JBL MR Series

[kidkarmadj]

I have started buying used JBL Sound Reinforcement such as MR Series and even some old school Cabaret Series. I've been taking the Cabarets apart and totally restoring them inside and out. Fortunatly I have a Certified JBL Speaker Tech in my neighborhood to do the recones and I'm a painter by trade so after a coat of low lustre oil enamel the cabs are looking and sounding brand spanking new when I'm done with them. So far over the past 7 months I've purchased 2 pairs of MR 822 and 2 pairs of MR 825 as well as a pair of TR225 and a pair of Cabaret 4628b's. I can care less about the TR's but I'll keep them around anyway. I have purchased (3) Crown XLS 602 amps (370 watts @ 8ohms per side & 600 watts @ 4 ohms per side) but I don't really know how to run all of them. I guess my question is can I run 2 pairs of the MR 825 off one XLS 602 amp? The MR 825 and MR 822 require about 500-600 watts program. Or instead of running 2 pairs at 4 ohms should I just run 1 pair for each amp at 8 ohms and 370 watts per speaker? If I choose to run my speakers at 4 ohms, will that cause them harm in the long run? These are a few questions about my mains. I also have a few bass bins that I need to figure out as well. Maybe I'll post those questions tmrw. Thanks!

[Zilch]

Do you have some purpose in running more than one pair simultaneously? Is this for some SR gig?

'Cause, if you're trying to make a "wall of sound" with them in the same room, it's a sonic mess you're creating, instead....

[kidkarmadj]

Yes, I am trying to create a wall of sound. I intend on using all of my speakers as a wall of sound with a single EON active as a booth monitor. This will be used in a DJ setup. I'm new to this and can't seem to stop buying up used JBL sound reinforcement like the MR and Cabaret series. I guess I want to get the most sound out of my system with out potentally causing any harm to the speakers in the long run. I'm slowly rebuilding my cabinets from the ground up and I'm want to be very cautious when using them for gigs. Is it safer to only run 1 - 8ohm cabinet on each side of my crown xls amp or can I get away with running a pair of the 8ohm cabinets on each side at 4ohms. Will the second option create any unneccesary strain on the speakers in the long run? I can designate 1 crown xls to every pair of speaker cabs but it would make things easier and lighter to designate 2 pairs of cabinets per amp and just back off the input levels a bit. Believe it or not I have spent $4000 on equipment in the last 7 months and I have not hooked it up all together yet. I finally got a DBX Drive Rack PA yesterday and now I'm ready to hook it all together.

[Zilch]

http://www.jblpro.com/assets/Dance%20Club%20Booklet.pdf

Lotsa club expertise on the forum. Someone will likely know your amps and how best to use them. :)

[edgewound]

Two key things to remember when using ANY sound system....(1)Don't overload your amps with too many speakers. Putting a pair of speakers on an amp channel is fine as long as you don't exceed the safe load impedance. If the amp is rated at 4 ohms into a certain amount of power...go ahead and use it, but don't go below 4 ohms nominal impedance, unless your amp can handle it. Don't mix a 4 ohm and 8 ohm speaker on the same channel. (2)The most critical thing to keep an eye on is clipping...distortion. Watch your VU meters on the amps. It would be to your benefit to have a limiter on your system after your mixer and before the amps to ensure you don't overdrive your amp inputs with too much signal. If you drive the amps too hard, the first thing to go is the tweeters. You can find lost of good info here:http://www.jblproservice.com/general_faq.htm (http://www.jblproservice.com/general_faq.htm).
Take a look at "Danger...Low Power".


Hope this info helps, and good luck with your DJ biz. Older Cabaret Series speakers are your best value for the dollar.

[LewisGoudy]

Don't mix a 4 ohm and 8 ohm speaker on the same channel.
Why not?

[grumpy]

Other than you'd be below 3 ohms (nominally... could be worse at particular frequencies) and would have no way to balance volume between the speakers? Have at it :)