It's been about 13 years since E-mu released the first Proteus, a single-rackspace sample-playback module that featured a highly effective collection

It's been about 13 years since E-mu released the first Proteus, a single-rackspace sample-playback module that featured a highly effective collection of sounds and an intuitive user interface. Since then, E-mu has introduced many successors to the original, typically offering more or bigger specialized sound sets and a few new features. The most recent model, the Proteus 2500, represents a quantum leap forward in the Proteus lineup. The module occupies a whopping four rackspaces and is adorned with plenty of knobs, buttons, and LED indicators. It has 128 notes of polyphony, a built-in sequencer, multiple arpeggiators, and extensive real-time control capabilities.

The Proteus 2500 can play 32 different timbres simultaneously, though the single MIDI In port limits you to half that number when you're using an external controller or sequencer. The 512 factory presets take good advantage of the 32 MB sample set. There's also storage for 512 user presets and ample expansion capability for new sounds.


The Proteus 2500's front panel contains 16 real-time controller knobs, 48 buttons, a 2 × 24 — character LCD, and a 4digit LED display (see Fig. 1). When I first saw the unit, I was concerned that such skimpy displays would be inadequate on a device of such complexity. My fears were unfounded, however; most of the buttons have built-in LEDs, and extra status indicators are scattered all over the front. The E-mu engineers did an excellent job of providing appropriate visual feedback for all operations.

The controls are grouped logically, and many of them have several functions. The 16 controller knobs, for example, might control the mix of your sequencer tracks, or they might provide quick access to common synth-programming parameters. Similarly, 16 buttons are arranged into two rows on the unit's bottom-right. Those buttons serve many purposes: they can mute tracks, give you quick access to a menu page, trigger sounds, and assist with step recording.

The 4-digit LED display can show sequencer tempo, the number of the Pattern in use, the current bar:beat position, or sequencer tracks and channels. A Select button lets you choose what you're viewing, and an Edit button lets you change it. Beneath the LED display are a set of transport controls for the sequencer and a Tap button that allows you to easily set the tempo. Cursor controls and a large data wheel let you freely change the parameters you're viewing, and a convenient Enter key flashes when it needs to be pressed. In addition, plenty of dedicated buttons access specific Proteus functions and menus.

Also on the front panel are a headphone jack, a master-level control, indicators for MIDI In and Out activity, and a power switch (which offers a handy delay feature to keep you from switching it off in the middle of a performance). Altogether, the Proteus 2500's front panel is well designed and intuitive to use.


On the rear panel are six unbalanced analog outputs on ¼-inch connectors for the main stereo signal and two stereo auxiliary sends (see Fig. 2). A coaxial S/PDIF connector carries the main stereo signal in digital audio form; if you prefer, you can configure that connector as an AES/EBU output.

The Proteus 2500 has one MIDI In and two MIDI Out ports. Two ¼-inch jacks accept either normally open or normally closed footswitches. Also on the rear panel are a standard IEC power connector (no wall wart!) and a USB port for connection to a host computer.

You can use the USB connection with the included E-Loader application (Mac/Win) to manage Patterns and Songs stored on the Proteus (see Fig. 3). Data transfer works in both directions; you can back up the module's music onto your computer, or you can download sequences (in Standard MIDI File format) to the Proteus. If your computer doesn't have a USB port, ELoader can use MIDI ports instead (but the transfer of data will be much slower). Some operations — such as upgrading the Proteus 2500 operating system — require the use of MIDI ports.

The presence of a USB port is encouraging, but unfortunately, the implementation doesn't go quite far enough. I wanted the ability to have a USB-connected Proteus 2500 show up as an available MIDI device on my computer, just as my USB-connected MIDI interface does. Instead, I had to use up limited MIDI connections and run multiple cables to the Proteus.


