kevin gilmore

max williams should be joining us soon. His entire thing was 3 pages of code. And one entire page of the code is to control the preamp inputs (of which there aren't any in the volume control only version) and to flip the MSB and LSB because he got the bits upside down. How someone else can turn this into 10k+ lines of code, i just cannot fathom Now as to morse code, we can certainly do that as long as you have 2 keys. One for clock and the other for data.

There will be multiple versions of things that can control this, from the simple to the very silly. Pretty sure this is 100% code compatible with the linuxworks stuff should he choose to ever release it. Standalone single chip arduino based thing with rotary optical encoder being worked on soon. 4dsystems thing being worked on also. (see picture previously posted, rest of parts to develop the software inbound) latest version here http://gilmore.chem.northwestern.edu/attenuatorsmt9.pdf all signal traces exactly matched for length and differential time distortion no more than about 50 femtoseconds. (Seriously) And mainly due to the slight differences in the internal ground planes. For the massively insane i have a 6 layer version which is absolutely and perfectly matched for capacitance too. This version should probably be made with multilayer arlon or similar material.

Yep i have one of those. Needed when i changed out my water heater. Not enough whoopie out of a propane torch to sucessfully solder the copper fittings. Almost as good as an oxy/accetyline torch without the required large cylinders. Have a small hydrogen torch for some specialty work

I was commenting on the heat from the power supply. Clearly the current sources and the tubes get hotter at higher voltages. The power supply heatsinks are slightly undersized and might be able to be replaced with the 2.5 inch versions. The current sources have plenty of heatsink. Most of the tube inside the chassis definitely raises the inside temperature a bunch.

Actually in this case if the unregulated primaries are where they should be (about 440 vdc under load) then running the outputs at +/-350 actually causes the pass fet to dissipate more power than if it was running at +/-400. Reason is that most of the power goes into the output tubes which are driven from a constant current source that will change very little between 350 and 400 volts. Suggest you measure the unregulated B+ under load to see if you can swap out the zeners for the higher voltage. Running the power supply unregulated is not really a good thing. BH and BHSE amplifiers were designed to run on +/-400 volts. T2 runs on +/-500 volts. kgsshv can run on 450 volts, or 500 volts.

i'm pretty sure i can do a 1206 inside the 2512 package, will look later. Compensation caps really not necesssary, the uln chips are just transistors anyway, and really don't need them, and for the other chips, its very close to the electrolytic anyway. May be able to add a cap on the bottom.

Ti has a lot to say about this. The dac i'm currently testing has between 30mv and 80mv of dc on each of the outputs depending on temperature. Ti says that the common mode servo needs to be extremely fast. My bench testing completely disagrees with this statement. balanced dynahi and balanced dynafet have a slow common mode servo. Further facts, if you are balanced in ONLY, and balanced out ONLY, then any common mode DC is meaningless anyway. You should further pay attention to things that are bridged amps (like 4 channel B22) and fully differential balanced amps (like B24). dynahi and dynafet orignal versions can be 4 channel, newest ones are differential balanced. The issue is whether or not the input has a common ground or not.

relay pads are 1.2 x 2.2 mm as specified by omron... what size do you want? edit: i'm thinking that programming this is gonna be very easy http://gilmore.chem.northwestern.edu/touchpanel.jpg

yep, on the back. look at the pdf file. updated picture http://gilmore.chem.northwestern.edu/attenuator5.jpg

depends on how good you are and if you buy the tacking glue. I can assemble it. I DON'T really want to assemble it.

Alrighty then, now an even bigger headache http://gilmore.chem.northwestern.edu/attenuator4.jpg just barely room for the 4 mounting holes, unless i make it bigger can't put mounting holes by the digital stuff. No room for on board 3.3V regulator. someone check for accuracy, the individual layers http://gilmore.chem.northwestern.edu/attenuatorsmt5.pdf Board is exactly 5 inches x 2 inches and 124 holes. 50 boards are $11.28 each plus $200 tooling charge from pcbnet.com So about $15.28 plus shipping, someone else should do this so as to avoid the 11% illinois state and local taxes. I could change the digital connector to a 10 pin ribbon with each pin doubled up. I'm pretty sure this will in fact fit into the T2. Need simplified single pot thing like the twisted pear to control it for this application. This exercise is left to the viewer.

pretty good guess. This is exactly 5 inches x 2 inches x 4 layers. not done yet, but the rest should be easy. My eyes hurt. Ground planes both sides. All audio in and out on the one side. http://gilmore.chem.northwestern.edu/attensmt4.jpg

latest http://gilmore.chem.northwestern.edu/attensmt3.jpg now what i could do is have 4 relays in series then flip the other 4 relays to the back of the board. That way the inputs and outputs are on the same side. It would absolutely have to be a 4 layer board. Not such a bad thing.

edit: http://gilmore.chem.northwestern.edu/attensmt2.jpg 5.7 x 2.6 inches, just this part. I would think that very few would be able to hand assemble this.

