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Helium

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Everything posted by Helium

  1. It might be transistors are heating THAT340 thru copper layers. Are they soldered directy to board, or plugged in sockets?
  2. @Laowei: Just curious, what GG board file are you using? What I'm looking at has slightly different traces layout (was posted 20160224). Can you check yours if its newer?
  3. Yep I'm working for Japanese company, and my eyes got used to seeing that)) whoever edited the file has OS with japanese language pack installed.
  4. Ok, I checked BOM and availability of parts here and there and it seems feasible to build but at enourmous price, almost prohibitive for own use. I guess ttl quantity of listed obsolete parts in whole universe is enough to build 10 units more of this thing. Maybe 15 (provided they are not 'wasted' for other projects). Then they will be depleted forever. I may be missing somehow but last year you mentioned: ===== diy-t2 with current production parts testing now obsolete fets 2sj79/2sk216 replaced with ksa1220/ksc2690 and 2sa1486 replaced with stn9360 ===== How about the progress? I guess board have to be redesigned to accomodate new parts.
  5. Kevin, could you please upload the latest BOM (both amp and ps) of DIY T2? Could not find it anywhere.
  6. I think he needs to try another opamp instead of opa445. Maybe DC must be decreased temporarily for another lower voltage opamp, but worth to try.
  7. Why do you guys always refer to 5-mm pitch connectors while the board has 5.08-mm pitch?
  8. Sh*t, I confused Alpha with Alps. Then TKD definitely better of course. Just place order for Alpha version, will contact PCB maker to replace Gerber.
  9. Yes, it's 4,8 x 6,8, and latest rev is 1.5. What's input impedance of 'portable' Dynalo? If it's low, then problem is that 5K RK27114 Alps hard to source, even on Ebay (they seem to disappear completely).
  10. What is exact board dimension of this PCB? Hi Kerry. Is SSDynalo-v1-4.zip from Kevin's depository the latest gerber? SSDynalo-v1-4.zip EDIT: Found, never mind.
  11. Kevin, Want to build this board and try it instead of e12. Few questions if you allow: Is trigger offset DC with standard resistors 0.5v? Is it from O+ to O- or from O+ to GND/O- to GND? Is it suitable for non-differentail balanced amps like 4-board B22, 2-board KSA5? Is it suitable for SE amps (like 2-board B22, 1-board KSA5)? Just use R+ and L+ terminals? Input GND taken from where? If it's signal GND, then take it from any board? Can it be left unpopulated?
  12. Hi Kevin, is KA5 fully-differential amp? I guess it's not, want to make sure. If it's not, then for balanced operation 2 boards are needed, and one board amplifies any 2 signals from L+ L- R+ R-. Is it correct?
  13. What is exact board size of balanced Dynahi with onboard heatsinks (aka dynahibal8f)?
  14. Can someone please explain what AT1000 data is? Is it related to Amprobe AT1000 tracer?
  15. Kevin, is this thread all devoted to goldenreference4.zip? What about goldenreference and goldenreference3? Is goldenreference4 direct replacement for those? And you opted to get rid of TO-3 transistors?
  16. It's because e12's virtual ground is referenced to PS ground. Imagine you are using 2 sigma22 and only 1 e12, which is referenced to one sigma22. Even if you built both sigma for the same voltage, due to parts tolerance the DC voltage of both will not be identical. Even 0.1v difference of sigmas output will make e12 false trigger because it will think that DC offset is 0.1v+amp's native DC offset.
  17. Try AMB's e12. I'm using it in almost every build of beta22, and will use for dynahi as well. To my opinion, 0.5v is too large and may damage some headphones, while others will survive. Anyway, I wouldn't risk my collection of 1000-1500USD headphones. I want the amp to be as most universal as possible.
  18. Kevin, are Golden reference boards finalized? You mentioned that there is oscillation unless some parts are not omitted...
  19. Sorry going to order for myself only, no experience to start GB if you meant it. Also, it's going to be rather expensive. The price of PCB house I've used to deal with is around 18-20USD per PCB of Goldenreference for the lot of 4 (180x110mm, double layer, FR-4, 1.5mm, 70um).
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