Convert Combo Amp to Be Extension Cab?

Discussion in 'Amps and Cabs [BG]' started by EdO., Feb 26, 2017.

  1. Probably (hopefully) a dumb simple question. I have a TC Electronic BG250 - 210 combo that I would like to convert to be able to use it as an extension speaker cab. In other words bypass the amplifier section and just plug directly into the speakers when using another amplifier.

    The speaker connection to the amp section is a simple two piece plug type connector, photos attached to illustrate. What I'd like to do is to mount a 1/4" plug in to the back of the amplifier section to use as an input directly to the speakers. I can remove the amp from the cab (6 screws, literally takes a minute), unplug the amp from the speakers, plug the lead from the speakers into the 1/4" input thus connecting directly to the speakers and completely bypassing the amp section. Simple enough. I just need another of the same type connector to make it a simple plug/unplug operation.

    So my question - anyone know where I can get the connector in the photos, or know what it's called specifically so I can dig it up on the Net and order one? Thanks in advance for your help/input.

    20170226_131930.jpg 20170226_131851.jpg 20170226_131836.jpg
    Last edited: Feb 26, 2017
  2. plav1959


    May 7, 2016
    Orlando, FL
    Looks like a simple Molex connector. But why pull the amplifier? I'm sure it doesn't add much weight. Just make a pigtail from Molex to 1/4" female phone jack. That way if you decide to sell at some point, just disconnect the pigtail, plug back into the amp and you have a combo again.
    nuage420b likes this.
  3. HaphAsSard


    Dec 1, 2013
    If you're already aware of the following please disregard and carry on with the thread - I guess it won't hurt to point it out anyway: AFAIR all BG250 series combos, with the exception of the smallest (the -208), don't have extension speaker capability, and put out the full power of the amp section. This implies that the cabinet section has 4-ohm impedance. Don't forget to always use the modded combo-as-extension-cabinet just by itself, never with another cab unless your head is 2-ohm capable (or unless you use a Y series cable).
  4. Thanks for the connector ID, appreciate it. To clarify, I'll take the amp loose, unplug the pigtail from the amp, plug it to the speaker input, reinstall the amp. That way I can quickly put it back to normal if/when needed.
    I did consider that but thanks for the heads up. I can't find anything on the BG250 that tells me what the ohm rating for the speakers is. I'd assumed 8 ohm since most 210 cabs are 8 ohm but you're correct, I don't know for sure. I do know you can't add an extension cab to the AMP but since I'm taking the amp out of the equation didn't figure it would be a problem. Need to dig a bit more on that point.

    What I'm doing is trying to add an extension cab to a Rumble 500 I just got without spending any more money. May or may not need it, just trying to add the option.
  5. ItaKK


    Oct 19, 2013
    Hi guys,
    my TC Electronic BG250 115 combo stopped working. I think something crushed in the PSU part.
    Considering the reparation cost, I was thinking of using just the cab with a stand-alone bass head (something not very expensive, like an Ashdown MAG 300 or others).
    It is possible to do it? To use just the cab?
    What kind of adaptor can I buy to use the connector of the BG250 cab that allows me to connect it to the inputs of the head?
  6. 6thplanet

    6thplanet Supporting Member

    Aug 17, 2019
    Id be more inclined to install an actual terminal plate in the back of the cab. Easy way, cut that connector off and install an inline female 1/4" connector, but I didn't tell you to do that.....
  7. ItaKK


    Oct 19, 2013
    Thanks a lot.. yep it is one good possibility. Cut the connector and install a Speakon connector. I would like to not modify or cut cables and use a connector, but I still not have identified the type of connector on board.

    Is the BG 250 combo cabinet, as I understood, a 4 ohm 250w?
    Can I use it with a MarkBass Little Mark 250W at 4Ω?
  8. Yes, 4 ohm.
  9. ItaKK


    Oct 19, 2013
    I've the opportunity to buy an used Orange Terror Bass 500 head with a very good price.. I always loved that sound..
    do you think that coud be suitable - 500w at 4 ohm head on that 250 w at 4 ohm cab?
    I will not push the volume so much as I will use it at home
  10. Killing Floor

    Killing Floor Supporting Member

    Feb 7, 2020
    Austin, TX
    If you’re gonna monkey with it why does it need to be that specific 2 pin connector? Why not just pull the clips in the speaker and wire in a new jack?
    EdO. likes this.
  11. ItaKK


    Oct 19, 2013
    yes.. I was thinking about it just in case I will repair the original head in the future and re-sell the combo.
    But the easiest and the best solution is to cut and wire a speakon connector and I'll go for that solution; to re-wire the original connector is not a big deal..
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