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Emu RFX32

Effects/Mixer Card For Emu Ultra Samplers By Nicholas Rowland
Published May 2002

The market for hardware samplers may be on the wane, but Emu aren't abandoning their hardware customers; their RFX32 effects/mixer card can add tremendous processing and routing power to any of their Ultra samplers.

When I was a lad, the slogan of a certain petrol company whose name I can't mention here simply because I've forgotten it rather than out of any coyness, was "Put a Tiger in your tank". The accompanying advertising suggested that filling your motor with said brand would turn your pootling little sedan into a supercharged race machine. That's what sprang to mind while I was reviewing Emu's effects processor card for its Ultra-series samplers. Only I think it's more appropriate to say the RFX32 puts a streak of tigers in your sampler.

EMU RFX32 Effects Card.If you had to decribe it in a few words, you'd say the RFX32 was a multi-channel 32-bit effects-processing card offering up to 16 simultaneous stereo effects, assignable between 14 discrete effects busses with up to six effects per buss. Emu were promising the arrival of this card as far back as 1999, as it gives their Ultra samplers multitimbral effects capabilities. However, it's important to understand that this isn't all it does. The RFX32 is described in full as an 'effects/mixer card' and while it does add the power of 16 stereo effects units to any Emu Ultra sampler, it also adds the functionality of a digital mixer and patchbay to give you considerable control over how voices are routed within the sampler, including their hardware input and output configurations.

The RFX32 also gives you real-time control over sounds and effects. With the card fitted, you have four stereo sends per voice (no mean spec in itself) but each of those effect sends can be modulated by virtually any source — velocity, envelopes, LFOs, MIDI controllers, foot pedals, even random sources. Given that you can use the same wide variety of sources to simultaneously modulate other parameters such as filter settings, you can begin to see how the RFX32 raises the bar in terms of creative control. You could say it's like adding a big chunk of raw DSP designed to transform your sampler from a specialist tool into a more general sound-manipulation machine. Indeed, Emu are putting a great deal of emphasis on this aspect of the RFX32's functionality, and are now selling their high-end machines as much (if not more) on their ability to function as a mixer/general command centre for your studio or live rig as for their ability to sample pure and simple.

It's true to say that Emu's new sales approach is partly due to a steep decline in the market for hardware samplers — particularly in falling sales of top-spec machines, where the ability to pull something new out of the bag is now relatively limited. However, it's also a genuine reflection of just how much the installation of an RFX32 extends the functionality of even the lower-end Ultra machines.

Open The Box

The stand-alone RFX32 package consists of the DSP card itself with instructions and manual, plus one floppy disk containing software to prepare the flash memory for new operating software, a second with EOS (Emu Operating System) v4.61 and two disks containing the effects themselves. Installation consists simply of opening up the machine and slotting the card in place, then installing the software. Of course, this second stage is something you may not need to do if you're already running the latest OS. If you're not, then you should still upgrade. Although the RFX32 card will work quite happily with EOS 4.5, most of the new features introduced in v4.61 relate to this board, so it doesn't make a lot of sense to run one without the other (for more information on precisely what EOS v4.61 offers, please see the box elsewhere in this article).

The top-of-the-range E4 Platinum supplied for this review, which contains all of Emu's add-on options as standard. However, despite the swathe of extra capabilities added by the RFX32 card, the number of front-panel controls remains the same, which means accessing the new features can be cumbersome.The top-of-the-range E4 Platinum supplied for this review, which contains all of Emu's add-on options as standard. However, despite the swathe of extra capabilities added by the RFX32 card, the number of front-panel controls remains the same, which means accessing the new features can be cumbersome.Photo: Mike CameronFor this review, I had the luxury of using Emu's top-of-the-range E4 Platinum, in which the RFX32 is installed as standard. This machine also comes fully loaded with all of Emu's other sampler expansion options including 16 balanced analogue outputs, AES-EBU digital in and out, eight channels of ADAT in and 16 out and two SCSI ports — in all costing just over four thousand pounds in the UK. The good news is that the RFX32 can be installed in all members of the Ultra family (namely the E4XT, the now-discontinued E-Synth, the E6400 and E5000); the only major limitation in functionality is that the hardware-routing combinations will be determined by the number of physical outputs installed on your machine.


The RFX's three main effects elements are the RFX Plug-in, RFX Preset and RFX Setup, which equate to the EOS Sample, Preset (ie. arrangement of samples across the keyboard) and Multi Mode (ie. multitimbral arrangement of Presets).

The RFX Plug-ins are the basic effects algorithms and as this naming suggests, Emu have followed the lead of computer-based programs and provided all the algorithms as software rather than encoding them on to the chips. This is very good news in terms of expandability and future-proofing, especially as all the new plug-ins so far have been available for free download from Emu's web site.

