kevin gilmore

great build job

go ahead and try other compatible tubes. whats the worst that can happen, fried tubes or blown parts. i have tried kt88, 6550 and 6l6, all end up the same way with G3 toasted.

yes you can do this, you need adjustable cathode tail resistors. basically the same as srm007t2 board is going to get a bunch bigger

because that is how jiml gets away with half the amount of parts. for the srx circuit it works because a low impedance ground is not necessary. i myself would not do this, i would do the usual 2 supplies tied together. It only took me about 1 hour to do that layout, so no biggie.

the all dht version is $18k or so in parts. you want the best thing there is, the ggdht (which i just posted) is as close as you are going to get for <$10k here is the thing, the gain of this amp, and there are only 2 other ways to do the filament, both have problems with the high gain. 1) hum pot between the 2 filament wires, the center of the pot is the cathode. This limits the voltage gain of the output stage a bit. 2) high frequency center tapped transformer, 40khz minimum (seriously, everything else sucks) and then there is still hum, but you can't hear it. this is the problem with using DHT's in a dc coupled electrostatic design. Also why 300B's are absolutely the wrong thing for the job. http://www.emissionlabs.com/Articles/APP-NOTES/AN6-Center-tap/center-tapped-index.htm

all those parts can be mounted on the other side. latest version of the board has silkscreens both sides for the pots

20B-v4 really is the only candidate that i know of that does both 800v and has a center tapped filament. Even if you run DC for the heaters, and then you need 4 of those boards.

nope, that is a different board. with the fets replaced with bipolar. practically they are almost identical.

here is something for you people to play with. emission labs 20b-x4 tube in the kgsshv-carbon-tube is a direct plugin. just cut the filament lines tying the 2 tubes together, there are already 2 connectors, one for each tube. 4 tubes about $2100. solves the center tap filament issue.

Pictures of the amp over there, 4 X 300b and a very large internal heatsink. who knows what the fuck is in there, transformers, current sources, given the lack of quality on the previous hifiman solid state amp, an overpriced piece of crap for sure. for the longest time I thought that a all dht fully direct coupled amp with an $18k parts cost was so out of line that no one would ever build it. Now we have 2 companies trying to sell $40k+ amp and headphone systems. stupidass

multi frequency ring a ding ding

anything that forces the bias voltage above 600v is going to damage the headhpones. So a fet that is shorted Drain to Source, or a tube that is shorted plate to cathode. or massive amounts of negative dc on the input.

tyll tested the korean version i think.

Actually it's ok for tube amps without a delay because the positive turn on bump subtracts from the bias

Winer project? drinking 1994 BV George's de latour now. left over from last night. Yumm

About 300 ohms is the right number, don't know if that's total or just the tail resistor. Less ohms in the pot and most in the resistor is what we are aiming for. zener needs to change to 18v

updated picture, everything is there. need something for C- supply board is 8.9 x 5.05 need to find hole sizes for the big caps

take a look at the picture which I just updated

I moved a whole bunch of parts

I have nothing to do for the next couple of days, so I could do the board. the one pass fet is not available at mouser, so something different is needed, need sizes of the caps and how much power (i.e. on board heatsinks, or aluminum bracket) etc

2sc5171 not recommended for new designs, which means soon to be discontinued. different pinout than the layout, it could make another layout if people are interested. Or you mount it upside down which is possible. 500 piece minimum from digikey, non-stocked at mouser. adjustable bias, current sources at the top

16 watts per channel for the 10m90s plus another 10 watts for each power supply

same as carbon makes it easy to fit in the box

those diyclub attenuators are the same one Mikhail used. They work fine. Physically pretty gigantic.

the 2sj79 and 2sk216 are 200v parts, the ksa1220a/ksc2690a parts are 160 volts. would probably work if you are careful.