kevin gilmore

when i do them, its a 3 step process per hole. which is why it comes out so nice. even though i'm using full up commercial NC mills, if i just drilled the holes single step, it would not be perfect. first you use a centering drill then you use a small drill bit then i machine each hole round with the mill bit now it really does not have to be this perfect, but its only a few minutes extra per bracket

what I do is float everything in the chassis. The chassis is connected to earth ground. everything else floats and the audio ground does not touch the chassis ground. this is easy with xlr connectors as the inputs only, and then rca to xlr adapters for single ended.

that is the company I buy from, but I go for the Teflon. its more expensive, but I have the right stripper and always liked Teflon.

raise the value of R1, say 1k will give you 3db more

you can give the amp a differential balanced input, and use the unbalanced output. why you would want to do this i don't know.

i wire 3 wires from each xlr jack to the pot for each channel, then the pot to the boards not a star ground, but works, and is completely silent the wires from the xlr jack are shielded triax

the cfa2 has gain, so it has feedback the cfa3 has no gain, so the phase splitter has the gain

sure you can do that, but you need a phase splitter, or have to run balanced input only if you want balanced output.

you should be able to use 15v regulators, the relay will get slightly hotter

if you are talking about the inputs, yes that is how its done. don't short the outputs to ground a stack of relays, or rotary switches is necessary to do the inputs right

speaking of krell klones http://www.ebay.com/itm/Assembled-Krell-KSA-05-Class-A-preamplifier-board-with-headphone-amp-CL-232-/191538328292?pt=LH_DefaultDomain_0&hash=item2c9892f2e4 and http://www.ebay.com/itm/YJ-Assembled-KSA-5-headphone-board-with-C1237-horn-delay-protection-circuit-/221740126195?pt=LH_DefaultDomain_0&hash=item33a0bdcff3

I'm sure I will add that. found a bunch of errors which hopefully I fixed. and I took out the surface mount transistors because they are only 200mw and there are a few places where its 270mw picture updated

preamp plus power amp please. I will send it back. actually more interested in the amp, because I know I'm extremely close on the preamp part. this really should be the end all dynamic amp, with 80 volts peak to peak output and up to 2.5 amps (more with a bigger heatsink) it should drive both hd800 and he6. you could actually put the volume control in the middle for even more reduced noise, although the noise is about 95db down.

well the phase splitter is just the ubal to bal board. and then there are pieces missing. plus you would have to build 2 more boards anyway. http://gilmore.chem.northwestern.edu/cfa3.jpg for your thing, you could just adjust the gain to 1 and then use the ubal to bal board. the stax mafia moves at light speed someone really needs to check this one over hard. the miracle of cut and paste is not necessarily foolproof. this is probably as close as I can get to the ayre stuff without actually having the schematics. I could go all krell on this and stuff it full of power supply caps...

by the way fully balanced version coming. lots of parts! 100% differential 100% complementary http://gilmore.chem.northwestern.edu/cfa3production.pdf not sure why it took me years to come up with this NO FEEDBACK of any kind thd <.005% and absolutely flat over the 10hz to 200khz frequency response +0, -3db .017hz to 4.43 MHz

for that price you could have 5 sets made, no problem. Some of this is beginning to upset me, people making money for stuff I give away. The Chinese ksa5 clones also piss me off, they are hacked up garbage. They have no idea why the original sounded so good.

and a face mask

I used some small vintage feet. No idea of part number. Justin's rubber feet are probably way to big, besides which the hole size is too small.

if you have open inputs on the lm339 the bias current will turn them on. need to make sure the inputs before the filters are tied to ground. +7.9 is the correct voltage wrt ground when the relay is on.

wouldn't the bass molecules like longer wires?

10 watts of heat per channel. As high as 15 with higher voltage rails. amp is 3db down at 4.3 MHz (seriously)

probably 100 ohm series resistor is good idea will add it to the board edit: changed 50 to 100

and that's the problem. the 4 pin is balanced only, no ground. can't be used on common ground headphones.

so far total length difference on the longest trace is .3 inches works out to about 100 picoseconds. if I was doing work in the 100mhz to 1ghz range, it would make a difference.

new feature for the freaks over there that don't like square corners... all board files with "m" at the end have mitred corners. I don't see the difference, but it only takes a few seconds to convert.