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JoaMat last won the day on October 27 2023

JoaMat had the most liked content!


About JoaMat

  • Birthday 12/26/1955

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Extra Special Silver Diner

Extra Special Silver Diner (5/6)



  1. All you need is a forgiving connector. Homemade, 3D printed, socket with “floating” Neutrik pins from NC3FD.
  2. A simple way to adjust offset is to replace R73 with a 10K trimmer. Looks like this on my amplifier. Works like a charm.
  3. Seems your balance servos are working since C and D have same readings. As for right channel where you have unbalance – investigate the R88 – R91, C8 and C9.
  4. Good point, indeed. Here is a picture I saved on my computer years ago. I don't know the source. Resistor in red circle, is that the 62K one? Zoom in and you get a good view.
  5. When things work as they should Q16 and Q17 have the same potential. The string R31+R32+RV1+R33+R34 determines the battery voltage. 6.55V cross R31+R32 gives 6.55V * 1655.8K / 13.8K = 785.9V.
  6. 6.55V cross R42 and RV1 to R32 side will (in theory) give you a battery voltage of 786V. You have 781V. Why then change RV2 and the 6.55V? Why not reduce battery voltage with RV1?
  7. JadeDubbleBottle is served. One 6922, two 300B and a few components on amp pcb. All DC filaments and GRHV at 140V. No cats and children have moved out so, no rush with chassis.
  8. A senior Head Case member sent me two tubes some days ago. An old 6080 and a Westinghouse 12AX7A. Today I completed this in my kitchen. Amplifier is based on Jade, what now that is? PSU as mentioned above is based on Kevin’s GRHV power supply. It has been some fun building days.
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