livewire

It means that one needs to troubleshoot the bias part of the power supply. Depending on who built it, there should be two diodes, two capacitors and two resistors in that sub-circuit.(or not) Very easy to check if you know how to work around high voltage. If you dont, dont bother going inside it. The high voltage can kill you. That's why they put them labels on things saying "no user servicable parts inside". Also, where did you get that reading of 235 volts? The true bias voltage cannot be read from the stax jack with a regular multimeter. You will always get a lower reading depending on the meter.

Check this out. A month or more wait may be involved... http://www.pricejapan.com/front/e_good_info.php?code=1048&category=10

That's what I'm calling it. O3 + BHSE = my dream setup. If that day ever comes, I'll say "stick a fork in me, I'm done!"

For my wife, a little gift from the hospital.

Same battery I have in my Yamaha 1000. When I saw your portable rig I was was impressed by the concept, albeit somewhat bulky. Realy dig the dated "old school" CD transport.

QUOTE: Don't be tied to that wall plug and that heavy power supply! Get Mobile! Go jogging with your T2 and Stax headphones! Ha! I think that KG beat you to the draw on that one. Although he used the Stax SRM-2XX with his Omegas. Somewhere around here is a pic of a travel bag outfitted with what looks to be a motorcycle battery (gel cell?), the amp, a Sony Diskman CD player source and Stax. Got a good laugh when I saw it.

@KG - thanks for the reply, time will tell if the second iteration of the kggsshv supply works for me. In the meantime I'm all ears. @ Linear - 82 batteries, what a novel idea. That should erase any noise caused by an input trafo & bridge. Dont need them. As I stated before, I'm all ears.

That sure looks "sharp". Great way to do it. I just break out the xacto knife and "cut & gut".

So what is the benefit of that design over another one of your earlier kgsshv power supply designs? (see attached file below) I am currently using the kgsshvps2 design because it works. Is it safe to power up w/o a load? I am striving to learn the mechanics of the hybrid shunt regulator as well. (the one in the kgsshvps3 psu) Heck, if you and Linear come up with something better, I may use it. Link: http://gilmore.chem.northwestern.edu/kgsshvps2.pdf

This evening I couldnt resist trying to stabilize the voltage regulation on the +450V rail. Here again, I suspected the active battery circuit was the culprit. I disconnected the amp board load from the psu and tested the voltage. It read +450VDC, steady as a rock. I then down regulated the (+)voltage with the trim pot on the psu to match the voltage output on the negative rail and then hooked it all back to the amp load. The positive rail started to swing wildly again, it was noted the LEDs on the amp board were flickering ever so slightly. So I did the zener string battery replacement on the positive rail as well. Problem gone, although I may up the zener values in the future. Both rails are now at ~427V. So the moral of the story is: I dont like active batteries, active batteries dont like me. YMMV.

I can only guess. (because I really dont know) Possibly due to oscillation brought on by the voltage imbalance? If the attenuator was hooked up backwards, causing full gain this imbalance might be amplified / multiplied? I'll leave it to one of the amplifier Gods around here to set me straight because i am only speculating and dont have a clue or an o-scope to prove or disprove anything.

I'm done for the day. Need some coffee. I hooked everything up and flipped the switch. Yay! No fireworks or Zzzzzzzzzzt sounds this time. All eight LEDs on both amp boards light up, although the LED's on both third stage current sources started blinking. This is the stage with the LED between the two 2sc1968 transistors. (see amplifier pdf attached below) The blinking started to speed up and I thought o_O! Something's gonna blow! So I shut it down and unhooked the left channel. I figured I would save one good amp board at this point if something goes south with the right channel under power / test. I fired it up a second time with just the right channel. Same M-O. Shut it down and unhooked the input attenuator. Switched back on for a third time and no more blinky-blinky. So I need to look at how the volume control is wired to the input. With the LEDs now glowing stable, I was able to do some probing. I noted some voltage fluctuation and imbalance between +/- 450V rails. I need to get that under control before doing any biasing of the amp board pots. Under load, the +450V rail is flailing around at 445V to 480V. The -450V rail (with the kludged zener V-ref string) is stable but sitting at 437V unloaded and at 427V under load. Almooooooooost there! I was hoping to hear music through it today. With work in the way, I wont be able to continue putzing around with it until next Monday. kgsshvproduction-final amp.pdf

Yeah, they are almost as rare as hen's teeth. The prices for those on ebay is becoming atrocious. Wont be long before fake ones hit the market, if they haven't already.

Well shiver me timbers, those are some good prices!

Good idea, I havent gone that route because that part was specified by KG in the BOM/schematic, I'm not inclined to research substitutes unless it is absolutely necessary. I had already replaced the 2sc3381 the last two times when I accidentally shorted the power supply. I think the one that's in there now is ok. As far as cost or scarcity is concerned, no biggie. Bdent has them in stock for ~$8 each. They are also on ebay for around ten or fifteen dollars each. The last time i bought a few extras.

Hmmmm. Just found a couple of fried resistors in the battery circuit. Both of the metal film 100 ohm jobs. No visual damage. They are not open either. One now reads 275K ohms, the other 5meg ohms. I thought that I had checked them before when I previously replaced the 2sc3381 sand. Guess not. They have one lead lifted now (desoldered), they would not test correctly for resistance while in the battery circuit due to the output capacitors interfering with the ohms reading, or some such thing.

I'm back in the hunt, the negative volts are a flowin. The zener V-ref string did the job. So, el problemo is somewhere in the battery circuit. Will order more sand for it from Bdent and ebay. Previously, I had replaced the 2sc3381 sand, but not the 2sa1486. Those checked out ok using a "double diode static test" on my ohmmeter. Due to my ignorance, i wasnt able to check them for voltage under power the last time other than doing a comparo with the positive rail. They didnt match too well. I wasnt able to pinpoint it otherwise, then "ZAP". Well you know that story. Time to button this thing up. (or is it time for "Chapter 2"?) The two amp boards are still an unknown quantity. I did power them up once in the distant past, all the LEDs lit. Still need to test for output, do the zero bias, then connect up the stats.

I'll pass. Seriously your Neko D100 rocks! I can't listen to mine enough with my Stax setup. It far surpasses my three other previous DAC's. I'll be bringing it to a small local meet next month to spread the word.

Thanks for posting your DIY trials and tribulations guys. Now I dont feel so bad. Spritzer I hope you get it sorted soon.

<<cough!>> I like the japanese pre-order price better. ~$4100

Hi Tim, My efforts have been made possible by the owner of this thread, Doctor Gilmore. Yes, mine is the first prototype as far as I know. "Working prototype"? No, not yet. I have a ways to go. There are at least two others that I know of who are building the KGSSHV at the moment. They have not been posting much here, so I am not aware of their progress.

Ok, after studying other similar power supply designs, in order to continue with psu troubleshooting, I think that a viable workaround has been found. Im gonna remove (for now) the 2sc4686a sand and the battery sub-circuit in the negative rail and replace it with a zener diode string. (150v-150v-150v) Hello (again) Mouser! Will update in a week or two...