kevin gilmore

at some point soon I will be posting in x2 format, so some gerber viewers might not like that.

for 12V you might want to go with the 7 volt version of the reference and recalculate the resistors. And probably lower the 9.1v zener to 7V I have not tested any of this. 15V should be fine with the standard parts

from the 280 watts total power consumption and 24 watts going into the 300b filaments and another 12 watts going into the 6sn7 filaments the maximum going into the plate and plate resistor would be about 55 watts. so 20 watts into the tube and 20 watts into the plate resistor seems possible. that would be 80 watts going into that heatsink, it is going to get extremely hot. likely 10 watts into the tube and 10 watts into the plate resistor. Notice the trimpot thing on the back for dc control, so definitely no self bias. And big capacitors between the front end gain stage and the grids of the output tubes. Still going to drift like crazy, and most of the gain is likely the input transformer. or there is some solid state inside, unlikely. Or interstage transformers. Definitely worse than Mikhail's attempts. And looking at the tube data sheet, extrapolating for -100 grid bias the distortion is going to be over 5% with no extra gain for feedback. Definitely euphonic

output transformers hifiman has in the past, and continues to make unreliable stuff. if the 300b amp really is direct coupled, he is going to have trouble getting more than 600 vppss without significant amounts of distortion

does the original T2 qualify as overpowering? because it runs on +500 and -550v and has more voltage swing than a bhse or any other electrostatic amp, diy or commercial. only exception is the koss esp950 which is designed for its own headphones. And i guess the original jeklin transformer box. now if you have a cavalli piece of shit with no output protection, or a transformer box, then yep you can and will do damage.

goldenreference6d posted, 2 x output power connectors. one should be the short variety, and the other one the taller one, or the angled one. board is now 3.95 x 4.32 inches its better to not use the pots and resistors, it probably increases the tempco. if you hand select the feedback resistors, or buy .1% parts its a better idea.

my guess is that the transient part is all discrete, and very similar to the soekris with fewer bits. and like the soekris, opamps to do the se to balanced, and more opamps to do the filter. there are no off the shelf 24 bit dac chips. if there was, things would be much easier regardless of their price

file server down till sometime tomorrow when the electricity comes back

not without making the board a bit bigger, its just about as small as I could get it

10k input resistor to ground, or relatively low impedance pot required, will up date board in a bit.

here is the soekris output section http://gilmore.chem.northwestern.edu/dac.pdf notice that the top set of switches is wired to +4 and ground, and the bottom set is wired ground and -4v (this is how you get sign/magnitude without any dc on the output. each audio-gd board is half (less than half) of a soekris single output. how you put two boards together to get rid of the dc is unclear. I see no way to wire one set of switches to ground and -vcc. soekris is sign/magnitude, audio-gd in single board form is definitely 2's complement switches look the same soekris does dsd by using just the 3 segment bits

goodies from the iceland

zsa zsa gabor died at 99 years old. rip

looks like a standard Hammond case to me and no pictures of the insides available. Stay away.

don't I know it. in 10 years I doubt we will be able to continue to run 9 nmr magnets, 3 mri, and 5 ft's, plus all those low temperature epr experiments. luckily I will be retiring in 2.5 years or less there are 400mhz superconducting liquid nitrogen magnets, but those are toys.

I pay $45 a gallon for liquid helium I get back $16 a gallon for the equivalent gas generated from a gallon of liquid helium The new liquefier we bought to recycle the recovered helium gas was $500k which did not include the raw gas compressor ($130k) the storage bag ($15k) and the storage torpedo's which are still in use from world war 2, and $20k for a 2000 liter storage dewar. To continue to get government grants we are required to recycle helium.

actually my price for a gallon of liquid N2 is $1.60 a gallon of milk is about $4

left 3 top and bottom blue resistors are the segment bits 5.11k 02C resistors and all the other blue ones in that row are 10.2k 69B resistors and the other blue ones in that row are 5.11k 130 is 13 ohms top switches v- = ground bottom switches vcc=ground

No schematic for the power supply that Kerry did. Unless he has it.

the cavalli liquid helium definitely sounds a lot like daffy duck.

note: liquid hydrogen is stupidly dangerous. besides which you are unlikely to get anyone to sell it to you. liquid nitrogen is better, and very cheap. been there, done that many times, no difference can be detected. cryo'd cables,cd's,tubes, flowers,bananas... liquid helium is even colder, and very expensive

that picture is not the holo dac. its something else. the holo dac has only a few caps.

actually the MIT cables are more than a resistor to ground. There is all that hot-glue. Dripping piles of hot-glue. And a couple of very small value caps. the guy at double-helix cables clearly has absolutely no understanding of electrostatic anything. Unlikely to have ever opened a quad56 or quad63 because if he had he would know that there is a reason why the wires are so thick. and so goes with his fancy silver wire in a high capacitance dielectric. Go to his website and count how many turns on the braiding and figure that the capacitance of his cable would be at least 3 times that of a stax cable. and then the BS about not plating the silver with gold because gold "slows down the signal" and yet all his connectors are cheap gold plated crap. etc. No one should help idiots like this mess up other peoples stuff.

not high enough resolution to see what is going on. like whether its sign magnitude etc. and the power supply box obviously does not have enough capacitors. This is overly goofy. Especially if one cap shorts out, repair could be just about impossible.

that one might be really good, real and matched cmos switches instead of digital outputs. But its pcm only, the cmos switches are not fast enough for dsd