Rane's new Mojo range aims to combine excellence of design with operational simplicity and affordable pricing. PAUL WHITE tests the MX 23 Divider, the MQ 302 Filters, and the MC 22 Squeeze.

Rane's Mojo series is the company's first serious attempt to produce a budget range of products aimed at semi-pro musicians, but instead of saving money by cutting corners on quality, they've opted instead to leave out unnecessary features. The core circuitry and components have much in common with their pro counterparts, but the front panels provide the bare minimum of what's needed to get the job done.

With the exception of a headphone amplifier (not reviewed here), the Mojo range is specifically aimed at the semi-pro live sound market where it is envisaged that the simplified operation will be viewed as a benefit rather than a limitation.

On review are the MX 23 stereo electronic crossover, the MQ 302 graphic equaliser, and the MC 22 dual channel compressor/limiter. All include novel design features, and in the case of the crossover, some aspects of its performance rival far more expensive crossovers due to an ingenious new approach to circuit design.

MX 23 STEREO THREE-WAY ELECTRONIC CROSSOVER

There are two electronic crossovers in the Mojo range, but as the only difference between them is the number of bands, we've decided to concentrate on the three-band MX 23. As you might surmise, the MX 22 is a two-band version, which is correspondingly cheaper at £349.

Specifying crossovers for a professional touring rig is quite a complicated procedure where an experienced audio engineer needs to consider the frequency ranges, roll-off characteristics, and sensitivities of the speaker cabinets before deciding on the crossover frequencies, filter slopes, and filter characteristics. The setting must then be verified using a real-time analyser.

The gigging band with their own system is unlikely to have the expertise or test equipment to make the necessary measurements or to meaningfully interpret the results, so Rane have come up with a much simplified crossover that has a single control to vary the crossover point between each band and a level control for each band. In the case of the MX 23, that means a total of just five front panel controls for a stereo system, but to give their product that extra bit of flexibility, there's also a mono feed on the rear panel with a switchable 100Hz low-pass filter that can be used to drive a single-channel sub-woofer system.

The filter slopes and characteristics are fixed (24dB/octave, Linkwitz-Riley), so all the user has to do is to adjust the frequency at each crossover point, then adjust the level of each band to get an acceptably even sound.

A conventional stereo crossover would require frequency control pots with four closely matched resistive elements — any departure from perfect matching would mean an unwanted change in the filter characteristics at the crossover point. Matched four-section pots are very expensive, so Rane have instead used a single pot to control a set of matched VCAs, which form part of the tunable state-variable filters. The result is near-perfect tracking, and because 24dB/octave filters are used, there's no unwanted phase shift and very little overlap between frequency bands.

Housed in a mains powered, 1U rack case, the MX 23 has balanced ins and outs on XLRs driven by the same high quality balancing circuit used in Rane's pro range of processors. The Mono Sub output has its own XLR socket, recessed level preset, and a slide switch to operate the 100Hz filter. This output contains a mix of the left and right Low outputs, but for use with a sub-woofer, the 100Hz low-pass filter should be switched in. This doesn't affect the feed to the main crossover outputs, it just ensures that little above 100Hz makes it to the sub-woofer.

Because the front panel controls are stereo ganged, there's no way to get a mismatch between the left and right channel settings. The only criticism I have of this otherwise excellent product is that there seems to be no way to lock the frequency controls against accidental movement once they are properly set. In all other respects, the unit works exactly as specified with more than enough tuning range to accommodate any sensible combination of speaker cabinets.

Rane's approach to the MX 22 and MX 23 means that the gigging band can afford a really high quality crossover that is as simple to set up as it is possible for an electronic crossover to be. The inclusion of Rane's high end balanced circuitry and a useful mono sub-woofer feed combined with very precise filtering and tough engineering makes this a very serious and flexible performer that should stand up to intensive touring with no problems. I'd be inclined to put it in a rack with some sort of cover over the controls to prevent tampering, but apart from that, it's ready to go and is very sensibly priced.

At this point, it's worth mentioning that the manual, although concise, contains some excellent advice on setting up crossovers; it also covers both balanced and unbalanced connections in authoritative detail. To the inexperienced user, this information is an absolute necessity.

MQ 302 THIRD-OCTAVE STEREO GRAPHIC EQUALISER

Rane were the first company to promote the idea of a graphic equaliser with constant Q filters, and their pro units have an enviable reputation in both live sound and recording studios. In live sound, graphic equalisers are indispensable for compensating for room acoustic problems and for notching out troublesome frequencies that threaten to cause feedback. Unfortunately, budget graphics often suffer, because adjustments in one band can affect the next band along. This is known as interband interaction, and one of the benefits of constant Q, as opposed to proportional Q (where the filter Q changes depending on how much cut or boost is applied), is that inter-band interaction is kept to a minimum.

