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Author Topic: dj sub system questions  (Read 9741 times)

bren collins

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Re: dj sub system questions
« Reply #30 on: July 16, 2015, 12:35:27 pm »

i did 7000 people with a jbl vrx system not with prx's i guess i didnt mention that sorry and how im deploying my prx's is 2 per side with the prx's 725 with a gap in between each speaker then 35 feet back i have 2 more per side 3.3 feet apart flying..... and rob i love that idea never thought of it maybe thats just what i end up doing for this gig
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Thomas Le

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Re: dj sub system questions
« Reply #31 on: July 16, 2015, 01:03:43 pm »

What Scott was trying to say earlier was that the PRX725 is not arrayable IOW those are going 90x45 which means "Hello Comb Filtering!" I admit I'm small peas compared to the rest of the guys here but even with a VRX system for 7k outdoors sounds impossible, you'd at least need VERTEC / VTX and possible some delay fills & stacks for that much on an open field.
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bren collins

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Re: dj sub system questions
« Reply #32 on: July 16, 2015, 03:39:21 pm »

it was 5 vrx boxes per side vrx932's i had custom mounting brackets built for the first 2 speakers to be straight in line with each other then after that start a curve...... i followed that with a delay stack consisting of the exact same setup and then yet another delay stack not the most convenient setup but it worked and it sounded pretty well with 12 peavey sp 218's (i had to rent 4 more for this gig) all clustered in the middle each powered by qsc plx3002's bridged. and as for the comb filtering that is something i see i need to take into consideration for this gig maybe reconfigure or bring a different top system.....
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Thomas Le

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Re: dj sub system questions
« Reply #33 on: July 16, 2015, 03:56:50 pm »

Uh Oh, "custom mounting brackets"???? Better throw those away before someone gets killed! Liability much?

Also, VRX is not designed to be straight boxes, only act as a curve. If you wanted straight boxes, rent proper cabs and not rely on dinky hardware.
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Luke Geis

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Re: dj sub system questions
« Reply #34 on: July 19, 2015, 02:29:56 pm »

15 years of doing this and you have not learned the most basic of math to do what we do? Your mentor left out some very important things. The questions you pose are rudimentary. They are the first things you need to know in order to spec a system for a gig. I can do sound for 7,000 people too using only an 8" EV ZX1, as long as they are running by it single file.

This is easy. I pretty much already told you what your subs are capable of. Leave the SP18's at home and just run the 4 JBL's. Those will outrun your tops anyway. It sounds as if your stuck with a more remote location so bring as few a number of speakers to do the job. The PRX will not splay together well. You could get away with 2 per side at best. If you bring more, set them up as delay speakers. For the love of god do not bring 8 tops and try to splay 4 of them per side............

Less is going to be more in terms of quality. Quantity is another thing all together. As it is you should be able to just have enough real spl to do the job with the tops. I don't see any reason why the 4 subs won't keep up. If your going to bring all your tops and run delay lines, be sure you have the proper processing to do it too. A delay line to function properly must have the speakers time aligned and the goal is to not increase volume as you go along, but to maintain it. That is to say that your not blasting all the speakers at the same volume. The delayed speakers will be lower in volume to simply help maintain the SPL from the front to the back of the venue. Remember the distributed system? If the two speakers are more than 20' apart you get destructive delay. With a delay line the speakers are purposefully delayed to eliminate that and account for a greater distance between speakers. As soon as you get between two speakers the delay is wrong and you will again have problems. So you want to keep it so the delayed speakers are not loud enough to be heard over the speaker it is supporting when you are between them. It should work much like a distributed system. The SPL at the first delay line is pretty much the SPL that will be maintained from then on. You can usually get away with 1-2 delay lines within a 100' span. Ideally you want to keep the delay lines within about 50' of each other. Beyond that and they are too far apart to really work well. It just sounds like another speaker making more volume. When done well you should be able to walk down the venue and not be able to really tell when you have walked between two sets of speakers. It will simply hold SPL until you start getting to the main system where it starts to get louder.
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I don't understand how you can't hear your self

Scott Holtzman

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Re: dj sub system questions
« Reply #35 on: July 20, 2015, 04:47:30 am »

15 years of doing this and you have not learned the most basic of math to do what we do? Your mentor left out some very important things. The questions you pose are rudimentary. They are the first things you need to know in order to spec a system for a gig. I can do sound for 7,000 people too using only an 8" EV ZX1, as long as they are running by it single file.



Yes, when your main defense is "I have a mentor from claire bros (sic)" you know you have reached the end of any semblance of a discussion. 

BTW Clair Brothers is a manufacturer and integrator.  Clair Global is the production house.

We have given you a ton of information.  When you are ready to "sharpen your saw (see 7 habits if you don't know the reference) feel free to come back with cogent questions.  We will still be here (we as in the collective forum, not me as an individual speaking as the collective  ::) )
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Scott AKA "Skyking" Holtzman
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Ghost Audio Visual Solutions, LLC
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Mark Cadwallader

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Re: dj sub system questions
« Reply #36 on: July 22, 2015, 02:20:53 pm »

Bren, did you have the chance to A/B your new and old subs?  If so, what was your impression?
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"Good tools are expensive, but cheap tools are damned expensive."

john sanders

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Re: dj sub system questions
« Reply #37 on: July 24, 2015, 09:47:50 am »

Bren, I respectfully suggest that you just run what you have, and those who want to hear a higher level will just come closer to you. If there are vendors in the area, they will probably appreciate that it is not club/concert level where they are trying to do business. 

As to which sub to bring, at some point you will just have to compare the subs out in the real world. Try the new subs; if they don't get loud enough for your tops, turn down the tops until you have the right balance.

Speaking as an audience member, it will probably be louder than I want to be subjected to at a non-concert event. But I'm old, and I generally think providers usually over-estimate how loud they should run.
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