kevin gilmore

A maida circuit with a tl783 is possible, ray manages to do the same thing at 600 volts without the front end voltage reducing transistors. I'll try it. But the idea is to use an unregulated voltage of about 625 volts to make sure that there is enough to do the 580v bias. Will order the parts and see what the real performance is. The problem will be voltage drift over temperature as there is no extrememly stable reference.

The universal series/shunt/hybrid regulator board will be posted soon Seriously, some things work out great, some things not so great. The tl431 has too much gain to make it useful. There may be other similar devices out there that work better, but it is unlikely. The idea of an amplifier with all isolated packages sure would make things easier. Don't know of any isolated versions of the 2sj79/2sk216 either. Any current source that references the unregulated input voltage (like the cavalli thing) absolutely guarantees that the spike noise from the diodes rips right thru the current source and the rest of the circuitry. This is why the 10m90s part works so well.

well for one thing, i had already been using that setup for some time, not sure how long. But the 16 bit dacs in the sony (and later the d-ej01 or some such) beat the crap out of the less than 14 bit ipod at the time. Too bad the stax eats so much power, a new version of that setup is something on my todo list. edit: d-ej01 corrected. I still have 2 of them.

The hybrid shutdown part combined with the required caps across the tl431's cause massive oscillations. hundreds of volts. with the shutdown part removed, it works and is about 35 microvolts peak to peak noise. The tl431's really like to oscillate, and once you add enough cap to shut them up, everything slows down.

media players did not exist back then http://gilmore.chem.northwestern.edu/porta.gif date... 2/20/2000 besides which, compressed to hell music from one of the early mp3 players on stax headphones... be serious. to bad sony never actually sold their portable sacd player. I would have bought it. Now back to our regularly scheduled program, food, a bit of rest, now lets see if i can't send some parts flying across the room.

Hey, i used that for years and years. But after 9/11 there was no way in hell they were going to let me on an airplane with that. It was a 12 volt 7 AH gel cell.

OK, so linear's first circuit with the ixys current source devices and the tl431 with a 10uf cap across it actually tests at 20 microvolts peak to peak noise. (10k load) about 4 to 5 times worse than the T2 battery version. With anything less than 10uf it has very nasty startup oscillations. Obviously with the cap across it, it is nowhere near as fast as the T2 battery. Absolutely needs a 24 volt protection diode across it. Going to try the tl431 as the current source next, but anything i have tried like this previously has a lot more noise from the switching of the diodes because of the resistor to the gate.

The current kgsshv power supply is a series pass design. Works just fine from 0 to full load. Alex Cavalli is now famous for making shunt regulators that blow up real good when the load disappears for any reason. In theory shunt regulators can be a bit quieter than series regulators. In practice, once you get into the hundreds of microvolts of noise or less its the power transformer and diodes that are most of the problem, and something not easy to fix. Compared to the hundreds of millivolts of ripple on most power supplies for tube use, we are well into the major tweek realm. I think that added zener diodes across the tl431's and tlv431's are probably necessary for startup and shutdown conditions. It sure would be nice to have 100% isolated packages for the entire designs.

Except for the srm300, none of the other stax electrostatic amps have regulated high voltage power supplies. Just diodes and capacitors.

sure is much simpler. I wonder how stable it is. Will evaluate my model for the tl431 is probably lousy, but load regulation is in the many percent, and the noise is 7 or 8 millivolts. You are relying on the pass fet to stay stable over temperature, and that certainly is not the case. Will play more can host ltspice stuff.

Actually if the batteries are adjusted well, the opamp output voltages are no more than +/- 3 volts. You could certainly turn the other opamp into an inverter and drive the current mirrors that way. A savings of a few parts. edit: if one of the opamps was at the rail, the other opamp would have to be at the other rail. Here is the first cut of the hybrid shunt regulator version of the kgsshv power supply. http://gilmore.chem.northwestern.edu/shuntregver2.pdf Unlike some other shunt regulators however, the current sources shut down if the shunt element pulls too much current, so its safe to power up with no load. edit: silly bench mistake fixed. Actual noise under load about 3.5 microvolts peak to peak.

The common mode servo is Q34,Q35 and Q36. You could replace those, but you would need another opamp to do it. Even though you could get rid of a few parts you still would need an inversion from the one opamp to drive both current mirrors. So you need 2 opamps for that.

Make sure you change out that electrolytic again, and throw the overvoltaged ones in the trash can. To everyone, power up the transformers on the bench to make sure you know how they are wired before you hook them to the boards.

So lets see, about 650 volts on a 450 volt cap. Yep that is probably going to cause it to get stinkin hot... And the regulator circuitry does not care, as it can handle 800 volts easy.

Actually the 2sc2240 would work just fine. But i was simulating absolute worse case. Lets say the current source on the top of the top input tube shorts, then the top tube shorts... Suddenly 250 volts on the cathode. Of course this has not happened yet, and is unlikely to ever happen. But i do wonder what would happen if just the tube shorted. This scenario would blow up the 2sc3381's anyway. And this is why i figured it would be easier to use the 300 volt versions. Which are still dirt cheap.

The simulation shows absolutely no difference between the 4 transistor current mirrors, and the single transistor circuit. Does need to be a 100 volt transistor however. Due to tube shorts, probably should be rated at 300 volts. Whatever the npn equivalent of the mpsa92 should work great.

just bought this, it will be here monday http://www.saeco-usa.com/en/products/household-automatic-machines/1/automatic/0/xelsis-digital-id/311/xelsis-digital-id.html replaces a 15 year old saeco magic deluxe that is finally beginning to show wear.

posted for linear http://gilmore.chem.northwestern.edu/servochange.jpg

So a couple of people have asked for a discussion of the design elements of the T2, and any observations and improvements that are possible. So as not to polute the T2 build thread, which is already seriously poluted, the discussion of T2 design elements, including kerry's dynamic amp should go here. doug wadsworth (wadia) should be stopping by soon Actually, a moderator change the thread title to discussion of the T2, and other circuitry as we see fit including but not limited to my other designs and shunt regulators and stuff like that etc...

Well with a set of linear supplies, it tips the scales at 800 watts of heat. I would say its kinda hot

I did pay extra to have the boards electrically tested. But who knows what really happened. I just don't see how the electrolytic can get hot unless its backwards, or over voltage. No matter what kind of load it sees. As far as kerry's amp... Turn up the bias current to 2 amps per leg. Replace the output fets with the SiC fets that nelson is using. BIGGER HEATSINKS. And my test bench thing works absolutely great with +/-24 volt power supplys, and does about 30 pure class A watts into 8 ohms. Currently using switchers for the power, and each amplifier puts out about 200 watts of heat. Sounds really nice into vintage VOTT's. REALLY NICE. OK, so VOTT's are really more like 12 to 16 ohms...

i'm pretty sure a while back i said in the range of $4500 to $5k. Looks like i was right on the money If i were you guys, to avoid getting ripped off, i would wait till someone reliable has them in stock for sale. elusivedisc, audioadvisor, woo audio...

has to be the cap or diode bridge. because it still makes the right voltage. my bet is the cap has the + and - mislabled. Caps get very hot this way.

And likely done on a very large bellows camera with a 6 x 10 inch plate. They don't do it that way any more. Too bad.

pretty sure the default pot is 50k. So use a series 25k resistor. Should work for any solid state source, but may not work well with a source that has a tube output stage. An input transformer won't help with the impedance, but will cause other grief. Also notice that very few pots actually go all the way to zero, so there will be some minimum volume. You are still going to have to punch holes in the back panel for the xlr jacks.