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Gutted out a Univox 1236 Bass Head!

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  • Gutted out a Univox 1236 Bass Head!

    And built a little something different.
    Single channel split gain controls.
    Three gain stages and a cathode follower tone stack, paraphase inverter, and 2x6L6GC cathode biased power section.

    So it's SLO style preamp married to a 5E5 Pro-Amp!
    Controls are Gain 1 and 2, TMB, and Master Volume.

    I was concerned the combination of those two styles of design would turn out to be a muddy mess on high gain but it turned out just fine.
    I like to build for great clean tone, then tweak for the high drive.

    I'll post the clips, but really need to do some better ones.

    Univox 1236 bass head, listed at 100 watts, but it really was about 50.



    Gut shot of what I built.
    UV protected Lexan sheets for board material, brass eyelets and risers:



    What it started as, the old Univox gut shot and cab:




    I got the amp for CHEAP in a multi gear buy.
    Fixed it up and wasn't impressed with the sound so I took everything out (including the sockets) and gifted them to a Uni fan for his own builds.

    Never apologize for anything (is what they say), but there is a running high frequency noise on the recording that isn't coming form the amp, it's somewhere between the mic and the PC.
    Too lazy to look it up, I just wanted to record.
    It's in all the clips.
    I will track it down and do it over.

    30 estimated watts given the nature of the bias and 405V B+.
    Tubes are:
    2x6L6GC, 5U4GB rectifier, 2x12AX7, 12AU7 PI.
    Iron is 1950's Masco Ma25 PA power and L-Series Hammond organ output transformer. (Or maybe K series...I won't gut a great Hammond, this one wasn't all that great...)

    So all in all, a little vintage iron, a little modern design mixed in together.

    High gain first:
    MP3 Player SoundClick

    Clean:
    MP3 Player SoundClick

    And dirt:
    MP3 Player SoundClick

    There is a noise issue in the background beyond that mic problem, just some fine tuning to do.
    But I feel the tone is there.
    Guitar is a gift, homebrew kit LP loaded with Stephens Design VL3 Proto bridge and PF Star neck, rolled back to about 70% volume and tone (you'll hear the transitions).
    High gain is all VL3 Proto bridge full on.

  • #2
    What...nothing?

    OK, let's wheel her up a little.

    MP3 Player SoundClick

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