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first DIY project - Musicmaster Bass Amp mods + rebuild

Discussion in 'Shock Brother's DIY Amps' started by cottontails1959, Jan 24, 2021.

  1. tele_savales

    tele_savales Tele-Holic Platinum Supporter

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    So far every old Fender I've bought, kept, sold, whatever, still kept making noise no matter what I did/replaced until I A) Cleaned the hell out of the input jacks and rebent them to make better contact, or B) What I'm doing now, which is to replace them without question with brand new Switchcrafts. I just really don't think I'm harming the long term vintage correctness or resale value by doing so.
    Maybe have a look at them.
     
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  2. cottontails1959

    cottontails1959 Tele-Meister

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    I've replaced these input jacks with Switchcraft +++

    I put everything back together this evening, and have a voltage issue somewhere. The switch was only putting out half-voltage (relative to ground) so I started undoing wires, eventually taking the out-leads off the switch ... then got full voltage back on the out-tab ... so now I need to start adding stuff back. If I have time tomorrow, I'll post the mains supply side layout.
     
  3. cottontails1959

    cottontails1959 Tele-Meister

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    I got help over at the Amp Tech Center forum and got my voltage issues sorted ... it was me, not the amp. It's all back together and in context, sounds pretty sweet. Definitely quieter/less hum than stock. @timfred ... look at this schematic ... with the tone stack and coupling cap mod ... and the bigger main filter cap ... it sounds very passable with a bass guitar. Interestingly, with guitar and bass, IMO it now sounds best with the treble tone rolled completely off ... with guitar, it sounds pretty good from 6-1/2 down on the tone knob ... the tone control is 1M audio, not linear. Thanks everyone for the help and consideration. I'll try to post audio in the next couple of weeks.

    MM73-006.jpg

    PKS MM 6AQ5 schem tone tilt 2021_0118.png

    MM73 final 2021_0222.png
    MM73-003.jpg

    MM73-002.jpg

    MM73-001.jpg

    MM73-005.jpg

    mm73-004.jpg
     
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  4. timfred

    timfred Tele-Meister

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    Cool! I tried a tilt control once but couldn’t get it to sound good. But I’m sure it was my choice of component values, not the circuit itself.
     
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  5. cottontails1959

    cottontails1959 Tele-Meister

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    The first time I tried it I did the mid-scoop version with 3.3n on one side and 1n on the other ... sounded like poop ... no sweet spot ... muddy bass and broken glass treble. Now it's 1n on both sides. When I redo my '77 MM, I might try the mid-hump version ... although with the 6V6 instead of the 6AQ5 tubes it may be a completely different sounding animal.
     
    drew1d likes this.
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