kevin gilmore

nice.

This is the headphone version of beveridge. 1350 volts bias, probably a couple hundred volts of music, single stator.

so the 2 piece version will be capacitor coupled output, the 4 piece version will be dc coupled output, the newest version of cast and cascode fet buffer. for balanced you will need 8 pieces. i'm sure a version of this is coming. as far as I know, no dsd but it should be capable of that. pricing is finally rational

can't use lt1021-5 in 2 wire mode.

10V reference on 13.5 v leaves only 3.5 v on the current source. not sure that would give the lowest noise. but you would have to try it

if either marc or nate decide not to, I would be interested in one of them just to mess with.

current mirrors used as voltage gain stages is very different from high power versions used as output stage. as far as I know bakoon is one of the very few that make transconductance headphone amps. It really works well only with very flat impedance headphones like ortho's.

for sure the audio-gd is NOT a transconductance amp. I have one. diamond buffer output. and If the bakoon is bridgeable for double the power then it cannot be a transconductance amp.

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