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Author Topic: QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S  (Read 8609 times)

Robert Chafe

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QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S
« on: January 21, 2011, 01:56:18 am »

Alright this is a very very lengthy post.

I purchased a powered QSC system for my band early last year ( (3) QSC K12 & (2) QSC Ksub).  Weve recently upgraded from the Ksub to the KW118 a BIG step up in my opinion.  How weve been running the system so far is stacking the (2) KW118 subs on top of each other on one side of the stage and running (1) K12 on a stand on either side of the stage.  At some venues that are a little wide we usually throw a third K12 up on a stand to cover the spread.  The entire band uses IEM so there are generally no monitors on stage.  Although we have had to use the 3rd K12 as a monitor before when we had a sub sitting in with the band who doesnt have IEM. 

A little about the band and our stage setup.  We are a 4-piece (Vox, Gtr, Bass & Drums) and play pop/rock music (Def Leppard, Buckcherry, Van Halen, Fall Out Boy).  We typically mic the kick, snare/hi-hat, overhead, guitar, DI the bass and have (3) vocal mics.  In addition to the band we of course pump the current dance music through the system on breaks much like your typical dance club.

I recently heard a pair of JBL MRX528S subs each powered by a Crown XTi200 in bridge mono mode and they completely crushed.  So it got my mind started about possibly switching our system over to a JBL MRX & Crown Xti system. 

Here are the questions.  First what are everyones opinions of the JBL MRX 18s paired with a Crown XTi compared to the QSC KW118?  Frequency response, spl level, etc?  Two options I am considering are adding another pair of QSC KW118 for a total of (4) QSC KW118s or replacing my existing pair of QSC KW118s with a pair of JBL MRX528S paired with (2) Crown Xti2000 amps.  The reason for this question is that I am only happy with the single pair of QSC KW118s in smaller venues (IE 150 people venue). Thoughts???

Next questions concern the high packs.  I have been nothing but extremely pleased with the K12s but if Im going to switch out the subs I would most likely switch the tops to a comparable JBL & Crown setup.  First question, would the JBL MRX512M or JBL MRX515 be a better choice for mains (either paired with a single Crown XTi200 in bridge mono mode)?  Keep in mind that I would only do this if I change to a JBL MRX528S per side. 

Would I even need to be concerned about the limited low end response of the MRX512M in comparison to the MRX515?   Ive read that some people think there is a marked difference in the eq curve between these two enclosures mostly saying the MRX512M is harsher opinions??  Ive always heard a 12 would reproduce vocals better - thoughts?

 For a wider spread I would also consider having a total of (4) tops (either MRX512M or MRX515) with (2) Crown Xti2000 amps.  Would this cover the width of most any venue (a generalization I know)?   Also, where would I set each crossover if I matched a pair of MRX512M with a pair of MRX528S and a pair of MRX515 with a pair of MRX528S respectively. 

There are a few other reasons I am considering the big change over.  First, Our system is currently just adequate for larger venues IE if I needed an extra 10-15% I just dont have it right now (highs or lows).  Second, it is actually getting a little cumbersome to setup the powered system.  Running a few extension cords, then individual power cords, then xlr to each speaker.  VS the JBL which would be a few short XLRs between the mixer to amp rack and then a single speakon to each cabinet.  Third, JBL system would give me a greater flexibility.  For small acoustic duo shows I could bring out (2-3) MRX512M and a small powered mixer.  Acoustic Trio with a drummer I could bring (2) MRX515 and (2) MRX512M with a small powered mixer.  Or (4) MRX512M and (1) MRX528S with the bigger mixer and amp rack.  It would also give me flexibility to run sound for other bands in smaller venues when were off.  IE (2) MRX 512M or (2) MRX515, (2) MRX528S and either (4) MRX512M or (2) SP112M & (2) SP115M. 

Which brings up another question, I would hate to throw MRX512M cabs down on the floor if I ran sound for another band.  Most bands would beat the crap out of them, so I would either use PV SP112M & SP115M monitors or possibly JRX112M thoughts?
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Fernando Lopez

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Re: QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S
« Reply #1 on: January 21, 2011, 07:58:58 am »

I think MRX would be a sideways move for you

I would either get 2 more kw181s or look into an srx system instead of mrx
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Rob Reda

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Re: QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S
« Reply #2 on: January 22, 2011, 10:13:35 am »

I currently run 2-MRX528s, 2-MRX525, 2-Crown XTI 4000 bridge mode, 2-Crown XTI 2000 bridge mode (one power amp per speaker) and a DBX PA+ loudspeaker management appliance. In one year of playing different venues  I have not even come close to maxing the system out. If you want that low end thump adding 2 more KW118 may help but I just don't think they are equiped with suffcient power in a larger venue. Also it depends on the system setup, but if you have no headroom now and you want to increase your low end response then there isn't much you can do except to maybe add 2 more.

