Does this look right?

CH46ECH46E Posts: 857
Im trying to wire up 3 single voice coil 4 ohm subs on one channel. If i can get 2.7 ohms like this pic shows ill be good to go.

This look accurate? And would all three subs receive the same amount of power? Ok to put them in one ported chamber?



  • FestYboyFestYboy Posts: 3,105
    Ok, so sub 1 and 2 make an 8 ohm load that is then paralleled to another 4 ohm load... To me that becomes something like a 5.x ohm load.

    I could be wrong though.
  • mhardy6647mhardy6647 Posts: 19,934
    It is as the Yboy says in principle, although I think he slipped a digit someplace doin' the arithmetic :(
    Ohm. He is the Law. B)


    Resistances (or Impedances)* in series are additive.
    Rt = R1 + R2 + ...

    Resistances (or Impedances) in parallel follow a rule like this:
    1/Rt = 1/R1 + 1/R2 + ...

    In the illustrated case: R1 and R2 are in series, so Rt for those two is 8 ohms.

    R3 is then wired in parallel to (R1 +R2), so, in this case:

    1/Rt = (1/8 + 1/4)

    1/Rt = 3/8

    Rt = 8/3 = 2.67 Ohms

    * Voice coils passing AC waveforms (music!) are reactive devices and as such the parameter of interest is impedance as opposed to resistance (which applies only to DC circuits or those without inductive or capacitive components). Technically, impedance is called Z and resistance is R, but both quantities obey Ohm's Law :)
  • FestYboyFestYboy Posts: 3,105
    When the doctor speaks, knowledge is bestowed. I neglected the least common denominator (derp).
  • mhardy6647mhardy6647 Posts: 19,934
    Well, you know what they say:
    Give a man a fish, and he is fed for a day.
    Teach a man to fish, and you won't see him for the rest of the weekend.
  • CH46ECH46E Posts: 857
    Well, after looking at all the specs for the class d amps i was looking at, i think i just need to source one more driver and make it 4 and just run two 2 ohm loads.

    Thanks for the ohms law lesson!
  • mlistens03mlistens03 Posts: 2,379
    CH46E wrote: »
    Thanks for the ohms law lesson!


    Main system: Technics SL3200, Shure M97xE, Lafayette LR1100 for tuner, Hagerman Audio Labs Bugle 2 phono stage, NAD C352 integrated, Boston Acoustics VR 2, Boston PV500, generic ICs, and BJC Belden speaker cables.

    Desktop: Dell Precision 690 running iTunes, Yamaha RX-v665, Monitor Audio R90s, Velodyne VA-907, generic ICs and speaker cables.
    I've always thought the goal of high-end audio was not to have your neighbors bang on the wall and say, 'Turn that darn music down' but to have your neighbors bang on the wall and say, 'Tell your friends to go home and you can practice later this week'.
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