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About gepardcv

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  1. @P3t4: The board and schematic archives are in a transitional period right now (read the stax mafia circuit boards thread). If you're after the solid-state Carbon, I think this post has links to the schematics of the Carbon amp and the GRHV power supply. As for boards, you can get your own made (links to recent Gerbers should be floating around here somewhere), or buy from someone who has extras. It'll help to review this entire thread, as I think it covers every tricky point of the build. Other things to read, and think about: The original KGSSHV thread has great info on the basics of building an electrostatic amp. It's old and long, but well worth reading. A few more basics are covered in the old DIY electrostatic amp thread. If you decide to build an off-board heatsink design (like all Carbon variants), I hope you have access to at least a drill press. A full metal shop would be better. Depending on your experience with building high voltage circuits, starting with something non-electrostatic — like a Dynalo with GRLV — might be a good idea.
  2. This is terrific work. I wonder if I have the SMT skills to stuff a board like that. 🙃 Could you explain the heat sinking story here? I always made sure to attach GRLV's MJW21194 and 93 to an external sink or at least the chassis. Doesn't seem like you're doing that here. Is the expected dissipation need really low? Same question about all devices needing a sink on the HV side. Run them to a sink with wires, as Kevin suggested?
  3. Boards came in today. They look great. Thanks again for the GB!
  4. Shipping fees sent. Thanks!
  5. Forndom — Flykt
  6. No, both amps are fully powered up all the time. Which definitely contributes to potential heat problems, though the Dynalo (and honestly all three GRLVs) run quite cool. It does seem likely that a bias device has failed, because the bias across an entire bank of output devices (not sure if the + or - side) drops. Wish there was an easy(ish) way to figure out which one, though, to minimize desoldering and part replacement. At least I hope it wasn't an output device. I matched those fairly carefully, and don't have (matched) extras lying around.
  7. Yes, this is the combined build. The Dynalo side works fine, as does the other Dynahi channel. I checked the PSUs, they all seem to put out the right rail voltages consistently. I've not tried to get it to happen on a cold start with the lid off, but it happens fairly consistently with the lid on. It's definitely a packed case with non-ideal airflow, but the heatsinks are pretty huge and the case feels cooler to the touch than my on-board heatsink KGSSHV. I don't have the right kind of grabbers, but I could order some and figure out a way to run a few wires out through the top vents. What do you think might be happening?
  8. I tried several Schiit amps, both at home and at shows, and most had something unpleasant going on. Most run crazy hot to the touch (not at all surprised the Jotunheim cooked itself), some have awfully scratchy and noisy volume controls, and some have appalling noise floors (with the Valhalla I heard with an HD800, the hiss drowned out the music). I've always been surprised that they come so highly recommended. But the DACs always seemed pretty decent. What's objectionable about the Yggy? (I don't have one, so not defending it. Just curious.)
  9. My Dynahi developed a problem on one channel: the offset jumps intermittently. It looks like the outer 8 output devices' bias drops from the ~0.40V I set it down to ~0.30V or lower. This causes noise, and, when the offset becomes sufficiently high, triggers the protection circuit and cuts off sound. The corresponding LED dims. The amp worked for weeks with no trouble, and developed this symptom a few days ago. The first time I opened it, the problem went away completely, and I suspected overheating. But it now occurs even after a cold start. Any tips on how to diagnose this problem?
  10. I use this for all my builds: Schaffner FN1394-10-05-11 (out of stock at Mouser at the moment but available from other stores). It's a bit bulky, but has everything I want: solid switch, two-fuse holder, voltage selector (just flip the fuse drawer), and quick-connect terminals (five: one safety earth and two per primary winding). The wiring diagram is printed right on the unit and easy to follow.
  11. @s_r: When you say no extra noise, do you mean that your T2 finally has a noise floor you're satisfied with?
  12. The 2SC1815 seems to be available from Digi-Key: But if that's not the right part, I'll gladly take a pair.
  13. That's unusual. Did you buy a ton of content from sellers like HDTracks and NativeDSD? Ripped your own from SACDs?
  14. I had the opportunity to try a Utopia this past weekend, running out of my Susy Dynalo and Dynahi, and I agree with @Jim L. I didn't try to compare it with the 009 side-by-side, but, from memory, they sounded similar. I also found the Utopia surprisingly uncomfortable, putting a lot of pressure on one thin band on the top of my head. Made me lose interest fairly quickly. As far as the sound of bright-leaning headphones goes, I'd be curious to compare the SR-009, the Utopia, and the HD800 with and without the SDR mod.
  15. Paid. Thank you!