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Digital Mixer With Amp Modelling By Paul White
Published June 2016


With its built-in Overloud guitar and bass processing, could this iPad-controlled mixer do away with the need for backline altogether?

Small-scale digital mixers offering remote tablet control are understandably very attractive to bands playing in smaller venues, as they do away with heavy multicore cables and racks of outboard processing, and may allow more sources to be plugged directly into the PA system because of their comprehensive internal processing. And RCF certainly seem to have performer control in mind with their new M18, although there’s no reason not to mix with it from out front if you work with a sound engineer.

Despite its small footprint, the 20-input (18 analogue plus stereo digital via USB) RCF M18 is surprisingly comprehensive, as it includes not only the expected EQ and dynamics processing on relevant channels, but also two channels of rather sophisticated guitar/bass-amp modelling courtesy of Overloud, plus further configurable insert effects, more of which later. Three send-effect engines provide a range of effects from the more obvious reverb and delay to modulation. The M18 can also record and play back stereo mixes to or from an external USB storage device, which is useful for those who use backing tracks.

The M18 is controlled via the MixRemote app for iOS, which I’m pleased to say is largely intuitive, to the point that you can probably figure out how to drive all the key functions without even looking at the manual; the full version of it is a free download. Remote control of all the mic/line preamp gains and of the first two line-input gains means there’s nothing to adjust on the mixer itself, and gain settings are stored within Snapshot memories. There are no physical controls at all on the mixer, so control relies entirely on the iPad (at the time of writing only iOS tablets are supported).

Everything is built into a compact but rugged plastic case, and all the connections are on the rear panel. Though there are apparently two internal Wi-Fi antennae, an external one is provided, which screws into place on the rear panel to ensure optimal coverage. No additional router is required. The Wi-Fi supports dual-band operation at 2.4 or 5.0 GHz. A light on the front panel shows the unit is active, with various flashing modes indicating the stages of start-up before the lamp lights solidly.

Making Connections

The mixer’s first eight channels have mic/line inputs on XLRs (the first two on combi XLR/jack connectors), and the next 10 line-only inputs on TRS jacks. Two of the line inputs (9/10) have a switchable High Z mode for instrument use, and these are the ones that can access the amp models. Augmenting the main stereo balanced XLR outputs are six balanced TRS jack outputs, which would normally be used to feed stage monitors (all sends have their own parametric EQ). The source for the TRS outputs can be selected between aux sends, main mix or phones; the mains/phones routing sends the left output to the odd-numbered TRS in a pair, and the right output to the even.

The M18 features eight mic preamps, which can accommodate mic or line-level signals and have remote-controllable preamps. The remaining inputs comprise eight further line-level jack sockets (including two with high-impedance instrument switching), and a  stereo USB playback input.The M18 features eight mic preamps, which can accommodate mic or line-level signals and have remote-controllable preamps. The remaining inputs comprise eight further line-level jack sockets (including two with high-impedance instrument switching), and a stereo USB playback input.

If you don’t want the headphone output to simply follow the main stereo mix, it can be set to PFL mode, where soloed sources are summed and sent to the phones output via the EQ and phones fader. In PFL mode, the PFL level is shown on the main meters as on a typical analogue mixer. Alternatively, a Personal Mix mode provides a separate headphone mix of all inputs, including the two-channel USB player and, if required, this can also be sent to a pair of aux outputs.

There’s also MIDI in and out on standard five-pin DIN connectors. This is used for controlling a number of key functions (that can be set up in the MIDI settings page). There’s also provision to connect an optional dual footswitch, this being configurable so you can use it, for example, to move through presets, control backing tracks played from a USB stick, or bypass the effects. A LAN port is also included, and this allows a remote external router to be connected if required. Mains comes in on an IEC connector so there’s no external PSU to worry about.

Once the MixRemote app is installed, it is only necessary to set the tablet’s Wi-Fi to access the M18 and then tap Connect. A password can be set to prevent rival bands sabotaging your mix! Mixer Snapshots and Shows (comprising multiple Snapshots) can be saved and recalled, as can effects setups, the latter storing all the parameters of a multi-effect chain, including the order in which the effects are used. These effects patches may be recalled independently from other mixer parameters.

Going All GUI

The iOS app’s GUI is nicely muted to offer good visibility in a typical venue, and the fader caps are colour-coded according to function, but what is lacking on many remote apps, this one included, is a high-visibility daylight mode with more brightness and contrast. If SatNavs can do it I’m sure app designers can come up with something similar. As things stand, mixing outdoor gigs using an iPad is quite a challenge, even in UK weather.