The Proteus 2500 has a nice scheme for locating and playing sounds. An individual sound is called a Preset, and you can scroll through Presets by number. By repositioning the cursor in the LCD display, you can also scroll to different MIDI channels, banks, or Preset Groups (a Preset Group represents a category of instruments, such as horns or keyboards). Move the cursor to the Preset name to scroll through the Presets within a Group. As soon as I figured out the scheme, I could get to any type of sound within seconds.

Proteus Presets are organized as four factory-programmed banks in ROM and four user banks in RAM; the RAM and ROM banks are identical when you first take the unit out of the box. If you install additional sounds using Expansion ROMs, those Presets will appear in new Preset banks.

A good collection of instruments is included, and all of the bases are covered to some degree. An abundance of percussion instruments and scads of electric and acoustic bass Presets supplement a nice set of synthesizer sounds. If you're into urban or techno music, you'll find plenty to work with. The collection of acoustic-instrument emulations is much less extensive. I had some difficulty finding string sounds that suited my music, and I wasn't at all impressed with the quality of the grand pianos.

Fortunately, some of those deficiencies can be addressed with Proteus Expansion ROMs. I checked E-mu's Web site and found several available, with sounds ranging from orchestral instruments to analog synthesizers; one even contains William Coakley's Perfect Piano. The Proteus 2500 has three expansion slots, and the built-in sounds occupy a fourth slot. According to Emu, nothing prevents you from replacing the built-in sounds with a fourth expansion module. In total, you can load up the Proteus 2500 with 128 MB of sounds.


The Proteus 2500 has a powerful sequencer that's capable of pattern-based and linear sequencing. You can record in real time or step time, or use grid-mode recording. Grid mode, which is available only when recording Patterns, is similar to the drum machines of days gone by.

Each Pattern can have as many as 16 tracks and can be as many as 32 bars long. You can record multichannel sequences into each track. Most sequence-editing features deal with track data; they don't necessarily let you restrict your edits to specific MIDI channels, though you can edit individual events.

A variety of tools are available to perform the basic editing operations you'd expect in any modern sequencer. You can edit individual notes and alter many events at the same time. You can quantize, thin, transpose, erase, and insert. If you want nice graphical tools for editing, though, you'll want to use your computer's sequencer instead.

You can cut or copy tracks (or portions of them), and you can merge with existing data when you paste. You might want to use multichannel tracks for track bouncing or mixdown; once your individual parts sound right, you can paste them into a single track to free up other tracks for additional recordings.

The Proteus 2500 provides 32 MIDI channels, and you can assign each track in a Pattern to send data to either the internal sounds or the external MIDI ports. The Proteus 2500's ability to play on 64 simultaneous MIDI channels (thanks to multichannel tracks) is an impressive feat for any sound module's sequencer. You can also sync the Proteus to external sequencers using MIDI Clock and Song Position Pointer messages.

You build Songs by stringing Patterns together. An additional Song Track is suitable for laying down an improvised solo for the entire length of a Song. Like the tracks in Patterns, the Song Track can record multiple MIDI channels. I was able to record two separate parts in two separate passes. The Song editing tools are similar to those for Patterns; most edits are applied to the entire track or a selected portion. Aside from individual events, there's no way to restrict edits to specific MIDI channels.

Pattern-based sequencers are usually too restrictive for my style of writing. I was initially disappointed to see only one track for linear recording, but I grew to appreciate the Proteus 2500's approach to sequencing. Because Patterns can be as long as 32 bars, I could record an entire song section into one Pattern. That helped me avoid the sterile and repetitive-sounding music that I've created with other pattern-based sequencers.


If you like arpeggiators, you will love the Proteus 2500. You can run as many as 32 arpeggiators at the same time, all synced to the same clock source. You can either use arpeggiator settings saved within each Preset or you can ignore the Preset settings and use a master arpeggiator.

