kevin gilmore

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.

http://gilmore.chem.northwestern.edu/srm323aorig.pdf balanced no problem. But you would have to change out the input pot, or bypass completely.

5. Anonymous but it should be obvious who this person is.

I was wondering about all the flipped parts myself, as i have an identical unit with the same revision of the boards. No flipping on the pins of the regulator. No crossing of the diodes on the input fets either. Clearly the +15 is not being regulated with the regulator wired like that. Measuring that voltage would give you the answer, likely +18 or more and unregulated and filled with hum.

The power transformer has clearly shifted in shipping. This needs to be fixed first. If the bolt is touching the inside of the transformer, all sorts of ground current and vibration is getting into the chassis.

posted on behalf of linear http://gilmore.chem.northwestern.edu/t2schemip.pdf http://gilmore.chem.northwestern.edu/t2schemop.pdf http://gilmore.chem.northwestern.edu/t2schems&b.pdf http://gilmore.chem.northwestern.edu/mjt2a.jpg http://gilmore.chem.northwestern.edu/mjt2b.jpg http://gilmore.chem.northwestern.edu/mjt2c.jpg http://gilmore.chem.northwestern.edu/mjt2d.jpg

if you look at the insides of the original, the 22k resistor was mounted on the backside about .5 inch from the board so that you could put clipleads on it to adjust.

i'm sure inu could translate it. but i know a couple of people at work that can do it too. maybe in the next few days. really, these things are just the srx circuit with an extra tube stage for more gain so that you can have more feedback. 50ca10's are probably impossible to get, as are the sockets, 6ra9's might be easier. Still nothing wrong with 6ca7's. But the resistor plate loads are guaranteed to do the same thing that has happened to a bunch of the es1/es2's when the output tube lets go. So much better idea to replace with current source. Then make sure you have adjustable bias on the output tube. Pretty soon you end up with the modified singlepower schematic. There are errors in the schematics, in the 3rd one, "B" is actually -440 volts. With the 50c10's you can do adjustable self bias without an additional negative power supply.

inu sent me these which are variations on the srx circuit. http://earsp.web.fc2.com/log/stax-r/stax-r-3.pdf warning, the 1150 volt version is only for those that really know what they are doing. And obviously the output caps need to be rated for 1200 or more volts. With respect to high voltage electrolytics, and also mylar caps, a resistor across the cap is pretty much required at all times. Even if you discharge the cap, and then remove the resistor, the capacitor will self charge, usually to very dangerous voltages. The higher the rating on the cap, the worse it gets.