kevin gilmore

you really want 100k. with 100k resistor, the servo gets it under 1mv in 30 seconds. otherwise its a few minutes. r7 and r8 can be up to .2 watt. if you short the output, about .5 watt and its a dual opamp in a single package you can get rid of both electrolytics, or the one electrolytic in the latest board by maching the fets and moving the left side of R21 to the junction of R1 and R2 and then shorting the bottom of R17 to ground. Then its fully dc coupled, but you have to go thru a bunch of fets to get the matching right.

following chinsettawong's idea ... http://gilmore.chem.northwestern.edu/staxmale.jpg will make more once I get some real Teflon. Plexiglass does not like to do this.

this is the final and correct schematic http://gilmore.chem.northwestern.edu/squarewaveproduction.pdf if you are careful and match the fets, you can get rid of the 1500uf caps. the original board had the servo inverted, hence the extra opamp to invert the output. latest stereo board http://gilmore.chem.northwestern.edu/sqwave9.jpg pair of boards installed in icariums SS1 http://gilmore.chem.northwestern.edu/sqwave10.jpg the corrected mono board is also available. R16 really should be 100k because the servo is too slow with 1M

so the real reason that 68k resistor was there is because otherwise the ccs transistor which is not heatsinked would get way too hot. And if the ccs transistor ever shorted the 68k resistor prevents the fets from blowing up. This is the problem when you try to make an amp with only the high voltage rails. same issue the one guy over did many years ago when he built a kgss with only high voltage power supplies.

Way simpler than what I was going to do. I was going to machine the pins from scratch. I will do it your way.

amazing job on those headphones. where did you get the male stax jacks?

http://gilmore.chem.northwestern.edu/dsc_0585.jpg http://gilmore.chem.northwestern.edu/dsc_0586.jpg on +/-15v power supplies maximum output is 16 volts peak to peak balanced into 50 ohms on +/-20v power supplies maximum output is 22 volts peak to peak balanced into 50 ohms

yep! Not quite that high unless you have big heatsinks

yep, due to solar/wind power stuff like this is rolling out the door. And way cheaper than the semisouth parts. Also way cheaper than the Fairchild parts which they don't seem to want to sell.

notice that those are TO247. Other than that, they are great parts as long as you bias them up heavy.

silicon carbide mosfet output version soon. all stock parts. too many projects in the air at the same time

same 10k input resistor, same 100pf cap. original was 10k x 4 pot.

my clone is an EXACT clone. every part in the same physical location as the original. Same exact board size etc. If I wanted to change it, it would not be an exact clone

same capacitance as 1 of them. Just bipolar. There were bipolar blackgates available, so you would need only 1

find me a piece that's 2 inch x 2 inch x 4 or more inches

Don't we charge for that?

actually you need 8 pins. the ccs transformers absolutely have to be inside the amp box, and you might as well put the other one there too.

you only need 6 pins which are a lot cheaper

http://gilmore.chem.northwestern.edu/knobs6.jpg bocote, lignum vitae, redheart snakewood,arizona desert ironwood, ebony black and white ebony red mallee and cocobolo as soon as they dry out.

should be final rev's of these two boards unbalanced/balanced to balanced http://gilmore.chem.northwestern.edu/ubaltobald3.zip ss dynalo balanced http://gilmore.chem.northwestern.edu/kgdynalobal5.zip

I have tested it, listened to it, works great. offset is 1.5mv going to swap out the opa445 for op27 and then remove the offset pots. and probably add a pot on the pnp current source to do a final trim. input impedance with the bipolars is 10k. replace them with the jfets and it works better

ball bearing from the back make sure no one pours water over the thing

because tyll's kgss absolutely needed a wood knob, I sent him the one I made out of Arizona desert ironwood. Which left me without one. So I had to make one, and I made another ebony one. black and white ebony and snakewood hopefully tomorrow. http://gilmore.chem.northwestern.edu/knobs5.jpg

http://gilmore.chem.northwestern.edu/ubaltobal1.jpg

the same connectors used in the diy-t2 but less pins. ugly but rated for the voltage and not plastic crap amphenol industrial circular connectors