Yep, down on your side of the pond. 4dsystems lcd touchpanel with cpu http://www.4dsystems.com.au/prod.php?id=148 i have one now, and it works absolutely great. add an arduino and the network stack board and program the thing from an ipod.

Not going to happen. Managed to take .5 inch by getting the relays as close together as possible. All the other relays are the same exact physical size whether they are surface mount or not. Each relay is 20mm width. I doubt i can rotate the relays, but will see. If i rotate the relays, by the time i locate the resistors, there would be virtually no benefit. here you go on the tightest fit i can get. http://gilmore.chem.northwestern.edu/attenuator3.jpg

should be room for the 3 volt regulator, one of the high frequency murata switchers. Then up the 5V to 12V. I can get the board slightly smaller, and will look into the other relays.

Not going to do the cmos switches thing. Measured them too many times, low level distortions i don't like. Nelson had a better idea, but those parts seem impossible to find too. Board is going to have to be re-designed. The 4PDT relays for switching the balanced inputs are discontinued. Attenuator board now available in the attenuator board thread.

I'll answer the sonic differences in about another month. I have one of each built up. Really the differences are very minor. For those smart people like me who have accumulated a lifetime supply of 2sa1968's its no big deal. The little to220 clip is probably going to push the size out just enough that it won't work.

Like i don't have enough projects going on at once I'm tired of waiting for someone to release boards that do this right. so here is mine in progress http://gilmore.chem.northwestern.edu/attenuator2.jpg Because i don't like any standing power on the relays, and i don't like the resistive drive either, this had to be a bit bigger. board is 3.4 x 10 inches. stereo single board, or two for balanced.

For the ixys part, the 4171g is required which is .07 thick The to220's are .1780 thick. So the absolute minimum standoff height should be .250 inch. But i would go .375 inch. edit: they lie. the .07 is actually .0780 which would make the minimum spacer distance .2560 So the .375 is exactly the board to heatsink spacer needed.

There are holes in the board to stick a screwdriver in. i may have to make them bigger. I figure the size of a hex head #4-40 should do it. About .2 inch. look here... http://www.amb.org/audio/beta22/ off board heatsinks, bottom mount. edit: like this http://gilmore.chem.northwestern.edu/kgsshvampv7.jpg now with .2 inch holes for hexhead screws.

justin pointed out that the transistors are at the top of the heatsink, but you also could just turn the board upside down. I don't have any decent thermal analysis software, but if you figure on about 18 watts of heat, the temperature differential (as measured on my T2) from the bottom of the heatsink to the top of the heatsink is only about .3 degrees C. (and the T2 is more power) Nothing to worry about. But still, i'm going to try and calculate by hand what the differential would be on a 3U size heatsink. I've seen ayre's and firstwatts with the transistors at the top... krell with top and bottom, B24 with top and bottom... I'm making all of the board files available. If people want to make multiple board runs of the multiple different versions, that is certainly OK. I of course will have at least one of each. But i can do my own chassis so for me its easy. What we need is some company like front panel express that can take standard heatsinks and drill and tap holes...

Yes, but the top and bottom bracket on the heatsink might get in the way of the transistors. Need much better real picture.

I took care of the high voltage fets instead of the 2sa1968's this way http://gilmore.chem.northwestern.edu/kgsshvampv7.jpg The ixtp parts are not isolated, you would need the ceramic insulator. From justin's measurements, the inside finger to inside finger is 4.740 and the board is now 4.570. The transistors are inset by an additional .20 so everything would fit perfect. (the ceramic insulator might be a tight fit?? will check) Its very hard to tell from their lousy dxf drawings but i think it would fit this case too http://www.modushop.biz/ecommerce/cat079_l2.php?n=1 edit: found a way to get both current sources on the board. edit: board reduced in size, that is about it.