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  • Question about powering subs.

    Still working out our PA tweaks and I have another question.  I have two subs I need to power.  One is a Peavey 118 and the other is a Yamaha Club SW118iv.  

    The Peavey is rated at 400/800 and the Yamaha is rated at 500/1000.  I will be powering them with a QSC GX7 which is rated at 725W per channel into 8 ohms or 1000W per channel into 4 ohms.

    If I run each sub on its own channel, they will be getting 725W each if I max them out.   If I daisy chain them both on one channel, each will get 500W.

    Question is, given that from what I've learned, speakers can be overpowered safely within reason, would I run a realistic risk of blowing one of the subs if I push 725W into each one or should I be ok as long as I don't push the amp close to clipping? 

    Or should I just play it safe and run both daisy chained on one channel so each gets 500W and is well within the power ratings of the speakers?

    BTW, this will be used for a classic rock band.  No real heavy hip-hop type bass or anything like that.  Just a live kick drum and bass guitar. 

    Current gear:
    A whole bunch of stuff!

    Hear me play at my Soundclick music page. Here.

  • #2

    Daisy chain and give each 500, better to be slightly over than way over. I know the pv is 8 ohm box assume the yamaha is as well, I have no experience mixing subs in a parallel config re sound quality but I would think it would be just fine curious as to others thoughts on mixing subs in parallel.

    Also if you daisy chain you free up one channel for other things, monitors etc since stereo is not necessary for a band mix scenario.

    QSC ratings are real, if you OP either of those subs probably going to cost more to replace those drivers than than the net investment you have into them. 100 watts over is about the headroom you want not 400 watts over.

     

    Comment


    • #3

      500W is not "well within the power ratings of the speakers". The Peavey driver is rated at 300wrms and the Yamaha at 250wrms. At 1.5x (which is pushing things) the Peavey shouldn't get more than 450w and the Yamaha more than 375w. I personally have powered PV118's at 500w with a GX5 but I understand the risk and am willing to replace the drivers if things go wrong. Why on Earth are you using a GX7 anyways?


      "We Have Met the Enemy and He is Us" - Walt Kelly​

      Comment


      • guitarman3001
        guitarman3001 commented
        Editing a comment

        RoadRanger wrote:

        500W is not "well within the power ratings of the speakers". The Peavey driver is rated at 300wrms and the Yamaha at 250wrms. At 1.5x (which is pushing things) the Peavey shouldn't get more than 450w and the Yamaha more than 375w. I personally have powered PV118's at 500w with a GX5 but I understand the risk and am willing to replace the drivers if things go wrong. Why on Earth are you using a GX7 anyways?


        The peavey is rated 400 program/800Max.  The Yamaha is rated 500 program/1000Max.  The QSC's wattage rating is for program.  I confirmed this directly with QSC.  The amp matches up very well with the speakers' ratings, especially if I daisy chain them both on one channel.  If I run them on separate channels, they will be a little overpowered but my understanding is that it's ok to run the speakers slightly overpowered considering you will rarely, if ever, push the amp to its max output at a sustained level.  

          Anyway, we actually have a few amps. The one we're using right now is a Crown XLS802 but the GX7 is lighter and slightly more powerful so we're going to end up either replacing the Crown with the QSC or adding the QSC as a dedicated amp for the subs.  The reason for the QSC in general is because it's lightweight, powerful, and I got it at a price I couldn't refuse.  I got it brand new for less than you can buy a refurb one for. 

        But based on the amp and speaker's rated wattage, it seems like a perfect match, especially running them daisy chained.  I'm just wondering if it's reasonable to run them on separate channels at 725W or if that's likely to smoke one or both of the speakers.  So far from the advice here it looks like I'll be safer daisy chaining them so it looks like we'll end up replacing the Crown with the QSC instead of adding it as an additional amp.  I'll use the second channel to run the mains.  


    • #4
      You completely misunderstood QSC's response. You are confusing what program ratings mean. Unfortunately, this is common with QSC's marketing approach but is good for recone shops...

      I would suggest no more than a GX5 for those speakers.
      -------------------------------------------------------------------------------------------------------------------------------------------------------------------
      Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

      Currently product development engineer: Mesa Boogie

      Comment


      • RoadRanger
        RoadRanger commented
        Editing a comment
        agedhorse wrote:
        You completely misunderstood QSC's response.

        Hey AH, you forgot the appropriate smiley:


      • guitarman3001
        guitarman3001 commented
        Editing a comment

        agedhorse wrote:
        You completely misunderstood QSC's response. You are confusing what program ratings mean. Unfortunately, this is common with QSC's marketing approach but is good for recone shops...

        I would suggest no more than a GX5 for those speakers.

        Here's what I emailed them -

        I am trying to find out if the wattage ratings listed in the spec sheet on your website for the GX7 are RMS or peak wattage.

         Per the specs in the spec sheet:
         8 ohm w/both channels driven = 725 Watts per channel
         4 ohm w/both channels driven = 1000 watts per channel
         It

    • #5
      RMS, their sales recommendations are based on program.

      This is where marketing folks should leave the heavy lifting to the engineers.
      -------------------------------------------------------------------------------------------------------------------------------------------------------------------
      Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

      Currently product development engineer: Mesa Boogie

      Comment


      • guitarman3001
        guitarman3001 commented
        Editing a comment

        agedhorse wrote:
        RMS, their sales recommendations are based on program.

        This is where marketing folks should leave the heavy lifting to the engineers.

        Not sure I understand.  Are you saying that given a Crown and a QSC with essentially the same power rating (in this case the amps I'm talking about), the QSC will be functionally more powerful because of the difference in the way Crown and QSC rate the power output of their amps?

        Or are you saying that QSC's recommendations are based on program?  If that's the case, then the program rating for the GX7 and the subs in question seem to match perfectly as long as I daisy chain them on one channel.  

        I'm starting to get confused......


    • #6
      For what you were willing or able to spend, it's the best option. It's likely that you didn't understand that the best option was not adequate to your expectations

      I agree with don that quality powered speakers (not cheap powered speakers) are your best bet.
      -------------------------------------------------------------------------------------------------------------------------------------------------------------------
      Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

      Currently product development engineer: Mesa Boogie

      Comment


      • guitarman3001
        guitarman3001 commented
        Editing a comment

        agedhorse wrote:
        For what you were willing or able to spend, it's the best option. It's likely that you didn't understand that the best option was not adequate to your expectations

        I agree with don that quality powered speakers (not cheap powered speakers) are your best bet.

        I think it'll meet my expectations.  We were managing ok with the single Peavey sub but needed something to beef up the low end a little bit and give us a more balanced sound throughout the entire room rather than having the bass be significantly stronger on one side of the room, which is what was happening with the single sub.  The additional sub should suit our needs ok.  My biggest question was just what's the best way to power them and if running them with 725W each was going to be too much.   I will be daisy chaining them on one channel so each one gets 500W.  Hopefully given their advertised power capacity they should be fine.  

        BTW, interesting to note that I have been running our current sub and crossover pretty much exactly the same way Roadranger ran his Peavey setup.  I have the low output on the x-over turned up to about +6db.  I expect I'll have to run it like that even with the second sub but hopefully it should give me a little bigger sound with the additional sub. 

         


    • #7
      I had seen a spec sheet on the SW118 Yamaha that suggested it might be a 4 ohm cabinet. An 8 ohm cabinet will have a DC resistance of about 6 ohms.

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