GXD 4 for tops and GXD8 for Subs pre sales advice needed.

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  • Hi guys I'm looking for some advice regarding power amps particularly the GXD 4 for my 2 tops and GXD 8 for my 2 subs

    Best get this bit out the way first I don't have a great understanding of power amps I'm very much a studio guy it's how I make my bread and butter I've never really had to deal with live sound rigs that haven't been pre installed.
    With that said I've bought some speakers and would really appreciate the advice but keep in mind some of what you say may confuse me I just need to make sure I'm getting enough power for the speakers I purchased.

    This is for a small sized 150 - 200 sized hall for drum reinforcement and such

    My speakers are a pair of
    2 full range
    15 inch
    400w Continuous
    800w Program
    8ohms each

    2 subs that are 18 inch each
    8ohms each
    1000w RMS each
    2000w Program ( Peak ) each

    I was advised to consider the GXD 4 for the tops and GXD 8 for the subs but on second look I'm confused by the difference of 8ohm dynamic against 8ohm continuous?

    Are my subs going to be getting 1500w per channel ? I've been told that's enough as I'm trying to reinforce the sound not break ribs.

    Same for the tops will they be getting 600w per channel ?

    I'm having doubts now after noticing the dynamic and continuous.

    This would be my choice over the GX 5 and 7 as I was lead to believe I'd get more out the system ?

    Any advice would be greatly appreciated before I order in the morning as I need to be up and running asap.

    Thanks to all in advance :)
    DrumBum
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  • Yes, those amps would be reasonable choices for those loudspeakers.

    Of the two GXD models, the power rating of the GXD4 (600W into 8Ω) is closer to the program power of the top loudspeakers, and the GXD8 (1500 W into 8Ω) is closer to the subs' program power rating.
    Bob Lee
    Technical Communications Developer
    QSC, LLC
    Fellow, Audio Engineering Society
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    "If it sounds good, it is good." —Duke Ellington
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    Bob Lee
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  • Thank you Bob ! I really appreciate the reply and have placed a order the GXD 4 for tops and GXD 8 should be here tomorrow I'll use them in conjunction with the DBX Drive Rack PA 2 and hope this is a good combination.

    Would you mind explaining the difference between the Dynamic and continuous rating on the specification chart from the GXD web page ?
    That's causing me confusion as the GX series just says "output power per channel"

    I had previously used the GX7 750w at 8 ohm on the same set of subs but it wasn't at all loud enough continually clipping before getting my mix anywhere around unity gain or reasonable volume and couldn't even reinforce the kick drum so I was concerned.

    Just to clarify you don't Forster any reason that I shouldn't be able to reinforce some drums using the GXD 4 on top and GXD 8 on bottom ? I'm just a little Bergius after needing to return the GX5 and GX7 then pay extra for the 2 GXD

    Once again I really appreciate you taking the time to answer and set my mind at ease.
    DrumBum
    Newbie
     
    Posts: 2
    Joined: Thu Dec 15, 2016 7:56 pm


  • Use the dynamic power ratings of the GXD amps.

    The GX Series amps are class AB, with linear output circuitry. They can be made to run with a continuous tone at the threshold of clipping for at least a short period of time. That could be used to calculate a "continuous" power rating. Keep in mind that this would be a test bench situation that would not happen in real life in a properly designed system.

    The GXD Series use a class D output circuit that is non-linear but has ultra-high electrical efficiency at moderate to high output levels. To protect the output circuitry and the power supply, it has a limiter that prevents sustained, continuous operation at the threshold of clipping, which is why its continuous power ratings are pretty meaningless. To assess what the amp will actually do in an audio system with real-life audio signals like music or voice, use the "dynamic" power ratings.
    Bob Lee
    Technical Communications Developer
    QSC, LLC
    Fellow, Audio Engineering Society
    Image
    "If it sounds good, it is good." —Duke Ellington
    User avatar
    Bob Lee
    QSC Audio Products
     
    Posts: 2518
    Joined: Thu Mar 06, 2003 2:01 am
    Location: Costa Mesa, California



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