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Converting a 4 Ohm cab to 8 Ohm. Worth it?

Discussion in 'Amps and Cabs [BG]' started by tspallone, Mar 12, 2013.


  1. tspallone

    tspallone

    Oct 13, 2011
    Nanuet, NY
    After posting and reading a bunch of things on impedance, I feel that I am now an expert!!!!! ok, maybe not.

    But, here's my idea. Please offer insite and thoughts.

    I have a really nice Peavey 1 x 15, 4 ohm (500w?) cabinet. I actually would love not to eff with it. BUT, I need a 1 x 15, 8 ohm cabinet and, not that it's a money thing, but really, how many cabinets is one person going to keep hanging around?

    What I'm thinking is to have a dual 1/4" input on the back of the cab where one input goes direct to the speaker (4 ohm) and the other input interrupted with a 4 ohm resister in series to make an 8 ohm.

    Is the heat disipation, along with the cost of a 500w 4 ohm resister worth it?

    Or,should I just bore ahead and either buy a 400w-500W, 8 ohm(my amp puts out 450W to 2 8ohms or 1, 4 ohm) speaker and replace the 4 ohm speaker in the Peavey cabinet or, just find another 8 ohm cabinet on ebay/craigslist?

    Just trying to do the most with a little.

    Thanks for telling me your thoughts.
     
  2. Forget about adding resistors. Search if you want explanation, it's not an uncommon crazy question.

    What's wrong the 4 ohm 15 as it is?
     
  3. A complete waste.....

    Whatever reduced wattage output you will get at 8 ohms will now be cut in half again it will be split evenly between the speaker and the resistor/space heater.
     
  4. Jaco who?

    Jaco who?

    May 20, 2008
    If you really want to keep it, someone around here compiled a pretty decent list of 2Ω capable heads. search.
     
  5. tspallone

    tspallone

    Oct 13, 2011
    Nanuet, NY
    Perfect. Thanks. That's what I thought.

    Downunderwonder - there's absolutely nothing wrong with it. I rather like it. It's just that I'm trying to put together a stacked rig where my 450 w goes to two 8 ohm cabinets. I already have the 4x10 8 ohm cab and I need a 1x15 8ohm cab to pair it with.

    Ok, looks like I'm shopping for a 15" 8 ohm speaker.

    Thanks for all your insight.
     
  6. That is a bad combo of cabs for a number of reasons.

    If you have to "shop", might as well be for a match to the 4X10 you already have.
     
  7. basscooker

    basscooker Commercial User

    Apr 11, 2010
    cincy ky
    Owner, Chopshopamps.com
    ya might as well get another 8 ohm 410, or get an 8 ohm 115 cab and find an 8 ohm driver for your current cab (if that driver has an 8 ohm version). either way, i'm confident that the advice on here regarding 410/115 is solid. it's just a gamble. it might work well for a given room, but there's just as much chance that it won't work well for any room.

    also consider the 2:1 "rule" with bass cabs. depending on how you eq, you should keep the "power" rating on the cabs 2x (+/- a little) the power your amp is rated for. for example, with an amp that has a rating of 450 watts, a pair of cabs (with the same #of speakers, the same impedance) should add up to about 900 "watts". although in the real world, you could still expose these cabs' physical limitations with a 200 watt amp and a badly smiley-faced eq.
     
  8. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    It is not worth pairing a 15 with a 4x10. It will always be a weak link and subject to being blown. If you want a second cabinet, add an identical one to what you have. that way there are less chances of an undesirable pairing.
     
  9. Bassamatic

    Bassamatic keepin' the beat since the 60's Supporting Member

    First, the resistor would be huge - it would have to handle at least half your power. and it would get HOT - how would you mount it and shield it??
    Second - that half of your power would go up in heat - what a waste!

    Just -
    Buy a new cab or
    Replace the driver with an 8 Ohm version.
     
  10. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    No, you don't. :) As the other guys said, you need another 4x10. You'll get far more low end strength that way, than by adding a 1x15.
     
  11. The OP didn't ask about mixing cabs, only changing the impedance of an enclosure. I would stay away from the resistor method. If the Peavey is a Black Widow or Scorpion, you can simply buy the correct replacement basket in 8 ohms and use the existing magnet. If not, just purchase an 8 ohm speaker appropriate to the tuning of the enclosure......or get a fearful :ninja:
     
  12. Mystic Michael

    Mystic Michael Hip No Ties

    Apr 1, 2004
    New York, NY
    Yeah. That means he got some great free advice - without even having to ask for it. :meh:

    Ain't TalkBass grand? :smug:

    MM
     
  13. "resistor method" implies some validity to that crazy scheme, there is none.
     

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