Pairing unusual head and cab: Can I do this?

Discussion in 'Amps and Cabs [BG]' started by JonathanDiN, Sep 7, 2022.

  1. JonathanDiN

    JonathanDiN

    Sep 7, 2022
    Question for anyone knowledgeable about bass amps & cabs: I recently found a Behringer 4x10 Ultrabass combo amp. I've been testing it out, and everything seems to work alright, but I was hoping to connect my Vox mini superbeetle head to it and use the 4x10 as a bass cab. My bass sounds killer through this head, but I think the particular Vox head I have is actually the guitar model, not the one for bass. I've heard that using a guitar head for bass won't damage anything so long as the cab used is designed for bass, so could I just unplug the behringer preamp in back and plug the vox head in? Would this work without damaging anything, or is it a bad idea?

    I've included pictures. The behringer lists "minimum load 4 ohms", which the Vox amp is capable of doing, at least according to the manual/settings. As shown in the pics, the 4x10's on-board preamp looks to be connected through two jacks; I assume one for each set of speakers? Could I use just the one side, or do I need some sort of adapter to connect both in order for it to function at all?

    Any and all input is greatly appreciated
     

    Attached Files:

  2. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Stop! Where the heck are you running the Vox's speaker cable??

    Riis
     
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  3. JimChjones

    JimChjones

    Aug 6, 2017
    SE England
    You're a little confused about terms I think.
    The electronic unit on the Behringer is a combined preamo and power amp.

    Before we go much further the imperative thing is that you *NEVER* connect the jack sockets on the back of the Behringer amplifier unit to any other amplifier, if you do very bad things will happen, quite probably both units will be destroyed.

    Its unclear from the manual (https://mediadl.musictribe.com/media/sys_master/h3d/h30/8849642094622.pdf) how the speakers are connected inside the cabinet. This is a pain in the neck, since while we could guess about how they are most likely to be connected, if we are wrong it could be awkward.

    Do you have access to a multimeter with a low ohms scale. I would take out the two jack plus that go to the cabinet and measure the dc resistance across them. I'd expect it to be in the range 10-15 ohms on each. I'd then get an adaptor and plug each jack in turn to a headphone socket on something convenient, play some music and see what sound came out where. I'd expect one plug to play two of the speakers, and the other to play out of two speakers and the tweeter, but I expect other things are possible if the designer were unwisely clever.

    From there probably best to report back, because otherwise we could get into lots of what ifs which might be risky.
     
    Last edited: Sep 7, 2022
  4. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Here's how i would handle it:

    Use the Vox's headphones / line output and run an instrument cable to the Behringer's "return". Make sure all your levels are set to -0- when firing-up. Quit messing with the speaker outs on both the Vox & Behringer before you damage something.

    Riis
     
  5. Kaa

    Kaa

    Sep 28, 2004
    Cleveland, Ohio
    Riis has the right idea, just use the Behringer as a slave amp.

    Now, and this is a purely theoretical question: since the Vox has 2 speaker outs, and the Behringer has 2 speaker plugs, could one simply plug in those 2 wires into the outputs on the Vox? (Assuming the would reach.) Thereby using the B'er as a separate speaker cab.
     
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  6. el murdoque

    el murdoque

    Mar 10, 2013
    Germany
    You could check what goes where by unplugging everything first, then holding a 9V battery to one of the jacks that come out of the behringer cab - and see what speakers will move.

    Never, under no circumstances, have two amps connected to one cabinet.
     
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  7. The real trick here is in knowing (not guessing) how the Berhringer dual plug and speakers are wired.
    This can be done visually by following the dual plugs all the way to where the connect to the speakers, or by using a multi-meter to "Ohm" them out. The multimeter may also act as the power source to do the battery test, which is option three.
    If this is confusing because you don't have experience with this stuff, find someone who does and have them help you.
     
    Last edited: Sep 7, 2022
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  8. I has that thought as well and then noticed the Vox has an impedance switch. That complicates things a bit.
     
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  9. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    I don’t recall that combo with 2 speaker wires, has someone modified it? I would want to be darn sure of what I was plugging into before anything else.

    Never plug 2 amps into the same cabinet.
     
