Outputs go down. JW suggested the Vbe position would be best facing up
for the best thermal stability. Therefore , the IPS side with the trimmers
would also be facing up.
Side mounted adjustment trimmers would allow all 3 adjustments
on a fully assembled amp.
If you decided to mount OP's up , trim the offset first.
Reorienting C1 would increase the short loop area of Rlift/NFB/input.
Or , just get real ... and use a 5mm LS wima for C1.
Many options.
OS
Thanks OS for your detailed answer, AND the bringing the forum all your expertise and knowledge. I have learned so much from you. Your analism is indicative of your quest to make things as good as can be. Many `appreciate it. My wish is for you to do a dual die 4 pair mosfet with CFA. I am getting long in the tooth, and would love to build that amp. Your sharing and giving, are admirable... Thanks again
Everything else looks correct. Looks almost ready for testing!
Just a couple observations, I see an LED on the negative rail but none on the positive rail. C109 is electrolytic here, in the Slewmasters it was film. R112 and R113 are pretty close together with 120 VDC difference between them. Might get exciting with some dust and humidity!
Just a couple observations, I see an LED on the negative rail but none on the positive rail. C109 is electrolytic here, in the Slewmasters it was film. R112 and R113 are pretty close together with 120 VDC difference between them. Might get exciting with some dust and humidity!
First candidate for the "interface".
1. - A novel servo implementation. No signal degradation , servo controls
the CCS's ... cool. Unbalanced diamond Q1/2 , servo changes the CCS balance.
OS
Nothing novel in this DC servo implementation, I simulated similar way, look here: https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-50.html#post3860799 but desided not to use it, need to large opamp output swing.
I use this offset settings since years in my CFA amplifier. Very good result, the offset is less than +/-5mV usually. No problem in a common living room, even if I open the window in winter times.
Diode in the current mirror is not magic, but cost reduction only
Sajti
2SC2837/2SA1186 has some tricky specification especially for the Cob, as it is specified for 80V, not 10-12V as usual. Good devices anyway...
Sajti
I would guess ... with R76 = 470k.
I use only 1.5v from the servo (and just 2 devices - 3 , LED). Ohhhh , I get shatty 16ppm..
You can pick on me for using too few devices , I can pick on you for
too many.
Too few = many builders.OS
Attachments
Thank you , my friend.
Corrected close R112/3 , The final board would be coated.
External requires - PCB Trace Spacing Calculation for Voltage Levels
.6mm , coated only .4mm. I believe in overkill (below). Then there is high
altitude. All is 1 - 1.5mm now.
PS - Blocked
that 2.5mm LS wima or any 1-2.2uf electro will do for C109.
OS
I use the same specs Stuartmp does. This is DC, which is a nastier mess than mains when things go wrong in my experience. No harm in erring on the side of safety.
One thing I've been meaning to check into is the coating on boards we have produced. Boards are coated in solder mask. Coated board ratings are for conformal coating, which is a coating applied after the board is assembled. I've never seen a voltage rating on solder mask so I'm not sure if it actually qualifies as a coated board.
One thing I've been meaning to check into is the coating on boards we have produced. Boards are coated in solder mask. Coated board ratings are for conformal coating, which is a coating applied after the board is assembled. I've never seen a voltage rating on solder mask so I'm not sure if it actually qualifies as a coated board.
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An external supply can be connected right at the input header if desired. If you're going to the trouble of an external supply, it's worth going the extra mile to a regulated supply so the cap multipliers aren't needed. We do this with our VZAudio amplifiers.
