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Rane MM42 In-Ear Monitor Processor

In-ear monitors, or IEM, have become a must-have for performers from the highest level of touring, to the late night storage center, undiscovered band. A key issue of IEMs is the potential abuse of volume, causing possibly permanent hearing damage, or at the least, loss of a few frequencies.

In-ear monitors, or IEM, have become a must-have for performers from the highest level of touring, to the late night storage center, undiscovered band. A key issue of IEMs is the potential abuse of volume, causing possibly permanent hearing damage, or at the least, loss of a few frequencies. A few manufacturers have decided to wisely address this issue by producing an in-ear monitor control device, that can potentially assist in the conservation of your ears. Rane has created such a device, called the MM42, In Ear Monitor Processor.
Product PointsApplications: Live sound, sound reinforcement, installation

Key features: Multiband compressor; five-band parametric EQ; peak limiter; band-pass filter

Price: $999

Contact: Rane at 425-355-6000, Web Site.

The MM42 ($999) is a single-rack-space unit with the connectors on the rear and controls on the front panel. First, the connections. The MM42 has four inputs, combination 1/4-inch TRS and XLR connectors. Flanking the inputs are direct out TRS 1/4-inch outputs, that allow you to connect additional MM42 units, that may share a common or identical input signal, a convenient feature when using multiple MM42 processors in one system. The processor has left and right outputs that are XLR balanced, as well as left, right (Cue Out 1 and 2) and sub output TRS 1/4-inch jacks. The sub output allows for connection of a sub-bass system (filter controlled on front panel) or butt-shaker, since some of the IEMs lack sufficient low end for some tastes, and the left and right outputs connect directly to the inputs of your IEM transmitter. One interesting feature of the MM42, is the cue buss scheme, which allows multiple MM42 processors to be combined together via an RJ12 telephone connector. Then the cue buss system has a TRS output that allows you to connect to a console channel, then using the console’s onboard PFL system to monitor individual IEM mixes.

Additionally, there are MIDI connections, that allow for external control of the MM42, assuming that you would have the corresponding computer/software tandem.

The front panel is an attractive array, with a friendly backlit LCD for easy reading of parameters and operations. Directly next to the LCD screen, is a control button field that offers access to the filters and sub frequency crossover point, multiband compressor, five-band parametric EQ, input and output routing configurations, meter assignments, cue bus configuration and assignment and memory presets. The LCD screen contains the descriptions of each of these parameters, as you use the button field to access the various functions. There are several LED meters on the front panel, showing such functions as actual gain reduction taking place in the compressor section, output meters displaying the signal being fed to the actual IEM transmitter, and input meters showing the amount of signal coming into each of the four input channels on the MM42. There is also a headphone output jack on the front panel in both 1/4-inch and 1/8-inch, accompanied by the associated volume control, offering the monitor engineer the option of listening in on each processor, or connecting the headphone output directly to the cue system on the monitor console.

In Use

I am an avid fan of IEMs or ear-worn monitors (EWM), but I have noticed a tendency of older performers, that might have already suffered some hearing damage, to abuse their IEMs, by running their

volumes way too loud, to compensate for their lack of frequency/volume response. I was hoping the MM42 would be just the ticket to help achieve the necessary loudness of the IEM, but without additional damage. This is where the compressor/limiter function of the Rane IEM processor could possibly the most important function it has.

My company was doing full production, and I was monitor engineer for Crystal Gayle, appearing with the Phoenix Symphony. Most of the band was using conventional monitor speakers, but still a good opportunity to test the MM42. I connected the outputs of the MM42 to my own Shure PSM600 in-ear monitor system, and even went so far as to insert a 1/3 octave EQ on the mix masters feeding Channels A and B of the MM42. The interconnect was simple and achieved in minutes with no effort at all, thanks to the Rane processor’s easy-to-access connections. I fed a fair amount of signal to the signal path headed to the IEM I was wearing. The meters on the MM42 displayed the inputs clearly, and as I adjusted the compressor mode, I accessed the meter menu to show the amount of actual gain reduction.

Throughout the show, I played (for lack of a better word) with the parameters of the MM42. I have always felt that IEMs, like conventional monitor speakers, require some EQ, though not as much, since feedback is really not a consideration, but more an issue of just making them sound a little better. I adjusted the MM42’s onboard five-band parametric EQ, and compared the results with the outboard 1/3 octave graphic, and I found the MM42’s EQ to be quite effective, eliminating the need for outboard graphic EQs.

I used the MM42 at four additional shows, and each time I became a little friendlier with the onboard capabilities and menu operations. Each time I tried to use different ear buds, which would require different parameters and adjustments. I found the navigation process to be quite a bit easier each time, not that it was difficult, but just gaining familiarity with all the parameters the MM42 has to offer.


After several use periods with the Rane MM42, I felt that it was a completely worthwhile investment, by enhancing the whole IEM experience. The compressor is a must for serious users of IEMs, and the EQ section makes most ear buds sound very good. If you are a regular user of IEMs, this product is a must if you wish to enhance your listening experience, but more importantly, if you wish to conserve your hearing. The Rane MM42 has earned my respect and recommendation.

Review Setup:

Soundcraft SM20 monitor console, Shure PSM 600 IEM system, Shure E1 mono element ear buds, Shure E5 dual element ear buds, Sensaphonics Pro 2X dual element ear buds (all ear buds placed in Sensaphonics fitted ear molds), dbx 2231 graphic EQ, Yorkville TX2M biamped monitor speakers.