Tube DIY Asylum

RE: Interesting parafeed observations.

216.68.190.16

In Reply to: RE: Interesting parafeed observations. posted by twystd on June 29, 2008 at 22:59:36

twystd,

Not really true the parallel feed cap only completes the required circuit for the output transformer. The power supply cap still has an effect.

BUT!!! Since you now have an L before the output instead of integrated into like a direct feed output would, then you are rejecting more ac noise that may otherwise get into the output or the output tube. Also many times it is much easier to make this L much larger than a direct feed counter part.

To all.... paralleling caps is a really bad thing. If you ever would look at the complex response of what happens you would never do this again.

That being said... I don't know what transformer you are using but 90k seems really high. You can't really think of the pf cap in terms of just the primary. It has too do with the PF inductor, plate resistence and the primary inductance and reactence. I would say 2uF sounds about right though.

I bet you would find spending a little more on a higher quality 2uF would sound better than paralleling.

Thanks
Gordon
J. Gordon Rankin

Follow Ups:

RE: Interesting parafeed observations. - Michael Samra 21:44:59 06/30/08 (0)
RE: Interesting parafeed observations. - twystd 09:03:47 06/30/08 (2)
- RE: KBG Parafeed Caps - mach1 19:50:27 06/30/08 (1)
  - Thanks for the reply. - twystd 21:02:39 06/30/08 (0)

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