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Can you fool an amp into thinking you are running a lower ohm cab?

Discussion in 'Amps and Cabs [BG]' started by HEADLE, Mar 12, 2008.


  1. I have an older Peavey 400bh mark IV and I want to get a 2x15 cabinet for it however they all seem to be 4ohm. My amp puts out 210w at 4ohms and 300w at 2ohms. Is there a way to fool it into hinking it's running at 2ohms? Maybe put a 4ohm resistor across the lugs in a cable end? This is probably a stupid question but I gotta check.

    H
     
  2. TrooperFarva

    TrooperFarva

    Nov 25, 2004
    New City, NY
    Just buy a second cab, it's the only useful option. You could use a power brake, which is basically a large resistor, in parallel, to get the full 300W from your amp, but then your cab would only see half of that, 150W, so it'd be quieter than if you just ran the amp at 4 ohms.

    Also, in case you were wondering, you can't rewire your cab to get a 2 ohm impedance.
     
  3. Kelly Lee

    Kelly Lee Yeah, I'm a guy! Supporting Member

    Feb 17, 2004
    Marana, AZ, USA
    This has been discussed before. Basically all you will accomplish by using a resistor is create heat in a resistor and see less power at your cab. It's not worth messing with. Other than that, there is no other way with the existing drivers in the cab.
     
  4. Jazzman

    Jazzman

    Nov 26, 2002
    Raleigh, NC
    You aren't going to hear a difference in the extra 90 Watts.
     
  5. Yes you can, it's called a transformer. It's how tube amps get to match a low impedance speaker to the high plate (anode) impedance of the output tubes. The problem is that sufficient power handling equals weight and cost. It'll be cheaper to trade in your current amp and get one more suited to your needs.

    Paul
     
  6. Thanks All, you confirmed my suspicions.

    H
     
  7. anderbass

    anderbass

    Dec 20, 2005
    Phoenix. Az.


    If your really serious about this scenario, you probably could special order a 2 ohm cab from some builders.
    These guys (among others) would probably do it: http://www.lowdownsound.com/customcabinets.htm

    (all you need to make a 2 ohm 2x15 is to correctly equip it with pair of 4 ohm speakers instead of the 8's they usually come with).

    If you were to run across a bargain priced used 2x15 with EV speakers (Mesa Diesel as one example) that happened to need its speakers re-coned, I believe you could have them done as 4 ohm. (possibly other brands too)
     
  8. +1

    You could get a cab with two 4ohm speakers, but getting a second 4ohm cab would give you, well... TWO CABS! lol

    5sg
     
  9. why not 2 2x15's ? should give you plenty of grunt :)
     
  10. NKUSigEp

    NKUSigEp

    Jun 6, 2006
    Bright, IN
    I skimmed through some of the responses you've gotten but just want to add my own for good measure :)

    Adding a 4 ohm resistor in parallel to the speakers would drop the resistance to 2 ohms, but you WILL NOT hear a difference since you have not increased your speaker surface area aka GET ANOTHER SPEAKER CABINET! :D

    Power does not equal volume. Speaker size, number, and efficiency DOES!
     
  11. For what its worth-I have a Peavey 215 cab (4ohm) with part-blown BlackWidows I need to get rid of somehow-maybe the local classifieds(?).
     
  12. CrashClint

    CrashClint I Play Bass therefore I Am

    Nov 15, 2005
    Wake Forest, NC
    DR Strings Dealer (local only)
    If you can afford it, get a new head you will be glad you did!!!

    Back in the very early 80s when I was in college I played in the Jazz Ban. The college owned a Mark III and a Mark IV bass head along with a 215 cab and a 2-118 cabs and they were all Peavey. I absolutely hated the sound of this equipment. I used to bi-amp the Mark IV into the Mark III which powered the two 18" cabs and used the Mark IV to power the one 215 cab.

    We were invited to play a Disney in Orlando. I remember it very clear, we were on a stage about 4 feet high and I :eek:Accidently:eek: pushed the 215 cab off of the stage. To my dismay, all it did was put a dent in the cab. :crying:

    I have never liked Peavey equipment, but they did make some heavey duty stuff back then.

    Honestly, I would recommend getting a new head. If money is a concern, I would pickup a used GK, they are pretty good amps and you can pickup a 600 watt used for about $200.
     

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