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RTW MM3 Music Meter

Stand-alone Meter By Hugh Robjohns
Published March 2017

RTW MM3 Music Meter

RTW are very well known for their professional metering solutions, and I reviewed their compact TM3-Primus meter in SOS September 2015 ( The subject of this review, christened the MM3 Music Meter, is the TM3-Primus’s (relatively) low-cost and slightly simplified sibling, which has been optimised for music, voice and multimedia producers. Its design shares the same form factor and connectivity as the TM3-Primus, with an L-shaped frame measuring 138 x 83 x 50mm. It weighs just 320g and features a 4.3-inch capacitive colour touchscreen, which can be used in either portrait or landscape modes — a vertical swipe across the screen toggles the orientation, while a horizontal swipe changes the display mode. As with the TM3-Primus, I found it essential to use lightweight, flexible cables to avoid the cable determining the display’s position on the desktop!

The rear panel carries four RCA phono sockets to accept a stereo unbalanced line-level audio input (the internal A-D runs at 48kHz), plus S/PDIF in (supporting sample rates between 28 and 104 kHz), and a buffered S/PDIF output. A pair of multi-turn trimmers allows the analogue input sensitivity to be adjusted over a range of -22 to +24 dBu, if necessary, although the unit is factory-calibrated to comply with the standard analogue metering reference levels.

Power is provided via a Micro-B USB2 connector, either from the supplied wall-wart PSU or directly from a computer. The USB2 interface can also be used to convey stereo or 5.1-channel audio from a computer, if desired (again, supporting rates between 28 and 104 kHz), and while an audio driver is required for Windows systems the interface works natively with Mac OS. Additionally, the MM3 is compatible with RTW’s ‘USB Connect’ software, which is a plug-in that integrates the meter with a DAW, providing direct audio and remote control connectivity over USB (and without needing to select the meter in the computer’s sound preferences. The plug-in is compatible with VST 2.4/3, AAX, RTAS and AU formats, and provides stereo or 5.1 metering channels as well as remote start/stop/reset control for the loudness metering, either manually from the plug-in or linked to the DAW transport.

On initial power-up the user is required to select the preferred language and input source (analogue, digital, USB stereo or USB surround), and then the unit is ready to use with the factory-default configurations for its seven metering display options. The configuration settings can be accessed at any time by pressing and holding the centre of the screen for two seconds, gaining access to the unit’s serial number, firmware version and updates, audio reference levels, loudness metering standards, metering scales and display configurations, and a factory reset.

The default display screen shows a combination of bar-graph level meters, a vectorscope, and an Integrated Loudness meter plus related numerical values, while the second screen (accessed with a swipe right) provides just the loudness numerical readouts in large characters. The third screen is the same as the first, but the vectorscope section is replaced with a loudness history chart, and the fourth screen gives the loudness chart on its own.

Another swipe calls the fifth screen which is, again, the same as the first and third, but with a third-octave (31-band) real-time analyser in place of the vectorscope/history chart. As you might expect, the sixth display gives the RTA analyser on its own. The final (seventh) display screen shows the level meters on their own, with a virtual LED giving an indication of phase correlation (green for 0 to +1, red for -1 to 0). These are bar-graph meters by default, but virtual moving-coil meters are available too.

Most individual elements of each screen are configurable to some degree. For example, the level meter scale can be selected from VU, DIN, Nordic, BBC, SMPTE (scaled to +24dBu), NHK, True-Peak, and conventional digital sample-peak — although the exact options depend on the input type (analogue or digital). The dual moving-coil display option is available in BBC PPM or VU formats. Loudness metering can be selected for compliance with all the standard variations, including ITU BS.1770-3/1771-1, EBU R128, ATSC A/85 (CALM Act), OP-59, ARIB, and AGCOM. The numerical display options include values for Momentary, Short-term, Integrated (in LU or LUFS), LRA, maximum True-Peak value and both Mmax and Smax.

Like its sibling, the MM3 is very easy to use and incorporates a comprehensive range of metering options, giving away surprisingly little to its more elaborate and expensive stablemate (really only the magic eye loudness range, stereo correlator, and downmixing functions). With DAW screen real-estate always at a premium there are genuine advantages to employing an external meter, and I quickly became quite reliant on the MM3 tucked neatly under my LCD monitors. The USB Connect plug-in enables simple and powerful integration with a DAW, but the hardware connections are also very useful, and the relatively low cost of the MM3 — it’s about 40 percent cheaper than the RT3-Primus — makes it a much more attractive consideration. Highly recommended.

£550.50 including VAT.