kevin gilmore

I think the cascaded fets instead of the 2 x pnp and resistors etc is the easiest to increase the performance.

so i have a big problem with the morons that charge stupid money to add a tube buffer to a solid state output stage. modwright instruments, and lampizator for example. you start with something that has a 200 ohm output impedance, and by the time you are done with the cathode follower, its a 1.5 k output impedance, or in the case of the lampizator something like a 3k or more output impedance. its stupid and counterproductive. but hey there are these glowing things sticking out the top. you can't make a decent i/v converter with tubes without 6 triodes per channel. and even then, solid state is far better. r2r is a voltage output anyway, not a current output

dac1541 is going to be the giant killer. r2r,sign/magnitude, fully balanced, and dsd for a price that is less than half of a yggy

that would be the krell. one of the few pieces i don't move to vacuum under or around. requires 3 people because the platform is stuck to the underlying plywood same thing with the wilsons

well obviously they know how to make pretty front and back panels. making circuit boards would have been easy. I would never touch that piece of shit. Nik's was much more poorly built. And I would be more than happy to say to your face directly anything I would say here. And so would birgir. after he squashed you into the ground.

definitely the t8000 is dc coupled. but it has a servo, so the frequency response low limit is .1hz

twice the impedance at 10k than a cascade current source alone, 20 times better than the t2 current source but by specs, only good to about 930 volts

I will synthesize that and get back to you

you can't, that is the problem. there are other depletion mode ixys parts with 1kv or more, but they are not sharp cutoff and have more capacitance so you have to cascade them.

not enough voltmeters

also notice the same rms voltage as 727 which means +/-350 power supplies

my guess is a single dual triode as the differential amplifier, probably a pnp cascode, pnp current source driving a npn only way to keep it all dc and still get the plate voltage down to something manageable

looking at the pictures, small surface mount transistors on a board that is insulated from the heatsink. so pretty much the couple of pnp and npn surface mount parts that are available plus a tube front end that emulates the t2 with a lot less parts price seems grossly high for that

T2 was the only stax with a servo. both common mode and differential mode. 717 had protection relay circuit if dc was out of spec

jude reviewed the new stax amp, t8000 over there

i suppose that should work. as long as all the parts are rated for the voltages you want to use

a room full of amplifiers?? ask birgir. how about 3600 square feet of amplifiers.

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