kevin gilmore

the first thing that happens is that all inputs get converted to balanced. So to use the thing as single ended you would need a bunch of dual rca to xlr adapters, and you have to jumper across the input amp, then it actually would work. The tape out would be unbuffered this way. I do have the cardas stacked rca jacks in house, so i could do a single ended board.

http://gilmore.chem.northwestern.edu/inputboard5.jpg the pass thru is much more easily done in software given the posibility of unbalanced input, balanced output. maybe a completely single ended version in the future.

I put in a bid on ebay, i'm sure i'll be overbid soon. I really hate ebay for this kind of stuff. I'll contact the other place on monday.

Finding the snakewood turning out to be very hard. I need at minimum a 2 inch cube. But 2 x 2 x 5 or better desired. If anyone finds anything interesting of an appropriate size, please email me the link to purchase. Air dried and no cracks... Also trying to find some merchaum and not having any luck there. I have found nice pieces of zebra wood and bocote...

lil-knight has the board files now, we are going to do a prototype board run to make sure everything is perfect. Same thing with the black hole.

cocobolo is also on the list. practically due to the setup time on the lathe, it makes much more sense to do 5 or so at a time, it goes so much quicker that way. Cut 5 on the band saw, live center and spin plate on the lathe, then step collet gripper for inside hole, then boring bar, then do up the aluminum pieces. Assemble, then micromachine. doing a marble one requires diamond tools, probably not ready to do that at the moment.

http://gilmore.chem.northwestern.edu/ebony9.jpg The "Knob of Voltron" is done and ready to ship. (the ebony one) I kind of like the rosewod one for now. Trying to find a decent size piece of snakewood.

We will soon find out how well the ebony knob tolerates the heat. Clearly the titanium knob and the aluminum knobs don't care. Machining corian turns out to be really miserable, dulls even carbide bits real quick. Which is one of the many reasons that wilson speakers cost so much. I did some corian stuff a while back, not going to do that again. I think i have a line on a piece of wooly mammoth ivory that is big enough to make a knob out of. I refuse to buy black market ivory for the obvious reasons. I think i can do marble... Lets find out. Voltron's knob should be done tomorrow when i have some more time. Then i have to find a suitable wood presentation box for it. Afterall you have to have a box to put your knob in

i'm beginning to hate ebony. http://gilmore.chem.....edu/ebony8.jpg tried a different direction for the 3rd ebony knob, broke after machining, and had 2 cracks by the time i got it home. The other one is perfect, so unless i screw it up, senior voltron will get his knob. I'm also really liking the rosewood knob.

There is a shortage of all sorts of transistors these days, and the floods in taiwan probably influence this very little, who knows. Its a massive pain in the ass to source parts these days.

i'm already using 8 bits for the relays, so the direct option is not going to happen via hardware. Via software its easy, just pick the input, set the attenuator for no resulting gain...

need to check over the board one more time, then its probably ready to be made. I was spending more time on the black hole

all the capacitors are 100 volt rated. possible output transistors sets usable at full voltage (really, don't do this +/-40V is already more than overkill) alf16n20w/alf16p20w 2sk1058/2sj162 BUZ901/BUZ906 2sk1529/2sj200 MN2488/MP1620 MJH11020/MJH11019

sillyness continues http://gilmore.chem.northwestern.edu/blackhole3.jpg now compatible with both kinds of fet layout GDS and GSD also usable with darlington bipolars and either lme49830 or lme49810

current version with the dual power supplies, i still think its a bit silly. Virtually 100% ground plane. http://gilmore.chem.northwestern.edu/blackhole2.jpg

For safety on a metal box, the chassis should be connected to earth ground thru the 3 pin IEC outlet. If its an all wood box, then this does not apply. Just make sure all the grounds get connected. input connectors, power supply and amplifier boards.

I did eventually decide on the ohmite heatsinks, some are on their way to me. Board size increased a bit to 3.6 x 3.6 inches. the idea of multiple power supplies is something i'll think of, not so hard to do, but really i'm doing this for a headphone amp, and don't need to run the thing at silly voltages and powers. (not the same heatsinks that the wire uses) The alfet parts sound so much better than the irf parts...

in the theme of new office... http://gilmore.chem....du/dsc_2376.jpg finally cleaned up a bit, new computer, moved the printer off the desk, now room for 2 monitors, one for schematics, one for the board layout. old computer to the far right, will probably stuff with new hard drives and load 2008server on it. birgir's next care package on the desk shelf ready to be shipped out monday.

OK, so blubliss has proven that a person with absolutely no experience can build a T2 as his first electronic project ever, and get it to work without killing himself. He did however have the patience (cough cough) and read enough so that he knew what he needed to do. He also had help from a friend, and another friend in high places. The kgsshv is WAY easier to do. I had a chance to look at my notebook, because when i built my 2nd kgsshv i wrote down how long i spent on various things. I stuffed both amp boards at the same time and the total time to stuff and solder the 2 boards was 6 hours. The power supply board took an additional 3 hours. I'm sure that justin can do it in half that amount of time, but most people are likely to spend twice as much time as i did. Checking all parts before you stuff and solder them in is pretty much required unless you want to spend more time fixing it than you did building it. I've seen mislabeled resistors before, and dead transistors out of the box. The $40 transistor tester is a great idea for this, and a decent 4.5 digit DVM is also necessary. Still, there are lots of ways you can get hurt if you don't pay attention. The chassis work and wiring also takes a bit of time especially if you don't have the right tools.

you missed the slight roughness and color change bit.

Yes i saved the ebony scraps just for that purpose. But i consider that cheating. Was planning on fililng the hole that way. On the other hand its a thing of beauty as is. Very little wood is absolutely perfect. Same thing the red mallee knob. A slight roughness and color change is in the red mallee too. I have more ebony to work with, for now

unfortunately there is a lot of wasted wood to make circles. Plus i want to make a couple in the other grain direction. I can always find another piece of wood, shouldn't take more than another year. Nice try steve. You can make these yourself anyway.

I have enough wood for 5 more. Should have the 2nd one done tuesday or wednesday.

micromachining revealed cracks and roughness, will have to machine up more wood. http://gilmore.chem.northwestern.edu/ebony5.jpg http://gilmore.chem.northwestern.edu/ebony6.jpg http://gilmore.chem.northwestern.edu/ebony7.jpg

I have a 7 lb chunk of pure berryllium in my drawer at work that i was thinking of turning into a knob. I have already been told that i will not be allowed to use the machines at work to do this. And i'm not stupid enough to try this on my lathe at home. Berryllium not so bad. Berryllium Oxide, very VERY bad. I also have about 25 lbs of mercury, not sure what to do with that either. Maybe waterford crystal knob filled with mercury might be neat. There are a number of kinds of stainless steel. The screws i have are non-magnetic. All my NMR magnets are made of non-magnetic stainless. I do remember the NS100's. Good speakers, a little bright. Very yamaha sound.