German manufacturer RTW has been producing audio signal monitoring tools for over 50 years. In 2010 RTW’s expertise in the area of monitoring tools culminated in the launch of the TouchMonitor range - a new generation of touch enabled monitors. To give you an idea of the success of the range, virtually all of the major mixing console vendors include OEM versions of their flagship TM7 or TM9 models.
   

Now we have the TM3-Primus, a compact entry level solution based around a 4.3” capacitive touch screen that comes in two flavours, a table top version and a 2U rack mountable version (for this review I was sent the former). The TM3-Primus is completely self-contained (i.e. no separate interface box), the rear panel sports a pair of analogue RCA jack inputs (with level trim pots), SPDIF in/out, a micro USB socket and a power input. The unit can be powered over USB or via the supplied wall wart, and the USB connection can also supply input in the form of a stereo or surround signal.

When you first plug it in and fire it up it asks you what country you’re in, which enables it to automatically set up the appropriate reference levels and loudness parameters, it then asks you for your favoured input domain (i.e. analogue, digital or USB).

Various instruments are available, but due to the limited nature of the available screen space (272 x 480 pixels), they’re only available in specific combinations so some experimentation might be required to get the display you want.

It can be used either in portrait or landscape modes, to switch you simply swipe the screen (up or left). The display is broken into two halves, the top and bottom if in portrait mode and left and right if in landscape mode. The top/left display can be either a vectorscope (VSC), a loudness chart, a real time analyser (RTA) or a moving coil (MC) whereas the bottom/right display can show a peak programme meter bar graph (PPM) or a moving coil, a loudness bar or a magic loudness range (LRA) as well as a correlator, a numeric display and a keyboard to start/stop the measurement, reset the loudness or adjust the reference level.

The vectorscope is a Lissajous display, which shows the phase relationship between the two channels on a co-ordinated plane, there are no adjustable parameters available (by default the automatic gain control is set to fast). The loudness chart displays the progress of TruePeak (TP) values over time as a line or a coloured area under a curve. The range can be switched between one minute, five minutes and one hour, other adjustable parameters include: mode (fill or line), active graph (M, S or I), toggling on or off of the info relative gate, I-sum bar or tolerance marker and adjustment of the lower and upper tolerance areas. The RTA displays the spectral information across the standard 31 filter bands in 1/3 octave steps from 20Hz to 20kHz with an additional high (H) band showing content above 20kHz, adjustable parameters include resolution, peak hold time and reference level.

The moving coil emulates PPM, VU or PPM + Loudness meter types, in PPM and VU modes it displays left and right in separate meters whereas in PPM + Loudness mode it combines them in one. The PPM bar graph can be switched between DIN, Nordic, British and TruePeak scales. The correlator displays the phase relationship between left and right on a scale from -1 to +1 (thus depicting mono compatibility). The loudness bar shows the combined total loudness and has two choices of scale, LKFS / LUFS (depending on the loudness standard selected) or LU. The magic LRA displays a graphical representation of the loudness range across an entire programme, which neatly depicts the dynamic range over time. The numerical display combines five of the measurements featured in the different meters (i.e. M, S, I, LTA and TP) into one panel, all of which can be toggled on or off. All of the current international loudness scales are supported (i.e. EBU R128, ITU BS. 1771, ATSC A/85, ARIB, AGCOM, OP-59 and CALM) and can be switched at any time. All settings are available from the main menu, which is accessed by touching the screen for two seconds.

In operation, the Primus is both intuitive and straightforward to use, the quick start guide is enough to get you going and if you know your way around metering you shouldn’t really need to consult the manual. Due to the limited screen size I did find myself switching between different configurations when I needed to focus on frequency, phase or loudness and while switching is relatively quick, it would have been nice to have some kind of preset option.

Engineers love data, and accurate metering can be incredibly useful, but despite the ubiquity of multi-screen DAW set-ups, meters will often lose out in the battle for screen space, so having external metering can be a definite asset.