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Ohm-age

Discussion in 'Amps and Cabs [BG]' started by Daveypunk, May 12, 2019.


  1. Daveypunk

    Daveypunk

    May 12, 2019
    So I have a 8ohm 400w 1x15 Warwick cab, I run this with a 4ohm amp, it’s okay....

    I’m planning on adding a 10inch 8ohm Midrange driver wired in parallel to increase output and gain more from the amp.

    Is there anyway of adding a horn (similar to the SWR Triad) without messing the Ohm-age about? If so what rating would this and the Mid driver need to be?!

    Cheers
     
  2. Jazz Ad

    Jazz Ad Mi la ré sol Supporting Member

    The word impedance isn't that complicated.

    Mixing a 15 and a 10 at the same impedance isn't wise. They will receive the same power and your 15 will be limited by the 10, which may risk a short life. Another 15 or a 2x10 shall work better.

    Provided a well adjusted filter, horns don't affect impedance.

    The sticky at the top of the amp forum shall help you.
     
    mcnach likes this.
  3. You want a passive crossover, aka filter. The basic nominal impedance will remain at 8 ohms.
     
    Daveypunk and wave rider like this.
  4. I'm about 117 (I thought this was going to be some "dog age" type thing I never knew about).
     
    Last edited: May 12, 2019
    Mingo Sanders likes this.
  5. Pocket4

    Pocket4 Supporting Member

    Dec 9, 2013
    New Hampshire
    Ohmage physics indicate that speaker life is inversely related to the mismatch factor. For example, a chain of a single 8 inch speaker with a 4x10 has a half life of one half gig.
     
  6. mmbongo

    mmbongo Five Time World Champion Supporting Member

    Aug 5, 2009
    Carolinas
    I love the word 'ohmage'! It's like wondering what the temperature is and asking 'what is the coldage today?' :)
     
  7. Rick James

    Rick James

    Feb 24, 2007
    New Jersey
    Don't do that. Look at the fearful 15/6 to see what you should be doing.
     
    bassmeknik and agedhorse like this.
  8. Not a silly idea. A 12/6 even.

    Plan A required buying crossover and 8" anyway. For not a huge extra investment after selling the Warwick you get a premium cab.
     
  9. Wasnex

    Wasnex

    Dec 25, 2011
    I believe the SWR Triad had a problem with blowing up the 10" driver. In order to prevent this you should apply an HPF to the 10" so it doesn't exceed its mechanical power handling limit. While your at it, you might as well apply a complementary LPF to the 15" so you don't get a lot of destructive phase interference in the mids. In other words you probably need a crossover network between the 15" and 10".

    Many bass speakers run the mid range without an LPF, but you will need an HPF to protect the horn. The HPF for the horn could be selected based upon the natural roll off of the mid driver. Or you could go ahead and put an LPF on the mid driver as well, so your system functions as a true 3-way design.

    HPF and LPF sections modify the system impedance. In the filter's pass band, the impedance is low so the amp sees the nominal impedance of the driver. As the frequency approaches the cutoff of the filter, the impedance starts to rise. So when you have complementary LPF and HPF sections, one sections cuts off as the other starts passing signal. The idea is there is a smooth transition of impedance through the crossover region, and the amp sees the nominal impedance of the drivers within their pass bands, unless other means are taken to modify the impedance. For example some crossovers are designed for an 8 ohm woofer and 16 ohm horn drivers, but present an 8 ohm nominal impedance to the amp.
     
    Daveypunk likes this.
  10. two fingers

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

    Feb 7, 2005
    Eastern NC USA
    Welcome to TalkBass!!!!

    The topic of mixing driver sizes and different cab physics can spark some interesting debates around here.

    Here's the short version.

    Frequency response and volume has as much to do with cab physics as it does driver size. So you could actually build an 8" cab that will sound more "boomy" than your 15" cab.

    Mixing driver sizes and cabs might sound amazing. But it might sound like warm garbage. Phase cancellation (I think) AMD several other terms play into it. The sticky up top has a lot of good reading on the subject.

    Hope you get it all hammered out.
     
    lizardking837, Daveypunk and Wasnex like this.
  11. Warpeg

    Warpeg Supporting Member

    Jun 20, 2005
    Ohio
    You are essentially describing the engineering behind the infamous Ampeg SVT-1510HE cabinet. The brilliant minds at Ampeg back in the day thought it would be a good idea to run two very different drivers in parallel with a crossed-over horn. As one might expect, it's difficult to find one of these cabs that doesn't have a blown 10" driver in it.

    Some advice: Ditch the 10" midrange driver idea. Either buy a second Warwick 15" cab, or start over with an adequate 3-way cab (if you're into bi-amping).
     
    gepettus, agedhorse and Daveypunk like this.
  12. I am sure someone in the marketing dept thought it up and his boss agreed it was brilliant. The engineers would have shrugged and got on with it.
     
  13. Sparkl

    Sparkl

    Apr 23, 2011
    Europe
    I laughed hard on this one :D
     
  14. Winoman

    Winoman

    May 15, 2005
    Vienna, VA
    I thought it was going to be an homage to the ohm. :)
     
    Smooth_bass88 likes this.
  15. Smooth_bass88

    Smooth_bass88 Groove it

    "OHMAGE" is not a word! An ohm is a unit of measurement, literally a unit of lectrical resistance.

    Homage on the other hand...
     
    Winoman likes this.
  16. Lowendtech

    Lowendtech Happily trending in my own peculiar direction. Supporting Member

    Ohm’s law is showing its age? A bad design impedes good tone.
     
  17. Wasnex

    Wasnex

    Dec 25, 2011
    IMHO....all of you who continue to bust on the usage of "Ohm-age" need to develop a sense of levity :rollno:.
     
  18. Lowendtech

    Lowendtech Happily trending in my own peculiar direction. Supporting Member

    Got one. A good one too. :cool:
     
    Wasnex likes this.
  19. But is it not also our responsibility as seasoned, knowledgable players to correct inaccurate terms when we see them and to teach where we can? The OP just joined our ranks on Sunday, welcome @Daveypunk, he now knows the correct term for what he is asking about. :)
     
    Jeff Scott and Lowendtech like this.
  20. Wasnex

    Wasnex

    Dec 25, 2011
    If the intent is to be helpful :thumbsup:, otherwise :thumbsdown:.
     

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