The highly configurable arpeggiators let you choose Up, Down, Up/Down, or Random modes or choose from three modes that are based on note order. You can specify any note length as short as 32nd notes (including dotted and triplet values) with fixed or variable Velocities. The Gate Time parameter lets you create staccato- or legato-sounding arpeggios and everything in between. Additional settings control the arpeggio's total duration, and Extension settings let you specify a range of notes outside of the ones you play. You can also specify a range of keys where arpeggiation can occur. By telling the Proteus to arpeggiate only the notes above middle C, for instance, I could sustain chords with my left hand while playing arpeggios with my right.

Pre- and Post-Delay settings allow you to play without arpeggiation before and after the arpeggio plays. For example, it's easy to tell an arpeggiator to sustain a chord for two beats, arpeggiate for two beats, and then return to the sustained chord for four beats. Recycle mode makes the cycle repeat, and Latch mode lets you take your hands off the keyboard until you're ready to make it stop.

Pattern mode is available for arpeggios that are more complex. In Pattern mode, you can create up to 100 arpeggiator Patterns or use one of the 300 ready-made Patterns in ROM. Arpeggiator Patterns can have as many as 32 steps, and each step can have its own Velocity, length, and number of repetitions. You specify each note as an offset from the note that you play. You can also indicate whether a step is a rest or a tied note.

When you play additional notes while a Pattern-mode arpeggio is playing, the new notes are added to the pattern already in progress. I was concerned that playing new notes might start new patterns of their own (which might clash with the patterns in progress). Instead, I was able to build some nice arpeggiating harmonies one note at a time.


More than 400 Riffs are programmed into the Proteus 2500's ROM. You can assign one Riff to each Preset, so you can try out sounds by simply pressing the Audition button. Audition mode stays on until you turn it off, allowing you to hear something interesting from each Preset as you scroll through them. Riffs are categorized by instrument type, so if you're building a brass sound, for example, you can easily select a Riff appropriate for brass (such as a fanfare). Unfortunately, you can't create or edit Riffs.

In Beats mode, 27 special Riffs contain layered rhythm loops (or grooves, if you will). You switch the layers (called Parts) in and out with the same buttons you use for note triggers and track muting. You can also use a MIDI keyboard, which might have the added advantage of providing volume control (using Key Velocity) for each Beats-mode Part.

Each Beats Riff provides a main groove, an alternate groove, four fills, and four instrument parts. Pressing the trigger buttons lets you choose from the different grooves and bring the various instruments in and out. I could even combine the main groove's bass drum Part with the alternate groove's snare and hi-hat.

Although you can't edit each Part's rhythms, you have considerable control over how they play. You can transpose each Part and adjust its Velocity response. (Because Beats Parts are typically drum kits, transposition changes the instrument that plays). You can assign Parts to groups and trigger them all with one key. You can even use MIDI Control Change (CC) messages to control Velocity, transposition, and the number of Parts that play.

Several Presets are programmed to take advantage of Beats Riffs. I typically record rhythm parts from scratch, but I still had fun playing with those Presets, which provide useful rhythm tracks that you can quickly access when you're composing or comping around.


The Proteus 2500's architecture speaks to the techie in me. Reading the manual made me want to hide in a room and program sounds all day. The Presets consist of four Layers. Each Layer incorporates an Instrument (a set of ROM-based, keymapped samples), a filter, an amplifier, three envelope generators, two LFOs, and a few other goodies.

E-mu's Z-Plane filters, which can change their characteristics over time, go way beyond the typical lowpass filters found in lesser synths. You set the filter frequency and resonance, and the remainder of the filter's behavior is determined by the filter type you choose. Fifty different filter types are available, from 2nd-order highpass to 12th-order lowpass and everything in between. Choices include bandpass implementations, sweepable EQ, and filters that emulate flanging, phasing, and vowel formants. (Vowel formants can change over time, sweeping from oo to oh to ah, for example.)

Many components of the synthesis engine go beyond the basics. The envelope generators have six stages instead of the usual four, and you can modulate them by tempo. Portamento offers nine different curves for gliding from pitch to pitch. The LFOs have some unexpected waveforms that include four different pulse widths and a combination of sine and noise for creating realistic vibratos. Several LFO waveforms, when routed to pitch, can step through musically useful intervals. You can control LFO rate with the Proteus 2500's master clock.

