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Re: Paramour with 10uF cap between A1 - A4

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James W.

(i)

In Reply to: Paramour with 10uF cap between A1 - A4 posted by VoltSecond on December 06, 2000 at 21:24:45:

Volt:
How's it going? Just how large are we talking here?
Is bigger better in this case.
Sounds like something I should possibly try. FWIW
I did find that shielding my filament heating wires(yes
they are elaborately twisted together) noticeably lowered
the hum in both my RCA blackplates and my meshplates.
The RCA blackplates are noticeably quieter. I really enjoy
the blackplates, they are surprisingly good and I get
more output from them without changing anything.
James W.

Follow Ups:

Where were the shield grounds attached? (nt) Voltsecond 19:28:42 12/07/00 (1)
.
- Re: Where were the shield grounds attached? (nt) James W. 08:00:28 12/08/00 (0)
  I ran the filament wires through the ground sheath floating them
  on both ends and running a drain wire to the AC side of my yin/yang
  diode star ground(ala Buddha). Actually this is how I ran all my
  ground shields as well.
  I wasn't sure it would do anything but I thought it was worth
  a shot. Definetly made a noticeable, although not huge improvement.
  Don't have an O'scope to give a proper voltage measurement.
  I just use the ear in the woofer approach. My low frequencies
  also got just a bit better after doing it.
  James W.
Bigger is better, but . . . Voltsecond 19:27:51 12/07/00 (2)
Bigger should be better. You'll probably have to double the value to get a benefit. But you have to be careful that the capacitor does not radiate noise into the driver or grid of the 2A3. Large capacitors can radiate magnetically and electrostatically.
I am planning on bypassing the 10 uF with back to back aluminums once I can find ones that will handle the current.
- Re: Pardon my ignorance! James W. 08:03:46 12/08/00 (1)
  Volt:
  What will bypassing it with aluminum caps bring to the table.
  I have some 20uf 250V SCR's around. Would those be appropriate?
  Thanks,
  James W.
  - Re: Pardon my ignorance! VoltSecond 21:45:13 12/08/00 (0)
    The 20 uF 250V SCRs would be a good choice. Make sure you insulate the leads and leave access to the pot. Keep the cap away from the grid resistors and capacitors.
    I am wanting to put 1100 uF of > 1.3 Amp AC rated capacitance across the filament. Aluminums are the only practical choice for that much capacitance. Back to back polar aluminums with a DC bias tend to work better than a non-polar aluminum capacitor.
    I am wanting to adsorb all the line noise coming down the filament leads into the filament with the filament capacitors. The 10 or 20 uF film will adsorb the higher frequencies. The 1100 uF low ESR cap is to adsorb the lower frequencies.

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