F4 power amplifier

Official Court Jester
Joined 2003
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And the hand test weighs in at one second. I may need to readjust the bias on the lower channels. I noticed that when I raise it, the hum in the transformers increases, and only one of them is humming loudly. And it was set right as the batteries on my multimeter were running out.

Anyone have any suggestions for where I could get better heat sinks that would fit there?
 
Finally got around to getting things buttoned up. That buzz, has totally gone away and returns at a nearly undetectable level once it warms up for 12 hours or so.

I'm curious if the F4 will drive what's behind garage door #1 in the second picture :Pinoc:
 

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I have been using the HFA15TB60PBF in Solid state equipment for a long time and in the applications I used them in there were no artifacts of nasty Diode switching and a scope across the Diode confirmed this.

I have been thinking of using these in some Tube circuits for Biasing, as opposed to the Conventional diodes. if anyone has used these in this application your View would be real helpful TIA.
 
Choky is always right !

Proper answer to my question can be found in the Nelson article
http://www.firstwatt.com/pdf/art_sweet_spot.pdf page 14 -15.
Yes you can change amount of distortion by trimming value of Jfet source resistors.
But change is not so dramatic in absolute numbers. So Zen Mod is right about it.

He knows everything about pass amps, don't forget, he's Papa's son :rofl::rofl::rofl::rofl:


Audiofanatic ;)
 
Not being willing to read 51 pages of blurbs, I'll just ask--
1. Are Cs 1 and 2 signal-coupling capacitors?
2. If so, what is the load impedance for filter-point calc?
3. Can the cap-value be changed to create a hi-pass filter in the audible range for a speaker that requires one? That speaker is a Vandersteen 5A that needs a filterpoint between 50 and 100 Hz.

Thanx much in advance to the much-more-knowledgable-than-I (and that doesn't take much) who answer.