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Power Amp Suggestions, Enough Power?

Discussion in 'Amps and Cabs [BG]' started by Bassy Davy, Feb 24, 2003.


  1. Bassy Davy

    Bassy Davy Supporting Member

    Jul 5, 2002
    Austin, Texas
    The main thing for me is that I don't want to get something that's underpowered. I have 2 cabs:
    SWR Goliath III Jr. 2-10, 350 RMS, 8 ohm
    SWR Son of Bertha 1-15, 350 RMS, 8 ohm

    I'm looking at the QSC line and I don't have much cash, so I'm looking at RMX's. I need the versatility to run either cab by itself or both together. If they're both together then that's a 4 ohm load.

    If I bridge the amp to run at 4 ohms (2 ohms a side?) is there a concern about over-heating? The RMX850 bridged @ 4 ohms is 830 watts, and at 8 ohms it's 600 watts.

    Will this give me enough clean headroom or should I get more power?

    Oh yeah, the loudest setting that I play in is a fusion type of a band (think Jeff Beck).

    Thanks
     
  2. secretdonkey

    secretdonkey

    Oct 9, 2002
    Austin, TX
    Hey, my grandmother lives in Round Rock. I know this may sound obvious, but the amp specs you're citing already exceed the limits of the speakers you have. If you're careful, you can probably get away with running the setup you describe, but I wouldn't go with even more power unless you were going to upgrade the capacity of your speaker complement.

    That much power ought to get you through most anything. I'm from the school that 'more is more' and my rig reflects it, but I've run 650 watts through a single 4x10 (with PA support for FOH) and found it adequate, if not perfect, on a large stage/venue about the size of the old Liberty Lunch in Austin (I know it's long gone, but that's the only handy comparison I can offer as I've been away from that area for 10 years).
     
  3. ZuluFunk

    ZuluFunk

    Apr 14, 2001
    Pennsylvania
    Running it bridged really won't give you any more noticeable volume than running it stereo, just more potential power.
    The RMX 850 will push 200w to each cab in this set up. IMO, pretty good power and you should get enough to play at higher volumes with out losing too much signal (unless you play low).
    In bridged mode you will have the power capacity that runs beyond the cabs' ratings.


    When you're running bridged you don't run "per side".
    Running bridged you'll have to wire the cabs together. In that case you'll have a 16ohm or 4ohm load depending on whether you set it up series or parallel, but they aren't on independent channels.

    One advantage running stereo with the set-up (210/115) you have the ability to balance the 115 and 210. If they are receiving the same signal, the sound you get will be dominant on the 115. Mono you can't adjust that...stereo you can push or suppress the signal on one side at a time.

    Look for Bob(QSC) for his recommendation, but I don't think you'll get the volume difference you expect, just more clean signal.
     
  4. Bassy Davy

    Bassy Davy Supporting Member

    Jul 5, 2002
    Austin, Texas
    SD- Thanks for the reply. RR has grown a lot in the last 10 years, your grandmother will tell you.

    Zulu- Thanks for the insight.

    Should I look for something that's rated close to 350@8ohms? Or is that too much power going to each cab? I apologize for all the questions, thanks for the responses.
     
  5. ZuluFunk

    ZuluFunk

    Apr 14, 2001
    Pennsylvania
    I tried to get enough power to match the peak handling of each cab. I know I have the potential of blowing the cabs that way, but I've never pushed the output on my amp to more than 1/2 and I've never had the gain on my pre past 3 o'clock.
    On the other hand, I know I'll never push my amp to overheat.

    Others have different feelings.

    BTW - I use the RMX 2450.