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EC Tremolux Mod ideas

Discussion in 'Shock Brother's DIY Amps' started by tubeswell, Sep 7, 2020.

  1. tubeswell

    tubeswell Friend of Leo's

    Jul 1, 2008
    Got one on the bench at the moment. Customer is complaining about lack of power and general 'fuzziness' (which is what this amp is known for). It just can't keep up at the blues club. While its a very 'tweedy' low powered amp, the stock amp is more of a bedroom amp.

    So amidst pandemic lockdown boredom, I came up with a few suggestions to clean it up and squeeze a bit more output power from it. All the mods can be done utilising the existing turret board, sockets, tubes and transformers without any need for re-fabrication (except for the choke, which will need 2 or 3 holes drilled in the chassis.

    Removing the 1M resistor on the back of the tone pot is obvious, but if done on its own will just result in more pre-amp distortion

    The power supply mods would be better done together for full impact. But even replacing the 4k7 screen supply node with a 1k resistor opens up the screens a bit. (small re-bias is necessary)

    The 5AR4 will give it more bite, and 47uF 500V reservoir is really what you want with this to take advantage of the potential increase in B+ (re-bias is necessary - hence the 0.22uF film cap in the AC-coupled bias supply). A CLC filter would also make the most of this situation. If you replace the screen node filter cap with 22uF 500V, its easier to get at the resistor for the choke installation.

    The unused input tube triode can be put to effective use as a single/parallel input stage (which can conveniently utilise the '1'/'2' input jack markings for secret meaningfulness)

    See schematic

    Attached Files:

    FenderLover, jsnwhite619 and dan40 like this.
  2. jsnwhite619

    jsnwhite619 Friend of Leo's

    Sep 10, 2013
    Single/parallel input has become my new favorite mod. I've found that I like a parallel 12ay7 better than a single 12ax7.
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