My favorite aspect of the Proteus 2500's architecture is its modulation routing. Each Layer has 24 PatchCords that you can connect from nearly anything to nearly everything. In addition, 12 Preset PatchCords are provided for connecting things that apply to the Preset as a whole (such as Effect Send levels).

Modulation sources include all that you'd expect, such as Velocity, keyboard tracking, envelope generators, and LFOs. Sources include the 16 front-panel controller knobs, which you can map to specific MIDI CC numbers — especially handy when you're sequencing. For a bit of randomness, you can use white and pink noise as modulation sources. Specialized modulation processors, such as DC offsets, flip-flops, diodes, and lag processors, process incoming signals in several interesting ways. You can also sum multiple modulation sources.

In addition to all the modulation destinations you'd expect (such as filter frequency and amplitude), there are some that are more esoteric. For example, you can modulate the parameters of other modulators (such as the EGs and LFOs). You can also control sample start times, looping, and retriggering (anyone up for expressive solo leads?).


The Proteus 2500 has two stereo effects processors that you can program as part of each Preset. If you're playing more than one Preset at a time, you choose between the settings from a particular Preset or the master settings in a global menu. Effects Processor A contains reverb and delay effects, and Processor B implements chorusing, flanging, distortion, and delay algorithms. Although effects are limited to one algorithm per processor, four Effect Sends help you get the most from what you have. You can either specify the Effect Send level for each of the 32 MIDI channels or revert to the send levels saved in the Preset on each MIDI channel.

The effects sound as good as or better than those of other synths in the Proteus 2500's price range. The reverbs and choruses are smooth. The distortion algorithms don't really crank my tractor, but they never do in a synth-based effects processor. Missing from the lineup are effects such as phasers, rotary speakers, and sonic enhancements (in the vein of Aphex's Aural Exciter or BBE's Sonic Maximizer).


The Proteus 2500 is a remarkably flexible instrument. If you're a sound designer, it offers almost any tool you could hope for in a sample-playback instrument. If you're a songwriter, its 16-track sequencer is great for developing ideas. If you're a live performer, the Proteus provides 32 arpeggiators and 27 Beats-mode Presets to play with.

The Proteus sounded great in my studio; I heard no self-noise or other artifacts. It is well supported on E-mu's Web site, and its documentation is extensive. The user manual lacks organization in places, but it still taught me everything I needed to know about using the module. Make no mistake: the Proteus 2500 is one awesome box.

Allan Mettsis an Atlanta-based musician who is also a software and systems designer, and a consultant.

Proteus 2500 Specifications

Sound Enginesample playbackData Encoding44.1 kHz, 16-bit linearPolyphony(128) notesMultitimbral Parts32Presets(512) ROM; (512) RAMWaveform ROM32 MB, expandable to 128 MB using (3) additional expansion slotsSequencer(16) MIDI channels per track; (16) tracks and (1) Song track per Pattern; (1,024) Patterns; (512) Songs; (384) ppqnArpeggiators(32) simultaneous; (300) ROM Patterns; (100) RAM PatternsEffects(2) 24-bit processors; (44) reverb and delay effects; (32) chorus, flange, distortion, and delay effectsAudio Outputs(6) unbalanced ¼" TS; (1) coaxial S/PDIF; (1) ¼" stereo headphoneMIDI Ports(1) In, (2) OutAdditional Connectors(1) USB; (2) ¼" footswitchDisplays2 × 24 — character LCD; 4-digit LEDDimensions4U × 8.75" (D)Weight20 lb. (shipping weight)


Proteus 2500
sound module


PROS: Powerful synthesis engine. 32-part multitimbral. 128-note polyphonic. Excellent real-time control. 32 simultaneous arpeggiators. Flexible sequencer.

CONS: Not enough acoustic-instrument samples. Only one MIDI Input. No Polyphonic Aftertouch.


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