kevin gilmore

There is also an alternative power supply board, cheaper than the T2 style, its pretty much identical to the BH power supply board, at 450 or 500 volts. No reference, opamp or 2sc3675 needed, and 2 less heatsinks. http://gilmore.chem.northwestern.edu/kgsshvps2.jpg option for 2nd pass fet and heatsink for better heat spreading. amp schematic updated. I've tried having someone else order the boards. But if i pay for them even if they ship out of state, they still charge me tax. For boards i buy for nwu with the tax exempt number, i still have to go over it with them every single time. A real pain. But they are the best boards i have ever seen.

The resistor may not be necessary as the output impedance of the reference is about 1k. In which case the cap would need to be 1uf. I have not tried this. Also instead of cutting a trace, you can put the reference up on a pair of sockets stacked together with the resistor in the middle. Picture on this at some point.

exactly the same crap as walker links High Definition Links but cheaper. Nothing but a capacitor. Takes a bit off the top. Causes instability in some high slew rate amplifiers.

OK, the holdup for the last 5 weeks was trying to supply 2sa1968LS at a rational price. ($7.13 each is not rational) I was told by the person that should know that they should be 70 cents each. So after contacting various unsavory ic parts companies only to be told that my offer of $1.29 (mouser price on the ixtp compatible part) was WAY too low, i just gave up and decided to modify the layout of the board to incorporate both current sources. Literally 10 minutes after i uploaded the files below, i get an email with a quote from a british distributor, and guess what... 70 cents each. (plus or minus due to exchange rate) Since lots of things have been changed or moved around, lots of checking needs to be done. also apparent discrepancies on the power supply schematic vs the amp board are due to the differences in voltage. If you go with the 2sa1968ls which i think sounds ever so slightly sweeter, the power supply rails have to be +/-450 volts. If you go with the ixtp01n100d, then you can go with +/-500 volt rails. http://gilmore.chem.northwestern.edu/kgsshvproduction.pdf http://gilmore.chem.northwestern.edu/kgsshvproduction.jpg http://gilmore.chem.northwestern.edu/kgsshvpowerproduction.pdf http://gilmore.chem.northwestern.edu/kgsshvpowerproduction.jpg The amp board is 8.25 x 6.25 inches with 240 holes. you need 2 The power supply board is 9 x 7.5 with 374 holes. The single transformer is going to be 4.5 inches in diameter and about 2.5 inches high. (if you go with the SumR) If i do the board run and do 20 sets, because i'm in illinois and so is imagineering... the price increases by 9.5% due to sales tax. Which would make a complete board set $71.46. plus shipping. If someone else wants to do the board run that's ok too, gerber files will be posted once people verify that there are no mistakes. Digikey is the only one with the 2.5 inch version of the aavid heatsink, mouser only stocks the 2 inch version. 2.5 inch version highly recommended. BOM now needs serious work. I'm not doing chassis on this one. (well except for my nelson pass style chassis which is for me only) Put it in a hifi2000 box, or hammond box, or a wood box. But plenty of top and bottom holes.

First things first. Then i will read upward later. The power supply problem is fixed. Verified by Inu. Took about 5 tries. Will have pictures soon. Power supply total noise is 26 millivolts at load. Under the noise of the tubes. Which is still very quiet. schematic updated with the fix. For those that want to play... http://gilmore.chem.northwestern.edu/T2PSfix3.asc get a copy of ltspice which is free. Simulate and put the probe on the output. Cut one of the wires to C3 (but not C3) and simulate again. ltspice likes to rearrange nodes sometimes for no apparent reason, so if things look screwy, delete the trace and put the probe back on. I still cannot get my spice machine which has never failed in the past to do what this does. But with the added parts, the optimization still comes out the same. I can't play any more for 2 days due to the labor day power shutdown. Lt spice completely fails with the same spice models on the amplifier schematic. 8 chassis have been delivered to the polisher. I expect them to be back in about 3 more weeks, then 4 go for anodizing. This is strictly a logistics problem now. All of the machining of every single part (except for more stax jacks because i keep selling those on the side) is finished before the increase in price of machine time on sept 1. When the chassis arrive from the polisher i will ask for payment on the next 4 chassis. Many who missed out on this want another run. Justin has a brand new heatsink that is 5 inches high. (like this thing isn't big enough already) the 5 inches combined with the 16.2 inch length of the heatsink means that i cannot machine the front and back holes. I would like to find a machine shop that would do the entire job. If someone knows a shop capable, i would like to know. Would have to be a featurecam supported shop, or have machines that i have a G code optimizer for already (i have most of them). The price on the chassis would definitely go up a bunch. Or people can do what luvdunhill is doing, which overall is a massive amount of work. On the current chassis, all pieces, there is 12 hours of machine time. That is just machine time, does not count the added load and unload cycles, or the cleaning of the goo afterwards. $700 of the chassis was machine time. But if people still want another board run, that can be done. All fixes have been applied to any future board run.