That point out of the way, the app layout is pretty straightforward. A row of buttons along the top of the screen lets you select various views for control and settings. Included here is a global metering page that shows all the input, output and effects levels in a single view.

The first view is Faders, which is where you’d expect to be most of the time when mixing, and you can scroll along the mixer to view eight faders plus the master fader at any one time. Included in the main Fader view are aux returns for the three built-in stereo effects engines, and one input for USB stereo playback, which can be from WAV files at 44.1 or 48 kHz, 16- or 24-bit. MP3s are also supported, and the default stereo linking can be disabled if you want to use mono backing tracks with a click in the second channel. Buttons to the left of the screen switch the view from the channel faders to the aux or effects-send faders.

A cog-shaped Edit button at the top of each channel (other than on the effect returns), just above the pan and mute buttons, provides access to a four-band EQ which can be selected from three types: Standard (interactive curve display), Vintage (knobs and an analogue flavour), or Smooth (gain knobs but with a more subtle character). In all cases the outer bands are shelving, with variable gain and frequency, while the two inner bands are for the mids. In the Standard and Smooth versions these are fully parametric, whereas in Vintage there are just two switchable bandwidth options. Smooth also offers three switchable levels of Smoothness, and if you change EQ types, the settings are retained. Those who find fully parametric EQs too daunting can switch from Advanced view to a simplified view with a more streamlined control set.

Tapping a tab at the left of the screen switches from EQ mode to a page showing the preamp settings, gate and compressor, in the form of a plug-in rack simulating what you might expect to see in hardware. Again there’s a simple mode that reduces the control set of the compressor to a single ‘more or less’ knob.

The on-board Overloud amp modelling offers extensive amp, cabinet and mic-positioning options.The on-board Overloud amp modelling offers extensive amp, cabinet and mic-positioning options.

The preamp section can be switched from -10dBV to +4dBu input sensitivity on channels 12 upwards, with continuous control over the gain on the first 10 channels. The input stage includes polarity invert plus a variable low-cut filter. Phantom power is applied in the global Settings menu, where it can be activated in two groups of four. A further Select button shows the three effects-send faders for the currently selected channel, as well as the six aux-send faders relating to the selected channel. A Back button takes you straight back to the Faders view. A headphone ‘Solo’ button is visible below the channel fader only if the phones mode is set to PFL in the global settings page, and this solos the track, pre-fader, to the phones output.

The main mix page of the MixRemote app.The main mix page of the MixRemote app.

Note that unlike some digital mixers that offer graphic EQs on all outputs, this one has the same four-band EQ as the channels for each of the auxes and a stereo 31-band graphic EQ only for the main output. When recording the stereo output (via the Play/Rec screen tab), the feed is taken before the graphic EQ. The Rec/Play page also displays backing tracks as a list, with transport buttons, elapsed time and a progress bar below.


The M18 digital mixer can power up to 19 simultaneous effects, but a slightly unusual feature is the ability to use four multi-effect setups in a channel insert configuration. MFX1 and MFX2 can be selected in the Effects page to be in either channels 5/6 or 7/8, whereas MFX3 and MFX4 (which include amp modelling) are always assigned to channels 9/10. These input channels can also be paired for stereo use in the Settings page. Specialised insert effects are available to the main output, specifically Valve Warmer, Xciter and Maximizer, the latter of which appears to be a type of compressor/limiter with a control to set the maximum output ceiling.

MFX1 and 2 are presented as stompbox-style pedals, where a pitch-shifter is followed by a choice of modulation effects and a choice of delay types. MFX3 and 4 can comprise up to five pedals, where the pitch-shifter is followed by a choice of overdrive/distortion, one of 11 guitar or bass amp models, a choice of chorus/flange/tremolo modulation effect, and a choice of mono, vintage or ER (short) delay. The default order of the effects is logical, but they can be reordered if required.

Of the send effects, FX1 is set up to offer a choice of reverbs such as halls, rooms or plates, and FX2 is a delay offering up to 2.5 seconds’ delay time, with filtering in the feedback path for creating tape-style delays and more. FX3 is a multi-effect offering a choice of chorus/flanging, pitch-shifting and tremolo, though this can also be set up as a second delay.

