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On-board pre into project box?

Discussion in 'Pickups & Electronics [BG]' started by Wilbyman, Jun 7, 2005.

  1. Wilbyman


    Sep 10, 2003
    Parkersburg, WV

    I just picked up a 4-band Bongo pre on the gearswap, and I'm thinking about putting it into a box for use as an outboard. Can anybody give me so pointers as to how I should go about this? I know I need to wire a jack to the input instead of the PU's. Should I build a wood box?

  2. luknfur


    Jan 14, 2004


    I used a 4 x 4 metal electrical box from Home Depot (like would hold dual receptacles (plugs) in your house. They work very well with no need to dirll holes in it. Stout yet not that heavy. The knock outs are taylor made for jacks without having to drill through the heavy gauge metal and the internal crimps/clamps to hold the romex wire are great battery holders (one on each side for 18v) mounted like ears ouside the box so you never have to open the box once it's finished. Nail holes for the box work for screwsholes to attach the battery holders/romex clamps (I think using the same screws that hold the clamps internally). The same holes also work to feed the battery clip wires through to connect internally to the preamp.

    I used a piece of doorskin for a lid (also Home Depot - they have cheap scraps). About 1/8" thick. Easy to drill pot holes wherever you need them and a nice veneer finish on one side. If fact, you could veneer the entire outside so it looked like a wood box. Stain it, varnish it, paint - whatever. I used copper shield tracks between pots on the underside of the doorskin for no wire grounds. Threw down a couple pieces of electrical tape below each jack to make sure there would be no possible shorting at the terminals. Used a couple screws from the clamps to fasten the lid to box - which is actually already setup for metal lids when used in a house as a junction box. By the way, it would be crazy to try and drill a hole through that thick metal lid for potholes, so don't even think about it.

    Chucked them all long ago so the wiring is not fresh in mind. The output is wired with a stereo jack like it would be wired in the bass though. The input is a mono jack with a I think the hot lead that fed the pre from the pups (volume or blend pup lead depending ) goes to the jack tip and the jack ground goes to ground.

    I put the input and output jacks on opposite sides myself.
  3. Rodent

    Rodent A Killer Pickup Line™ Commercial User

    Dec 20, 2004
    Upper Left Corner (Seattle)
    Player-Builder-Founder: Honey Badger Pickups & Regenerate Guitar Works
    Hey Will,

    Great idea for that Bongo pre. A guitarist I know did a similar thing for his accoustic, and he used woods similar to that on his thin string. To make sure he didn't swap the in/outs, he used a plug type that was not 1/4" mono on the output. I don't remember if it was a micro jack like a set of headphones would have, or if it was an XLR - could be the XLR, as I think the box also contained the guts for a direct box as well.

    The box was lined with copper foil (all joints soldered) and had a latch lid so he could easily change batteries.

    When you get done, you've gotta post an image or two ...

  4. xbradx


    Oct 25, 2004
    Bloomington, IN
    i just did something very similar recently as a test for building my own aggie outboard pre. i took the pre from my fender marcus(i know, not the best pre to use, but wanted consistent sound from all my basses, and it's just a test shot anyway) and wired it into the casing of my old ProCo Rat pedal that'd died. the Rat box was setup pretty much perfectly, three knob holes on top for a V-T-B setup, left the marcus' output jack wired to the pre and put it in the back along with an input jack. and since i wasn't sure about wiring up the tommy thompson modified bypass switch to the footswitch(or hooking up the external power adaptor to the battery line), i used the smaller power adapter input mounting hole in the back to stick the bypass switch.
    once i get around to ordering my aggie opb-1 to put in, i'll try to put the external power adapter jack back in and get one of those multi-voltage adapers to use for it since you can get those that can be set for 18v, and find a way to hook up a footswitch for the bypass.
  5. A9X


    Dec 27, 2003
    If you're going to do this, spend the extra couple of dollars and get diecast alloy box for it. Available from electronics wholesalers. Stronger, more professional looking and doesn't need to be shielded. For example (I just picked it at random from the list and they come in a large range of sizes)
  6. Wilbyman


    Sep 10, 2003
    Parkersburg, WV
    You guys are all terrific for giving me this info. Everybody is a star on this one. I'm going to pass the Bongo pre on to someone more in need of it than myself, but I'm going to bookmark this threat because I'm POSITIVE this is going to come up again soon. I couldn't find another thread like it on TB. Thanks again guys.


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