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4 ohm and 8 ohm together?

Discussion in 'Amps and Cabs [BG]' started by bass2020, Feb 14, 2002.

  1. bass2020


    Aug 27, 2000
    Memphis, TN
    Can you put 4 and 8 ohm cabs together?
  2. YES............

    As long as your head is rated down to 2 ohms.

    A 4 ohm and an 8 ohm cab together will produce 2.67 ohms resistance.
  3. boogiebass


    Aug 16, 2000
    Correction: As long as the head is rated at 2.6 ohms, minimum. You don't need a head rated down to 2.
  4. I stand corrected.....I think.

    I have never seen a head rated at 2.6 ohms specifically. Have you ? What would be the point ? Making a custom head just to handle a combo of 4 ohm and an 8 ohm seems rather dumb.

    All I have ever seen are the even, whole number ratings of 2, 4, or 8 ohm.
  5. Brendan


    Jun 18, 2000
    Austin, TX
    The SWR Power 750 is rated at 2.6 Ohms-

  6. Well......I'll be dipped in sh*t !!

    Maybe I need to get out and look at some of the newer high end gear.

    Just a dumb question.......but why didn't they just make it workable down to 2 ohms. At 2.6 it keeps you from using two 4 ohm cabs. Seems strange to limit you to using 8 ohms cabs or a 4 and an 8 together.

    TheDominoKid likes this.
  7. Hategear

    Hategear Workin' hard at hardly workin'.

    Apr 6, 2001
    Appleton, Swissconsin
    An amp rated at 2.6 ohms sounds kind of asinine to me.
    TheDominoKid likes this.
  8. PICK


    Jan 27, 2002
    Sydney, Australia
    In parallel mode(one cab out of each output) the lower-impedence(the 4 ohm one) cab will hog most of the power and the opposite will happen in series(both cabs out of one output hooked up to each other)
  9. boogiebass


    Aug 16, 2000
    Correct you are, my friend. As is the Bass 750. Very handy when you want to add an 8 ohm cab to the 4 ohm you normally run with (or 3 8's, for that matter). Puts out 850 watts at 2.6 ohms, too.
  10. Ty McNeely

    Ty McNeely

    Mar 27, 2000

    Asinine? Nah.

    I do think it should be selectable to 2, 2.6, 4, or 8, however. If it DOES in fact limit you to 2.6, that's not the brightest, but in no way is it asinine.
  11. No, that's still parallel.
  12. TCollins


    Apr 4, 2000
    If you have a Mesa 400+ that has outlets
    for 2, 4, & 8 ohm cabs ...
    How do you hook up a 8 ohm and a 4 ohm cab?

    Would it be unwise in your opinion to hook an
    8 ohm and a 4 ohm cab to a M-2000 which
    "recommends" a 4 ohm load?

  13. boogiebass


    Aug 16, 2000
    I responded to the other thread you started but the short answer is: run both cabs from the 2 ohm jacks. As to your second question, the answer is yes. If 4 ohms is the minimum recommended load, don't hook up 2.6.
  14. webavant


    Dec 28, 2004

    I have an SWR sm-900 amplifier, a 4 ohm and an 8 ohm speaker. The manual says that it's minimum load is 2 ohms. It also says that although the minimum impedance that the SM-900 is designed to drive safely in the Stereo Mode is 2 ohms (per side), 4 ohms per side or greater is recommended. It also says that connecting multiple enclosures that have a combined totaly impedance of less that 2 ohms per side may result in damage to your amplifier.

    Is this amp/cabinet combination okay? What are the pros/cons? Thank you!
  15. This is the way I've taken it to mean.

    If you're using the stereo mode you should be able to run each channel independently down to 2 ohms. In other words, you should be able to run up to (2) 4 ohm cabinets per channel safely in stereo mode. In bridge mode you can use (1) 4 ohm load- as the amp "sees" the load "halved" in bridge mode.

    So using a 4 ohm cab on one side of the stereo while using a 8 ohm cab on the other side should be fine.

    I've used my SM-900 to push a 4 ohm Triad and an 8 ohm Goliath II. I've also used it with a 4 ohm Big Bertha (generally) bridged. While all these cabinets are well within the operating specs of the amp, and are, in fact, "suggested" speaker combinations in the back of the manual, I have had serious overheating and fuse problems with mine. Although my indiviual amp may be a dud, as many times as it's been in for service, and to as many SWR authorized service centers say it's fine.

    Most of the problems with my amp have been solved with installing a fan in the rack to get the hot air out. The handles on the face still get pretty toasty warm though.

  16. Bongolation


    Nov 9, 2001
    No Bogus Endorsements
    You're right, and that's why I can't understand why SWR recommends this. The 4-Ohm cab will draw twice the wattage of the 8-Ohm cab. A 2.7-Ohm load is easier on the amp than a 2-Ohm load, but running a 4-Ohm and an 8-Ohm cabinet in parallel doesn't make good electronic sense from the standpoint of the speakers.
  17. TRU


    Apr 12, 2002
    Northern Europe
    Unless you have something like 4ohm 4x10" and 8ohm 2x10". That would be a perfect match.
  18. Bongolation


    Nov 9, 2001
    No Bogus Endorsements
    That's a possibility, I guess...seems like it would work, maybe. :meh:

    My problem of course is that I have a "Black Beauty" with a 4-Ohm internal impedance (weird I know, for a 1x15", but it's true) and everything SWR/Pro I've been seeing around here is like 8-Ohm Goliath III, which would be totally backwards from what I'd want to do.

    I also just realized that you can't wire a 8-Ohm G3 for 4-Ohms.
  19. Slipsen


    Jan 11, 2005
    Hello! last friday i buyed a totaly new rigg..with Behringer BX3000T Ultrabass, Behringer BA410 and Behringer BA115..and i know that it is 4ohm in the 410 and 8 in the 115.. and the amp is on minium 4ohm..as i understanded of this posts..that would be no good?i have the 410 connected to the amp and the 115 conencted directly from the 410..
    will this be dangourus?!! after all they did sale the stack with all 3 things in a packet :S
  20. dangerous as in : will I get killed ? NO..
    I had the same problem.. I had one trace elliot head (4ohm) and a 1524 dual 15inch trace elliot speaker (also 4 ohm) so far .. that's ok .. but then I bought another speaker (8 ohm) and I hooked it up and after a session the amp was EXTREMLY HOT !!!! so I just bought another trace elliot head to run the second cab through :bassist:

    So if your amp is 4ohm and you're hooking up 2,6ohm through you're cabs.. it'll work BUT you're amp will have to produce more power that will have no effect on the wattage It will just go in to extra heat = this could become dangerous because you could then just fry your amp if you're not carefull and your amp isn't cooled properly.
  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.

    Feb 28, 2021

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