|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
152.163.100.16
In Reply to: Not dogma, not bickering, not outdated. posted by Ray Moth on March 3, 2007 at 10:37:09:
Ummm, a SE amp is going to have the PS seeing a *VERY* variable signal. Cut the final off, and demand from the PS goes to zero. Swing the grid full positive and demand doubles.I think you were talking about Class A PP amps. Even those see a rather interesting AC component.
Follow Ups:
Sure, SE doesn't balance like PP and the demand on the PS will be modulated by the signal. However, the reservoir cap absorbs this modulation, if it's doing its job as a decoupling cap, rendering the net DC demand essentially constant. We rely on decoupling caps at every stage, including the final.
The big final reservoir cap absorbs the modulation all right, and it also absorbs the MUSIC SIGNAL in a SE amp ....thats why we now design with all Cs under 50 uF, and maybe even under 40 uF.'Same absorption applies to high value ( over 1/2 HY ) and high DCR ( over 10 ohms ) chokes ( loses the music ) .... and absorption of the music signal through the SE supply also occurs with inadequate gauge wiring ( loses the music ).
Your thinking ( and posting ) is only static Ray, its outdated / incorrect now in relationship to optimized SE audio amplification, it needs to become dynamic.
"The big final reservoir cap absorbs the modulation all right, and it also absorbs the MUSIC SIGNAL". To my understanding, the modulations ARE the music signal. They're meant to be absorbed, otherwise you have inadequate decoupling. Where the "hot" end of the OPT primary goes to B+ it should be the same as ground, so far as the signal is concerned. If it isn't, we have a problem.I'm not sure what you mean by "low C". Fifty or more years ago, 16uF caps were commonly found doing service as reservoir caps. Now, that's what I call outdated! Fortunately for us, it's now much easier than it was then to make big caps with high working voltages, so we are free to make our choice based on our needs, like the 40uF-50uF caps to which you refer.
'Same absorption applies to high value ( over 1/2 HY ) and high DCR ( over 10 ohms ) chokes ( loses the music )' I don't know where you get this from. As I explained, a good reservoir cap stops the signal dead. Whatever comes between the wall socket and the reservoir cap (be it the usual power tranny, rectifiers, smoothing cap(s) and choke(s) or a bank of car batteries) should make no difference to the signal.
This post is made possible by the generous support of people like you and our sponsors: