kevin gilmore

Except that the attenuator is a 6 layer board which would force the rest of It to also be a 6 layer board and that is a bunch more money. Probably enough room to add the mounting holes for a pair of them. The 1u chassis is impossible due to the height of the caps. Maybe if you lay the caps down. Also the electrolytics are too big, And the attenuator is 1 inch thick

The advantages are more gain and one less capacitor. Trust me, you want the feedback, otherwise it sounds like crap. This is the one that will probably make it to production. http://gilmore.chem....rn.edu/beac.jpg Its 10.8 x 9.2 inches 7 x 6.3v filament supplies. I could split out the front end power supply, then you could run +/-500V for the output stage. The nice thing about this one is auto balance output. In fact you could act like that knucklehead in israel, and swap output tubes with the power on. And no nasty silicon to go up in smoke.

Whats also interesting is on this version you can build an unbalanced only one with just a single board. Figure the board and all the parts on it to be a total of $100 (the opamps are $21 each), add transformer, box and input output connectors.

The latest pictures that were acquired prove that the A10 was in fact wired as srpp. Very hard to determine from the low quality layout. Broskie will argue that due to the load, it cannot possibly be srpp. With very little additional work, this is easy to turn into a super B52, with dc coupled outputs. (+/-125 volt power supplies) (needs a servo to be safe) birgir has decided to tackle this piece of shit next. a full channel on one board including power supply. 5.1 x 3.85 inches http://gilmore.chem....du/dorkstar.jpg

paralled, yes. srpp, definitely not. srpp takes the output from the top cathode and is bad when driving electrostatic loads because of the huge change in impedance over frequency. This takes the output from the plate of the bottom tube. So its a tube driven constant current source. Substantial difference. The reason its doubled up is the cathode to filament voltage limits. No other way to do this with a 5687. Unless you are mikhail and can magically have a filament voltage at both ground and -400 volts at the same time...

The input section is the stax srx circuit. Which is easy to model, but is hard to explain. And it works and works well. The output stage is a tube constant current source. It would be easy to do the same thing to the bae, which would result in a total of 8 output tubes. The feedback is important and reduces what would be 3% THD to less than .2% THD. At some point these things start looking like, and are the size of the VTL WOTAN. The power supplies get to be very large.

i would make a new top out of 1/4 material and machine out areas for the heatsinks. the heatsinks are grounded, so this would work great.

why do you need to unsolder the heatsinks? It was designed to be repaired without ever doing that.

We always do the schematics last after the prototype is working. http://gilmore.chem.northwestern.edu/srxa10.pdf more than 1kv peak to peak stator to stator with .6 volt rms input signal.

that was not delrin, it was something else. I have one at home, will look at it later.

And this is the right way to do it. And its constant current, not srpp! http://gilmore.chem.....edu/srxa10.jpg dc coupled input, dc coupled and self balancing output one cap in the signal path. 10db of feedback, 54db gain and a thd of about .2% max at 20khz

Not sure since i've never seen an audio note up close, but the voltages are about half that of electrostatics. Its unlikely to actually be black teflon. I did test black delrin, and it starts conducting at about 200 volts. All of the connex octal sockets are white teflon. Probably for a reason. If its bakelite, then that is a different story. Not sure what the real stax jacks or the amphenol jacks are made of. I can probably test an amphenol jack, but i'm likely not to have the time to do that for a few months.

just have not had the time to test the final version. i can give you the board layout, have a few made and test. Biggest problem is that i'm moving my lab beginning of august, and i'm working 10 hour days in prep. Plus the stax mafia seem to be doing every possible electrostatic tube amp at the moment, all at the same time.

so its been over a month since andy has built an amplifier, and the stax mafia needs to keep the guy busy. So here is the bae. I changed the front end with a current source, and its dc coupled input and dc coupled output. 2 caps in the signal path. http://gilmore.chem....ern.edu/bea.pdf http://gilmore.chem....ern.edu/bea.jpg http://gilmore.chem....du/beapower.jpg The power supply has a + and - 15 supply, because later i will probably add the servo but at the moment with virtually all of the good opto isolator parts no longer in production, the ones i would use are way over priced. And the test version oscillates very nicely at about 2 volts on the output of 2 hz. So that needs more work. Next up what we are now calling the 2B10. only one cap in the signal path. Paralleled 5687's and DC coupled outputs with the above power supply set for +/-300 A total of 8 5687's. 6 seperate filament supplies... I'll also be doing a new version of the kgsshv power supply with the added 60 volt supply to make a high end, and universal power supply.

I have been thinking of adding a resistor string to the -HV line. But really i would like to add yet another power supply, say -30 volts, and do a current source instead. No reason to have more capacitors in the signal path if they are not necessary. Could use the input filament supply doubled and inverted. More on the srx circuit later. Also thinking of adding an opto coupled servo to the output stage. That gives me the excuse to add 2 more power supplies.

updated Megatron schematic. If you manage to figure out what the stax mafia is doing, please let us know. We are having a hard time keeping track of it all

100 ohm 2 to 5 watts

http://gilmore.chem.northwestern.edu/bae.pdf

you wanna build one of these! http://gilmore.chem.northwestern.edu/beveridge.jpg

It is certainly not compact. Unless you are comparing it to the DIY T2. It's about half size. Amp Board is 10.5 x 6 maybe it will end up A bit smaller. The power supply board is bigger. 2 power transformers are required if you Don't want to trash the output tubes.

Yep, just like it should be. 6sn7 is max gain of 20 (10 is reasonable for low distortion) 12ax7 is max gain of 100 (50 is reasonable for low distortion)

So the stax mafia has been hard at work on many versions of simple tube amps. Here is my favorite. http://gilmore.chem....ern.edu/bae.jpg birgir did not want to use the 6sl7 because of availibility issues, so this uses the most common in production tubes. 6SN7 just do not make sense, they do not have enough gain. Mikhail learned that first hand, someone else is about to learn the same lesson soon. With not enough open loop gain, all sorts of issues including much higher distortion, and channel balance issues... Of course you really should do 10m90s current sources, lowers the distortion a factor of 10. And i don't think this can be crammed into one box. DC coupled outputs. i'm sure some people will want to use 6L6GC fatboys instead.

A cat scanner. The whole inside section rotates about 2 rps. MRI are just giant superconducting magnet. Nothing inside but a coil of wire and lots of liquid helium. There is a reason these things are over $2M Upper left with the big high voltage lead is the xray tube. Lower right with the 5 fans is the detector module. upper right with the warning sign is the xray power supply, typically 60kv at about 500ma.

I have three sets of pins here, the originals I took from the conex sockets, The luvdunhill pins and the newest ones from Justin. All are slightly Different in diameter and the bigger ones require a slightly bigger drill Than my original print. Machining Teflon is a pain, I used water cooling to prevent creep. What I will eventually do is make some from macor and then there won't Be any dimensional change ever. And they will be $ 300 each

http://gilmore.chem....ern.edu/srx.jpg uses cheap current source.. Just 2 power supplies. 12 volt filaments for input and output stage. Need 2 seperated windings. Same holes and size board as the bate. power supply is the bate power supply with the C- supply not stuffed. About as simple as one can get. the current source really takes the distortion down a fair amount. To about .03% thd. edit: birgir wants to do dc filament supplies. That is next.