kevin gilmore

Absolutely not. Stax D10 uses apex high voltage opamps and is class a/B with limited voltage swing. other amplifiers out there use class D amp driving transformers. birgir has a couple of them. they suck. If your amplifier is indeed $400 then i want to buy one NOW. Since the design is virtually identical to my design there is no reason for me to build one when i can buy yours.

that looks very close to my design. no surprise i guess.

nope, not mine but may be close. definitely want more information.

ciss of 1350pf work, yes. sound good, unlikely.

NO, the incident with the T2 was a real original T2. The fake siemens tube made on RFT equipment arcs over when you use it in the cascode position. Then it shorts out the gain tube and puts 200 volts on just about everything in the front end including the volume pot. Lots of damage. I've never tested with lower voltage rated parts. probably they will eventually blow up as the 2sk216 definitely sees about 200 volts on it.

6922 and el34 only. the pinched waist siemens tubes on ebay for stupid amounts of money are all fakes that blow up as soon as you put 75 volts on the grid.

DO NOT ROLL TUBES on a T2. Definitely do not roll fake siemens tubes as they cause the amp to blow up many expensive parts.

take them completely apart and use male xlr pins to open up the socket pins

i've noticed that anything after 8.9 will only open gerber files that it created. also has something to do with gerber vs gerber x2. gerber seems to always work. one recent file i sent to jlcpcb as x2 failed with all sorts of errors yet the gerber version of that file was fine and the resulting circuit boards were perfect.

got the second batch of transformers from SumR. Now the filament voltages are 14% too high, but transformers run cool. 7.3448 volts on the 6.3v line (zoom in) in other news the 300v regulated power supply with the appropriate fixes works great.

i have been told that the new vendors supplying to92 parts have acquired the semiconductor lines from the previous manufacturers, so they should be identical. but i have not tested this. it is certainly a pain in the ass.

1 year old lg gram laptop. upgrade took about 30 minutes. no issues. not much of a big deal unless you like windows with rounded corners.

power supplies are not supposed to go beep.

if you use a circuit board system with integrated schematic, if the schematic is right, the layout has to be right. Believe me i have found out the hard way.

there was a long explanation on this topic somewhere at diyaudio. in general N x smaller transistors is going to have less total silicon area than 1 bigger transistor at the same power dissiption which probably means less cob. edit: without the servo 70mv on the output is about right. i don't remember what the output stage bias is supposed to be, too lazy to look it up. hook up signal generator 16 ohm load and scope and you will know whether its working right or not. edit: edit: your desk is way to neat. nothing good can come from something this clean. look at pictures in the megatron thread for what your desk shoud look like.

because 4 x small transistors in parallel are faster than 1 bigger transistor. paralleling lots of transistors is still a thing on all current krell amps. if you change out the opamp to opa541 then you can boost the rails to 30v.

that one is identical sized.

bad power switch? which would be an easy fix. could also be a burned out light bulb and the amp actually works fine. or no power to the amp. voltmeter even super cheap piece of crap is very helpful.

that is the input fuse and looks ok. The other fuses are on the circuit boards the power light is hooked to the fuse on the right channel circuit board. That piece of paper is protecting something from shorting out and definitely was not stock issue. attached manual shows how to get the circuit board out. 2 screws and 11 connectors... pioneer_m22.pdf

i have the schematics if you need them. no power on light means that either of 2 of the 5 fuses have popped. If its the primary fuse, put in a new one. If its the secondary fuse, likely you have shorted output transistors. And getting parts for something that old in this covid economy is next to impossible. replacement semiconductors work but don't sound anything like the originals. And some oscillate etc... Or just replace all 5 fuses and turn it on and see what happens. You might get lucky But given its age... input fuse is 3 amp amplifier fuses, 2 each on each circuit board are 500ma all are 3ag size

no power on light? There are 5 fuses inside. You will need an ohmmeter to actually check them.

the janzen caps are definitely between stage 2 and stage 3. The orange caps are the output caps. the output is a center tapped inductor, not a transformer. B+ is 525 volts on the center of the transformer.

even the mistakes are outrageous.

Best place to measure is the scope set to AC and tied to either side of the janzen caps. the side next to the gain tubes is likely to be about +150v dc with music riding on it, probably 15 volts of peak to peak AC when volume is cranked. There should be music on both sides of both janzen caps. If there is still music on the caps when the sound disapears then the problem is the output tubes or output transformer

Tore one of the dead transformers apart. At least a little bit. There was no wiring error. 3 amp winding is .0485 inch diameter which is 17 gauge and good for 2.9 amps (2 x el34) 1.5 amp winding is .0295 inch diameter which is 21 gauge and good for 1.2 amps (1 x el34) American Wire Gauge Chart and AWG Electrical Current Load Limits table with ampacities, wire sizes, skin depth frequencies and wire breaking strength (powerstream.com) Other charts do less current. Some charts do higher current. So at a minimum, right on the absolute edge. Can’t get deep enough to measure the primary winding which might be more important. and the bergquist stuff is non-stock, lead time 26 weeks Some of the toroid companies sell covers for their transformers. I would think that as a blackbody radiator, they would help the cooling, not hurt it. But next time i will be testing without the covers on. With the transformers the amp is tipping the scales at 75 lbs. Making it really hard to work on.