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2 channel combo build

Discussion in 'Shock Brother's DIY Amps' started by JohnnyCrash, Jul 24, 2009.

  1. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    Got my blank 20 x 6" x 2.5" aluminum chassis from Ken at Turretboards.com.

    Here are step-by-step photos of me cutting/drilling the chassis and installing the hardware.

    I used a step bit in my drill press to get the 12AX7/preamp tube socket holes. Also drilled for the die punch shank so I could punch out the power tube sockets:

    [​IMG]

    [​IMG]



    Here is the Harbor Freight punch kit:

    [​IMG]
     
    Last edited: Jul 24, 2009
  2. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    Next I tried to use the nibbler cutter to make the power transformer and AC plug square holes:

    [​IMG]



    This chassis was a bit too thick for the nibbler so I had to use my scroll saw for the PT:

    [​IMG]



    I used my Dremel tool for the AC receptacle:

    [​IMG]
     
  3. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    Front panel: Input jack, Gain and Volume for channel 1, Gain and Volume for channel 2, Treble, Mid, Bass, lamp, and power switch.

    The empty hole between channel volume/gains is for the front panel switch and I haven't drilled the holes for the channel LEDs yet (one green, the other red):

    [​IMG]



    OEM style replacement transformers for a BF Fender Vibrolux/Tremolux, OT is a 35w to 4ohm, choke is Fender OEM style as well:

    [​IMG]



    Bottom of the chassis has: a space-saving AC receptacle with built-in fuse holder, two octal sockets for 6L6 power tubes with bias points and pot between them, a speaker out jack, PI tube socket, channel footswitch jack, and the two preamp tube sockets:

    [​IMG]
     
  4. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    As far as the build itself, it cost under $300 in raw parts (shipped with a pair of speakers).

    I will be using 5 volt DPDT relays in the channel switching circuit. I am going to supply the relays by "borrowing" some of the 6.3v heater supply and running it through a bridge rectifier to convert it to DC.

    The "channels" are actually just two sets of Gain and volume controls. The relays will simply select which Gain and Volume is inserted into the circuit (at the tonestack and at the PI).

    The preamp itself will pretty much be the high gain JCM800 setup with a fatter preamp cathode. The PI, typical Fender/Marshall long tailed pair 12AX7. The power section will probably look very close to a BF dual 6L6 fixed bias Fender and will have a set/fixed negative feedback (no Presence control). Solid state rectified.

    I'll be building a 2x10" combo cab and have a pair of 8 ohm Jensen MOD 10-35's to try first.

    This is meant to be a cheap (but great quality), portable gig amp. My 50w dual channel "JCM800" build head into a 2x12" cab is my main gig amp, so this will be a perfect compact backup, or a grab-and-go.
     
  5. jh45gun

    jh45gun Banned

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    Nice Job I might have to order one of them and redo my Super build with the right power transformer for winter project. While my super amp head works it is not exactly right as the bias circuit has been rigged diffferent since the PT did not have a bias voltage lead. So I would have to make the parts on the bias circuit back to normal and then get a PT and start from scratch.
     
  6. Quintin

    Quintin Tele-Meister

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    Nice work. Wow under $300. You appear to know the right folks ;)
     
  7. Engraver-60

    Engraver-60 Friend of Leo's

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    JohnnyCrash: How's this going to set in a cabinet? Knobs UP? I cannot picture it yet in my mind. Is this going to be a foot-switchable 2 channel amp? OOPS (I just re-looked at you last photo - corrected). $300? Wow.
     
  8. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    Yeah, knobs up.

    Yes, footswitchable. I can set one channmel clean and the other dirty, or one for dirty rhythm, the other for louder leads.
     
  9. P-Zilla

    P-Zilla Tele-Afflicted

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    You got a name for this beast yet?
     
  10. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    Not yet... its gotta be an evil name though, this thing will be high gain :twisted:
     
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