kevin gilmore

this is already very similar to the grlv. missing the double noise inverting current source, but that is about it. ic2 is an optional and higher quality alternate reference.

these headphones stopped by in Chicago on their way to Iceland, I listened for a couple of hours. My initial comments was that they were very sterile, but really I think it was the complete lack of imaging that is the problem. removing the foam probably fixed a bunch of that. The stax plug is a major fuckup. And I don't see why. Everyone else including stax,hifiman,kingsound,chinsettawong,birgir and Justin are capable of making plugs that are the right dimensions, no reason why this has to be a piece of crap. Yes they are about 6db less efficient. And the case is some kind stupid. I did not measure the capacitance of the cable, but i'm going to bet that its twice that of the stax made cables. birgir will hopefully do that. Next up the monoprice things once they actually start shipping.

Mismatched very high cacitance vishay siliconix output mosfets. And ground splitter. Otherwise identical current feedback amplifier same as liquid gold,liquid carbon,Cth, liquid platinum etc. at least it's better assembled than schiit.

that was ray's darkstar amp. the blackhole is something different. the blackhole uses a national semiconductor driver chip lme49830 and a pair of alf16P/alf16N semisouth fets for the outputs. You can probably substitute something else for those parts, including bipolars, as the board has options for that too, but I never tested that way. the darkstar sounds absolutely miserable, and these days has stupidly large voltage swings guaranteed to set just about anything on fire. the blackhole is suitable as a small speaker amp.

The company that made the output transistors went out of business

The problem with the D10 is that the power supply voltages are +/-175v so it clips pretty easy into standard sized headphones. The shure is very nice but power supply voltages are +/-200. Which works great on the supplied earbuds but would have trouble with standard sized headphones.

something screams kingsound to me for both the amp and the headphones. built in battery pack, usb charging, 1/8 input jack.

does not look like a stax plug to me, it has a shield around it. definitely really cheap for headphones and amplifier.

guess you did not look at the schematics. i'm talking about the current sources at the top of the gain stage before the output stage. main difference between 717 and 727 was 2sa1968 current sources (and local vs global feedback) srm353, T8000,D50 are back to being all resistors. and the german copy of the srm323 also uses resistors because of the 400v power supplies.

The 323 had a p-channel jfet as the input, +/-350v power supplies, 2sa1968 as the current source for the drivers etc. The 353 is a srm717 with all of the extra transistors removed. Very similar to kgss. D50 is identical to 353 running at slightly lower power and lower voltage. Current source is resistors on both. T8000 also uses resistors for the current source. seems that stax has run out of 2sa1968. d10 uses apex opamps with a power supply of +/-175, not great for large voltage swings. stax may be forced into using parts in the future that it does not want to use for some reason.

probably not worth making a balanced version, the output impedance is not super low.

sure

Mikhail rebuilt an original with black gates. Probably not possible these days. A few were the wrong voltage.

in theory with appropriate adapters or the right circuit board layout it would work. Lots more filament power. Lots more heat.

Yep that is the idea

should be possible to put the input tubes in the middle of the board, then left and right versions of the board will not be necessary

i'm think there is something wrong with the frame. you can keep putting bearings in, but they will continue to die.

at 1kv, into cold tubes when the turn on delay is not working, yep lots of plasma that said, the T2 (both of them) can eat input tubes real easily especially when you put fake siemens tubes in there

switching half the lines is not the main problem. the main problem is that dc on the input with an unbalanced input will generate differential dc on the output which the epsilon 12 will not detect.

I made them as gerber version 2, that is what everyone seems to want to use these days. no idea which polygon or layer... here it is as rs274x staxt2powershrunk - CADCAM.ZIP

measure the bias wire from stax jack to stax jack. Had better be 10 meg (5M x 2). Anything else and the thing is not good for the headphones.

Justin and birgir sell stax sockets.

On the t2 and diyt2 the front end tube filaments are referenced to ground with resistors

8.7sp3 I have 8.8sp0 but many things have changed and its not backward compatible, so have not installed it yet.

definitely. ratsnest mode in proteus. makes things much easier when you have to make changes to something that works.