There are currently 20 plug-ins available, including various reverbs, choruses, delays and EQs. Introductions in EOS v4.61 comprised the 13-band Modular Vocoder which can be linked together over four busses to create a 52-band vocoder setup, as well as Ring Modulator, Phaser and the less self-explanatory Muxter. This is an LFO-controlled, tempo-sync'able gate — essentially a slicer and dicer designed for dance and electronic music. In fact, it comes in two flavours — a single-channel version and Quad Muxter, which allows you to simultaneously run your signal through four independent paths, each of which can be fully programmed with different note durations and levels.

RFX32 Effects Plug-ins

  • Simple Reverb.
  • RFX Hall.
  • Long Delay.
  • Stereo Delay.
  • BPM Delay.
  • Rhythmic Delays.
  • Slap Delay.
  • Stereo Slap.
  • EOS Chorus (lite).
  • Para/shelving EQ.
  • Four-band Split EQ.
  • 10-band EQ.
  • RFX Flanger.
  • Muxster.
  • Quad MuXster.
  • RFX Phaser.
  • Envelope Phaser.
  • Ring Modulator.
  • Mixer.
  • Vocoder.

The most recent additions to the downloadable plug-ins on the Emu web site are Mixer, Flanger and Envelope Phaser. Mixer is a virtual two-by-two design, with the separate signal paths offering phase inversion, high shelving EQ, parametric EQ, low shelving EQ, volume control and either pan or balance, depending on which mode you're operating the mixer in. RFX Flanger is something of a deluxe model, offering true stereo sweeping with an extensive modulation section that can be controlled by tempo, a variety of LFO shapes or MIDI. Envelope Phaser is also slightly unusual in that it offers an envelope follower in place of the usual modulation section. This envelope tracks the amplitude of the incoming sound and then converts it to a signal that is applied to the phaser's phase-shift input. [Note: as this review was completed, five more free plug-ins, RFX Chorus, Ultra Chorus, and the intriguingly named Grungulator, Stereo Grungulator, and Grunge FX, were added to the Emu web site, but there was no time to try these out before this issue went to press.]

Using the plug-ins as the basic building blocks, you then create an RFX Preset, which is basically a plug-in plus all its associated parameters. Emu provide a large number of factory-programmed presets which can be easily edited to create your own custom versions. The programmable parameters available for each RFX Preset are quite extensive, enabling a high degree of fine-tuning. What's also good is that the ability to edit RFX Presets has been well integrated into the overall sound-programming hierarchy, so that, for example, if you need to tweak an effect as part of editing a sound Preset, you don't have to back out and then drill down through another set of menus to do so.

Accessing one of the effects added by the RFX card.Accessing one of the effects added by the RFX card.The top level of the effects hierarchy is the RFX Setup, which contains all RFX mixer routings and amounts, all input and output routings, and all effects used in the setup. Up to 1000 RFX setups can be stored with a bank. Incidentally, for the sake of backwards compatibility, the setup hierarchy can emulate the old-style EOS 'TwoFX' mode, which means all your pre-RFX32 presets and sequences will continue to have the right effects assigned to them. Note that banks created under the old regime automatically default to TwoFX mode.


The mixer/router element of the RFX32 is a pretty complex beast that is a lot harder to explain than it is to use. The concept is straightforward enough — it's a mixing desk which routes channels through to the effects busses. Fundamentally, the RFX32 gives you four programmable stereo effects sends per voice and each of these effects sends can be routable to either the Main buss, which is always dry, or one of the remaining 14 stereo effect busses. Each of these busses can have up to six effects assigned (in series), subject to a maximum limit of 16 simultaneous effects in the RFX system as a whole (however, see 'The Small Print' box below for a more detailed explanation of the limits of the system). Furthermore, the outputs of each of the 12 discrete effect busses can then be sent to either of two global effects busses (known as GFX1 and GFX2) or to the Main buss, or they can be routed directly to the analogue and/or digital outputs.

If you've stayed with me this far, then it's time to throw in the fact that there are in fact three ways of programming the routing — by Voice, by MIDI channel or by switching to RFX Mixer mode. The first is perhaps the most conventional way of handling sounds and internal effects, in that the four effects send levels and their buss assignments are simply programmed and stored as part of a Preset's Amplifier/Filter parameters. This is the kind of approach you might expect when, say, setting up a drum kit so that you get different amounts of reverb (say) on the bass, snare and so on.

When RFX busses are programmed by MIDI channel, any preset on a particular channel will be routed to a particular effect buss. This setting is particularly useful for multitimbral setups, when you need to easily assign different sets of sounds to different types of effects — the brass sounds to one type of reverb, the strings to another and so on.

