100W Ultimate Fidelity Amplifier

Here's a weird thing. I built another one of these using the original layout from the other thread. The positive side works but the negative side acts the same as this one. Has this PSU been successfully built before or is it a concept?

A couple of pics as tested. The jumper on the bottom is to correct the layout mistake. If I get the issues resolved I will do a more sanitary fix.

Blessings, Terry
 

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Here's a weird thing. I built another one of these using the original layout from the other thread. The positive side works but the negative side acts the same as this one. Has this PSU been successfully built before or is it a concept?

A couple of pics as tested. The jumper on the bottom is to correct the layout mistake. If I get the issues resolved I will do a more sanitary fix.

Blessings, Terry

This PSU is successfully built before, I made it but with BF245A.
Regards
 
I tried pulling the two Jfet and replaced them with 1k resistor. It still doesn't work.

I set it aside and decided to hook up the LinearPre and Shunt regulator along with the A2 with lateral MOSFETs and the DC protect. All last month's projects. It sounds very, very good.

What a hobby!!!
 

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Almost the same circuit, no tricks...just plane ingeeniering. Replace 15k resistors on the left size of differential with, say 6V8 zener diode, replace adj. CCS with app. 4k7-6k8 resistor and see if it works. If it works then you have false j-fets...if it still does not work, then it is something wrong with layout or bad component.
 
I made a quick sim of A Class PSU to find out if the SK devices will work.
I used SK117, a low noise jfet counterpart for SK246 (no model available in Multisim lib). All 2N devices for the small TO-92s and TIPs for the output regulator. It seemed to work without a problem, trimmer adjust is set to 80%.
At 100% it is outputting 32vdc.

Terry, perhaps one or two of the SK device is failing, have you tried replacing them with newer ones?
 

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Replacement of 2sc4793/2sa2690.
I know that this question has been asked before and commonly found mje15033/15032 are recommended.

However I have a handful of TO126 driver such as ksa1220/ksc2690.
I look up to their spec sheet and found that SOA for this TO126 drivers are comparable to SOA of 2sc4793/2sa2690 even though they (ksa1220/ksc2690) have smaller package.

Is it possible and safe to use smaller package drivers to replace 2sc4793/2sa2690 for apex amp with single pair of output?
Or what am I missing here?

Thank
C.S.