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  • Generator for basic wedding ceremony use with PRX system

    Hey all,



    I am getting more of a need to use generators for remote wedding ceremony's who I hire part of my PA system to. The PA hire for a wedding ceremony usually consists of:

    • 2 x PRX612's

    • 1 x small basic mixer such as the A&H ZED60-10FX or Peavey PV8

    • 1 x Wireless microphone - Line6 XD-V55



    The couple of times I have used a generator they have been 4kVA or larger as there are usually a few other things running off it.



    I am looking at either investing in or hiring a much smaller generator to run only the equipment above. The 612M's would often only be at 1/4 volume, usually with some background music being played through an iPod or such.



    I have been looking at the Honda EU20i for this purpose. Would the Honda be beasty enough to run the basic equipment on my list above?



    I'm assuming the 612's would hardly ever pull 1000W each as this rating has been pulled more for a marketing side of things?



    Would appreciate some thoughts on whether the EU20i should be ok to run the above system - really appreciate your thoughts guys. It's 1/3 of the weight and obviously cheaper than the EU30is so I would prefer to go with the 20.



    Edit: If I were to buy one, I notice you can link the EU20i's with another EU20i to double your power. In the event that I needed to run more gear than my usual list, this feature would be handy as I could hire a second EU20i.



    Cheers!

  • #2
    Yes. It looks like the model sold in the USA as the "EU 2000i"; that's the one I plan on getting for my PRX gear. Mark C.
    "Good tools are expensive. Cheap tools are damned expensive."

    Comment


    • #3






      Quote Originally Posted by Miko Man
      View Post

      Yes. It looks like the model sold in the USA as the "EU 2000i"; that's the one I plan on getting for my PRX gear. Mark C.




      Yep - same one!



      Thanks for the comment, makes me confident in that I didn't miss anything obvious! What gear in particular do you plan to run of the generator?

      Comment


      • #4
        The "1000 watt" PRX really has two 500 watt class D amplifiers. The power to the 2" driver in the 612m is limited via the internal processing, and probably never sees more than 50 to 100 watts. Even at full power (which is only typically momentary with music), the generator has sufficent output for two tops. Actual power consumption will typically be substantially less.



        However, it is also my understanding that it is a good idea to have a generator with twice the expected power consumption, in order to deal with the dynamic nature of many styles of music. I have no doubt that a pair of 612m speakers, plus a mixer and some outboard gear will be fine with that generator. For spoken word, I think that I could probably get away with four 612m tops. A pair of tops and two xlf subs for some music is probably the most I would dare try to run at moderate levels, but that's more guesswork than science (at this point). I haven't personally tried that combination, but that seems consistent with what similar threads have suggested.



        Agedhorse, care to weigh in and let me/us know if I've miscalculated? Mark C.
        "Good tools are expensive. Cheap tools are damned expensive."

        Comment


        • #5
          Good choice for the application. Plenty of genny headroom for the intended application.

          Comment


          • #6






            Quote Originally Posted by Miko Man
            View Post

            The "1000 watt" PRX really has two 500 watt class D amplifiers. The power to the 2" driver in the 612m is limited via the internal processing, and probably never sees more than 50 to 100 watts.




            Mark - this was what my thinking was based on as well. I highly doubt these speakers will ever go past 1/2 way volume wise in the application I described and will more often be less. Given the fact that my understanding of the 2" driver was similar to yours, I am comfortable with this.









            Quote Originally Posted by agedhorse
            View Post

            Good choice for the application. Plenty of genny headroom for the intended application.




            An now even more comfortable! Thanks for your input Andy, always good to have someone with your knowledge and experience pitch in with some feedback.



            There is a place in Aussie that seems to have them at a reasonable price at the moment with free shipping and a few extras if bought before Christmas. Might have to treat myself!



            The local hire places seem to hire these for $65ish per day so it wouldn't take me too long to get my monies worth, given that I usually just pass the cost on for generator hire.

            Comment


            • #7
              A 1000 watt PRX - is a thousand watts OUTPUT. Oddly - I don't think that means 1000 watts of "input draw" - for determining amperage requirements of a generator - does it? Asking here - not telling.
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              • #8
                It is interesting - the equation I have always used to figure amperage is volts x amps = watts is this right?



