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Can I use an 8 ohm amp into a 4 ohm cab?

Discussion in 'Amps and Cabs [BG]' started by Zaney, Apr 15, 2010.


  1. Zaney

    Zaney

    Aug 17, 2007
    Hampshire, UK
    I've been offered a Hartke 200w amp head cheap but on the back it states 8ohms. My cab is 4 ohms. Is this compatible?
    Thanks for a reply
     
  2. If 8 ohms is the minimum, then NO you cannot run a 4 ohm cab
     
  3. nooooo. id stear cclear of that head anyways.... not enough power to really efficently run anything.

    Save up some cash and shoot for at least another 100 watts. And one that runs 4 ohms
     
  4. Edword

    Edword Supporting Member

    Jun 23, 2005
    Detroitish
    My Traynor YBA-3 manual says I could use one or two 4-ohm cabinets with the 8-ohm amp, but it's a very old valve amp that probably doesn't have much in common with yours.
     
  5. badboy1984

    badboy1984

    Mar 27, 2007
    United Kingdom
    200watt head that can drive one single 8ohm cab is not alot of power.

    I say look for another head that is listed as 4ohm.
     
  6. Turock

    Turock Supporting Member

    Apr 30, 2000
    Melnibone
    I would be willing to bet that head is designed to run at 4 ohms. If it is the 2000 series head, running 4 ohms is the only way to get 200 watts. Does it have two 8 ohm jacks?
     
  7. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    +1, I'd be surprised if that amp isn't rated for 4 ohms.
     
  8. Zaney

    Zaney

    Aug 17, 2007
    Hampshire, UK
    yes it has two speaker jacks. how would I connext to a single input on my cab though?
     
  9. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    With a speaker cable. One output from amp, to one input on speaker cab.
     
  10. Turock

    Turock Supporting Member

    Apr 30, 2000
    Melnibone
    Just run a speaker cable from one of the jacks to your cab. Don't try to run another cabinet (4 or 8 ohms) at the same time.
     
  11. Zaney

    Zaney

    Aug 17, 2007
    Hampshire, UK
    what is the purpose of the amp have two speaker jack outputs?
     
  12. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    To run two 8 ohm cabs.
     
  13. Zaney

    Zaney

    Aug 17, 2007
    Hampshire, UK
    so am I right in assuming it will be ok to run this 8 ohm amp from one speaker jack to my 4 ohm cab?
     
  14. Turock

    Turock Supporting Member

    Apr 30, 2000
    Melnibone
    Most likely, it's not an 8 ohm amp (what is the model?). it has two jacks marked 8 ohms so that you won't try to use two 4 ohm cabinets. It should be fine at 4 ohms.
     
  15. Zaney

    Zaney

    Aug 17, 2007
    Hampshire, UK
    Its a 200w hartke transient model 2000 head removed from a combo.
    I'll find a pic and post
     
  16. badboy1984

    badboy1984

    Mar 27, 2007
    United Kingdom
    i guess is all clear now that his Hartke amp is 200watt rated 4ohm.

    So basically that means you can run two 8ohm cab so it becomes 4ohm to get the full 200watt power or you can run one 4ohm cab to get the full power as well.

    Or you can run one 8ohm cab but you will only get around 100-120watt power.

    DON'T try to run two 4ohm cab or your amp (might be cab) will get some serious damage.
     
  17. Zaney

    Zaney

    Aug 17, 2007
    Hampshire, UK
    here it is

    hartke amp back view.
     
  18. keyboardguy

    keyboardguy Supporting Member

    May 11, 2005
    Here's the Hartke 2000 specs:
    ==================
    200 watts at 4 ohms/120 watts at 8 ohms.
    Selectable tube & solid state preamps. Bass & treble Contour controls. 10-band graphic EQ. Adjustable compression. Effects loop.

    Power: 200 Watts at 4 Ohms
    120 Watts at 8 Ohms
    Selectable Tube & Solid-State Preamps
    Rotary Bass & Treble Contour Controls
    10-Band Graphic Eq
    Adjustable Compression
    Total Harmonic Distortion: Less Than 1% At Rated Power
    Signal-To-Noise: Approx. 70 dBm
    Effects Send & Return
    Bipolar Design
    Passive/Active Input Jack
    Rack-Mountable
    Dimensions: 2U Space, 13" Deep
     
  19. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    What model is it? The Hartke 2000 can handle a 4-ohm load. In fact, it develops its 200 watts of power at 4 ohms, and only 120 watts at 8 ohms. It has two jacks marked 8 ohms, and you can plug an 8-ohm cab in each one. Since the jacks are parallel, you could plug a 4-ohm cabinet into one (but not both) of the jacks.

    Here's a link to the manual.
     
  20. Alex1984

    Alex1984

    Jan 16, 2010
    Vancouver
    Yep. Like many have said, single 8 ohm @ 120W, double 8 ohm @ 200W, or single 4 ohm @ 200W.

    Anything below that, even a 8 and a 4, you risk overdrawing current, causing overheating and ultimately amp failure. But realistically, that's kinda silly, 'cuz mismatching impedance means unevenly distributed power, though it can sometimes be used to compensate for mismatched sensitivity, but it's just too much of a hassle to think about.
     

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