kevin gilmore

And i get bottles of the black death in return. And goodies from birgir's bakery, whose version of fruit cake is just amazing. (not what we think of as fruit cake in the usa which is generally useful for pounding nails and not much else) Birgir calls the stuff "stolen" but stolen here is not anything like that. Its a great deal. Testing indicates that to get the same distortion levels as the kgsshv does at 18 watts per channel, you have to go to 38 watts per channel on alex's fet design. Or lower the power and suffer significant THD at higher frequencies. I completely expected this. All parts now ordered for the preamp and blackhole. Mouser must love me.

The connectors are on .2 inch centers. But i can certainly change it for production. There are right angle plugable connectors that work great, its the kind of connectors that crestron uses on just about all their products. Will look tomorrow.

The parts situation is a royal pain in the ass for sure, unless you had the foresight to buy lots of stock of stuff a few years ago. Which some of us did. The idea is to have all the parts sourceable from mouser. On my kgsshv power supply, the ksc5026 replaces the 2sc3840 directly The ksc1156 can replace the 2sa1486 with an added zener on the drive transistor, but a better solution is the pin compatible (you have to flip it) Fqp3p50 The lt1021 is a digikey only part. For the amplifiers, when the 2sc4686a parts dry up, the 2sc4686 parts will still be available, or you can use the same ixys ixta3n120 alex uses which is a special order part. Or the fqpf8n90c at +/-450 the lsk389 or the singles are available at another distributor and are standard production parts. The 600 volt pnp is available as a 2sa1807 which is surface mount only, and the adapter boards will be needed. Or the 2sa1413 which may be discontinued. Alex's design is all mouser parts except for the 2sj74 which is discontinued but still largely available. At some point these will not be available anymore and then linear systems will really HAVE TO GET OFF THEIR FUCKING ASSES and deliver the p-channel parts. The bipolar version of my kgsshv is twice as fast (250khz -3db) than the fet version (130khz -3db) due to significant gate capacitance of the output fets. The n-channel input part is 30% faster than the equvalent p-channel input part. Although you can go bipolar here too. It all sucks i tell ya. Unless you are Nelson Pass and can pay stupid money for custom Static Induction Transistors which are n-channel only.

I believe he had to sleep on the couch a couple of days!

I'll do up the power supply later. I don't think much of the power supply. The amp part has 30db less THD than the exstata. Way better. about -80db second harmonic distortion across the full frequency range, and a rising third harmonic that is -70db at 20khz. Peak to Peak voltage really is close to 1350. Some people are going to like the mosfet sound better than the bipolar of the kgsshv. Nothing stops you from building the kgsshv with mosfets however, other than the fact that the parts are not isolated, they are a direct drop in for the 2sc4686a

Inu still holds the record for attempting to do powder coating in his old kitchen stove.

Not sure what you mean, for the terminal strips, they make 45 degree versions. For balanced its definitely stacked boards on top of each other. I already see a silkscreen error, so there will be for sure a couple of very minor changes for the production version.

Wow, alex actually does exhibit some learning after the exstata debacle. Well at least he knows better now where to acquire working schematics. http://gilmore.chem.northwestern.edu/liquidlightning.pdf For those that don't recognize it, its none other than a stax srm323 with mosfets in stage 2 and 3, and cavalli style current sources, and a stacked current source in stage 2. But for $4k+ ?? AH well the price of progress. Now alex needs to go back to the liquid fire, remove the tubes, replace them with jfets, just like the schematic he borrowed from about 1981.

Well you want 2 for balanced.

Well the critical stuff fits. http://gilmore.chem.northwestern.edu/kgitsojc.jpg

http://gilmore.chem.northwestern.edu/blackholebd.jpg The critical stuff fits. Now on to massive parts ordering binge.

Sorry, i'm tired and could not be much more creative.

Yeah Team. Boards at the post office , will pick up tomorrow. prototypes of the multiamp,blackhole and preamp. Will be sending justin his knob tomorrow also, i had better see pictures of it mounted.

Those are the top output transistors, and you can't measure them in circuit that way and get reliable results.

Somehow that is not the magazine i would not expect steve to be reading ??

