Combo to Head / wiring

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by ChrisP, Aug 23, 2005.


  1. ChrisP

    ChrisP Member

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    I've got a Crate VC 20 combo and I'd like to put the chassis into a head.
    coming out of the back of the chassis with the pos/neg for the speaker is a brown wire. The brown runs back to the transformer. I'm not sure where the brown actually terminates...but it goes in that direction!

    On the front of the chassis is a 1/4" speaker out. SO, i'm thinking maybe the red/black can be tied off and the 1/4" on the front can be used for a speaker cab. However, I'm fairly clueless about electronics and I don't want to die just yet.

    Is the brown wire a ground? It doesn't seem to have anything to do with the speaker but it is coming out of the same hole as the speaker wires. I looked for a manual online but could not find one...can anyone shine some light on this?

    thanks!
     
  2. John Phillips

    John Phillips Member

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    What does the brown wire connect to at the speaker end? - that will tell you what it is.

    For this kind of conversion it's always better to use the stock 'internal' speaker connection as the speaker-out BTW - the extension speaker jack on amps like this often does something else as well, like switching the transformer impedance.

    Make your head box with a rear panel across the bottom, and fit the speaker output through that, using the same kind of jack and mounting plate you'd normally find on a cab.
     
  3. ChrisP

    ChrisP Member

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    I will check where the brown wire goes when I go home.

    All I can see w/o taking the chassis out is that the brown wire comes out of the grommet at the back of the chassis and then it goes back in near the txformer...it goes nowhere near the speaker.

    thanks,
    Chris
     
  4. ChrisP

    ChrisP Member

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    Alrighty.

    They sent me an owner's manual, which has a schematic...that I can't really read.

    From the power amp the chain is split.

    1] towards extension speaker then splits towards ext spk or loudspeaker

    2] towards headphones then splits towards headphones or loud speakers.

    Did I mention there's a headphone jack earlier in my post? :D
     
  5. ChrisP

    ChrisP Member

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    EDIT: I just read on the owner's manual that plugging into the speaker output on the front of the panel disconnects the internal speaker. I guess I should still terminate the speaker wires on the back so there aren't 2 speaker wires flopping around in the back. Does this matter?

    If someone has the time I would appreciate the questions below being answered :) thanks, Chris

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


    Ok…I've taken some pictures…

    The brown wire does not seem to be associated with the black/red other than it goes through the same hole as the B/R wires.

    The brown wire terminates to the board.

    Coming from the transformer are red, green, black and red wires. The black terminates to the speaker out (on the front) and the green terminates to the headphone jack.

    The black and red terminate to the board. Are they for power???

    SO, it seems like I should take the obvious B/R speaker wires and terminate them to an input on the back of the amp.

    brown should not be touched. Black/Red coming from the transformer should not be touched.

    What about the headphone/speaker out? can they just be unclipped from the board? Just curious....
     
  6. ChrisP

    ChrisP Member

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  7. John Phillips

    John Phillips Member

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    If the speaker out on the front panel disconnects the internal speaker, and so does the headphone jack (but by the opposite connections) it does sound like you can remove the two wires to the speaker at the amp end, yes.

    The only disadvantage is that your main speaker output is now on the front of the amp - rear is more convenient usually. I would still do the obvious thing and connect the two wires that went to the speaker to a new jack, but that's just me.
     
  8. ChrisP

    ChrisP Member

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    cool...you are one informative dude!
     

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