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  10. arbiterusa

    arbiterusa

    Sep 24, 2015
    SoCal
    this will end in tears.
     
  11. JimChjones

    JimChjones

    Aug 6, 2017
    SE England
    Peculiar isn't it, and there's no mention I can find in the manual which is odd. But I tried an image search on line and found a couple of images showing two wires and the same jack plugs, and none at all with a single one.

    The manual I found on the Behringer web site has almost nothing to say about the speakers, and describes a switchable tweeter, but doesn't tell you anything about how to switch it. I'm not even certain from the manual whether the specs they give for the speakers are per driver or for the whole cabinet.

    My best guess, for the OP, is that plugging the cab portion into your Vox amp will be a problem because you need to use the jack plugs on leads sticking out of the cab, and I bet they won't reach. It would be possible to make up small speaker extension leads, but in line jack sockets are very frequently flakey in the extreme: you need to use expensive ones. You also need to be able to find out enough about how the cabinet is configured inside to be sure you are doing it right.

    You absolutely must not use the standard jack to jack speaker lead that you use for your Vox cabinet!
     
    Last edited: Sep 7, 2022
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  12. JonathanDiN

    JonathanDiN

    Sep 7, 2022
    Hey, thanks for all the replies everyone. As indicated by my first post, I have very little experience setting something like this up. You guys will probably be relieved to hear that I still haven't even attempted to connect the Vox head with the 4x10 cab; I wanted to make this post first, in the hope that I could to consult some of the more knowledgeable forum members. I really appreciate the input, and all of the thoughtful replies. Evidently, I have a lot more details that I need to figure out before I'm ready to give this shot, but the information that I've gained from reading through this thread has definitely provided me with some much needed direction. I'll post an update if I'm able to make any progress, and thanks again!
     
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  13. sawzalot

    sawzalot Supporting Member

    Oct 18, 2007
    Yeah, until you can see where those wires go inside the Behringer, you have at least a 50% chance of causing the Magic Smoke to come out of one or both amplifiers. Holding off until you know what's in there is best.
     
    agedhorse likes this.
  14. two fingers

    two fingers Opinionated blowhard. But not mad about it. Inactive

    Feb 7, 2005
    Eastern NC USA
    Welcome to TalkBass!

    We're not saying it definitely won't work. We're saying that we don't know until we know where the other ends of those speakers wires are connected. If you can pop a speaker or two out, and take some pics from the inside of the cab, we can get a clearer picture of what we're actually talking about.
     
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  15. mikeswals

    mikeswals Supporting Member

    Nov 18, 2002
    Seattle / Tacoma
    This is what I'd do, unplug both speaker cables on the Berhringer and do the simple 9V test to each cable, watch which speakers move.
    I have a feeling one cable feeds two speakers, and the other cable feeds the other two speaker. Strange, but whatever.

    Most tube guitar amps do. (Even if its not tube)
    So if the cab is a 4ohm load, then simply set the impedance switch to the corresponding load.
     
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  16.  
  17. I find the impedance switch on the back of what is presumably a solid state power amp that appears to be doing not much of anything weirder than the dual speaker cables on the behringer cab.
     
  18. $x10 cabs usually are wired to be 4ohm output. That means there are 4 32 ohm speakers in that cabinet, wired in series/parallel to get that output. Ohms are a measure of resistance and they apply to speakers ( or cabinets) usually. Only connect one lead to that cabinet and use the other amp as a preamp for the Behringer. Be careful. Often that doesn't work. Don't combine any other cabinet with the 4x10 cabinet. The impedance will be off.
     
  19. baddarryl

    baddarryl

    Oct 26, 2008
    Cape Fear!
    THIS ^^^^^^^
     
  20. definenredefine

    definenredefine Nobody likes a drummer... Supporting Member

    Mar 11, 2022
    North Carolina
    This is where I got tripped up as well. I was hoping the rear baffle was removable but that does not appear to be the case. The other way to go is removing the grill and the individual drivers in order to trace the wiring. That's doable albeit kinda tedious.

    If you decide to take out the drivers, do not use a drill or powered screwdriver! There's a good chance that the driver bit will skate and you'll put a hole in the speaker surround. Ask me how I know...
     
    Last edited: Sep 8, 2022
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