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from 4 to 8 ohms

Discussion in 'Amps and Cabs [BG]' started by Hounddog, May 13, 2006.


  1. Hounddog

    Hounddog Supporting Member

    Dec 2, 2004
    Southern, Illinois
    Sadowsky Featured Artist
    I have used the stickys and the search and cant find the answer. I have an ampeg 410 cab. It has all 4 of its 16 ohm speakers wired in parallel. I wired the first and last speaker in series and the two middle speakers are paralleled together. When I check it with a meter it says 8 ohms but I wanted to hear from you guys before I powered this thing up. I realize that if I lose a speaker that is in series with the rest of them then they will all quit. Is this the right way to do this? I got a great buy on an 8 ohm 15" JBL and I want to stick it under the 410 and the two 8 ohm cabs would = a 4 ohm load which is what I want. Thanks in advance.
     
  2. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    16 and 16 in series is 32.
    16 and 16 in parallel is 8.
    8 and 32 in parallel is 16.
     
  3. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PHL
    hmm... i dont think the way you have 'em wired up is a good idea.

    edit: cause i have no idea of what i'm talking about. :rollno:
     
  4. John East

    John East Commercial User

    Jan 10, 2002
    Oxford UK
    Owner of E-Pro & East UK
    Checking the speakers with a meter will measure DC resistance which a different parameter to impedance. DC resistance is normallly lower than impedance.

    [Impedance is AC resistance where the AC (alternating current in the form of a pure sine wave tone) would normally have its frequency specified too, as impedance often has some variation according to frequency in a loudspeaker. Or the nominal impedance may be an average of the impedance across the audio spectrum]

    The other issue with your scheme, is that the power wont be distributed evenly to all LS. Also, it's thought better to wire speakers in parallel as they all get the amplifier output signal directly. Any drivers wired in series receive their signal passed through another driver, which is then not controlled directly by output of the amplifier, in other words not such a 'firm and controlled' drive signal.
     
  5. You aint wired it up for 8 ohm :p
     
  6. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    That's 32 ohms
    And that's 8 ohms. Parallel the two sets and you have around 6.5 ohms, with the paralled pair receiving about 80% of the amps power, the series pair about 20%.

    If you have four 16 ohm drivers you cannot get an 8 ohm load with equal power distribution amongst the drivers. Period. Put things back the way they were before you burn something up.
     
  7. RobertUI

    RobertUI Thumper Supporting Member

    Apr 7, 2005
    Herndon, VA - NoVa
    You simply CAN'T do what you're trying to do without swapping the speakers out with 8ohm ones. Your ONLY bet would be to wire this cabinet in stereo with 2 8ohm inputs. That STILL is going to net you a 4ohm load if you were to use both sides. I SERIOUSLY recommend that you go back and read the sticky's again, and you'll see that speakers are chose for their specific loads. You should also read this http://colomar.com/Shavano/4x12wiring.html because it's got LOADS of important information that should result in you realizing that you should re-wire it the way you got it, and just live with the 4ohm cabinet.
     
  8. With 4 16-ohm drivers the only combinations you will get equal power distribution are the following:

    4 16-ohm drivers in parallel = 4-ohms

    4 16-ohm drivers in series = 64-ohms *almost useless*

    2 16-ohm drivers in series (32-ohms), paralled with 2 16-ohm drivers in series (32-ohms) = 16-ohms *good if you have four cabs wired like this and the power to push them*
     
  9. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    Why is that about once every week on this forum, someone is trying to get their dog to quack like a duck?
     
  10. LucyQuack.
     

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