Turning a guitar combo into a bass combo

Discussion in 'Amps and Cabs [BG]' started by TonH, Mar 18, 2018.

  1. TonH


    Jan 26, 2011
    The Netherlands
    For my Audiovox 736 replica Audiovox 736 replica I was looking for an amp/combo that would be somekind of period correct (6V6 tubes). But not to expensive.

    There are still amps made with 6V6 tubes and the Ibanez TSA15 is one of them.
    I was able to score one second hand. The previous owner already had the stock tubes replaced by tubes of TAD (tube amp doctor).


    It sounded oke with the stock speaker (Celestion Seventy 80) but for bass not good enough.

    Removing the back panel already helped.



    I also ordered an Emenince ALPHA-12A speaker and installed it. The Emenince is even lighter and the magnet isn't as big as the one on the Celestion.

    Now is sounds great. The combo can be used for practice in the livingroom or bedroom.

    And it has a build in tube screamer, that sounds oke on bass (add just a little to your sound).
    Duder, mikewalker and Bassbeater like this.
  2. TonH


    Jan 26, 2011
    The Netherlands
    To close the back for cosmetic reasons, I made a frame, painted it black and put some speaker cloth on it.


    Duder, mikewalker and Bassbeater like this.
  3. BassmanPaul

    BassmanPaul Inactive

    An open back cabinet is OK for a guitar amp but can be fatal when used with a bass. With just about 10W output you could still damage your new driver with no cabinet to support it.
    Urich_jr, spaz21387, MDBass and 3 others like this.
  4. There is a really good reason why there are NO open back bass cabs.
    mbelue, MDBass, Ekulati and 2 others like this.
  5. TonH


    Jan 26, 2011
    The Netherlands
    Could you explain how I could damage the driver? What would go wrong?

    By the way, the Audiovox 936 amp had an open back.
    Last edited: Mar 18, 2018
  6. BassmanPaul

    BassmanPaul Inactive

    Over excursion. Your driver is, in essence, in free air with nothing to support the cone. In conditions like that it doesn’t take much to push the cone too far.

    Changing out drivers is something that some guitar players do all the time. It works at the frequencies they use. Bass cabinets need to have a lot more engineering done to get a satisfactory system.

    Do a search on Thiele Small parameters.
  7. guy n. cognito

    guy n. cognito Secret Agent Member

    Dec 28, 2005
    Nashville, TN
    I turn guitar cabinets into bass cabinets by selling the guitar cabinets.....
    mbelue, tepperware, 4dog and 19 others like this.
  8. TonH


    Jan 26, 2011
    The Netherlands
    I am using a HPF set at 25Hz and not playing at loud volumes. The speaker will be fine.
    Bassbeater likes this.
  9. BassmanPaul

    BassmanPaul Inactive

    Good luck with that then.
    Kro, mbelue, -Asdfgh- and 4 others like this.
  10. Paulabass


    Sep 18, 2017
    I can't imagine this sounding good. There is not one single perameter of the whole design that is right, and a lot that is just wrong. You have created the equivilent of just putting a raw speaker on the kitchen table and playing- it will make a noise...but.
  11. superheavyfunk

    superheavyfunk 音楽は人生だ

    Mar 11, 2013
    The amp looks great! :thumbsup:

    I'm sure it will be fine for living room playing. I've had and used old open-back guitar practice amps for kitchen jams for years and never had one blow. You should still be careful though and remember not to get overeager with the volume. And definitely don't run any drive pedals thru it!

    EDIT: Oh, you might want to turn that HPF up since you've got one. 25Hz is pretty low even for a full sized bass amp. I'd recommend like 80-100Hz... You most likely won't hear the difference anyway, given the nature of the enclosure and the way you plan to use it - plus it'll help keep your driver sounding and playing nice for a whole lot longer.
    Last edited: Mar 18, 2018
    deathness, TonH, tfer and 3 others like this.
  12. Bassbeater

    Bassbeater Guest

    Sep 9, 2001
    For a low volume practice amp, you'll be fine.
    It does look great too.
    Cool project, I bet it sounds great for jazz guitar.
    superheavyfunk likes this.
  13. JKos

    JKos Supporting Member

    Oct 26, 2010
    Torrance, CA
    Why is there always so much negativity when folks do things like this!? You would think no one is ever allowed to try anything different. Ever.

    How do you think new tones have been invented over time?

    - John
    4dog, Barticus and Bassbeater like this.
  14. superheavyfunk

    superheavyfunk 音楽は人生だ

    Mar 11, 2013
    I think a lot of people spend a quite lot of time, money, and thought on their gear and human psychology dictates that all this effort must be justified... I don't think it's all meant to be malicious. It comes out that way sometimes.
    BuffaloBill likes this.
  15. Paulabass


    Sep 18, 2017
    ^^ huh? I said that to my ears, and in my experience, I cannot expect pleasing results.
    That was opinion, and I said nothing negative.
    I did NOT say it would sound bad to HIS ears.
    When I state 'In my experience' that is not completely out of the blue either. I designed, manufactured, and sold over a thousand low frequency units while I owned Magnum Touring Enclosures. I'm no Paul Klipsch, but I must have been doing something right because he sued me.
    Anyone who wants can ignore science, but there really is some design principles to making a good sounding cabinet, and not following them may create a less than ideal cabinet.
    You can also haul bricks in a porsche, and without having done it, I can opine that it is not the ideal tool for the job.
    Last edited: Mar 18, 2018
  16. Lobster11

    Lobster11 Supporting Member Supporting Member

    Apr 22, 2006
    Williamsburg, VA
    Cuz reality. For every hundred new ideas, one is actually better than the tried-and-true, and 99 aren't. This is one of the 99.
    Ekulati and dan1952 like this.
  17. superheavyfunk

    superheavyfunk 音楽は人生だ

    Mar 11, 2013
    Who cares? He's not creating a new product, he's made himself a nice little project that he's proud of. He's said that it sounds great for his purposes, which have been specifically stated as living room and bedroom practice purposes.
    Barticus, TonH, Spectrum and 3 others like this.
  18. Bassbeater

    Bassbeater Guest

    Sep 9, 2001
    Low volume, practice amp. Relax people, no crime has been committed.
    Furthermore, sometimes these "wrong" hooligan amps sound amazing when mic'd up in a studio.
    Last edited: Mar 18, 2018
    knumbskull, Barticus, TonH and 3 others like this.
  19. Marhmol

    Marhmol Supporting Member

    Nov 6, 2016
    Bay Area Ca
    Yeah. More power to um.
    To succeed, one must first try.
    Bassbeater likes this.
  20. two fingers

    two fingers Opinionated blowhard. But not mad about it. Gold Supporting Member

    Feb 7, 2005
    Eastern NC USA
    This. Turn up the hpf. It's doing exsctly zero set that low. A Low E is just over 40Hz to begin with. That will help protect the speaker a little. Be sensible about volume amd maybe even throw a little compression on it. It should make a great knocking around the house amp. Looks sharp too.
    TonH, DrummerwStrings, MDBass and 2 others like this.
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