Replace drivers- 4 ohm to 16ohm?

Discussion in 'Amps and Cabs [BG]' started by pisces_bass, Jul 9, 2019.


  1. pisces_bass

    pisces_bass

    Jun 8, 2019
    Central WA
    My SWR Goliath III Jr 2x10” 4 ohm cab has one damaged driver. It’s probably 25 years old so I can’t complain too much. A friend who is handy with cabinet builds is offering to swap out with a pair of Genz Benz 10” drivers (likely 16 ohm)

    We’ve talked about trade offs that come with going this route vs dropping some $$ on Eminence Legend CA10’s. Other than changing the load on my amp (Quilter BB800) and not getting quite as loud (I don’t do high volume gigs anyway) are there likely to be any problems with this experiment?

    I will use the cab as an extension for my Bag End SD15 for outdoor gigs.

    **Post edited to remove obvious technical inaccuracies **
     
    Last edited: Jul 9, 2019
  2. Kriegs

    Kriegs

    Feb 14, 2018
    Recone or replace? Those are two different things :thumbsup:
     
  3. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    Vestal, NY
    Received a gift from Sire* (see sig)
    It ain't the cone, it's the coil.
     
  4. I've never seen a 12 ohm voice coil. Are you sure it isn't a 16 ohm that someone was assuming the DC resistance is the actual impedance?
     
    Paulabass likes this.
  5. pisces_bass

    pisces_bass

    Jun 8, 2019
    Central WA
    My bad. I’m talking about swapping out the drivers.
     
  6. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    This would be an interesting trick, since there are no 10" Genz Benz driver models available in 12 ohms...
     
    Last edited: Jul 9, 2019
    chadface and pisces_bass like this.
  7. pisces_bass

    pisces_bass

    Jun 8, 2019
    Central WA
    Hmmm. Train wreck in progress here, I see. Let’s assume the drivers are 16 ohm.
     
  8. Paulabass

    Paulabass

    Sep 18, 2017
    Assuming he measured the drivers with a VOM, those would be 16 ohm. speakers. He could make you an 8 or 32 ohm cabinet.
    The much bigger problem is- Do you know all the parameters of the speakers, and cabinet, and know that they will work together? Replacing speaker willy-nilly is usually a disaster.
     
    dan1952 and BassmanPaul like this.
  9. seamonkey

    seamonkey

    Aug 6, 2004
    so you have a Quilter and you're looking to cheap out on a cabinet with some unknown drivers tossed in, and no info as to if they are fit for the box.

    I'd suggest going for a new cabinet designed around a new set of drivers. You and your Quilter would be happier.
     
    MattZilla, mcnach, dan1952 and 4 others like this.
  10. pisces_bass

    pisces_bass

    Jun 8, 2019
    Central WA
    Thanks all. I think I have my answer. As the saying goes...education is expensive (but ignorance is more so).
     
  11. I think the success rate is higher with 15's but I am certainly 0/1 with upgrade 10's that ''should be fine'' and wheezed like an asthmatic baboon in my SWR JR.
     
    pisces_bass likes this.
  12. Have you looked into reconing what’s in the cab now? The result is more likely to be good than replacing the speaker with something that’s a genuinely different animal (i.e. with characteristics that don’t match the cab). Besides, you just might be able to get the impedance you want/need with reconing.
     
  13. pisces_bass

    pisces_bass

    Jun 8, 2019
    Central WA
    Following up. This was the problem:
    A4530735-CBD0-4287-8D02-39608D96033C.jpeg

    I was ready to let the cabinet go but my friend with the speakers was keen to try a swap. So he did it.

    My “new” old cabinet:
    7E5C3AFF-B931-4718-BE7A-B4DE693E149A.jpeg

    And the stack. I haven’t had it up to rehearsal volume yet but it sounds good so far. Need to see how it does with other players in the room. I may have lucked out.
    F476B9B5-9221-409A-ABC6-A4A06352942A.jpeg
     
  14. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    That's the classic case of way too much power for those PAS drivers... 150 watts RMS was pretty much the mechanical limits at low frequencies. There was so much stress on the cone that it collapsed under excessive excursion. If one is bad, it's almost certain that there's damage to the other.
     
    BassmanPaul and pisces_bass like this.
  15. I am guessing he replaced both. If it works you got lucky. Nice improvement in the impedance so long as he wired two 16 ohms in parallel.
     
  16. pisces_bass

    pisces_bass

    Jun 8, 2019
    Central WA
    Yes, both speakers were replaced. If my rig still sounds good after a few gigs, I will be very happy with the experiment.
     
  17. I see you are set at the 40w output setting on the Quilter. That isn't going to reveal a lot of the port restriction. The Genz drivers are likely Eminence oem similar to what I tried in mine so be on the lookout for extraneous noises as you increase volume.

    The low shelving is in your favour.

    It will be easy and cheap enough to insert a couple of round tube ports and block the slot if it comes to it.
     
    pisces_bass likes this.
  18. pisces_bass

    pisces_bass

    Jun 8, 2019
    Central WA
    Pretty sure I know exactly when the damage was done. The first rehearsal with the BB800 I stayed after everyone else left and let ‘er rip. I had the master up around 500 watts and experimented with using the gain to control volume. Then I plugged into an octave pedal. I won’t be trying that again :D
     
  19. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Yup. Recently I got ripped by a TB member for using the term "momentary lapse of good judgement and common sense", something I have said many times before. He insisted that it was insulting but your experience is exactly what I was referring to and is not made in a disrespectful way.

    This kind of damage happens all the time, I deal with it on an almost daily basis, and mistakes, errors in judgement do happen. The key is to learn from it, some folks do and some seemingly never learn.
     
    pisces_bass likes this.
  20. Probably the only thing that saved the BagEnd from the same end was double the impedance.

    Get to the HPF thread(s). The octaver is an ever present hazard even at modest volume.
     
    agedhorse and pisces_bass like this.
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Jul 25, 2021

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