The SRX728 series are great speakers but you will need some massive power to adequately supply them so you do have the headroom when you need it. No sense to buy a system like that and not power it correctly. I don't agree that he MRX would be a sideways move if they were adequately powered. A power amp 2x the speakers continuous power rating or equal to the program poser rating with give you the headroom you need. Also how is the system EQ'ed and how is the system setup from speaker to mixer? Whats in the chain?

Have a great day!
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Fernando Lopez

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Re: QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S
« Reply #3 on: January 22, 2011, 03:37:27 pm »

Guess you are right, the MRX is a downgrade from the KW series
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Bob Kenton

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Re: QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S
« Reply #4 on: January 22, 2011, 04:55:29 pm »

I wouldnt consider the KW's to be a down grade from the MRX line myself. Pretty much targeting the same crowd, coverage and SPL are all pretty close.
If you need more lowend, buy more subs.
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Robert Chafe

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Re: QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S
« Reply #5 on: January 25, 2011, 10:53:12 pm »

I too consider a MRX system to be sideways move as far as sound quality.  My main complaints with our current system are the KW118's.  They just don't "thump" as I've heard a single MRX528 with a XTi4000.  Also now that I'm getting up to (8) seperate cabinets plugging in (3) cables per cab (in, out and power), cabling is getting a little overwhelming. 

I know the srx system would be a nice step up but the cost (40% more per cab) vs what I would use them for doesn't make sense to me.  Having (4) MRX512's I can arrange (2) per side to cover a wide room with 140 degrees of coverage.  Or (2) for mains and (2) for monitors on smaller trio gigs. Etc. etc.

Thoughts??
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Rob Spence

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Re: QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S
« Reply #6 on: January 25, 2011, 11:13:31 pm »

My main complaints with our current system are the KW118's.  They just don't "thump" as I've heard a single MRX528 with a XTi4000. 
I think you mean KW181 but what ever...
I had an interesting discovery last weekend when my pair of KW181s were not thumping like I thought they should...
Close inspection showed me that one of the subs had the polarity switch pushed in so they were canceling each other  :-[

Also, consider when you heard other subs pounding... what was the rest of the system and the skill of the engineer?
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Robert Chafe

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Re: QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S
« Reply #7 on: January 28, 2011, 01:29:00 pm »

Yep KW181's.

Comparing a pair of KW181's to a single MRX528S powered by a XTi2000 bridge and crossover @ 100hz with program music - IE current dance stuff.

Here are the specs between the three boxes I'm contemplating.  +/- 3db Frequency response MRX518 = 45-200Hz, SRX718 = 34-220Hz, KW181 = 40-112 Hz.  Maximum SPL MRX518 = 133db, SRX718 = 130SPL, KW181 = 135db.  So an I correct in taking this to mean with adequte power to the JBL's - the frequency response of the KW181 is only slightly worse than the SRX718 and the KW181 is capable of being 5db louder??
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George Dougherty

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Re: QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S
« Reply #8 on: February 02, 2011, 12:51:05 pm »

The max output spec is largely theoretical BS.  It's calculated rather than measured and it would take a cool driver with brief bursts of max power to achieve.  Anything that's already warmed up will quickly move into power compression on the driver and the actual max sustained output would be much below that.  Some drivers will cool better than others and will also give more output than others as a result.

The K12 will not have the bottom end of a 15" loaded cab, but it will also likely have better midrange dispersion and response.  One thing you can try is letting the sub cross higher and reinforce the low-mids a bit in the 100-120Hz range.  "Thump" typically requires strong output in the 80-120Hz range. 

The JBL MRX system may have more low-mid harmonic distortion adding to the appearance of more thump, it may have had a bit of a bump in the system EQ, the subs may have been running hotter, they may have had a Sonic Max-crapalizer patched in that was boosting harmonics adding to the appearance of more thump but muddying up the bottom end as well, they may have had a better engineer mic'ing, EQ'ing and compressing the kit and bass.   Lots of different reasons for why you heard more thump from the one setup vs your typical setup.
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Bob Kenton

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Re: QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S
« Reply #9 on: February 03, 2011, 12:25:05 pm »

Another thing to consider, according to the Crown gurus on the Crown forums the XTi amps are not really designed to run hard bridged.
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Re: QSC K12 & KW118 vs JBL MRX512M/515 & MRX528S
« Reply #9 on: February 03, 2011, 12:25:05 pm »


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