kevin gilmore

I'm liking it just fine with 2 ohm emitter resistors. Vbe multiplier just fine with 10k resistors and 20k pot. a resistor in series with the 20k pot is a really good idea. I'm not using the input bias trimmers. As long as the voltage at the output of the opamp is less than +/-2V no need to trim. working on a custom fully machined heatsink now.

NO. And here is why. Its a whole bunch of work, and the amount of work depends on which of the 7 known different types it is. The worst being the circuit board version that neil has. The early circuit board versions are a lot easier. The schematics have grown to a complete re-design of the power supply, and some significant modifications to the amp which include replacing the 4 pots with 8 pots, and dealing with the coupling caps. latest schematics here. http://gilmore.chem.northwestern.edu/singlehoures1fix.jpg but really the bass really comes alive when you change out the .01 caps with .05 caps. http://gilmore.chem.northwestern.edu/singlehoures1psfix.jpg but really a KGBH regulated supply is a much better idea. So the parts list is 8 x 10 turn really good pots with 10 turn locking dials ($35 each) (bourns plus clarostat knob) set of 4 amphenol or equivalent plugs $150 for the real thing, or half that for the chinese copy BH power supply board with all parts (may or may not fit depending on chassis) extra filament transformer extra C- transformer and parts... And 20 or more hours of labor. What you end up with is very stunning. And how you adjust it is measure voltage between Tp1 and TP2 and adjust rv1 for zero volts, then measure TP1 to ground and adjust rv4 for 200 volts. Then adjust rv3 for zero volts to ground at TP3 and rv4 for zero volts to ground at TP4.

I don't know where the production boards are at in the production stage, but if possible it would be nice to move the two different feedback methods to the top side of the board with a 3 pin user configurable jumper... requested by icarium...

But that was when there were only a total of 4 fets. and its still the same 300ma and 18 watts... So i doubled the number of fets and halved the current per fet.

So i think people are pushing this thing way too hard. The design goal is 75 ma per fet times 4 fets (1 x p channel and 1 x n channel) For a total power supply of 300ma at 60 volts which is 18 watts. My heatsinks get to about 96F after being on for an hour or more. The fets can certainly take way more than this, and the board will happily drive them that way, but you have to take the fets of the board and heatsink like crazy. Then you should be able to get to about 50 watts pure class A into 8 ohms...

I was just teasing. I sure hope she does not find out about this. Yep she is a full fledged SOFTWARE ENGINEER.

I'm about 95% done stuffing the board marc sent me, this is definitely NOT a beginner project. I'll be machining up some custom brackets in the next couple of days. If anyone sells boards to -=her=- i will hunt them down and kill them. Seriously a person with her skills has no chance at this thing.

May the glow of your new ES1 lightup the day.

Hey at the time i was one of those wippersnappers that did (god forbid) "sand" The art performed by those tube wizards was amazing. Especially the stuff that zenith did for the military. There were all these rules that everyone paid attention to back then, like the fact that all passive components had to be secured at both ends. All wiring had to be tied together every inch with a loop and continue... None of mikhail's air mounting of components. Or mounting a component at one end and soldering unsecured wire to the other. That kind of crap would never have been tolerated. Go and look inside any 50 year old tektronix tube scope and see how the stuff was built to last forever. Most people don't know this, but image intensifiers was a zenith invention. The BHSE supply will supply +400, -400, one of the 2 filament supplies and the bias supply. And it will certainly fit in that box. To finish the thing correctly you need one more filament supply (a transformer is just fine) and a small C- supply, plus new umbilical cables and connectors. Then in the amp box you gotta get brutal. Unsolder every fucking piece of wire. Get the board out there. Take a dremel tool and cut away circuit lands to seperate the two filament sections. Then modify to take the 4 new output tube bias pots. Then replace the 50k pots with 5k pots and hide those inside somewhere... Use 10 turn pots and hopefully they will fit in place of the old ones on the front panel (pretty sure they will fit if they are at least .9 inch center to center). Use really cool locking 10 turn turns counting dials. And when you get done it will work forever. But an all tube power supply would be way cool, and a bunch more work. And i forgot the best part. Take the fucking orange drop cap out from being in series with the audio note cap that is already rated for voltage.

Lots of people think they can design electrostatic amps. Lots of people have failed too. My guess is that there is a new amp destined for failure soon. The original circuit works just fine if built correctly.

You want a denon, onkyo, the new sherwood newcastle thing, or the new sony all of which definitely do audio over hdmi. Including native sacd.

