I have 340/350 predrivers mjw3281/1302 drivers and 3281/1302 outputs. 5 pairs. This seems to work long term at both +-72vdc and+-82vdc. My scope is old and slow but sine waves looked OK. I followed attached schematic. I have only used this ops with the cfa x h ips. It did not like the tubsumo ips. csa and csb are I believe 33pf silver mica. This is a nice sounding very powerful amp...well worth the time.
Evan
Evan
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"squirry bias" is the poor man's hint of OPS oscillation.
I discussed this with you .... slewmaster is a"poor man's thermaltrak".
NO load 17mv bias ... overload it to hell , the driver Vbe - with it's 100ms
thermal time constant ... compensates until the outputs catch up (thermally).
WOW , Evan's trafo puts out 65-0-65 , just 8 short of my big amp PS (below).
Kypton C VAS jumped about 1 mA , this is because 1/3 the current is just shunted
by the blue LED's. BTW , D8 led is the one reversed on the silk screen , Jeff.
OMG all 6 small caps on that OPS just EXPLODED !!! I put 100u/35V's in there.
35V'ers lasted a full 5 minutes before popping !! 😱😱
Ha , yanked the caps - OPS still lives.
Whoa - scary !! 😱 No more shine for me 😀 .
OS
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I have the exact same setup as Evan right down to the MJW3281 drivers. I don't have the csa, csb installed though. I have used them with CFA-XH and both BV derivatives, Symasui, Wolverine, Spooky, Eyesee, Krypton C, Krypton V, Low TIM hybrid, Infidel and even an Apex AX11 IPS. They just work. I'm not sure what is going on in yours. I notice on one shot you have flying VBE and on the other it looks like the vbe is under the board. I have one set with the vbe under the board and two with the vbe flown. The only difference I can see between them is the one with the vbe mounted on top of the outputs is quicker to settle.
I took out a couple rectifiers in the supply. I'm going to test this out with a 40 volt supply.
OS,
Glad to see you helping to solve the current issues for jwilhelm.
Off topic here we have been having some discussion of speakers over on the Blowtorch thread and I wasnted to show you a concept to reduce distortion in speakers and bring the speaker into the feedback loop; Do you think this could be implemented with the Slewmaster Krypton-C amp? Let's see if I can attach the picture which is post #604092. This whole point was to lower distortion in the speaker, not the amplifier.
Glad to see you helping to solve the current issues for jwilhelm.
Off topic here we have been having some discussion of speakers over on the Blowtorch thread and I wasnted to show you a concept to reduce distortion in speakers and bring the speaker into the feedback loop; Do you think this could be implemented with the Slewmaster Krypton-C amp? Let's see if I can attach the picture which is post #604092. This whole point was to lower distortion in the speaker, not the amplifier.
I screwed up !
The sub amp also had 4 of the 6 output stage 22u/100V'ers swapped with 35V units 😱.
I yanked them ... might just place a couple 100uf/100v units in the empty spaces
(where there are no outputs). 😱
Wolverine/ sub OPS (below) likes the 65V . IPS is still exactly 5.5ma 😎 .
Bias did settle down to 21mv (<100ma) on the sub after a few minutes.
Cool that Evan's trafo does 65V ,the sub will rock !!!
I did put all 100v caps in my big amp with the 5 pairs , already subjected it to
73V overnight , any 35V cap would of smoked - for sure.
OS
The sub amp also had 4 of the 6 output stage 22u/100V'ers swapped with 35V units 😱.
I yanked them ... might just place a couple 100uf/100v units in the empty spaces
(where there are no outputs). 😱
Wolverine/ sub OPS (below) likes the 65V . IPS is still exactly 5.5ma 😎 .
Bias did settle down to 21mv (<100ma) on the sub after a few minutes.
Cool that Evan's trafo does 65V ,the sub will rock !!!
I did put all 100v caps in my big amp with the 5 pairs , already subjected it to
73V overnight , any 35V cap would of smoked - for sure.
OS
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OS,
Glad to see you helping to solve the current issues for jwilhelm.
Off topic here we have been having some discussion of speakers over on the Blowtorch thread and I wasnted to show you a concept to reduce distortion in speakers and bring the speaker into the feedback loop; Do you think this could be implemented with the Slewmaster Krypton-C amp? Let's see if I can attach the picture which is post #604092. This whole point was to lower distortion in the speaker, not the amplifier.
Actually , the slewmaster would be the forum's best bet to test out what is
in your schema.
The NFB return is a wire !!!
PS - you might have to manipulate the NFB ratio to do this - and
check loop gain effects.
OS
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That's prudent. you can't do much damage with a 250va 40-0-40.
If I just exploded my caps on the big 1kva 73V'er , they would of flew off the boards-
imbedded in the wall 😀 .
OS
The other channel seems to run okay on a 50-0-50 supply. I'm thinking I damaged the set of outputs from oscillating.
I've got a rail each of njw1302/2381 in stock but I wonder if I should just spring for some Sanken MT-200s? I don't think I could hurt them.
I blew up my IRF output OPS with a Tubsumo IPS. I tried replacing just the outputs that measured bad. It wasn't until I replaced the diodes that it worked properly again.
Or maybe you had a bad set to begin with. I actually Hfe check every device
before I populate it.
Don't even trust new stuff from mouser (pessimist) 🙁 .
OS
I've been wanting to make up a proper HFE test jig for bigger devices. I've been matching small signal devices in breadboard. I don't have any cheap meters with an HFE test on them.
MT-200's = "muscle amp" (like a "muscle car").
Really cooked them - blew the fuses , ran again with bigger fuses.
Sucks I have to disassemble them to put new caps in 🙁 .
OS
Ha, I was referring to measuring components carefully before installing. I have been bitten with that more than once. I have had caps explode right in front of me. Scary!!!
Looks like I got the other channel a little too warm. One of the outputs shorted after I shut it down.