The third way is to employ Mixer mode. This is by far the most flexible approach, not least because EOS v4.61 has introduced a number of enhancements that enable you to get around the system much more easily. With just a couple of button pushes, you access the new Multi mode screens that enable you to program the four RFX buss sends per MIDI channel without the need to modify routings within the RFX preset itself. You also get full MIDI control of up to four effects per MIDI channel, and your effects routings can be saved as part of your Multi setups.

The effects send levels can all be changed via MIDI controllers, which is great for real-time manipulation of sounds. But if you really want to shift up a gear, you can take advantage of the fact that while the MIDI controllers for the four RFX sends are set globally, they are addressable by a different MIDI channel for each mixer channel. In other words, with 32 MIDI channels and four MIDI controllers, you have a maximum of 128 possible fader channels to play with — effectively turning your sampler into a MIDI-automatable digital mixer.

RFX32 The Small Print

While everything I've detailed in this article adds up to what must be the most comprehensive and versatile system available for any hardware sampler, it's worth noting some of the small print concerning the inevitable limitations of the system.

The RFX32 is actually reliant on two Emu R-chip processors, one handling the duties for busses 1-6 and the first global buss, while the other handles busses 7-12 plus the other global buss. These two parallel systems can each deploy up to eight effects, but only if the effects are allocated to the busses which the chips control. A further limitation is that certain algorithms are somewhat more processor-hungry than others, so they effectively take up the space of two effects. To simplify this in the minds of users, Emu have rated effects as 'Thin' or 'Fat', the latter (as you might guess) representing the double-whammy effects types. If you were to use only Fat presets throughout, then you would be limited to just eight effects right across the system, with a maximum of four per effects buss.

Living Vibes

One of the most creative aspects of the RFX32 is the ability to process external sounds in real time. There are various ways to do this; you can route signals through the RFX32 just as you would with an external effects unit. Or you can treat external inputs just as if they were samples and also process them not only through the effects but also through the Ultra's voice architecture and Z-plane filters. Either way, signals can be passed into the machine via any available input: the analogue sampling jacks, the AES-EBU port, the analogue input jacks, or the ADAT interface, and you can permanently bind an external input onto a specific RFX buss regardless of the RFX Setup that is selected.

The E4 Platinum's rear panel, where the full weight of the range of built-in options becomes apparent. The four expansion option ports are filled with analogue output expansion boards, a second SCSI option, analogue inputs, and an ADAT optical I/O board. AES/EBU digital connections are also available on XLRs, and there are word clock and two full sets of MIDI connections as standard. This connectivity is impressive, but it's the RFX32 inside the Platinum that really makes the difference, allowing complex routing assignments and extensive processing of the signals flowing in and out of all of these connectors.The E4 Platinum's rear panel, where the full weight of the range of built-in options becomes apparent. The four expansion option ports are filled with analogue output expansion boards, a second SCSI option, analogue inputs, and an ADAT optical I/O board. AES/EBU digital connections are also available on XLRs, and there are word clock and two full sets of MIDI connections as standard. This connectivity is impressive, but it's the RFX32 inside the Platinum that really makes the difference, allowing complex routing assignments and extensive processing of the signals flowing in and out of all of these connectors.Selecting RFX Setups via the RFX Setup menu or by selecting Presets will change the effects and effect routings. This means that any sound patched into the inputs is treated exactly the same as an internal sample. So not only can you route those external inputs through the filters and VCAs, you can also assign up to four effects with the effects send levels modulated by any source.

Another approach is to use Live Samples mode, which treats incoming audio like a voice in the sampler itself. In order to hear the external audio, you have to trigger it via MIDI — in other words, 'play it' rather as you would an internal voice. In this case, the external input behaves just like a voice in Solo mode. And as with internal voices, you can use a MIDI controller to switch or velocity crossfade between a number of external inputs. At the very least, this makes a fully loaded Ultra something of a handy sub-mixer complete with effects for the rest of your keyboard rack.

The fun really starts when you combine external audio with the ability to control effects mixing and routing via MIDI. For example, you can pass a live audio stream through the sampling inputs, then route that audio to different effect busses according to which keys you press on your MIDI keyboard. So one key might send the audio to (say) a hall reverb effect, while the next might send it to tempo delay, and a third might send it to a tinny telephone speaker effect (fortunately, there's no audible glitching as the audio switches from buss to buss). Of course this is only the start, as you can also modify parameters such as the level of the effect and the wet/dry mix via MIDI controllers. This has a variety of applications; you can process live audio and trigger new samples and sequences alongside it, for example, which could make for creative remix possibilities. In a live situation, you can also automate changes of effects by triggering them with MIDI note commands from a sequencer. The creative potential here is enormous, particularly when you combine real-time mixing and switching with plug-ins such as Vocoder, Muxster and the new RFX Flanger.

