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12bh7

  1. knotscott

    NOS Tung Sol 12BH7a

    Anyone else running US made Tung Sol 12BH7a? I picked up two for my modified Dyna/VTA 70 amps a couple of weeks ago to use as voltage driver tubes. I liked them from the start, but they've really opened up beautifully with some hours on them now. I liked the new issue EH 12Bh7a quite a bit...
    • knotscott
    • Thread
    • 12bh7 nos tubes tung sol tung-sol tungsol
    • Replies: 15
    • Forum: Tube Audio
  2. C

    MC30 schematic question

    Hello, everyone. First post here. I am rebuilding a pair of MC30s. I am using the instructions from the Mcintosh MacKIT30. In the instructions I can find no mention of a resistor that shows up on the schematic (dated 5.17.60). This is labeled R29, and it is listed as 330kohm. This resistor...
  3. P

    MC240 - 12BH7's - should they have balanced sections or is it not as important in it's application?

    Hi! Just wondering if I can sub in an old RCA black plate that has differing GM readings (perhaps 20% difference) without it affecting the rest of the amp's performance. Also suggestions about tolerances for all the other tubes with respect to each other and their own individual sections would...
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