kevin gilmore

wired in series for +/-24v and then connected to each channel

Gertrude sounds like a great name.

I would think that a minimum of 50 watts of heat per channel seems reasonable. a dissipante 3U seems like it would work. probably 1 size down would also work if there is enough room for the switchers.

Takes out the 6db bass boost filter.

Well cheap compared to all the monster amps out there So correctly done, one would do the Uberamp2-Raal edition, which results in something really big,heavy and lot of heat. And a custom and large chassis, and a pile of $$$ This is a bit cheaper and easy enough for just about anyone to do. From the Ti Opa541 datasheet, showing paralled opamps good for at least 7 amps rms of output into anything including a dead short... Designed to be mounted directly to the heatsink, amp board right angle to the heatsink. All wires to the board directly soldered, 4 oz copper highly recommended. Power supplies are a minimum of 24V at 10 amps, like this, but more current not a bad thing. You need a pair of these! https://www.mouser.com/ProductDetail/MEAN-WELL/UHP-350-24?qs=YCa%2FAAYMW011AuZKubw9Sw%3D%3D So by the time you get done, about $400 in parts. Better than spending $4500 on an unknown made in croatia thing with inside pictures deliberately hidden. .02uf is a film cap, 10uf are mlcc caps, .1 ohm resistors are caddock https://www.mouser.com/ProductDetail/Caddock/MP930-010-1?qs=%2Fha2pyFaduhEz86YdyVUnzk8BCJOExJuzQrioCIidHi6TdsKxEEAVg%3D%3D raalopamp - CADCAM.ZIP

nope that is not the psu for that board. much simpler, 10m90 feeds zener string, drives single pass transistor

warning: check with ohmmeter to make sure the transformer is wired like all other stax transformers for 100v jumpers at J1,J3,J4 grey to white green to brn remove other jumpers for 120v jumpers at J2,J3,J5 grey to white purple to blue remove other jumpers for 220v jumpers at J5,J6 blue gry to purple remove other jumpers white ties to yellow thru fuse white,green,purple is one winding 0,100v,120v grey,brown.blue is other winding 0.100v.120v

the connectors are nice, he should sell those.

if the thermal grease really is the color of artic silver, that stuff is electrically conductive. causes all sorts of problems.

It is actually possible for something with no voltage gain and no feedback to oscillate, but it's difficult to do so. a lh0032 with the input tied to low impedance ground will oscillate.

measure output voltage. probably zero. replace power supply

15lyl... if you are running ss and don't have the latest board, the feedback might not be correct. Check your board with the schematic posted. i don't know of any way to make ZF oscillate

the 2 n's need to be flipped. this error got there when changing from the 2s transistors to the bc transistors. edit: updated schematic cfp3rssfixedsssw - CADCAM.ZIP cfa3productionss.PDF

final version of SS/ZF board with jumpers to go from one to the other. 5 db of gain unbal to unbal 11db of gain ubal to bal 17db of gain bal to bal thinking of a relay board to sit on top with front panel SS/ZF switch. would be a unique feature cfp3rssfixedsssw - CADCAM.ZIP

60mv without the opamp is the right number.

It's. not that hard to drill and tap the heatsink on the thick part to mount the board to. It was designed that way from the start. And that's a furtech label on a cheap plastic knockoff.

Here is another one. I know its different because the caps on top are different. And its 1oz copper.

changed size of cap cfp3rssfixedss - CADCAM.ZIP

latest board file with all fixes cfp3rssfixedss - CADCAM.ZIP

any ac voltage on the filament? likely the regulators are on the verge of dropping out of regulation. is your 230v about 3% low?

the unbal to bal part of the board had a problem with the current source, this was discussed over at diyaudio on the negative current source the 10k resistor went to the emitter. it needs to go to the base. first picture is the fix, second picture was the original with the error.

should be 12.6 vac rms measured blue to blue should be 8.5 vdc on that cap. should be 6.3 vdc after the regulators measured at the tube filaments. everything referenced to -350V

so you did not get the information you wanted over there, and now you come here. nice. from pictures elsewhere, the transformer winding is blue-black-blue and is 12.6v center tap, 2 diodes to capacitor full wave bridge. This is the filament supply and has high current ripple. The cap you have chosen is completely wrong for the job. All the original caps were chosen for a reason, if they are not dead then you should not be replacing them. And you should be careful touching that cap with the power on, as its sitting at -350v.

smallest 550v rated electrolytic is 47uf and still is 1 inch diameter.

capacitance multipliers don't work for low voltages and high currents. unless you do silly like denafrips. Which takes up huge amounts of space. And then one bad cap and you will wish you were dead trying to find it.