts, because as the B+ changes so does the Biasing of the tubes ( I think). I'd rather have everything steady, and the only way I can think of is to regulate the A.C. Thanks.

[Paul Birkeland]

I would recommend using a tube rectifier with more voltage drop when you know your line voltage is high.  IMO, I'd optimize the amp for solid state diode operating during the lower line voltage part of the day, then plug in your 5AR4 when your line voltage pops up.

[mcandmar]

What about working out the optimal value for the 1st power supply cap for high and low mains voltage, then use a few values in parallel and switch them in and out of circuit as needed.

[2wo]

You could use a varic, or get a filiment transformer and wire it with a switch to eather buck or boost around your middle voltage, that would give you 3 points of adjustment...John

[ToneDeaf]

 Thanks for the reply's. I will consider all of them. I know I have a variac some place. I think I might give that a try. Thanks again to all.