                Using this formula - I would "think" that a 1000 watt JBL PRX 612 operating at 110 volt line current would be drawing um -



                110 x A = 1000 devide both sides by 110 makes it 9.09 amps. But I see on the back of the PRX cabinet pictured on the JBL web site - it is rated at 5 amps.



                Using this formula - I would "think" that my yorkville NX 550 P ( 550 watt ) cabinet - operating at 110 volts would draw um -



                110 x A = 550 devide both sides by 110 makes it 5 amps. But I see on the back of the actual yorkville NX 550 P sitting in my living room that it is rated at 2 amps.



                So - somehow - OUTPUT wattage does NOT equal INPUT wattage for figuring amperage draw?



                (I actually asked a "tech" at yorkville about this one time - and he said "I'm not smart enough to explain it to you - and you're not smart enough to understand".) (But - he said this in a really kind way.) (Then he said something about transformers - that I didn't understand - because I wasn't smart enough.)
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                • #9






                  Quote Originally Posted by Rbts
                  View Post

                  It is interesting - the equation I have always used to figure amperage is volts x amps = watts is this right?



                  Using this formula - I would "think" that a 1000 watt JBL PRX 612 operating at 110 volt line current would be drawing um -



                  110 x A = 1000 devide both sides by 110 makes it 9.09 amps. But I see on the back of the PRX cabinet pictured on the JBL web site - it is rated at 5 amps.



                  Using this formula - I would "think" that my yorkville NX 550 P ( 550 watt ) cabinet - operating at 110 volts would draw um -



                  110 x A = 550 devide both sides by 110 makes it 5 amps. But I see on the back of the actual yorkville NX 550 P sitting in my living room that it is rated at 2 amps.



                  So - somehow - OUTPUT wattage does NOT equal INPUT wattage for figuring amperage draw?



                  (I actually asked a "tech" at yorkville about this one time - and he said "I'm not smart enough to explain it to you - and you're not smart enough to understand".) (But - he said this in a really kind way.) (Then he said something about transformers - that I didn't understand - because I wasn't smart enough.)




                  I guess it's mostly that he wasn't smart enough to explain it. It's really not very complicated to explain in a basic manner.



                  Just as your car's engine can't convert all of the energy stored in a gallon of gasoline or diesel fuel into forward motion, so too all audio amplifiiers are far less than 100% efficient. Some of the electrical power is converted to heat dissipated by the electronics and wiring. If the amp was 100% efficient, all of the input power would be converted to audio output power. But this isn't possible.



                  But wait, you ask, why is it that the nameplate power rating is less, not more, as I implied above? Because the power ratings are based on an audio output less than full power. UL typically tests amplifiers at 1/8 power, and the nameplate input power draw could be based on this. This is because the normal use of the amplifier is with an audio signal. Music doesn't have a constant level...there's a lot more silence than sound than you may think. The amplifier doesn't amplify silence, so part of the time it isn't producing audio output. This is part of why there are so many ways to define audio output....what do you want to look at?...the continuous average power (sometimes sortof described as "RMS"), or the very highest peaks that only happen momentarily, or something sortof in the middle ("music program power")??



                  So essentially, the amp is inefficient, but the input signal is really way less than what the amplifier is capable of handling, so the amp is usually coasting along at far less than what it could produce.
                  Write something...

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                  • #10
                    Hmmm -
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                    • #11
                      It all has to do with peak to average ratios.



                      Music has dynamic range, this dynamic range is typically a factor of (power-wise) 8:1 for non clipped, non-compressed music program. The power supply inside the amp averages the input power and the average output power of an 8:1 program is 1/8 so even if the amp is 50% efficient (typical of traditional class AB amps) it's still 1/4 average input power to rated output power. On some of these powered cabinets, the HF rated power can never bedelivered so the ratio becomes closer to 32:1 of that portion.

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                      • #12
                        Hmm - nothing about transformers at all?
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                        • #13






                          Quote Originally Posted by Rbts
                          View Post

                          Hmm - nothing about transformers at all?




                          Transformer is just a part of the power supply, only plays a small part of the averaging process.

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                          • #14






                            Quote Originally Posted by Rbts
                            View Post

                            Hmm - nothing about transformers at all?




                            Transformer is just a part of the power supply, only plays a small part of the averaging process.

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                            • #15
                              Nods. Average power requirement.



                              Like Craig said - there is a lot more silence in music than I might think.
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