TCTp - The Clone Tone project

Peavey Rock Master tube guitar preamp clone project

This project never finished as general interest in the Rock Master took a hit when everyone
wanted a modeler amp I finally had the opportunity to own a real Rock Master preamp.
Now at this moment in time interest in the real tube pre-amp has grown again I desided
to post my old web page for others to maybe learn from.

  • "Why bother cloning the Rockmaster? You can have one dirt cheep from eBay!"
  • Well, that doesn't seems to be true any more. Many people that own one often make sure they got
    two or three units these days. Past year I'm been offered only two units, and asking price was
    equal to decent combos...

    If you already own one you might want to improve part of it's design but hesitate to tweak your
    perfectly working tone machine. Building one from scratch you can experiment with tone controls,
    remote switches, MIDI control and more.

  • Idea for the project
  • The idea for this project is not to clone the complete preamp with bolts and nuts, but rather
    try to nail the tone this beast is famous for. If possible we could break down the amp in smaller
    modules that can be build on. For instance first start with the clean channel and leave out EFX
    loops and maybe make them optional later on. Or separate the tone control so it can be duplicated
    to other channels... - Maybe make it more simple and stuff it inside a stomp box?

  • Project start, collecting info for the project
  • Schematics
    Foot switch schematics
    RM foot switch control schematics

  • Flow chart
  • Redrawn from usermanual
    Only the clean channel. Maybe the first stage of the to be cloned?

  • User manual

  • Sound clip

  • Mods
  • A collection of mods for the Rock Master

  • Peek inside
  • Parts list - incomplete

  • Breakaway Board - All components acountet for - total of 38 including tubes
    V1, V2, V3, V4 - 4 pc 12AX7 tubes

    C3 - 22uF 25V
    C14 - .001uf
    C16 - .22uF 400V
    C17 - .47
    C18 - 22uF 25V
    C25 - 22uF 25V
    C40 - .1uF 250V
    C42 - 100pF

    R3 - 150k
    R4 - 1k5
    R12 - 1M
    R13 - 150k
    R14 - 2k2
    R16 - 220k
    R17 - 470k
    R20 - 100k
    R21 - 1k5
    R22 - 680k
    R23 - 1M
    R24 - 100k
    R25 - 1k5
    R32 - 100k
    R37 - 1M
    R38 - 2k2
    R39 - 100K 1W
    R41 - 1k5
    R43 - 100k 1W
    R55 - 470k
    R103 - 1k5
    R150 - 100k 1W
    R308 - 100k

    CR1 - 1N4148
    CR2 - 1N4148
    C400 - .1uF 400V

    Main Board

    R1 - 22k
    R2 - 22k
    R5 - 220k
    R6 - 68k
    R7 - 220k
    R8 - 220k
    R11 - 2k2 or 2M2
    R27 - 10k

    R105 - 470k
    R600 - 10k

    VR1 1M log - Clean Gain
    VR2 250k log - Low EQ
    VR3 50k lin - Mid EQ
    VR4 250k lin - High EQ
    VR5 10k lin - Presence
    VR6* 50k log - Crunch Gain
    VR7 50k lin - Crunch - Prost
    VR8* 1M log - Ultra Gain
    VR9 50k lin - Ultra Post
    VR10 250k lin - Bottom
    VR11* 250k lin - Body
    VR12 250k lin - Edge input

    (*) original with pull switch

    C1 - 39pF
    C2 - .1uF 250V
    C4 - .047uF 400V
    C5 - 820pF
    C6 - 270pF
    C7 - .1uF 10V
    C8 - .047uF
    C13 - .047uF 400V
    C15 - .47uF 10V
    C24 - .047uF 400V
    C306 - .1uF 10V must be verified
    C600 - .047uF

    Other stuff
    4 pc 9 pinn tube socket

  • Relay function
  • K1 K5 K7 controlled by foot switch Normal/Bypass
    K2 K3 K8 controlled by foot switch Ultra/Crunch
    K4 activated by both Ultra VR8 & Crunch VR6 trough K2B
    K6 activated by Shift VR11
    Look at the layout diagram

  • Tube layout and function
  • Posted by tmenzo on the Peavey Forum in thread "Rockmaster preamp tube layout..."
    Order is V1, V2, V3 and V4 from the input jack end.
    The functions are:
    V1A - input stage
    V1B - pregain recovery stage
    V2A,B - Ultra/Crunch circuits
    V3A - active EQ for Ultra/Crunch
    V3B - FX loop driver stage (cathode follower)
    V4A - FX loop recovery
    V4B - output stage (cathode follower)
    V1 and V4 are always in use, while V2 and half of V3 are only used in the Ultra/Crunch channels.

  • PCB
  • Layout using the free ExpressPCB / ExpressSCH applications -
    You might want to use another pcb cad, but please share your design with us anyway :-)

    Schematics and PCB layouts

    Custom SchComponents used in this projct like 12AX7, relay

  • Parts details and data sheet
  • JJ Electronic ECC83S / 12AX7 tubes -
    9 pinn tube socket example with shield and one without shield from Banzai Musical Products
    J174 P-Channel JFET Switch [Fairchild] used in the effect loop section
    Local folder