i'm having no luck... don't know what to stick (the spice model for the 2sc3675) and where to stick it, or how to get it to simulate what Inu see's... Then i'll get around to figuring out how to add/chance component values... Time for an early dinner.

tympanni 1's were about 1974, so the patent would have run out 1992 or so... Got to be public domain now.

any details of the lawsuit? those patents have to be way out of date by now.

looks like i'm going to have to learn ltspice... wonder what happens if i put in something fast. I'll try that when i feel a bit better... stomach flu and high voltage probably don't mix.

probably NSFW luvdunhill will appreciate. http://www.youtube.com/watch?v=Fow7iUaKrq4?version=3

what does that moron's opinion have anything to do with the price of tea in china. I really like the lcd2, but there are things that i don't like also. Some of those resonances need some work. And besides, motional feedback sure seems like a great and easy thing to do with dipoles... These guys could learn a lot from how magnaplanar does stuff.

anyone ever heard a phillips david?? Probably way before most of your times... But it would be interesting to put a capsule mic inside the audeze, and do active balancing of frequency response with feedback just like the phillips did. Turn the thing ruler flat in a jiffy. Would be super easy as the thing is a dipole.

Outstanding. I would have no idea how to make a chassis like that.

A little too much inductance in the cable could possibly do this. I kept mine rather short because i was running out of 10 colors of wire. Eventually i was going to make a much longer pair. I just do not understand how ST can make crap like the 7912. I finally got a couple of these, and no matter what i do, even in the most simple of circuits with 100ma of load, they just don't fucking work.

You better look at the -15 again... If you put in a 12 volt regulator, then you forgot to flip the one diode. Not that it probably matters, but if the diode is in wrong, then its gong to be about -18.

Its hard to tell from the picture, but you did use the ceramic washers right?? at least on the non-isolated parts.

In general the distortion goes down, not up. As long as both sides are well matched. impedance does go up, but compared to the impedance of the wire feeding the headphones it makes little difference for things like dynahi,b22. slew rate doubles. noise cannot be determined, but probably goes up.

I think that is right, but if you have the 100 volt windings, don't hook them to anything.

you can certainly power it up without a load, but make sure the angle brackets are attached otherwise the current source that drives the zener to power the opamp gets very hot very fast.

And then you really abuse them like singlepower does, and they really do burn up.

So both hammond and plitron are worthless... You would think that companies making this stuff for the last 75 years would have a clue.

Schematic updated with note from Inu. I'm using vintage parts, because with the amount of stuff i have in stock, i don't actually see the reason to buy more. Inu's mod increases the open loop gain of the power supply feedback. So the new versions of the op27's must be a different process or gain from the old ones. Completely makes sense. Now i'll spend the rest of the day synthesizing it, trying to find a better op27 model.

+/- 10 volts in any direction is just fine. You can get it to zero but it won't stay there due to the unregulated power supply. Has to work.

First time i've even heard of 8cg7's in an 007t. if the unit really was set up for the 8cg7's then the filaments of 6cg7 would be way high. In any case unless the tubes are competely toast, if they bias right, then they pretty much have to work. In fact if the tubes are toast, they would not bias correctly. offset to make the difference between the tubes zero bias to make the difference between each tube and ground zero.

The specs on the transformer was to deliver 130ma on the high voltage line DC. SumR calculates however they calculate from there. With all the problems i had with plitron, i made sure that he understood the current requirements. 60ma on the 285 volt winding and 60ma on the 75 volt winding. I did actually use the minus transformer for the 60 volts, but switching to the other transformer is definitely an OK idea. As people can attest to that visited CJ, the thing was on all day, and was definitely HOT, but not untouchably hot.