Converting a Superlead to Superbass specs

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by EXP, Aug 5, 2006.


  1. EXP

    EXP Supporting Member

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    [​IMG]
    i have a Metro Amp ' 68 Superlead ptp in my 1959 SLP(Sozo caps, MM OT/choke) that im thinking of changing to Superbass specs. i know the early ones just didnt have a bright cap. is it just a few value/resistor changes? a totally different tone stack? increase in power supply filtering?

    i was also going to switch out the JJ EL-34's for a quad of Shuguang/Valve Arts KT66. im running it though a 1960AX loaded with Scumback H55/75hz. i love that Band of Gypsies clean tone which is why i want to make the switch.
     
  2. Roe

    Roe Member

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    ask at the metroboard and at the plexipalace
     
  3. EXP

    EXP Supporting Member

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    i did at plexipalace, no replies yet.

    my account is still inactive at the metroamp forum.
     
  4. JimiB

    JimiB Member

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    Change V1 split cathode to shared 220uf/820ohm combo. and cut the bright cap out. that should get you real close.
     
  5. rhinson

    rhinson Member

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    hello, i'm not sure about the filtering---that'll vary depending on the the type of feel you want. but the basics are to change it back to tweed bassman/jtm45 part values on the board: changes are----.1mf coupling caps to the power tubes in the phase inverter, .022 cap instead of .002 cap in the bright ch., 56k slope resistor instead of 33k; remove .68mf from across the 820ohm resistor in the second stage; shared instead of split cathode on the first stage (820ohm/330mf cap), use a 100pf bright cap on the bright chan. vol pot. that's about it. you will probably want to change/clip the bright cap across the 470k resistor from the bright ch. vol. rh
     
  6. JimiB

    JimiB Member

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    oh yeah and what he said also :AOK
     
  7. EXP

    EXP Supporting Member

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    thanks rhinson and JimiB!

    that really helps me out.:AOK
     

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