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4 ohm cab + 8 ohm cab, doable?

Discussion in 'Amps and Cabs [BG]' started by vagenisour69, Aug 9, 2003.


  1. vagenisour69

    vagenisour69

    Aug 9, 2003
    Hello, i currently am running a peavey 4x10 cab at 4 ohms, and a hartke ha3500 head. Ive been loking around for a 1x15 cab to get that great tone, only thing is im broke, so the hartke VX 115 is lookin pretty good, only thing is that its 8 ohms. The HA3500 plays 350 watts on 4 ohms and 240 watts on 8 ohms. One, Ive heard its bad to combine 8 and 4 ohm cabs, true? and if not, what would the cab be? 4 or 8 ohms when combined?


    Thanks
     
  2. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    The total load would be 2.67 ohms, but I don't think the Hartke can go lower than 4.
    If your amp is able to take a 2 ohm load, you're fine.
     
  3. Ziggy

    Ziggy

    May 9, 2001
    Orange County, CA
    Hmmm... 2.67ohms???

    Perhaps I'm mistaken, but if the cabs are connected in series, the total load would be 12ohms. And, as most cabinets seem to be, linked in 'parallel' would a total of 6ohms... not 2.67

    Anyone else want to chime in on this one??
    michael s.
     
  4. MJ5150

    MJ5150 Terrific Twister

    Apr 12, 2001
    Lacey, WA
    Ah-Ha!

    I have this same head. You can NOT do what you want to do.

    Sure, the head will run with the 2.67 load on it....prolly for awhile. But, it will eventually turn into a pile of melted plastic, and hot metal on top of your cabs. Even if you do not play long enough to melt it, you will still cause an early death to the head running it at 2.67.

    Do not run those two cabs at once.

    Do not, do not, do not.

    What you want is two 8ohm cabs. Or a different head, like a power amp set-up.
     
  5. bobaloo

    bobaloo

    Aug 26, 2001
    Newport News, Va.
    The correct impedance is 2.67 ohms. It's hard to express the equation here but search for it on the web to get the formula. Just remember that when adding impedances, total impedance will always be something less than the lowest one you are adding.
     
  6. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    Whenever you hook up 2 cabs to an amp or daisy-chain 2 cabs, you're running them in parallel.
    And it's not 6 ohms in parallel mode:

    1/Rt=1/R1+1/R2=1/4+1/8=2/8+1/8=3/8

    Rt=8/3=2 2/3= 2.67
     
  7. vagenisour69

    vagenisour69

    Aug 9, 2003
    if i went to the store and saw that my setup worked i wouldve bought it and then have been screwed out of over 1000 bucks


    thanks
     
  8. dace

    dace

    Dec 25, 2000
    sydney, australia
    if i can remember way back to my electronics class in high school, it would be 2.67 ohms in parallel, but 6 ohms in series.

    vagenisour69, if u really insist on using the 8ohm cab with the 4ohm cab, i suggest u make ur own speaker cable to connect them in series.

    i remember bassplayer had an article on this a while back. hang on, it might be on their archived website...

    OK. ur in luck. here's the url:
    <A HREF="http://archive.bassplayer.com/z2000/0008/ampclin.shtml">Impedance article</A>
     
  9. ihixulu

    ihixulu Supporting Member

    Mar 31, 2000
    getting warmer
    No. It would be 12, since when resitances are tied in series they are simply additive to one another.