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Considering amp duty reassignment, thoughts?


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  • Considering amp duty reassignment, thoughts?

    I've been working in a club recently that has a pair of Ramsdell Audio 660R subs (http://www.ramsdellproaudio.com/products/subs/660r.htm). The rest of the system is mine, consisting of JBL MRX512m's for tops and monitors (drum monitor is a JBL VRX915). Currently I'm powering the monitors with a pair of QSC PLX 1602's, one cab per side. The subs are running off of a PLX 2402, also one cab per side. The tops run off of a PLX 3002. I also have an additional 2402 that is currently unused. This configuration is plenty loud and clear for the FOH. My concern is that the monitors may be a bit on the weak side before feedback sets in. I have to crank them pretty hard sometimes to be heard clearly. What I'm considering is rearranging things so that the monitors run off of the pair of 2402's, and the subs run off of the 1602's in bridged mono one cab per amp. This would bump my available power from 300 to 425 watts/channel on the monitors at 8 ohms. It would also bump the subs from 800 to 1600 wpc at 4 ohms. Would this give me any benefit regarding increased monitor volume at lower gain, thereby reducing feedback? Or would there not be enough difference to be worth the trouble? Or am I just inviting calamity?

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  • #2

    I'm not following the feedback issue with the monitors and how it relates to the amps. If you're getting feedback now that's telling you you've reached the limit of practical volume on stage. You either turn down or eq the feedback out. A larger amp won't help. If anything it will hurt as you'll now be able to get louder which will mean more potential for feedback.

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  • #3

    lonotes wrote:

    Would this give me any benefit regarding increased monitor volume at lower gain, thereby reducing feedback? 

    If you end up with the same level you'll end up with the same gain ... so no difference.

    Unless ......

    The only time you will benefit from lower feedback because of a bigger power amp is if you are increasing the gain of a smaller amp because it is not loud enough that would not be necessary with a bigger amp.

    Feedback happens because of "gain" but not because of "power".  But if you were comparing say a puny system  to a system that had enormous what could end up happening is that you may continue to boost the gain on the smaller system even into  clipping in order to get enough level.    The loud parts wouldn't get any louder at this point but if you continue to increase the gain the quieter parts will (average level).  This increased gain will cause feedback sooner.


    With the small difference you are describing I doubt it's worth it.

    Don Boomer


    • lonotes
      lonotes commented
      Editing a comment

      Thank you all for your responses. That's why I love this place.

  • #4
    On today's modern power amps, the limiters prevent the amps from hitting the rails and clipping (for practical purposes) which allows for more latitude.
    Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

    Currently product development engineer: Mesa Boogie