Greg
Nice online calculator here lets you try different values and see the result.
http://www.sengpielaudio.com/calculator-RCpad.htm
HTH....
Q: Voicing
Moderators: pompeiisneaks, Colossal
Re: Q: Voicing
In theory, theory is the same as practice. In practice it's different.
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iknowjohnny
- Posts: 1070
- Joined: Thu Apr 24, 2008 2:10 am
- Location: los angeles
Re: Q: Voicing
Do you or anyone here use the cap across the PI's input plate resistor along with the one from plate to plate? or do you use only one or the other at once? I tried the cap across the PI input plate resistor the other day and left the 50pf i have from plate to plate of the PI. I also have a cap across the V1A plate and all those caps at once hasn't dulled the amp at all. It sounds great. I've used every one of these 3 before either one at a time or one of the PI scenarios and the V1 cap at the same time, but this is the first time I've used all 3 at once and it sounds better than ever. The highs are smoother but not lost. oddly i seem to recall a definate high loss in the past, tho that was likely with one of them across V1B instead of A or maybe across the NFB side of the PI.iknowjohnny wrote:mine is 50pf. 100 just seems to dull the top every so slightly but enough to change it too much to my ear.
- Reeltarded
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- Location: GA USA
Re: Q: Voicing
Leave the plate-to-plate in situ. That is part of the circuit.
You should look up the maths on all this stuff. You will never hear any of those things you did, except removing the smoothing cap from the PI plates. Oh yeah, your tubes know. Do that again with the lights off. Electron bloom. Pretty blue! They are working at 70 or 80% just to keep up with the ultrasonic signals from Jupiter and Cygnus X-1
If your amp is doing work on something you can't hear it is not doing work on what you can hear. It eats tubes and fizzes and sounds like dead like a hammer.
A plate bypass on either leg of the PI cuts frequencies above a range. The other side of the PI now doesn't cancel that range. There is some beauty in there if you tweak but I skip all that and just use a 100-150p in place of the 47p depending on how nasty dirty the amp gets.
You should look up the maths on all this stuff. You will never hear any of those things you did, except removing the smoothing cap from the PI plates. Oh yeah, your tubes know. Do that again with the lights off. Electron bloom. Pretty blue! They are working at 70 or 80% just to keep up with the ultrasonic signals from Jupiter and Cygnus X-1
If your amp is doing work on something you can't hear it is not doing work on what you can hear. It eats tubes and fizzes and sounds like dead like a hammer.
A plate bypass on either leg of the PI cuts frequencies above a range. The other side of the PI now doesn't cancel that range. There is some beauty in there if you tweak but I skip all that and just use a 100-150p in place of the 47p depending on how nasty dirty the amp gets.
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.