Those two amp-modelling channels deserve a closer look, as they include all the tools needed to create the kind of sound you might expect from a dedicated amp-modelling box or plug-in, complete with stomp effects. The Hi-Z input mode matches guitars and basses with passive pickups, and the amp simulations offer a choice of Darkface ‘65, Jazz C, Rock ‘64 , Rock 800 Crunch, Rock 900 Lead, Top 30, Modern, BassMate, BassAmp, Markbass Little Mark III and Markbass TTE 500. Amps can be teamed with different speaker cabinet models, mic emulations and mic placement to cover a lot of tonal ground. These sound to me pretty much the same as you’d expect from an Overloud amp-modelling plug-in, and cover clean, slightly dirty and overdriven rock tones.


Technically the mixer performs very well, having the expected 20Hz-20kHz frequency range and employing 24-bit/48kHz conversion and 32-bit floating-point internal processing. The input noise figure is quoted as -128dBu A-weighted, which is around the same as for a typical analogue console, and there’s up to 60dB of mic-amp gain available. The main output can accommodate levels of up to 21dBu, and the specified dynamic range of the mixer is quoted as 114dB. These figures seem to hold up in practice, as there’s negligible noise at typical operating levels.

The per-channel gain control and dynamic-processing options are presented as a  virtual rack.The per-channel gain control and dynamic-processing options are presented as a virtual rack.

The effects are adequately simple to adjust, yet they sound good and cover plenty of ground, with the range of Overloud guitar amps, cabinets and mic positions being particularly impressive. Similarly, the channel gates and compressors work perfectly well, though they lack any form of gain reduction metering or even activity LEDs, which would really make them much easier to set up. I also missed not having tap tempo for the delays.

Among the EQ options is this Classic analogue emulation.Among the EQ options is this Classic analogue emulation.

The designers have done their best to keep the operation as simple as possible while still allowing a useful degree of flexibility, such as using an external MIDI control source to start and stop playback, adjust fader levels, bypass effects and suchlike, but there’s no simple way to bypass all the send effects in one go other than using a footswitch, and if you are mixing from out front, that means relying on the performers to do it. As it is, if you want to use the iPad to control the effect switching, you have to scoot to the end of the Faders page and then hit the three mute buttons on the three effects returns, or hit the Effect tab followed by the three power switches on the three effects.

Other omissions include the lack of ability to create fader groups or mute groups, and the lack of a physical output volume knob on the mixer as a safety option in case the iPad loses contact for any reason and you need to pull the overall gain down in a hurry. On the whole, though, the mixer is very well thought out, easy to navigate and it sounds very good. It is also competitively priced, compact, and needs no additional Wi-Fi router, so there’s a lot to like and some of the minor shortcomings could easily be addressed in a future software/firmware update.

Who Is It For?

With fewer than half of the inputs being mic inputs, RCF seem to be aiming this mixer at the band who want to plug several things, such as keyboards and guitars, directly into the PA along with their vocal mics and perhaps a small number of drum-kit mics. In that role the lack of fader and mute grouping really isn’t a deal breaker, and the footswitch provides a practical method of effects bypass. Backing tracks are also well catered for, not only by the USB record/play functionality but also in the various control options provided, and the ability to split mono backing tracks with clicks. Where more mic inputs are needed to accommodate a fully miked drum kit, it would be perfectly practical to plug a small analogue mixer into two of the line channels and set up the drum-mic balance on the analogue mixer.

The effects sound good but can still be adjusted with stomp-box simplicity, and there are enough options to cover most eventualities, with the guitar-amp modelling channels being particularly impressive. So, while it’s not perfect, the M18 represents a very impressive package at an attractive price point, and it covers pretty much all the bases for bands who need a small digital mixer.


The current alternatives at a similar price point include Mackie’s DL1608, Behringer’s X18 Air, Phonic’s Acapela and Soundcraft’s Ui16.


  • Straightforward GUI with excellent graphics.
  • Wi-Fi built in.
  • Strong audio performance with very capable effects that include guitar and bass amp modelling.
  • Remote preamp gain control on all mic inputs and the two amp modelling channels.
  • Effects can be bypassed via footswitch.


  • Tablet control for iPads only at the time of writing.
  • No global effects bypass in the app.
  • No gain-reduction metering on compressors or gates.
  • No delay tap tempo.


A flexible and very practical self-op mixer for anyone who wants to DI as much as possible and to control their show from an iPad.


£714 including VAT.

RCF UK +44 (0)844 745 1234


RCF USA +1 732 902 6100