Dismiss Notice

Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

qsc rmx

Discussion in 'Amps and Cabs [BG]' started by thetaurus, Sep 19, 2002.


  1. thetaurus

    thetaurus

    May 28, 2002
    Muncy, PA
    anyone run this power amp at 4 ohms bridged? it's safe to do so right? any bad experiences other than the weight? i'm gonna run one with an svp pro through a 4 ohm peavey 8x10. then sometimes with an 8 ohm 1x15. eventually i'll add an 8 ohm 2x10 to the 1x15. does this sound good? is there much of a wire change required to run the amp at 4 ohms bridged using either a speakon to 1/4 inch, or a 1/4 to 1/4?

    thanks
     
  2. seamus

    seamus

    Feb 8, 2001
    Jersey
    should be fine bridging into a 4 ohm load, totally within spec - I don't have any problems running in bridged mode, but I don't bridge my amp that often just due to my setup and all - bridging into the (2) 8 ohm cabs you mentioned should be fine too since the effective load should also be within spec - since it's your amp though, you may want to check with qsc for a definitive answer

    as far as a wire change, not exactly sure what you mean - my amp has two speakon outputs on the back - not all cabs have speakon inputs, but most every cab out there should have 1/4" inputs - for that reason, I always keep (2) speakon to 1/4" speaker cables on hand - that way, I'm pretty much set to run into any setup - when running bridged, you just need to adjust the DIP switches on the rear of the amp accordingly - in bridged mode, input #1 and gain control #1 will be active
     
  3. ZuluFunk

    ZuluFunk

    Apr 14, 2001
    Pennsylvania
    Is it safe? That depends...
    Which model RMX do you have and what is the power rating on your cabs?

    My RMX-2450 will push 2,400watts bridged mono with a 4ohm load. More potential power than my cabs could handle...so I have to be careful or it won't be safe.

    I'd be plenty happy running stereo with 750 on one channel and 500 on the other because I use an 8ohm 115 and a 4ohm 210.
     
  4. Touch

    Touch

    Aug 7, 2002
    Boulder, CO
    I run a QSC RMX-850 bridged mode into an Acme B-2 (3-way, 4 ohm) cabinet.

    No problems at all. Remember though that the Speakon jack on the QSC is wired differently for bridge mode. There are actually 4 connections in the Speakon jack. For non-bridged use, connect the speaker between the "1+" and the "1-" terminals of the Speakon.

    For bridge mode, use the upper Speakon jack only and connect the speaker between the "1+" and "2+" connection.

    If you buy a "standard" Speakon to 1/4" adapter, it will only work in normal mode. You will need to make an adapter cable for bridged mode.

    Use thick speaker cables. Bridged mode pushes a lot of current.

    The QSC RMX are nice amps (I have 2) but a little on the heavy side... Can't beat the price though.

    Good luck.
     
  5. thetaurus

    thetaurus

    May 28, 2002
    Muncy, PA
    how would i make an adaptor cable to run in bridged mode? can't i just run a speakon to 1/4 inch cable from the amp to the cab? i was told that a simple re-attachment of certain wires inside the amp would do it. i don't know. anyway...i'm getting a qsc rmx 850 that's 2 months old for $200 shipped. what do you think?
     
  6. ZuluFunk

    ZuluFunk

    Apr 14, 2001
    Pennsylvania
    You can also use banana clips. Just hook up to the red terminals and run to the first cab and then parallel to the next. Or just to the first one if it's a 4ohm cab.

    From the looks of what you have, you may want to run two 4ohm loads in stereo mode. Using all of your cabs would bring it to a 2ohm load.


    I'm not sure about this so you ought to check with QSC. I only see specs for either 8 or 4 but not 2ohms run bridged. If you run that 2ohm load (with the 2450) through one channel in stereo mode you'll get 1200watts in that channel. With the 2ohm load split to two 4ohm loads run stereo, you get 1500watts with the same speakers.

    Unless you could run that 2ohm load bridged (which again I don't see specs for) I think you're better off in stereo mode. Of course you could have just either 4ohm load run mono and get 2400 watts, but then it's less speaker area than you'd get running all your cabs so you'll end up being quieter.
     
  7. rok51

    rok51

    Sep 2, 2002
    Crawfordville, FL
    You could always take an end off of your current speaker cable (should be at least 16 gauge) and replace the phone plug with a bananna plug. Then insert the bananna plug into the two red five-way binding posts(the little"flag" on the bananna plug goes to the negative, lower on an RMX, side). Use channel 1 input only and set the DIP switch to bridge mono.

    Kim
     
  8. Touch

    Touch

    Aug 7, 2002
    Boulder, CO
    You CAN run a speakon from the amp to the cabinet. You just need to wire the speakon cable correctly. You can download an owner's manual that will show which terminals to connect to what. You can also use the binding posts.

    Manual is at www.qscaudio.com

    Do NOT run the RMX series bridged mode into a 2 ohm load. 4 ohms minimum load impedance.

    $200 sounds like good deal. New I think the RMX-850 goes for around $300.
     
  9. thetaurus

    thetaurus

    May 28, 2002
    Muncy, PA
    yeah, so...i'm definately not planning on running at a 2 ohm load. what i was saying is that i'd either run my 8x10, or a 1x15 by itself and maybe adding a 2x10 later. only a 4 ohm load bridged though. alright, so i can use a speakon to 1/4 inch cable from the amp the cab. alright...now to figure out how to do the rewiring. and to get a preamp. anyone know of any used svp pro's out there.
     
  10. ZuluFunk

    ZuluFunk

    Apr 14, 2001
    Pennsylvania
    Don't forget, right now with the cabs you have, you can still run an 8ohm 115 on one side and the 4ohm 810 on the other (the beauty of a stereo amp). You are likely going to have to control the power to balance the output. It works well if you want to run a monitor cab for you and/or the drummer. Also, when you get that 8ohm 210, just daisy chain it onto the 115.

    Good luck.
     
  11. thetaurus

    thetaurus

    May 28, 2002
    Muncy, PA
    i'm not gonna be running them together. the only cabinets i would use together are the 1x15 and the 2x10 (which i don't have either yet, just using for referece). i will be running into a 4 ohm 8x10 mainly. when i get my 1x15, it will be for practice in my room...or occasional gigs w/ a band other than my main bands. anyway...i'm sending out for the amp today. i think i'm gonna go with the speakon to the 1/4 inch to connect the amp to the cabinet.
     
  12. patrickj

    patrickj

    Aug 13, 2001
    Baltimore, MD
    Would it be possible to run two 4 ohm cabinets on the amp in bridge mode?
     
  13. ZuluFunk

    ZuluFunk

    Apr 14, 2001
    Pennsylvania
    Only if you can wire them in series so that they consititue an 8ohm load.
     
  14. patrickj

    patrickj

    Aug 13, 2001
    Baltimore, MD
    via a custom daisy chain cable?