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JBL MRX512M Live Monitor

The MRX512M should be a top consideration for anyone in need of a fully professional, full range wedge/utility speaker.

Neither large nor small, the MRX512M deserves the “utility” moniker; it is built to serve well in essentially any application, from one of many top touring act’s wedges to a musician’s main live speaker at an intimate coffee shop gig.

For this evaluation, I used a MRX512M pair in the most common applications I work in: monitors for both amplified and acoustic multi-musician/band rehearsals, wedges for high-volume amplified indoor and outdoor full-band performances, and mains for small restaurant/bar/club gigs. These wedges were used with a variety of amps — Behringer, Crown, Mackie, QSC Audio, and Yamaha represent the gamut of power sources paired with the MRX512M during their impressive, comprehensive run in my own gigging world.


The MRX512M is a two-way, bass-reflex monitor speaker for live touring, club/theater, installed, and musician-based applications.

Specifications of the MRX512M are as follows: Frequency range (-10 dB) is 60 Hz to 20kHz and the frequency response (+/- 3dB) is 90 Hz to 20kHz. It is a passive speaker, and the crossover frequency is 1.7kHz. For 2 hours performance, the power rating is 400W continuous, 800W program, and 1600W peak; maximum SPL is 123dB SPL continuous. System sensitivity (1w @ 1m) is 97dB SPL. Nominal impedance is 8 ohms.

The enclosure is made of plywood at 15 and 18mm thicknesses with black DuraFlex painted finish. One JBL 262H 12-inch Differential Drive woofer and one JBL 2408 H 1.5-inch annular polymer diaphragm, neodymium compression driver reside behind the 16-gauge perforated grille. Dimensions are 25.25 x 15 x 13.5 inches; the MRX512M’s net weight is 33 lbs.

Mounting hardware includes a dual angle (0- or 10-degree) 35mm pole socket. Carrying is easy via an integrated handle/input cup featuring two Neutrik Speakon NL-4 connectors, one on each end of the box.

In Use

In rehearsal and small room applications, the speakers served well as full band wedges and mains. The 10-degree angle available from the pole socket made it very nice for in-studio use (reinforcement while recording, writing, and rehearsing) as well as a small, acoustic club gig (one was used as floor monitor for singer/guitarists and the other was used as a main, angled down to the intimate crowd from an elevated corner stage).

Fast Facts Applications
Live touring (club/theater, amphitheater, and arena use); permanent installation (club/theater and houses-of-worship); musician and personal PA use

Two-way, bass-reflex monitor speaker; un-powered; 1 262H 12-inch Differential Drive woofer, 1 2408 H 1.5-inch annular polymer diaphragm, neodymium compression driver; 400W continuous, 800W program, and 1600W peak (at 2hrs); 123dB max SPL, continuous; dual angle 35mm pole socket. two Neutrik Speakon NL-4 connectors

$799 list

JBL Professional | 818-894-8850 | www.jblpro.comWith no drums or bass guitar present in the club mix, the MRX512M’s accurate, detailed midrange and pleasant, smooth highs allowed the speakers to be driven rather hard. The venue was a small yet narrow, long one; to get diction-friendly vocal transients to the levels they needed to be at the very back of the room, SPL was pushed a bit harder than I would normally prefer. The proof of the JBL’s quality was that not a single person in the acoustic music loving crowd complained of loud levels.

In loud club use — wedges aiming back at a loud “Les Paul/Tele-via-Mesa Boogie” driven rock band — the MRX512M pair covered the entire front stage, easily pleasing a finicky “more me” vocalist. Further, sufficient guitar, bass and kick in the mix kept the two string players’ fingers on their axes and off amp volume knobs, thus saving the main mix (through the club’s rather old but trustworthy JBL/QSC PA).

Outdoors with an R&B/oldies band, three vocals dominated the dual MRX512M monitor mix at stage front; again, the monitors received compliments, as the singing trio collectively agreed that their vocals sounded better than normal (with the monitors and a QSC GX5 amp as the only variables from their normal on-stage environment).

I must comment on the quality of the MRX512M’s construction: these wedges are built to truly professional standards, nothing less. I have no doubt that these speakers could be treated rather badly for a decade and still glean the same results as I reported above.


The JBL MRX512M is a fully professional wedge resistant to every kind of physical use (and abuse). Best of all, it sounds as good as, and in many cases, much better, than most of the wedges you see sitting on typical club/theater stages around the country. I would recommend the MRX512M to anyone wanting to buy a flexible wedge/small main