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Space Race

Roland M480 & M240R Rackmount Line Mixers

The competition to squeeze the maximum number of inputs and effects busses into the smallest possible rack space continues, as Kendall Wrightson discovers.

As an aid to spontaneity, rewiring a mixer is roughly comparable to recovering a corrupted MIDI sequencer file. However, due to the proliferation of multi-timbral, multi-output instruments, cable swapping has become an all too frequent occurrence.

Like many other manufacturers, Roland's response to this problem has been to produce a range of compact, line level mixers. Their last effort — the M160 — crammed 16 inputs and four effects sends into a 4U, 19" rack unit. However, last month Roland removed the M160 from their range to make way for the new 6U M480 and 4U M240R which, with 48 and 24 inputs respectively, make even the M160 seem like a criminal waste of space.

As with the M160, the M480 and M240R offer no EQ section and employ tiny controls. However, to gain even more space, both new mixers have rotary volume pots (in both channel and master sections) rather than traditional faders. On a recording console this would be a heinous crime, but it makes perfect sense for a compact line mixer, and Roland have ensured that all controls can be read from a fair distance by incorporating thick white position indicators into each pot.

Another break with established practice is that the M480/M240R's pan pots are located at the top of the channel strip, sharing a dual concentric control with input sensitivity. This is a bit of a shock at first, but it creates no real hardship. On both the M480 and M240R, sensitivity is adjustable from -30dBm to +4dBm, so only line level devices can be connected. The old M160 provided -50dBm to -10dBm sensitivity on channels 1 and 2 so that microphones and guitars could be hooked up. The new mixers are therefore more suited to users who either use no mics or guitars, or who intend to use the line mixer as a complement to a recording console.

Above each pan/sensitivity concentric is a small LED which glows green when an input signal is within -20dB of the nominal 4dBm level, turning red -6dB short of clipping, which occurs at +24dBm. The M480 has two rows of 24 pan/sensitivity controls so that all 48 inputs — labelled 1 to 24, A and B on the rear panel — can be fed into the 24 channels. There are 24 channel strips on the front panel, and a pair of push buttons allow you to select A or B, both, or neither, for each channel independently.

With a diameter of 5mm, the six (M480) or four (M240R) effects sends are the smallest pots on the front panel. Their small size and high density make it impossible to adjust them without brushing against other controls. Fortunately, all pots offer sufficient resistance to prevent unintentional movement through such accidental contact. The effects sends are labelled EFF(ect and AUX(iliary), with the M240R offering three Effect and one Aux, and the M480 four Effect and two Aux controls. Unlike Effect sends, Auxiliary sends are switchable between pre and post fade from a button in the master section.

On both mixers, the rear panel provides six stereo returns, which are switchable between -20dB and +4dB, and can be used in mono by plugging in the left hand jack only, a very handy feature.

Although the M480/M240R are 24:2 and 48:2 designs respectively, each provides two stereo busses, Master and Sub, with routing switches located directly under the effects send controls. The Sub output does not include effects return signals, which could be either useful or frustrating depending on the application you have in mind.

The Master and Sub mixes are also routed to an additional Monitor output which has its own independent volume control, and a switch to select between Master and Sub signals. The Monitor signal is also sent to the headphone output. The M480 has an additional row of buttons, labelled CUE, which allow you to solo channels on the Monitor bus only.

Directly beneath the Cue buttons on the M480R (or the volume pots on the M240R) there's about a centimeter of space, which is just enough room for a scribble strip, though none is provided with the units.


With no faders to worry about, Roland have managed to pack the master section into the lower 1U on both the M480 and M240R. The section is divided by two, 5-segment LED level meters for the Master and Monitor busses (indicating -20, -10, 0, +4 and +20dBm levels). There are also two small status LEDs indicating power on and Master output mute. The M480 has a third LED which indicates a Cue (solo) button is pressed.

