Guitar combo to Bass combo Conversion

Discussion in 'Amps and Cabs [BG]' started by Nlenhard17, Apr 5, 2018.

  1. Hello,

    I have a Zoom Fire 30 guitar combo and I’m interested in trying to change it into a bass combo. I like the sound of the distortion coming from the guitar amp, I just don’t want to accidentally blow the speaker. Would it be as simple as switching the speaker to a bass speaker and sealing the back? Do i have to do anything with the electronics?

  2. BadExample


    Jan 21, 2016
    The head might not be the best, and probably not much you can do with that.

    You might get a decent bass cab by getting a good speaker in there that is made for a sealed cab and can handle the LF power, but it won't break up nice like you want it to. If you keep the current speaker in there and play it into breakup, I'm afraid it will die.

    You might get close to the distortion you like with effects pedals or a more expensive amp.
  3. mbelue

    mbelue Supporting Member

    Dec 11, 2010
    If you can measure the internal dimensions of the speaker cavity it might be possible to just swap in a speaker that would handle bass guitar if you can seal it up.

    Looks like that has a 5 ohm speaker already so most likely the amplifier can handle any speaker greater than that and likely 4 ohms as well.

    As stated before you might get something that sounds nothing like what you are looking for.
  4. Stumbo

    Stumbo Guest

    Feb 11, 2008
    Do you mean you're turning up the amp and the speaker is distorting? Or is there a distortion setting on the amp that you like?

    If it's the speaker distorting, yes it will go out sooner rather than later. Changing out to a bass speaker will not give you the same distortion.

    What's your bass rig? Which bass do you play? Adding a distortion pedal to your bass rig is probably the way to go.
  5. Prana Ferox

    Prana Ferox

    Dec 4, 2015
    - Get a Speakon jack like this one: "Neutrik NL4MP Speakon Connector 4 Pole Panel Mount" from!
    - With the amp off (obviously) carefully disconnect the wires from your combo's speaker by pulling the terminal lugs off the terminals. Needle nose pliers help.
    - Plug the wires into the +1 and -1 tabs on the Speakon. With luck the terminal lugs fit right on, or at least well enough not to fall off and short anything. I'd give them a wrap with electrical tape if they're loose.
    - run a Speakon-to-whatever cable from your amp's new output jack to the bass cab of your choice.
    - See if you actually like the sound of your amp through an actual bass cab. From there you can determine how much effort you want to put into building a bass combo with it.

    If executed correctly (i.e. don't fry the amp or mangle the connectors) this would be quickly and 100% reversible.

    E: you also have the headphone / recording out jack which you could use to run to a proper bass combo. Frankly at the power outputs of this amp I'd just use headphones to get better bass and call it a day.
    Last edited: Apr 6, 2018
  6. I like the distortion setting on it, it gives off a motorhead kind of sound. I use a Ric 4003s and split the signal to go to a hartke b900 combo, and the other through some effects to the zoom
    BadExample and Stumbo like this.
  7. BadExample


    Jan 21, 2016
    In that case, if you do like the sound of the head, like was stated above, post up the volume and see if we can find a bass driver that works.

    It should be well sealed and you will need to get the speaker wires up to the head, so you might need a "dish" or back plate with an output connector. There's also a fair chance you'll need some internal bracing added to the cab. I'm guessing you're going to be close to 2 cu ft in your combo if it's about a foot deep. Most 10" drivers will want a smaller sealed space for that. You could shrink the box and add some bracing with vertical panels on each side of the speaker.

    If you want to do some reversible testing, and if the back of the cab is flat, use window weather stripping to seal the back and screws to secure it.

    If you want to start hunting for speaker candidates, look at 10" 4 and 8 ohm, open the spec sheet and look at the volume "requirements" under "mounting information." While there, take note of the required hole size. It will be under 10" and may or may not fit your cab's existing hole.

    I would start with Eminence, because they give full and honest specs and building plans that you can look at for an idea of how it might perform. I suggest 8 ohms, because once you're hooked, you're hooked and you might decide to build a matching extension cab. 4 ohms if you are absolutely sure you will never want a second cab.

    Guitar Speakers & Bass Guitar Speakers in the Speaker Components Department at Parts Express | 37

    One of the first two listed from the above link just might be the ticket:

    On sealed box size, the smaller the box, the more control of the cone, the tighter the bass. Larger, less control, deeper bass, but can get flabby and (not so much worry with a 30 watt guitar amp) reduce the safe wattage for mechanical limits. See the first plan for a sealed 1 x 10:

    Close to a cu ft, 75 Watts safely and an F3 of 70 Hz. I think good for a 4 string. If your not boosting the bass a bunch with pedals, you might even try it at 2ish cu ft, or whatever the box size comes to with a back added. I might even put on my asbestos flame suit and suggest trying it open back.

    Put it in a corner if you can, or close to a wall if you can't get a corner; good, safe, free (or very dangerous and expensive is it results in a divorce) bass extension.

    Ignoreing the above hoopla:

    Alternate approach... Pinging @honeyiscool ! His OP states he likes the sound, but fears damaging the speaker. 30 Watt amp I think, how about a higher wattage guitar speaker as opposed to all the redesign work for a bass speaker? Got Suggestion? I think an HPF might be in order and maybe an 8 ohm 100 Watt RMS Celestion would be better suited to handle the mechanical stress? You be knowin' more than me for sure on this.
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