No chance He can't afford me... Neil's amp rebuilt right is probably 30 to 40 hours of labor. Plus a bunch of parts. I don't even have the time to build my new stuff

If your build 2 of my schematics as in 2 filament supplies and 2 of the high voltage supplies tweeked for 400 volts (and one of them grounded upside down to make -400) plus a bias supply you would have one kickass power supply. And a small C- sully. Sort of like that 12 tube thing mikhail built except mine would be built with the right parts and actually work instead of blowing up. (yes one of those has died recently too, looks even worse on the inside) So here is a story. Out of college 34 years ago i went to work for zenith radio and learned lots from the true tube masters that worked there. Most of which were at least 30 years older than i was at the time. So recently i've contacted a couple of them, as most have already passed into that great DHT heaven in the sky, and i found one of them who was willing to work on the SP stuff after i told him of people' woes. That is until i showed him pictures of the stuff. At that point he said no fucking way, it would be easier to strip it to the bare chassis and start over wiring things correctly. The 3 pictures i showed him was this SDS mess, neil's amp, and spritzers amp. So i'm back to trying to find someone who will work on this stuff. If i do find someone, it ain't gonna be cheap. Unless i find a high-school kid that wants to learn. For neil's amp, the 4 pots on the front panel HAVE TO CHANGE. Plus they have to be wired differently. Schematics of the modifications have indeed been tested and work fine. But spritzer needs to test his way on his amp.

blu-ray burner absolutely required. And pretty cheap. Since you are going to use a tv as your display device make sure that your video card has a hdmi output.

depends on whether the fet is in a fully isolated case or not. In any case thermal grease or a silicon grease washer is a real good idea to keep the board from burning up.

this is the correct way to do this. Lock-in amplifier - Wikipedia, the free encyclopedia I have a recent vintage SRS amp, now i just need some time to set the thing up. Does not really measure impedance as such, but is real good at measuring phase. I think that increasingly stereophile is more and more full of shit. What you can do is put a 300 ohm pot in series with the headphones and turn it up and down, simulating a low impedance and high impedance amplifier. Sound is hugely different. Grado's and hd600's don't exhibit the same kind of behaviour. If stereophile would do the same thing with different damping factors, things would come out very different.

actual measured voltages with quickly built hacked together power supply with 0a3 (75) output voltage range 123-216 0b3 (90) output voltage range 140-257 0c3 (105) output voltage range 159-298 Looks like 150ma no problem. 520 volts at the plate of the regulator tube.

Switching with the power on is a gigantically bad idea. Maybe next time i go in there i will add a couple of extra resistors to make sure the switch does not temporarily disconnect all the feedback.

I have a switch that allows me to change between the two. So the answer depends on the day and on the music... And the phase of the moon and the temperature outside And how much booze... Some people really like amplifiers without global feedback. Especially when female voices are involved. (no, not the B&C)

complete with all the glorious fuckups... http://gilmore.chem.northwestern.edu/singlehourextreme.jpg

updated schematic with correct 6au6 pinout http://gilmore.chem.northwestern.edu/sdsgaspsfix.jpg

There are lots of ways to do this, i think this is the best. Some notes. voltron really liked the sound of 2 x 75 volt tubes... i.e. 150 volts for the power supply. The WCF amplifier he has is AC coupled between first and second stages so you can definitely have 2 different voltages if you want to. The design as introduced works with just about all gas tubes and has a intentionally limited voltage range. With a 75 volt gas tube the output is about 90 to 150 with a 90 volt gas tube the output is about 110 to 180 ... with a 150 volt gas tube the output is about 170 to 300 And yes you can adjust the voltages with the amp on. You would want to turn the output section voltage up and down slowly otherwise you will get a slight bass thump.

OK, i have something that i really like. It is completely in the spirit of the original power supply, fixes absolutely everything, can't burn up as there is no sand in the high voltage section, no dangerous anything, nothing out of spec... Best part, no modification of the chassis. Well almost, need 9 pin to 8 pin adapters for the 6au6's. Keeps all the iron. Otherwise adapter plates for the 6au6's. Uses only one gas tube per channel, 1 socket is for the 6au6 and the other is for the 6l6. http://gilmore.chem.northwestern.edu/sdsgaspsfix.jpg unfortunately, still sand in the filament supply, but absolutely nothing can be done about that. WARNING: pinouts of the 6au6 completely wrong. And the picture of the 6l6 is not correct either, but the pinouts are right. Cute part 2. The switch that was the voltage selector is now the voltage pot. It can be a dual section in which case both supplies adjust at the same time, or if you do it as 2 seperate knobs on the same shaft, you can adjust the front end gain power supply seperate from the output power supply. Now all you need is an ultra trendy analog meter to stick into the front panel. (ok, now you have to do some chassis work) do it eddie current style and it will look real cool.

That also works for me. Sounds sooooooooo nice with hd800's... Wish someone would allow me to buy connectors so that i could go balanced. (hint hint)

I'm using different fets on the prototype, but if you make the bias pot 100k you should be able to get down to 250ma.