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Author Topic: Using JBL PRX518S subs next to new QSC KW181 subs?  (Read 2225 times)

Mick Howen

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Using JBL PRX518S subs next to new QSC KW181 subs?
« on: August 01, 2011, 06:30:19 pm »

Hello, I'm not an expert (I've owned equipment for many, many years, but I'm more of a plug and play person).  It seems to me that it doesn't make sense to run JBL PRX518S sub cabinets that are self-powered with 500 watt crown amps next to QSC KW181 cabinets that are self-powered with 1000 watt QSC amps.  It would seem completely sensible to me that the 1000 watt cabinets would render the 500 watt cabinets basically useless unless you limit the ouput on the 1000 watt cabinets.  Am I completely off base here?  Can someone explain why I'm right or wrong?  Thank you so much and be gentle please.  I know I'm not an expert and that's why I'm here asking for your time...respectfully.  Thanks!
« Last Edit: August 01, 2011, 06:39:09 pm by Mick Howen »
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Mike Christy

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Re: Using JBL PRX518S subs next to new QSC KW181 subs?
« Reply #1 on: August 01, 2011, 08:08:29 pm »

Hello, I'm not an expert (I've owned equipment for many, many years, but I'm more of a plug and play person).  It seems to me that it doesn't make sense to run JBL PRX518S sub cabinets that are self-powered with 500 watt crown amps next to QSC KW181 cabinets that are self-powered with 1000 watt QSC amps.  It would seem completely sensible to me that the 1000 watt cabinets would render the 500 watt cabinets basically useless unless you limit the ouput on the 1000 watt cabinets.  Am I completely off base here?  Can someone explain why I'm right or wrong?  Thank you so much and be gentle please.  I know I'm not an expert and that's why I'm here asking for your time...respectfully.  Thanks!

Mick, Your intuition is correct, but not for the reason stated.

The wattage of the internal power amps are not the issue. With sub frequencies it is important to have the outputs aligned, in-sync in layman's terms, basically synchronized or in phase.

You want to use all the same sub cabinets, to assure coherence across the bandwidth. This will give you the best output, without weird unforeseen phase cancellations - which will occur using different cabinets.

With powered boxes, there is no way to tell what the real sensitivity or phase is without using measurement systems like SMAART. This is because 1) they arent published and 2) the built in DSP could perform almost any processing available on the signal.

So, back to your original question, try not to use different subs, unless you are just DJing where it probably would not matter.

I suppose you could use an external DSP to align your subs, but it would be cheaper to just purchase or rent the same types.

Mike

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Mick Howen

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Re: Using JBL PRX518S subs next to new QSC KW181 subs?
« Reply #2 on: August 01, 2011, 08:22:13 pm »

THANKS MIKE! I appreciate you taking the time to respond and your consideration.  I look forward to learning more :)



Mick, Your intuition is correct, but not for the reason stated.

The wattage of the internal power amps are not the issue. With sub frequencies it is important to have the outputs aligned, in-sync in layman's terms, basically synchronized or in phase.

You want to use all the same sub cabinets, to assure coherence across the bandwidth. This will give you the best output, without weird unforeseen phase cancellations - which will occur using different cabinets.

With powered boxes, there is no way to tell what the real sensitivity or phase is without using measurement systems like SMAART. This is because 1) they arent published and 2) the built in DSP could perform almost any processing available on the signal.

So, back to your original question, try not to use different subs, unless you are just DJing where it probably would not matter.

I suppose you could use an external DSP to align your subs, but it would be cheaper to just purchase or rent the same types.

Mike
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ProSoundWeb Community

Re: Using JBL PRX518S subs next to new QSC KW181 subs?
« Reply #2 on: August 01, 2011, 08:22:13 pm »


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