To the left of the meters are the master effects send and return controls (all dual concentrics), plus a switch for aux pre/post selection. There are also two 1/4"jack sockets (with associated stereo volume control) labelled EXT IN. The jacks accept -10dBm level signals, and are best used for devices offering no integral volume control such as domestic CD, DAT or cassette players. You could also connect a mixer output to these inputs, although a better way of making such a connection is offered on the rear panel where inputs to the Eff, Aux, Master, Sub and Monitor busses are provided, offering full function mixer stacking.

To the right of the Master and Monitor meters are rotaries for Master and Sub bus volume and pan, the latter being a dual concentric. The Master volume control has a mute switch to its left which silences the entire bus, though only at the Monitor/headphone outputs. Finally, there is a button to switch the Monitor between Master/Sub signals, and a mains power switch.

The rear panel inputs and outputs are all 1/4" jacks, but an additional XLR Master output is also provided for connection to balanced systems using the pin 1 ground, 2 cold and 3 hot convention.


The M480 and M240R will find uses on both stage and in the studio. On stage, the Monitor Out mix could be used for foldback, while the Master is sent to front of house. The Aux mix could then be used to supply a click for a drummer.

In the studio, there are many possibilities. Simple grouping can be achieved by routing signals to the Master or Sub busses from the front panel. By connecting the Sub bus outputs to the Master bus inputs, the Sub Out volume can then control the sub-group. In fact it's a shame that this can't be switched directly from the front panel. Alternatively, the Sub bus could be connected to a sampler's input.

In fact there are so many possibilities, particularly with all the send/returns and bus input/outputs, that it really makes sense to use a patch bay with the M480/240R, unless you are likely to have easy access to the rear panel.


Both the M480 and M240R are extremely well made and offer excellent sonic performance, fully living up to Roland's published specifications (see box). It's only a shame that digital multi-effects outputs are so noisy! The high specification is reflected in the M480 and M240R price tags — £2300 and £1699 respectively, which puts them out of reach of most home studios. However, anyone who may be considering the purchase of a second recording desk to cope with all their inputs should have a good look at the new Roland mixers — the potential savings in terms of cost and space could be very significant.


Roland M480 £2300 inc VAT.
Roland M240R £1699 inc VAT.

Roland UK, (Contact Details).


Channel Inputs 48 (M480), 24 (M240R), mono unbalanced 1/4" jack
Sensitivity Control -30dBm to +4dBm
Effect Sends 4 mono (M480), 3 mono, (M240R) +4dBm
Aux Send 2 mono (M480), 1 mono, (M240R), +4dBm
Outputs Stereo Master, Sub and Monitor, unbalanced 1/4" jack +4dBm
Additional Master Output Balanced XLR, +4dBm
Returns 6 Stereo, 1/4" mono jacks
External In Stereo, 1/4" mono jacks on front panel
Bus In Master, Sub, Eff 1 to 3 and Monitor, 1/4" mono jacks
Stereo Headphone 1/4" stereo jack
Frequency Response 10Hz to 60kHz +1/-0.5dB (Sens = Min)
Total Harmonic Distortion 0.06% or less
Residual Noise Level -102dBm All Volume Min
-80dBm Master Volume Max, All Channel Volume Min
-79dBm Master Volume Max, All Channel Volume Max, All Sens Min
-68dBm Master Volume Max, All Channel Volume Max, All Sens Max
Crosstalk -70dB or less between channels (1 kHz)
-70dB or less between L and R (1kHz)
0dBm = 774.56 VRMS

Previous Article in this issue

Knobular Synthesis

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Up, Up And Away!

Sound On Sound - Copyright: SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.


Sound On Sound - Apr 1991

Donated & scanned by: Mike Gorman

Gear in this article:

Mixer > Roland > M480

Mixer > Roland > M240R

Previous article in this issue:

> Knobular Synthesis

Next article in this issue:

> Up, Up And Away!

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