Rane figured that they couldn't cut costs by simplifying the circuitry, but they could switch to using stereo faders so that the same fader controls both left and right channels. This not only saves on parts costs, it also means that stereo mixes are easier to control with no possibility of the left channel being set up differently to the right channel. The MQ 302 is, in all other respects, a straightforward device with both XLR and jack electronically balanced inputs and a choice of outputs on both balanced XLRs and unbalanced jacks. The unbalanced output has its own driver circuit, which means that it can be used at the same time as the balanced output, if there's a need to split the signal. What's more, the provision of an unbalanced output means that there is no level loss when connecting to an unbalanced piece of equipment, as would usually be the case when unbalancing a balanced output. There is a single input level control (but regrettably no overload LED), a single bypass button, and 30 short-travel faders, each providing up to 12dB of cut or boost. There is no external power supply — a captive means lead feeds a low-noise toroidal transformer, and the audio circuitry provides a very respectable 115dB dynamic range.

"... one of the benefits of constant Q... is that inter-band interaction is kept to a minimum."

The faders, which have a lovely smooth, positive feel, are centre detented and very clearly labelled. They are also divided into three groups, presumably for ease of construction, but this also makes it easier to identify the frequency band you want to work on.

In use, the MQ 302 is a very clean, musical sounding equaliser that doesn't seem to introduce the tonal fuzziness or phasiness that cheaper designs sometimes do. The overall effect is best described as positive, and because the controls set both channels simultaneously, setting up takes only half the time. Indeed, there are so many applications for a stereo graphic equaliser that I imagine this model will find its way into keyboard rigs and recording studios as well as PA rigs. You can still buy cheaper graphic equalisers, but this one is a truly professional performer.

MC 22 DUAL CHANNEL COMPRESSOR/LIMITER

The MC 22 has undergone a great deal of simplification in terms of its control interface, but you still get a very sophisticated compressor behind the front panel. Indeed, not only do you get a variable ratio, progressive knee compressor, you also get a completely automatic expander which acts almost like a gate, cleaning up the output when no signal is present. What's more remarkable is that all this is accomplished using just three knobs per channel — and one of those deals with the input level.

Like the graphic EQ, the 1U MC 22 is mains powered and features balanced inputs on both XLRs and jacks. The outputs are on both balanced XLRs and unbalanced jacks. There is no side-chain access, but you can tie both channels for true stereo operation using the Link switch. Each channel has its own Bypass button — although no bypass LEDs, which could be confusing in poor light. In stereo link mode, the compressor seems to take an average of both right and left-hand channel settings, so it makes sense to set the two channels to as near the same settings as possible.

Unusually, the MC 22 doesn't have an output make-up gain control, but instead has an Input Level pot which should be set so that the +4dBu LED flashes (but with the overload LED remaining off). This brings the signal up to the optimum level for the compressor circuit and also ensures that the expander will come into play at signal levels of around -55dB. Whenever the expander is active, the ADX LED comes on to show that 2:1 expansion is taking place.

Setting the compressor is simply a matter of choosing a ratio, then turning the Threshold knob until the 5-section LED gain reduction meter shows a suitable reading. Although the Ratio control only covers the range 1:1 to 10:1, the progressive knee nature of the compressor circuit means that if the input signal tries to push too far past the threshold setting, the compression ratio rises automatically to a higher figure than that indicated by the control. Because of this useful characteristic, when using higher compression ratios, excess levels are eventually subjected to limiting, hence the compressor/limiter title.

There are no controls for attack and release times — Rane did a lot of research to find out what setting experienced engineers tended to use and then built these into the MC 22. The figures arrived at were 30ms/10dB for the attack and 0.3dB/ms for the release.

Despite its simplicity, the MC 22 does the job of regulating signal levels very positively and controls are a positive bonus, and it's very difficult to get this little box to misbehave. On a subjective level, I'd say the sound is quite assertive, and you can usually tell that compression is taking place, but in quite a benign, almost flattering way. The expander comes in quite transparently at about the right level, and although some experienced engineers are likely to bemoan the loss of a separate expander threshold control, the inexperienced user has a lot less to worry about. In some ways, I'd have liked to have seen the traditional make-up gain control on the output, but other than that, and the lack of bypass status LEDS, there's nothing to complain about.

All in all, the MX 23 Divider, MQ 203 Filters, and the MC 22 Squeeze appear to bode well for the future success of the complete Mojo Range.