3.73 watts for each of the 4 output devices .9 watts for both of the 3rd stage current sources (2ma) .9 watts for both of the 3rd stage amplifiers (2ma) About 20 watts for each amplifier.

I'm linking this one a lot. Needs a wood knob though. Now if customs would just pass thru the latest board sets from lil-knight i would be even more happy.

So i spent about 5 hours last night trying to find a matched set of tubes so i could have a listen. With about 100+ 5687's and an unlimited supply of 12ax7's, the best i could do was about 1 db differential and 1.5 db left to right channel. So matching is just about impossible. And after an hour of running, the numbers changed. Unlike the ES1/2 for which significant modifications can result in a pretty decent amp, for this mess, the surgery has to be extreme. Take the output preamp tubes, and turn them into input gain tubes. Take the original input gain tubes move them to after the volume knob, and apply local feedback from the output tubes. Then seperate the filaments for the output tubes and lift them to +300 volts. It might actually sound half way decent this way.

I am personally not going to spend any time whatsoever doing an A10/B52 board. Neither am i going to do an opa541 board because i have used my old power supply boards to test what it sounds like. The blackhole sounds way better. Especially with the alfet output devices. I will probably do a modification of the current kgsshv power supply board to do 600/300 volts for aristaeus/triode amplifiers. It definitely was worth the effort to reverse engineer ray's piece of crap. The fact that the stealth,raptor,B52 and now A10 are all exactly the same is quite entertaining.

I'm going to disagree with this, i have measured many a marshall amplifier. Unless you push them well into clipping, they typically measure .1 to .2% thd across the audio band. Besides which the job of the headphone amp is to accurately reproduce the distortions in the recorded sound. With something like a synthesizer, this is not as easy as it sounds due to rise and fall times that exceed what any musical instrument can do.

Fine, Dewey Cheatem and Howe it is. But later because i don't have the file at work.

So here is how this went down. Someone over there really pissed off Birgir. Its not nice to piss off the head of the stax mafia. I mean its REALLY NOT NICE to piss off the don of the stax mafia. So pictures were acquired. And reverse engineering proceeded. Starting at about 11am today. Then by about 4pm the stax mafia had an epiphany. And so while a slight bit more work is necessary... http://gilmore.chem....ern.edu/a10.pdf Now there is just so much wrong with this thing, i don't know where to start. OH wait, i do. http://gilmore.chem....raptorschem.jpg So Ray says the A10 is SRPP. Well go and look up the article written by Broskie... Its SRPP only when the load is resistive and close to impedance of the cathode resistors. Which by the way an electrostatic headphone definitely IS NOT. As usual ray does not have a fucking clue. Whats more the thing is completely open loop, and i just finished testing about 50 x 5687's in the output circuit, and guess what, a variance of about 4+ db. Reminds me of mikhail's ES1/2 disaster... And the same goes for the input section. What a piece of work. But let that not stop Moljinor(sp) audio... Who will be releasing a board that is both a B52 and a A10 at the same time. Add much bigger output caps for the dynamic thing, and put in a switch to lower the output section power supply voltage. Cheap as hell. Still the 5687 is being driven way over its cathode to filament specs, just like mikhail's disaster... By the way, just the output section of this thing has distortion specs that rival the Darkstar, >5% at even 200 vpp. And the power supply... What a clusterfuck. Not even worth the time to key that one in.

I was thinking of doing something similar. Find some real good epoxy, and glue it together and put it in a press overnight at say 1000 lbs. Then drill and attach the metal mount with flat bottom wood screws and more epoxy. It will definitely hold together so that i can machine it.

justin's knob and the tool i'm going to use to turn it to the final dimension http://gilmore.chem.northwestern.edu/justinknob.jpg

http://gilmore.chem....du/woodies3.jpg so i took some lacquer, dilluted it 5:1 then applied it with the lathe running. Came out like glass. And now the mounting thing for doing BHSE knobs (not cleaned up yet) Justin is getting a cocobolo knob. The smaller diameter goes inside the knob so everything is flush. http://gilmore.chem....u/bhsemount.jpg