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cab/ohm/power amp question

Discussion in 'Amps and Cabs [BG]' started by skunkrawk, Dec 16, 2003.


  1. skunkrawk

    skunkrawk

    Apr 25, 2003
    DC
    ive seen alot of threads asking similar questions and i still cant get a clear answer in my head (sorry). i soon hope to order an avatar 2x12 and an avatar 2x10. id power them with either a carvin dcm 1000 or one the the qsc rmx series poweramps and use a tech 21 sansamp rbi pre (i cant decide whether to get carvin or qsc :meh: ) the question is should i get 4 ohm cabs or 8 ohm cabs? thanks! -dave
     
  2. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    How do you plan to use your power amp of choice...parallel input (one cabinet per channel) or bridged (both cabs on one output)?

    If you'll dedicate a channel to each cabinet, 4 ohm cabinets would allow you to get the most power out of the power amp. If you're going to bridge, then 8 ohm cabinets are the only choice as these amps can't bridge into 2 ohms (two 4 ohm cabinets in parallel present a 2 ohm load to the amp...two 8 ohm cabinets in parallel present a 4 ohm load to the amp).

    Does this help?
     
  3. skunkrawk

    skunkrawk

    Apr 25, 2003
    DC
    i had planned on running them parallel, is running bridged any better or worse?
     
  4. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    Not really better or worse...just different.

    If you run parallel inputs, you can control the volume of each cabinet individually at the expense of less total power being available (if the two power amps put out their max wattage at 2 ohms per channel...and I believe that they do, but I didn't look) because you'd only be able to run each channel at either 4 ohms or 8 ohms.

    Bridged, you only have one active volume control, but you'll get maximum power out of the amp when bridged into a 4 ohm load (two 8 ohm cabinets in parallel).

    Volume wise you might not even hear a difference.
     
  5. skunkrawk

    skunkrawk

    Apr 25, 2003
    DC
    oh ok, thanks alot for the help man. i still cant decide on whether to go carvin, qsc, or crown for power amp. im pretty sure im going rbi for the preamp. anyone care to share some insight?
     
  6. In Flames

    In Flames

    Dec 11, 2003
    Ohio
    Get those Cabs,8 0hms each, Bridge em with QSC 1850 power amp with you're rbi preamp... that'll be good
     
  7. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    I have a PLX2402. It replaced a Crown CE1000. Any of the amps that you mentioned would be very usable...I like my 21 lb. power amp though.
     
  8. skunkrawk

    skunkrawk

    Apr 25, 2003
    DC
    i think instead im going to get two 4 ohm cabs and run them paralell so i can control the volume of each cab individually
     
  9. amos

    amos

    Oct 23, 2003
    SE Portland Oregon
    and just a reminder
    running an amp at 2 ohms creates more resistence on the amp making it work harder and also creates more harmonic distortion.


    I actually just got to use my new rig (close to yours) tonight at practice, and it was spectacular. after the first two hours of playing my rig, the neighbor complained! splendid!

    my gear:
    QSC PLX 1602 (QSC I think is avery durable brand)
    Tech 21 SansAmp rbi
    I'm running two 8 ohm GS112s in parallel mode and its putting out a ****load of sound.

    I have an equalizer I haven't hooked up yet and a dbx 160a compressor in the mail.

    david
     
  10. MJ5150

    MJ5150 Terrific Twister

    Apr 12, 2001
    Lacey, WA
    yeah amos....i heard your blasted rig way up here!!

    turn that crap down man!! :)

    -Mike
     
  11. Just another reminder.

    If the amp is designed to handle 2 ohms, there's no problem whatsoever. It will run a little hotter, but hey, go figure, it's putting out more power!

    And with today's amps, harmonic distortion is practically non-existant to begin with, even at full load and full power. And I doubt you or anyone would be able to descern between 0.001% and 0.1% of THD, let alone if you're playing at 110dB+ sound pressure levels.

    Just my E0.02
     
  12. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    Guys, Skunkrawk is going to run the power amp in the parallel input mode, meaning that each channel will have it's own 4 ohm cabinet to drive.
     
  13. skunkrawk

    skunkrawk

    Apr 25, 2003
    DC
    correct