kevin gilmore

I expect to now be able to spend significant amounts of time on new designs

huh? where you getting the high voltage power supply?

i have turned in my retirement notice, so my file server probably won't be up for more than a couple of weeks, get copies now. i have a complete backup and will be moving to my own domain soon.

that works too. seems like the world stock of 2sc4686a are about to go extinct.

probably a regulated version might be better

yes that is the idea, something with at least 1kv isolation. 12v to 12v, series resistor, tantalum cap, and then a resistor to get to the right led current. but you do need 4 of them per amplifier, but they are cheap any changes to the board will keep all the spacings intact.

I did both ksa5 power supplies. The original is triple pass transistor/zener regulated

here are 3 current sources at 10khz currentsource.PDF

its ac coupled and there is no servo

the closest thing to a perfect current source is a high voltage tube with a cathode resistor, i.e. megatron T2 current source is actually not really very good because the resistor divider for the pnp current source causes a significant change in current for example 700v peak to peak on the plate the current varies from 13.3 to 15.8ma same thing for a cascoded depletion mode is 14.8ma to 14.85ma a better idea would be to replace the stacked pnp and resistor with a very highly isolated dc to dc converter, something good for 2kv of isolation and you would need 4 of them per amplifier.

the copper ground straps are a bit of overkill. definitely make sure all the tab transistors are flat to the heatsink

no, not a modification of the power supply, that current limit is before the regulated cap. talking about adding a to-247 on a heatsink with a single resistor. since these are not sharp cutoff devices, the value of the resistor is unknown, would have to test it with lower voltages say 30v. but about 3 volts across the resistor so about 60 ohms The adapter is added on the + side of the power supply line. If it works which I suspect it will, can add it to a new version of the board, but the board might have to get bigger.

soren came up with this to limit the output current of the hv900 supplies http://www.mouser.com/ds/2/205/DS100183B(IXTA-TP-TH6N100D2)-368848.pdf put one on a heatsink and adjust to limit output current to say 50ma

its balanced so a fair bit more power the first ebay link is the one I use at work. really sounds great, although getting the drivers out of them is fun because they send you to a link that wants your cell phone number. the drivers are available on the web anyway.

audio-gd nfb-1 amp is $485 plus $50 for remote and then any of the dsd dac's on ebay like the douk super pro for $90 audio-gd is infinitely better for little more, way better built, way better sound etc, and a se to balanced conversion that actually works right correctly balanced, differential complementary, zero feedback...

piviot point? where ? more like 3 db of differential gain when you use single ended input and balanced output (high gain mode) worse in low gain mode. there is a way to do this correctly, and you only need a couple of super cheap extra parts. hint: a real differential input, like say the one on the kgss power switch as all the other switches are cheap parts, and the power switch failed shorting one side to ground blowing the house circuit breakers. also for places where the thing is wired for 220v, only one side of the mains is switched. fake on left, real thing on right other side of the switch is used to dump the output relays on turnoff, and there is no protection circuit from dc, just a 1 minute delay timer even the magni 2 uber is better than this piece of shit. at least its a balanced vas stage. here is the updated final schematic http://gilmore.chem.northwestern.edu/sj.pdf and yeah the 4 diodes around the opamps are missing from the schematic, i'm lazy

not really sure what the point is. you took one of my layouts, and removed all the resistor values making it harder to stuff and verify. you also took off the acknowledgements of kerry gerontianos and james lin please take my name off the board

stax is certainly not the only company doing this. krell in a whole bunch of its products puts in a custom microprocessor chip that looks at line frequency, so if you have a usa unit at 60hz it won't even turn on at 50hz. and of course a few have developed plug and play circuits to fake the 60hz.

12v filament version posted pretty sure the original was done the way it was to accomodate the 6dj8 tubes for those that wanted to do that edit: the filaments of the output tubes are tied to -450v on the board

the conversion to 12V filament for the small tubes is easy and I should be able to get that done tomorrow, too many other things got in the way today.

1 ) yes 2) yes 3) the 4 tubes in the middle can either float or tie to -vcc yes the front end tubes are 6.3v, so 1.2 amps

no on the 3 terminal regulators. each output tube is 1.5 amps so that is 4 x 1.5 amp windings and 1 x 6 amp winding all the input tubes are in parallel, so 12V at 600ma

228.0 x 228.0

that looks a fair bit different than the first units

why no one tell me I got the wrong hole size... updated goldenreference6d file.