kevin gilmore

these http://www.mouser.com/ProductDetail/Neutrik/NA2MPMF/?qs=sGAEpiMZZMtUKTCHc2CNRBaiw9SrxpJs and these http://www.mouser.com/ProductDetail/Neutrik/NA2FPMF/?qs=sGAEpiMZZMtUKTCHc2CNRAvIKttWysf6

not an engineering drawing. pretty much useless to lay out the board with. why those morons can't post something useful is beyond me. When i asked, i never got the engineering drawing. Measure and post please. more editing, switched to the dip version of the lme49720 so that there is less surface mount work required. http://gilmore.chem....inputboard4.jpg approximate pricing lme49600 need 4 for balanced stereo $10.50 ea lme49720 need 4 for balanced stereo $3.08 each (dip) opa1632 need 2 for balanced stereo $5.88 ea nc3fdh xlr male need 14 for balanced stereo $4.52 each (probably cheaper) nc3mdh xlr female need 4 for balanced stereo $5.55 ea ds2e-sl2-12v relays need 16 for balanced stereo $6.37 ea (digikey) overpriced boards at $37.50 each in quantities of 10 (lil-knight is going to be much cheaper) so about $375 plus resistors plus power supply plus chassis plus plus plus. RK50 (don't ask) my step attenuator (i don't remember how much) arduino (cheap) ...

Nope, not designed for that. I could however change out all the xlr jacks with stacked rca jacks and then change the input amplifier. Then it would be a SE in only, SE out only thing. If there really is interest in this, it would not be too hard as long as i can find a suitable stacked rca jack.

walk in with the el-cheapo transistor tester, test them all, and buy the real ones. Say 50 cents each... Kind of surprised that someone would stock those, and that they were bent into shape like that.

like this ?? http://gilmore.chem.northwestern.edu/inputboard3.jpg I can still add the servo on the input, but probably not necessary. Servo on the output takes care of all issues with DC. Why no one else is doing servo's i just don't understand. Still think that when you need unbalanced inputs, you use the neutrik converters. This way you don't need extra relays and configuration for inputs, and you can change on the fly. The discrete output amplifier is still better, but not by much. The bang for the buck on this one is way high.

so i've been playing with this for a couple of days. The unbalanced and balanced to balanced front end. Its virtually impossible to hear the difference between this and my fully discrete version. To be fair, it does not drive cables as well, and definitely has a higher output impedance, but it is about as simple as it gets. Turns out the rowland criterion preamp uses virtually the same circuit. The 50 ohm output resistors are definitely required if you want to drive 10+ feet of cable without it oscillating. The servo actually is required and i bumped the input impedance a bit to be more friendly to some high impedance sources. (which evidently some others are not paying attention too) http://gilmore.chem....u/ubaltobal.pdf Something like a pair of lme49600's with your favorite choice of opamp in a closed loop configuration as the output amplifiers after the volume control, and you have something super simple to build and way good for cheap. The discrete stuff is still better, especially the output amp, but the chips are damm close. This is the technology texas instruments licenced from nelson pass.

much more suitable for quick go/no go, and for obvious fakes. for critical matching you have to build something custom.

So 70+ horsepower and drum brakes. Yep, definitely a safe item.

sure looks like an early 1950's 1200cc 4 cylinder VW bug engine. About 50 horsepower. Which would make that thing pretty fast and dangerous for its age.

yep, balanced dynalo, same setup as the balanced dynahi. i've been listening to a lot of different configurations, including what has been represented as an identical blowtorch clone with all the exact same parts and values as the original. Blowtorch has almost 2db of unbalance between the + and - output, and it gets worse with low impedance load. Blowtorch also does not drive headphones very well. i did shrink the board to make it fit into a standard chassis. http://gilmore.chem....inputboard2.jpg Its now 12 x 4.5 inches and uses the same neutrik jacks as the T2. Everything in stacks of 2 boards, hole thru the input board to run the control from the bottom board. still no p-channel fet samples as promised by linear systems but i do have a clever way of using the singles fets on a 14 pin dip header with one spreader bar with all 4 glued to it for thermal stability. The thatcorp parts are definitely very low noise.

The stuff sold in the local drugstore is about 3%. You can gargle with it. Although its probably not a great idea. Some of the health food nuts probably disagree. The stuff i have in my basement is 35%. Gets stains out of carpet like you would not believe. Also takes enamel paint directly off of metal. You could probably drink some of the stuff and not die, but it would tear your stomach apart very quickly. Heavy water (Duterium oxide) is definitely a bad idea to drink. I have a bottle of that in the basement too. (not sure why)

Great job. Now time to do up some proper wiring assemblys with the wax coated cotton. Khozmo pot, i sure wish i could get one of those where all the positions actually work.

Should you decide you want to keep the ZD, you may consider replacing those crappy plastic power connectors with the amphenol military things. There is a size that fits the chassis holes directly. About $200 in parts plus the labor to rewire everything.

http://gilmore.chem....du/multiamp.jpg 6.1 x 3.4 inches, 233 holes buildable either super symmetry, which works out great for a gain of one, unbalanced and balanced to balanced converter buildable with john curl jc2 style feedback which works great for gain of 5 or 10 for the output amplifier buildable with the thatcorp quad bipolar input chip, or singles fets thermally glued together. also drives headphones NO PROBLEM. So a full preamp, would be 4 of these boards, plus 2 step attenuators (or balanced pots) and the input switching board. the input board. http://gilmore.chem.northwestern.edu/inputboard.jpg

I'm going to agree that some very low noise jfets are available, and there is no reason to use tubes just to say that you have a tube phono section. If you are going to use some sand, might as well use all sand, and a much lower power supply voltage.

doesn't seem to be the same multi-color thing. But close.

anyone know where to buy the hello kitty spinning light toy?

500 volts at 2ma is 1 watt, and on my board with the on board heatsinks, there is enough heatsink to limit the heat on the part, and therefore the drift. The off board versions should have even more heatsinking. The 10m90s has less voltage swing, but is more stable with respect to temperature.

If the west coast (usa) stax mafia can do it, you can too. Only 3 projects are planned for 2012. (well maybe 4)

Got the wish you were here sacd yesterday, dropped everything else to listen to it. Just amazing. Lots of stuff that was never audible now comes thru with clarity.

The idea with everything including the very stable power supply is to set the thing once after about an hour of warmup, and likely never touch it again. 10 to 20 volts of offset for electrostatics is nothing. My T2 stays at -13 volts and its just too much work to open it up and adjust it. Has not drifted in 2 years. This amp is no T2. But it is pretty close, and about 15% of the parts cost. A hybrid T2 output stage with a solid state front end is next.

Remember that O+ and O- are now flipped, so wire accordingly to maintain absolute phase. new board layout has both items fixed.

The 2ma is the target number. Anything within 10% is more than enough. The 1.2k should be just fine. If you have lots of heatsinking you can increase the third stage current. Which increases the high end frequency response a bit. I have fixed this board layout and will upload files later.

Actually 1350 ohms for those particular parts would be right on the money.

Sure enough, the feedback is flipped. Not sure how i missed that one. Easiest way to fix it is to cross the 2 x 50k resistors. Or cross the 2 x 1n914 diodes. Someone with fresh eyes needs to check this. This is for the off board heatsink boards.