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Adam's Amplifiers: A full subminiature amp
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A full subminiature amp
Thursday May 18, 2006 by adam

Jon Anderson just let me know about an amp he’s built using 6112 and 5902 subminiature tubes. The 6112 is a dual triode (mu around 70, I think, like a 12AT7, and the 5902 is a power pentode. He’s posted a schematic and sound clips – it’s sounds great! Go check it out.

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  1. Hi,
    Please is it possible to have the description about the project using 6112 and 5902 sub miniature tubes?
    Please send me the wiring connections (pin number)for to optimize the impedence transformer hammond mod.125E from tube to speaker.
    Giovanni Italy

    Giovanni    Dec 21, 05:39 PM    #
  2. I’ve been looking for a schematic for these tubes. It sounds great. Thanks for the info.

    Bob Clark    Mar 11, 05:27 PM    #
  3. Where on that schematic is the input impeadance for the output transformer? 125Es are both expensive and overkill for this application, and for $10, a very similar transformer can be had on eBay – providing you get the values right.

    spasticteapot    Jun 28, 06:58 AM    #
  4. Hi Adam, great website. I’m thinking of putting an amp with subminiature tubes together myself. I would incorporate a 12ax7 tube effects loop. It would only consume 4 mA or so + the filament current for the heater. Do you think the 269EX can support that? I would base the schematic on the 5902 amp Jon Anderson made.
    He’s using an 125E output transfo. Is that correct or is it a 125BSE like you’re using? Thanks a lot.
    kind regards,

    bart    Jul 7, 01:50 PM    #
  5. I’m not familiar with mu? However, I assume this is less than one watt in overall power. Killer recording. Will he be producing these. I use many small amps for recording.

    James P. Alters    Dec 3, 05:09 PM    #
  6. Hey, I’ve been searching all over for more information on these tubes. I would like to build a Marshall circuit using these tubes, but what the heck would I have to change? I know there’s gotta be more than one or two hurdles. I’m not quite savvy with tubes yet. My email is

    — Nanoo Man    Jan 24, 12:04 AM    #
  7. Adam,
    When I look at the specs for the 5902 it appear that the max plate voltage is 165 volts. Can you shed any light on this?

    Bruce Brown    Jan 30, 03:27 PM    #

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