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JoaMat

High Rollers
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Everything posted by JoaMat

  1. Once I cleaned a straight six BMW cylinder head in dishwasher. Very handy.
  2. Glad to hear it was that easy get rid of the oscillation. My idea is to build a version with ksa1220/ksc2690 replacing the old and hard to get mosfets. Have listen to an original DIY T2 with the mosfets replaced for a week. My impression is that it works well.
  3. Good news. What was the problem and its solution? Might be valuable information for us.
  4. This is my modified T2 from 2014. Later further modified with Cascaded CC a la JimL, replaced a bunch of to92 with small smd ants and replaced one battery with, an all SMD battery on a small daughter board. No oscillation, no hum or other issues. Works equally good as the three original T2s I’ve built. I frequently make layouts, mirrored or symmetrical and make the boards in our kitchen. For me it’s a hobby and I’m really enjoying it.
  5. Did this last night, not finished yet. Modified T2 output section. All parts available at Mouser. SMD give space for bracket. Board size 150mm x 100mm. Darlington pair in the middle, one on heat sink and partner standing. Below: draft of an input board. Right/left channels will be mirrored.
  6. IMO split washer is good enough in T2.
  7. Get a working T2 needs a little more than pure luck........... Glad noise is solved. I use 7721-3PPSG whenever insulation is needed. First I considered drilling but tried pressing the shoulder in place be means of a small vise. Pressing turned out to work all right . Set torque by feeling of wrist, but last year I’ve used a Swiss made torque screw driver with torque set to 0.8 nm. Steel screw is what I use.
  8. Great! Personally I think the original T2 PSU is a very nice design. A modern SMD version is nothing but awesome.
  9. Regarding the opto servo. Eventually I spotted the fault. Transistor mounted the wrong way. Now servo working and it works very nice. Really like the opto coupler. Many thanks Kevin.
  10. While speaking servos. The small board between tubes on Blue Hawaii (right channel) is a servo a la T2 (picture a few posts up). Did built it after Kerry suggested that one maybe should do it simple when we tried different servos some year ago. That servo works great.
  11. As I posted earlier I rebuilt a Blue Hawaii to GG. And now this new one. I can only say that Kevin’s GG works very well. I’ve the opto servo on the board, didn’t flip (or, did flipped it, depends on ones perspective) the opto coupler when mowing it to the other side of board. After correcting the connections to opto coupler the servo still doesn’t work. Have to find the reason for failure. The opto servo should work, shouldn’t it?
  12. Left channel is a GG. Followed Kevin’s schematic. Intention is to use Emission Labs DHT, didn’t dare to test it with DHT so it’s populated with some modern less expensive EL34. Right channel is an old Blue Hawaii. The combination of BH and GG works terrific.
  13. Have a great day, Wachara !!!
  14. bdent.com seems to have a few in stock. USD14.29 each if you buy 25 pieces or more. You need 28 pieces?
  15. If interested in the story of EL34, I recommend Guide to the EL34 / 6CA7 by Pasquale Russo.
  16. There are all kinds of EL34. Some good and some better. A few years ago I acquired those EL34. Probably manufactured in Eindhoven Feb. 1951(left) and Feb. 1954(right).
  17. Birgir is most certainly right about KT66 and T2. EL34 and equivalent are the one to use. Regarding datasheet. Most of us aren’t competent enough to read them, including me. Anyhow I make a try. KT66 max working voltage is 500V and absolute max is 550V. DC voltage on output tube of T2 is about 450V. You will probably easily overstress KT66 and eventually maybe destroy them. If that happens – please let us know. I’m especially interested in effects on the amplifier. I’m sure that there are members out there that can tell us pros/cons KT66 with T2.
  18. OK, now it’s done. Swapped the small tubes for solid state adapters. Kept +250V voltage and battery voltage unchanged. The 2SC3840 dissipate some 0.8W each. Might need small heat sinks. If you decrease voltage by 100V you also decrease power dissipation to >1/3W. And yes, they need covers. Working on it.
  19. Didn't found heat shrink wide enough. So printed some covers for the connectors. Not so elegant but it serves its purpose. No, but now that you brought it up - well, why not.....
  20. Managed to open it in DipTrace. Looks very interesting. Anyone capable of making it in .jpg format or similar? Worth showing!
  21. heat shrink, first thing in the morning.
  22. T2 with Emission Lab’s EML 20B-V4. Transformer to left is for filament 4 x 5.0V. Adapters are made by some help of a 3D printer, Teflon tube sockets, slauthered Neutrik XLR connectors, two pole male connectors. All held together with really good Loctite super glue.
  23. If builder decide to use only one series of resistors, then one should probably choose 1/2W. Othervise most of them could be 1/8W.
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