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I have 2 JBL SRX4725 cabs and 2 JBL SRX4722 cabs - Need Amps

CountryBoyCountryBoy Posts: 2
edited November 2008 in Configuration Wizard
First off, let me say that I am not a Pro Audio anything ..

I have a 4 speakers setup that I know I am not amping correctly so I want the right equipment for the job and am willing to pay for the right equipment... and I want it to be touring quality equipment.

These speakers all sound great .. the 4725's were reconed in 04 and new crossovers were factory installed at that time. The 4722's were purchased at that time and have been the work horses for our \"small hall\" venues ever since.

Here is the information that I have been given in the past, any corrections or advice will be greatly appreciated ..

I was told that the 4725 cabs need to be overpowered by not less than 50% due to the 15\" speakers and that the 4722 cabs need to be overpowered by not less than 30% due to the 12\" speakers. Is this information correct?

This being said..

I assume that since the 4725's are rated at 600W RMS @ 8 ohms each, I need to have no less than 900W @ 8 ohms per speaker supplied by the amp.

I also assume that since the 4722's are rated at 600W RMS @ 8 ohms each I need to have no less than 800W @ 8 ohms per speaker supplied by the amp.

The individual that told me this information suggested that I purchase amps in the QSC PowerLight 3.4 or Crown MA 3600 range.. would the users here agree?

Any suggestions or discussion about this will be greatly appreciated.


  • DraDra Posts: 3,844
    600w RMS / 1200w Prog
    Go with 2x the RMS (or = the Prog) rating of the cab.

    Go here to see what QSC recommends for your rated speaker. Then compare with comparable Crown, etc.
    http://www.qsc.com/products/amps/advanc ... lector.htm

    You can go beyond 2x, but the higher that you go, more attenutation of the amp will be required not to melt your coils. Also you have to have self control if you go with bigger power than 2x.

    So for your cabs, a 1200w @ 8 ohms capable amp will get your speakers as loud as they will go (safely) and the amps will have at least 3db head room to stay out of clipping.

  • GadgetGadget Posts: 4,915
    Ok, you want professional sound...I have a problem right off the bat... those speakers are so different they aren't going to play nice together...Oh you may stand in one spot and hear ok, but move around the room and you'll find nulls, and cancellations .. and even lobes of bass... Unless you have NO OVERLAPPING coverage, you will have these problems..I take it you have no subs...so power IS a problem since you run them fullrange I assume you have a Driverack?

    The speakers should have (by Crown INT) 2-4 times the rated power...Hey Dra... those speakers aren't in the QSC data base that I could find...and no \"this is the closest to them\" since the design is somewhat outdated...and they don't use those drivers any more...Yes I know those and they do require a lot of juice...most JBL's do...The 4719 subs for instance require HUGE power to perform properly..like a MAC 5000 per speaker...Simple \"this amp is best\" statements aren't useful to me...For instance, the new amps that have high tech power supplies don't sound as good as the older super heavy Mac amps...The problem is, I don't think you can tell the difference with those speakers...I'd consider the MA 3600 as an excellent choice, if a bit heavy...I use them.. I love them..but In INSTALLS... not portable sound...They are just too heavy for this old man...

    To get an amp that's capable of 1200-1800 watts [email protected] ohms..is gonna COST you...If I was you, and I wanted to get tour grade amps that are the \"real deal\" I'd look at Powersoft...Now they will as I said COST you. Even in the Digam line the 5000 is only 750 watts per channel @ 8 ohms.. it will however drive your speakers more than adequately...they don't make them any more however.. so to get that kind of power your either going to need to go bridged mono, or spend thousands per amp or settle for less power...

    Well that's the long of it from my point.. questions?

  • DraDra Posts: 3,844
    I put in the rated power for the cab.

    List pricing used here.

    $2500 for (1) RMX5050 1100w @ 8 per pair of cabs.
    $1750 for (2) RMX2450 1500w @ 8 (bridged)
    $1500 for (2) RMX1850HD 1200w @ 8 (bridged).

    Crown, Yorkville, ect have amps that are comparable in output.

  • GadgetGadget Posts: 4,915
    Those won't touch a Mac 3600 though...not even in the same league...the 5050 is gutless unless run 2 ohm stereo...plus it's 230 volt ...the same with the 4050...I know those list more power... but it just ain't the same watts...that's my experience , and I have ALL those amps...same with the Power soft amps.. in a class by themselves...

    Better have some serious edison available with all but the Powersoft too...they are all power hungry. Maybe the QSC PL380, plx 1802...bridged...Or cheapest Crown XTI 2000...less weight, more power... less juice...
    my $.02
  • DraDra Posts: 3,844
    Ah, there's the rub. To get a 3600 you HAVE to buy used or spend BIG money getting a SINGLE production run SE version. Best sound but at the cost of tons of required AC.
    Wouldn't it be great if someone would make 200w @ 8 base amp that like a computer could have power module plug-ins. Need 3 db, add another 200 watt \"stick\". Need more, buy the 1000w'er. 8)

  • GadgetGadget Posts: 4,915
    Yes... I did point that out...but they are still making the Mac 3600vz ...and they have a high tech version thats supposed to really be something... (Mac 5000 i)and again if cost wasn't the issue, but commercial tour audio were the issues my list...
    Lab Gruppen
    Peavey...like amps...

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