kevin gilmore

4 x 5.1k resistors in series with all 4 outputs L+,L-.R+,R- changing the bias voltage to negative means that any dust that gets inside the headphones will accumulate on the diaphram. Definitely not what you want.

if that is really MINUS 645 volts as the bias, bad things going to happen to the diaphrams. Flip directions of D3 and D6, change R10 to 5M

no 5.1k series resistors on the outputs is a super bad idea. definitely bad for the headphones and a safety issue if the mosfets ever short.

current version, front end at +/-35v power supplies, output section +/-24v from switcher, twice as many output transistors still need bass filter on the front end poweramp3a - CADCAM.ZIP poweramp3a.PDF

the jumper was supposed to be .1 newest software loves to keep switching to metric (fixed) forgot about the size of the caps, can always put them on the bottom. i had thought that 18awg was enough. size increased to 60th not going to be able to move the caddock resistors much. only 25th. then runs into the output wire

no it should not act like this. maybe it is oscillating in one mode. one person had a problem similar to this and fixed by adding 500pf B to C on the output transistor pair. Maybe the output transistors have changed over the years as i still have 100's of older ones.

The feedback is crossed for SS on all but the very latest board which was posted somewhere in here and is not in the archive.

r274x version of file but really you should find a manufacturer that does gerber x2 raalopamp - CADCAM.ZIP

if they are just making boards from the gerbers, i'm fine with that. But the people taking the gerbers and then re-editing the hell out of them causing all sorts of issues (like taking all the values off the resistors) or making clone boards like the one above that require obsolete parts are just causing people trouble. find the gerber you want and have boards made.

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.