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PA Question


Thunderbroom

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Yeah, I know this isn't Live Sound.

 

I have the opportunity to obtain a really nice 18" JBL MRX sub and two 12" JBL MRX mains that I'd like to use to replace the crap stuff (unknown model Yammy 15's and unknown dual 215 subs) the band is using now. The price is great but the deal has to be done quickly. I've been reading and asking questions to quite a few folks about this.

 

Are 12's suitable for mains? I may be able to get 15's instead but like the idea of 12's.

 

Will one sub be enough typically if I'm able to push max power (it's 500w continuous) to it?

 

Are any of you familiar with these cabs? I've been told good things about them by others.

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$.02

 

DISCLAIMER: My response here is keeping in mind that I don't know how those particular JBL 12" cabs are rated, nor do I know their frequency response curve -- Im just making a blanket statement of 12"/driver PA cabs in general....and I am basing my post here on the limited data that I have of what you tell me about YFC here on the forum --- I haven't actually seen you myself:

 

12 PA Cabs: 12s (generally) are good mains for duos and lite acts, and even then I still prefer 15s (or a tri system cab)..... A trio or quartet with one or two vocalists that understands the concept of "stage blend" and doesn't exceed the PAs potential (minimum stage volume) in a small to medium room can actually work with 12" Main cabs coupled with subs but - Judging from what you tell me about YFC's live situations ( particularly the volume issues onstage) - I really don't think 12s will be efficient enough for YFC's needs (mainly for vocal depth and clarity - this should be a primary emphasis of any band - but especially for a band that that desrcibes their sound as "Modern Country With A Rock Edge")...Once again, just a non-expert opinion....

 

Subs: One sub is good for a small room...Some of the pics I have seen of YFC shows you in large rooms and outdoor venues which I don't think (upon visual inspection) one sub would handle - particularly in a crowded room...Couple that with your stage volume issues, and I'd have to (IMHO) say "No"...

 

A PA doesn't need to be big, but it needs to be efficient...technically, every band should have a PA thats tailored to suit their needs but such is not the case in real life applications.......but, in your case - from what you describe - you need the headroom (power) and dynamic range (15"/driver cabs coupled with subs) --- Also, from what you describe and what I can see, you guys are a BIG band (two gtrs,bs,drms,keys, lots of vocals) therefore you should be one of those bands that uses a 3 way system with an active 3-way crossover for seperation..................

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Thanks for the input DRF!

 

I can likely get the MRX 15's as well and have no problem with that, it's why I'm asking here. Andy (agedhorse) recommended 12's on Live Sound. I've had others that I've conversed with echo what you've said about 12's vs. 15's.

 

As far as the gig shots of my band, many of those shots were taken at shows where we've not used our PA. The reality is we don't use our PA much any more for gigs. The next time we'll likely use it is in May for a wedding. I'm pretty sure one 18 will be enough for that gig. I've also thought too that if the gig is too big for us to handle with our own PA, we can politely decline it. We can always add another sub at some point. We're currently using two 215's for subs. They sound okay but are effin' huge and are HEAVY.

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I think the business about 15" PA cabs being better or louder than 12" PA cabs is a bit of a myth.

 

I'm in a loud rock band. I use a pair of Peavey 1012Ps with a 1x18" sub that I built. I have two subs, but I rarely use both.

 

They are always more than enough and the only time my system has ever been pushed was when we played a huge room and I had both subs going at their max. Even then, I ran out of sub before I ran out of PA Main.

 

 

The only advantage of a 15" main over a 12" main is that the 15" will have a larger horn for the compression driver. That may or may not improve the output of the HF driver.

 

If a crossover and a sub are both used, the difference in output between a 12 and a 15 is negated because the limiting factor will be the compression driver long before the woofer reaches peak output.

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I think the business about 15" PA cabs being better or louder than 12" PA cabs is a bit of a myth.


I'm in a loud rock band. I use a pair of Peavey 1012Ps with a 1x18" sub that I built. I have two subs, but I rarely use both.


They are always more than enough and the only time my system has ever been pushed was when we played a huge room and I had both subs going at their max. Even then, I ran out of sub before I ran out of PA Main.



The only advantage of a 15" main over a 12" main is that the 15" will have a larger horn for the compression driver. That may or may not improve the output of the HF driver.


If a crossover and a sub are both used, the difference in output between a 12 and a 15 is negated because the limiting factor will be the compression driver long before the woofer reaches peak output.

 

 

I'm not sure about all that technical jargon. But. If you've got good subs I don't think you'll have a problem using 12's for mains.

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Since I can get either, should I get 12's or 15's? I guess that's the real question that I have. We will run at least one sub any time we use this system.

 

 

Get the 15's.

 

It wouldn't hurt to have bigger speakers. And. Aren't you going to do an acoustic thing in the future? Two 15's would be perfect for that.

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The big advantage of 12s over 15s is portability and weight.

 

The MRX 15 weighs 43 pounds, which is pretty freakin light. The 12 is 33 pounds, even better.

 

 

They both have exactly the same horn and driver, so I'd lean toward the 12s.

 

 

 

For acoustic gigs, the 12 will do fine without sub support.

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Get the 15's.


It wouldn't hurt to have bigger speakers. And. Aren't you going to do an acoustic thing in the future? Two 15's would be perfect for that.

 

I talked with one of our soundguys just now. He said to go with the 12's and the single 18 sub. He thinks it will be plenty.

 

As far as the acoustic thing goes, I don't have to provide PA for that stuff.

:)

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I would listen to them if at all possible, I own a system similar to what you are shopping for (srx-715's over MP-418's). The sensitivity specs are 96db for the 715's, 97db for the mrx512's and 98db for the mrx515's. I wanted to buy the srx712's to save a little weight and for the supposed better sound over subs. (as well as saving a few hundred dollars) I listened to them both over subs,(we left the x-over settings the same as well as the EQ flat) I preferred the 715's. (I do not wish to differ with people who's opinions I have the utmost respect for (Agedhorse etal.)) That is just how I felt.

The weight of my cabs 48lbs(srx715's) is similar to the Mrx515's 43lbs. and I have no problems pole mounting them myself. It is obviously much easier with 2.

One great advantage to the mrx512's is they can also be used as a floor wedge for your bigger gig's. (I seem to recall you were considering IEM's but opted not to, correct?)%ll be happy with yours, whatever way you go.

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another point no one has considered is that the quality of the JBL speakers is probably considerably better than the yamaha speakers. just comparing the product pages of the current yamaha BR series speakers and the JBL MRX speakers is a revelation. i would have no concerns that a pair of MRX512s and an MRX518S will outperform your current system.

 

robb.

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15s, also - it's rare that a pair of 12+horn combos will put out as much sound as a pair of 15+horn combos... You rarely, if ever see 12s in large FOH systems - there's probably a reason for that...

 

I also mean no disrespect towards others who's opinion is different than mine...

 

 

- georgestrings

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If your always going to haul in the sub, then the 2 x 12's will be fine. The MRX stuff is great sounding as long as its paired with the correct amp. Most JBL's need the right power to obtain good performance from my exp.

 

If your doing a no sub gig, then i find the 15 inch bass cab will help out.

 

At least when you want you can get the 15's at a later stage and use the 12's as wedges. The 15's are not wedged shape. I also find it best to make sure pa gear can have many uses to max its return.

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