kevin gilmore

this is what you want i think. kgdynalobal9 - CADCAM.ZIP

i went back and looked at everything. there is no servo in the amp part itself because its in the front end. the latest file which should be posted somewhere above is cfp3rssfixedsssw also attached here. cfp3rssfixedsssw - CADCAM.ZIP

which ever has the later date. definitely has the latest servo

so the idea is a 10 hour runtime. so a 3 cell lipo battery with 2.8 amp hour batteries is the target. if it has to be a bit bigger then it has to be a bit bigger. the amplifiers are 200 microamps output stage bias with 1.5ma current limit. Could certainly bump up the current limit a bit. the benefit of kerrys power supplies is that they are extremely small, max component height is .3 inch. if we change to a transformer based supply then the transformer is .8 inch. if we use the hvm supply for the bias it is .5 inch high. Smaller is better! For a given chassis size more room for the battery is a good thing. The final product will likely be a single circuit board with the power suppies on one side and the amplifiers on the other. The components with the largest height will be the stax jack and the volume pot.

the 300 volt supplies are about 110ma each which is acceptable. the bias supply is 200ma. This needs to get fixed. there is a resonant hvm module that does the bias for 25ma, but its a $135 part. if i could get someone to make us a custom switching transformer, we could do better. but no one will even return my calls or emails.

In progress Amp design by me, power supply designs and circuit board layout by kerry, support by birgir +/-300 volt power supplies. complementary push pull all bipolar design with cmos style multiplying current mirror.

pretty sure you have the pinout of the 2sa1699 wrong. emitter connects to source of the jfet. At least it does for srm212 and srm252

suitable replacements seem to be 2sa1552 / 2sc4027 toshiba tta004b / ttc004b also look compatible

amir is just another idiot with an audio precision. And is concerned about .000000001 thd. And is otherwise clueless. look at his review of glite.

not ideal, maybe find 20k?

+/-12v should be fine for a balnced setup. 50 amp power supplies would be perfect.

you need AC 120v not 12v and that is for low bias only

this is not a balanced input amplifier

wire the headphone grounds directly to the amp boards, not the power supply

The Thd is going to be higher at lower driver board voltages. Not a lot higher, but the idea is that the driver board needs to be able to fully drive the output board, so the driver board needs at least a couple more volts than the output board.

yum

i have a pair of 801 mk 3 that i still use as television speakers. with the arcici stands. in black. and the B&W bass alignment active filter somewhere.

for people building their own bh, one side of the filsment winding has to be connected to v-, not ground. also applies to all other tube output stax amp.

you better take a real good picture of the voltage selector block. there are many different kinds. if blue and purple are jumpered together then its 120v if brown and green are wired together its 100v white should be wired to grey the correct fuse for 100v should be 1.5 amp

take a look at the transformer and see if the 120v windings are cut or not. if they are intact, rewire for 120v. and replace the power electrolytics.

actually even easier assuming the drive is glass platters, open up the top and fill with battery acid. the plating comes right off the glass.

go to one of the sites selling magnets and buy a 1 tesla magnet, or bigger. they are cheap. take the drive apart all the way to the platters, and swipe the magnet on both sides of each platter several times in several directions. not even the nsa will be able to get the data back. one of these is way more than enough https://www.kjmagnetics.com/proddetail.asp?prod=DX0C

if you rotate the left transformer 180 degrees, makes the high voltage wires a lot shorter.

you can do up to 3 amps of class A bias with big enough heatsinks. The one feedback resistor, you can make into a resistor that is in series with a resistor that is in parallel with a cap. pick the numbers you want for appropriate bass boost. once in a while you get a bad transistor or low hfe etc, so always buy more than you need.

so its a balanced amp with only unbalanced inputs. only 2 gain stages so its already low on voltage gain, and then if you put in 12bh7 as output tubes it has even less voltage gain. stax jacks with what looks like heatshrink on the pins? no 5.1k safety resistors, relying instead on the current source to limit output stage current. electrolytics not secured to anything. nice chassis.