RFX32 Edited Highlights

  • Four sends with send level per voice. Send levels controllable through a range of modulation controls.
  • 15 stereo effects busses comprising main buss, two global busses, plus 12 auxiliary busses.
  • Six effects per buss with control over wet/dry mix, mute, solo and bypass.
  • Up to 16 effects at once.
  • 32-bit processing throughout.
  • Effects updateable through software plug-in architecture.
  • Multiple effects setups and routing combinations.
  • Live sample feature enables use of external audio as a sample, allowing you to process it through effects, filter and synthesis sections.
  • Support for new 24-bit analogue and ADAT I/O cards.
  • MIDI synchronisation of effects parameters is built in.
  • Multi-buss resampling allows you to blend external and internal audio with effects to create new samples.


As you've no doubt gathered by now, Emu's claim that the RFX32 should be viewed as something more than an effects card is justified. The RFX32 adds a lot more to the overall sound-processing functionality of your Ultra machine, and also adds to the general usefulness of the sampler within your studio setup, as it really does give it the potential to act as the routing bay for all the rest of your gear.

The flipside of the power and flexibility coin is that conceptually there's quite a lot to take on board. Squeezing the creative juices out of an RFX32-equipped Ultra sampler is not a task for the casual samplist, although I'm sure long-time Emu users will quickly adapt to the new ways of thinking. While the Emu operating system has, to my mind at least, always been relatively less painful to operate than those of other samplers, you are still limited by the hardware interface: an RFX32 may double the functionality of your machine, but you've still got the same number of knobs and buttons with which to access it.

All that said, this is the kind of product that should be snapped up by any die-hard Emu fan and/or serious sound designer. At the current street prices for the RFX32 card, it represents pretty good value for money bearing in mind that you are getting a whole lot more than the ability to simultaneously stick reverb on your drum loops and a flanger on your funky guitar samples.

Maybe the RFX32 should come with a sticker for your Ultra's front panel that simply says 'This is not just a sampler'. Certainly if you invest in an RFX32, your sampler will cease to be merely what it says on the box, and have a whole lot more to offer.

EOS v4.61 — Edited Highlights

As most of the new functionality introduced in EOS v4.61 relates to the RFX32 card, it doesn't make an awful lot of sense to run one without the other. Apart from the RFX plug-ins, (notably Ring Modulator, Phaser, the 13-band Modular Vocoder, Muxter and Quad Muxter) the main development is an improved Multi mode with RFX (Mixer Mode) which includes the following:

  • The ability to override all four voice effects sends (busses and levels) at the Multi setup level.
    Four new MIDI continuous controllers for send levels, dedicated for use in Multi mode.
  • The ability to select an external audio input in lieu of a preset on a MIDI channel in the Multi setup.
  • External audio input to MIDI trigger (note on, note off) conversion.
  • RFX MIDI Modulation.
  • Modulation of effect wet/dry mix, input level, and output level.
  • Modulation of effects parameters (on effects that support modulation).
  • >Support for 32MB Flash memory boards.

EOS v4.61 also brings Ensoniq ASR10 and EPS File import via SCSI and floppy, and improved Solo mode operation. A number of bugs have also been fixed, including one where the optional ASCII keyboard would drop out during heavy MIDI usage, one which caused problems when files where being managed on large drives, and one which caused glitches and clicking on the attack portions of heavily layered sounds.

And finally, an RFX32 feature which doesn't fit into the conventional realm of effects, but which is definitely worth a mention is the MIDI Triggers function. As the name suggests, this allows you to trigger MIDI notes using audio inputs. Potential applications here include exercises in creative resampling, creating MIDI sequences from audio drum tracks, and replacing old drum sounds with new ones.


  • Open-ended effects architecture.
  • High-quality effects, including some very creative ones.
  • Flexible modular vocoder.
  • Huge potential for live sound manipulation.
  • Can be fitted to all Emu Ultra machines, even the £899 E5000.
  • Good value for money when you consider what you get.


  • Complex routing system can be hard to get a handle on.
  • The vastly increased capabilities still have to be accessed via the same number of hardware buttons.
  • There are limitations on just how many effects can be deployed at once — although they're not too serious.


Whether its capabilities will have appeal outside the circle of dedicated Emu owners is moot, but there's no denying that the RFX32 significantly upgrades an Ultra sampler into a machine capable of highly complex sonic manipulation. It's far more than just an effects card — but will people see the point?


RFX32 £479; E4 Platinum (includes built-in RFX32, plus balanced outputs, AES/EBU I/O, ADAT I/O, and dual SCSI ports) £4149; E4 XT £2169; E6400 £1399; E5000 £899. Prices include VAT.

Emu-Ensoniq Europe +44 (0)131 653 6556.

test spec

  • EOS version reviewed: v4.61.