Re: Effect of Variac on Monoblocks

Why did you change the caps? Are the new ones larger? Trust me, the
electrons are not brand concious. They don't care what the label on the
caps is. Brand X is just the same as Brand Y to an electron. Now labels
and my teenage daughter, that's another story.....

The voltage tolerance on your caps is going to have safety factor so you can
run it at rated voltage.

"Wink" <x@xxxxx> wrote in message
news:2c2du3529iu69fpq2np7cmfr61405lvb68@xxxxxxxxxx
I happened to snag a set of 63V/10,000ufd FK BG caps for my monoblock
PSUs. The rail voltage with stock Hafler xmfr is ~ 63 Volts so to
avoid exploding my $$ BGs, I'm using a Variac to reduce the AC mains
input for a rail Voltage of ~ 53 volts until I replace the Hafler
trafos with lower sec V Toroidals. [Refer to "Hafler Monoblock
Project..." thread]

The mystery is the sound, which is sort of peculiar. Hard to explain,
but what is the source? Of course there are 3 variables that have been
changed: PSU caps from Chemicons to BGs, lower rail voltage (well
within the operating range of the PA-3D driver board), and inclusion
of the Variac twixt house mains and both amps.

Should I expect some odd interaction between the Variac and existing
Hafler power xfmr? Nothing obvious comes to mind. Running stone cold,
the 1500VA, Powerstat Variac has plenty of capacity.

Not much to go on here, but thought I would throw this one out to you
guys. Thanks again...
Dave


.

Relevant Pages

  • Re: Effect of Variac on Monoblocks
    ... When the stock Hafler 10 kufd Sangamos started to die several years ... Brand X is just the same as Brand Y to an electron. ... input for a rail Voltage of ~ 53 volts until I replace the Hafler ... of the Variac twixt house mains and both amps. ...
    (rec.audio.tech)
  • Re: Can I use a 120V Variac to get 220V?
    ... While one might imagine situations where this technique is ... If your caps don't need reforming, ... current through transformer and bleeeder resistors, ... what voltage do you set the variac too? ...
    (rec.radio.amateur.homebrew)
  • Re: Sending power into rig unused for 30 years : Precautions ?
    ... means is that there is some validity to bringing up the voltage slowly ... using a Variac as the caps will see a gradually increasing voltage - ... A variac is really no better than a dim-bulb tester unless it ... nicely until you reach operating voltage over 4-5 minutes or so. ...
    (rec.radio.amateur.homebrew)
  • Re: Can I use a 120V Variac to get 220V?
    ... While one might imagine situations where this technique is ... If your caps don't need reforming, ... current through transformer and bleeeder resistors, ... what voltage do you set the variac too? ...
    (rec.radio.amateur.homebrew)
  • Re: Capacitor replacement on Fisher X202-B, is it necessary
    ... typical urban-myth uses for a variac: ... Apply power to a radio slowly to see ... Reforming caps: Unless a radio has a SS rectifier, ... You need an AC current meter accurate to within a very few watts (or ...
    (rec.audio.tubes)