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Options for Powering 2 (4-ohm) Cabs

Discussion in 'Amps and Cabs [BG]' started by Poon, Nov 2, 2004.


  1. Poon

    Poon

    May 20, 2003
    Los Angeles, CA
    Okay guys. I've decided that I need to have more speakers going in my live show in order to preserve the life of my speakers.

    I'm going to be powering two Aguilar GS410's. Each cab is a 4-ohm Cab and handles 700 watts RMS.

    My Current Rig is a Euphonic Audio Iamp800
    500 Watts at 8-ohms
    800 Watts at 4-ohms
    1000 Watts at 2-ohms

    and I have a QSC PLX1602 at my disposal as well.

    Should I
    a.) Power each GS410 with the Iamp alone running it at a 2-ohm load. Meaning 500watts into each cab.


    b.) Power one of the cabs with the Iamp 800 with 800 watts running into one cab and have the other cab run through the PLX1602 (Bridged-Mono 1600 Watts into 4-ohms)
    1600 watts into 1 & 800 watts into the other.

    c.) Power one of the cabs with the Iamp 800 with 800 watts running into one cab and have the other cab run through the PLX1602 (Stereo or Parallel 500 Watts into 4-ohms)
    500 watts into 1 & 800 watts into the other.

    d.) Some other option with a different power amp/amp.
     
  2. Nick man

    Nick man

    Apr 7, 2002
    Tampa Bay
    If you need the volume then go with both, otherwise just use the Iamp.

    Thats extra gear to carry.
     
  3. pickles

    pickles Supporting Member

    Mar 23, 2000
    Ventura, CA
    A single GS410 has had plenty of sound for me with 4-500 watts, so I'd think "a" would be just fine!
     
  4. Poon

    Poon

    May 20, 2003
    Los Angeles, CA
    Does it reduce the life of the Iamp to be running it at 2-ohms all the time though?
     
  5. jobu3

    jobu3 Artist formerly known as Big Joe

    Feb 17, 2002
    Mountain Top, PA
    I'd try the iamp at the 2 ohm load first. If that's not enough juice, you can always get one heck of a power amp for it in trade. It should be fine at this as long as you're careful to keep it from clipping, overheating, etc.

    Are you dialing in enough mids to cut? I know it's tough to do with the F1-X, but that coupled with the iamp's super EQ should suffice. Especially when it's running at 1KW. ;)
     
  6. jobu3

    jobu3 Artist formerly known as Big Joe

    Feb 17, 2002
    Mountain Top, PA
    As long as it's not getting dangerously hot, it should be OK. If it couldn't run at 2, the guys at EA wouldn't list it as capable as such...
     
  7. pickles

    pickles Supporting Member

    Mar 23, 2000
    Ventura, CA
    I did notice when reading my QSC's specs that running at lower loads causes the amps THD ratings to go up significantly ... and I have noticed over the years that amps sound different into various loads even after balancing the volume....

    You could try running your iAmp as a Pre into the QSC (stereo) and see if that sounds better.
     
  8. jobu3

    jobu3 Artist formerly known as Big Joe

    Feb 17, 2002
    Mountain Top, PA
    This is all true and I wouldn't recommend cranking the amp like you might at 4 ohms. IMO, the fact that the speakers have doubled will give more volume than the extra 200W or so will. Not to mention the fact that you can stack the cabs to get them closer to ear-level.
     
  9. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    i say go with option a
    in a real world gig situation you probably wont notice the slight increase in thd. Not to mention that your higher wattage options won't give you a significant increase in volume, and only a little more headroom. one grand thru eight tens is gonna be hella loud
     
  10. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    another vote for "a". If the amp gets too hot, get a small fan to keep it cool. I've used those tiny PC fans in the past with good results.
     
  11. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    I've used my iAMP 800 to run 2 ohm loads, and it handles it just fine. Loud as all get out, too. At our last gig, I ran the iAMP 800 into both of my Accugroove cabs (Whappo, Jr. and Tri 210L), and this combo was incredibly good.

    So, I'd go with option A), and if you need more power than that, then to (mis)quote Chief Brody from Jaws, "I think we're going to need a bigger amp..." So, you might want to think PLX 3002 or CA9...
     
  12. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    No, that is not true.

    That would be more a function of the different loads' performance--probably not much of the amps', if at all.
     
  13. pickles

    pickles Supporting Member

    Mar 23, 2000
    Ventura, CA
    Really? Cause is says so in the manual :confused:

    I don't have it in front of me but I think it went:

    8 ohms 0.01% THD
    4 ohms 0.02% THD
    2 ohms 0.1% THD
     
  14. Poon

    Poon

    May 20, 2003
    Los Angeles, CA
    I've read this before as well...Does the same apply to the Euphonic Audio Iamp as well?
     
  15. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    I wrote the manual, and it doesn't say that. ;)
     
  16. zombywoof5050

    zombywoof5050

    Dec 20, 2001
    Well then they must not have posted the one that you wrote on the website, because it's right there (though the figures are different).
    Look under the box at the bottom of page 1.

    http://www.qscaudio.com/pdfs/plxspec.pdf
     
  17. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    The THD specs are on page 2, not on page 1, and they say "Less than 0.01% THD." What are you looking at?
     
  18. pickles

    pickles Supporting Member

    Mar 23, 2000
    Ventura, CA
    I think its even printed on the shipping carton. I'll take some digiphotos when I get home.
     
  19. zombywoof5050

    zombywoof5050

    Dec 20, 2001
    Like I said, look right underneath the box that shows the different PLX models and watts per channel, at the bottom of page 1 (increasing the magnification of the PDF to 150% helps to see it better).
    See it now?
     
  20. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    There aren't any THD specs on page 1. Are you mistaking the power specs as being THD specs?