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Ensoniq DP/2

Parallel Effects Processor By Derek Johnson
Published December 1995

Derek Johnson opens up the latest effects box from Ensoniq and finds that they do sometimes do things by halves!

Ensoniq's move into dedicated multi‑effects units has been unusually cautious. The DP/4 stereo parallel effects processor, released in 1992, was a bit of a breakthrough, with its provision of four independent and freely‑interconnectable processors in a 2U package, and for the following three years Ensoniq were content to use this technology in their synths and samplers — until the release of the upgraded DP/4+, and now the DP/2.

One point against the DP/4 has always been its price. The new DP/4+ lists at almost £1,300, and while this price is reasonable in view of the facilities on offer, it does exclude some potential customers from joining the Ensoniq camp. Hence, the DP/2. While appearing to be half a DP/4+, the DP/2 actually scores over the more expensive unit in some areas — for example, it has 12 more basic effects algorithms (see 'Those Algorithms In Full' box), and 50% more preset memories. Given that the algorithms include some killer guitar‑orientated effects, the potential market for the DP/2 is quite large, taking in guitarists, keyboard players, and the studio musician.

Keeping Up Appearances

Externally, the DP/2 looks a little like the bottom half of a DP/4+, with some minor differences. Gone are the chunky chrome‑effect input and output level controls and large data‑entry dial, the DP/2 adopting sober black pots in their place. The data‑entry knob still offers a positive click for each move though, which is certainly welcome. The display is identical — 2‑digit LED for preset and parameter numbers, and a 2‑line x 16‑character LCD for preset and parameter names and values. The buttons for navigating the system are all clearly named, although you'll need a look at one of the two manuals (one is a handy tutorial) to get to grips with what they actually do.

The inputs and outputs, situated on the rear of the unit, are on balanced quarter‑inch jacks, and there are a pair of each. A duplicate of input 1 appears on the front panel (for ease of guitar use, for example), and this takes precedence over the rear connection. Also at the rear are a pair of dual footswitch sockets, which can be set up to control several of the DP/2's functions. Unfortunately, they won't work properly with ordinary mono footswitches unless you perform the wiring modification provided in the manual. Lastly, there's a volume pedal input, plus a trio of MIDI sockets (In, Out and Thru).

Power is supplied via an external power pack. The handful of demerit points awarded for this are further compounded by the fact that: a) the PSU is huge; b) it requires a mains lead to be plugged into a flying lead; and c) the lead that connects to the DP/4 is not terrifically long — the power unit had a tendency to not quite touch the floor even when the DP/4 isn't all that far from the ground. I also discovered that it induces hum in guitar pickups.

The Look Inside

Looked at simply, the DP/2 is half a DP/4+, and (in common with the Digitech TSR24S, reviewed in October's issue of SOS) offers two separate true stereo effects processors, referred to in the manual as Effects A and B. The DP/2 can use these effects to process a single mono or stereo input Source (such as guitar or stereo keyboards), or two Sources (guitar and bass, or two mixer effect sends, for example). In the first case, your guitar or keyboards are processed by both effects (in series, in parallel, or with a choice of two feedback options), and in the second case, your mixer effects sends each have access to a fully independent effects unit. While this latter setup might sound limiting, as each independent 'unit' only has access to half the processing power of the DP/2, in practice it isn't really a problem, since many of what Ensoniq call single effects (or algorithms) in fact contain a chain of two, three or even four effects.

Not surprisingly, each algorithm has a number of parameters associated with it. These can be tweaked at will, and the resulting effect named and saved as a Preset. (Note that the term 'Preset' does not indicate, as in most cases, unchangeable factory settings, but what might normally be called a patch, whether factory ROM or user RAM.) Presets are divided into three types:

  • One‑Unit Presets are effects which use one half of the DP/2's processing power. They have their own memory section (two Banks of 100 Presets are stored here, with 50 Presets in each Bank being user‑definable).
  • Two‑Unit Presets are effects which use all the DP/2's power. They also have their own memory section, organised exactly as the One‑Unit presets described above.
  • Config(uration) Presets essentially allow you to split the DP/2 into two units, and use both independently. They contain all the routing information used to guide input signal(s) through the DP/2 to the stereo output. Broadly speaking, there are two Config types: One‑Source, and Two‑Source, as given in the example at the beginning of this section. A One‑Source Config would allow you to create a custom Two‑Unit Preset (for use with a single source such as a guitar), rather than editing what is provided in the two Banks of Two‑Unit Presets, and a Two‑Source Config lets you construct a setup using both Units with two input Sources, such as guitar and vocal mic. Further Config parameters allow you to choose mono or stereo outputs for each Unit. Config Presets are also saved in two banks of 100 Presets each.

Pick Up A Preset...

Figuring out which sort of Preset (One‑Unit, Two‑Unit or Config) you're using or trying to edit can be confusing at first, but keep the pair of manuals to hand — and read them — and you should get the hang of it (refer especially to section 6 of the main manual, and most of the User's Guide). A useful fact that isn't immediately obvious is that Config Preset 50 selects the Two‑Unit Preset Banks with mono input, Config Preset 51 selects Two‑Unit Preset Banks with stereo input, and Config Preset 52 selects the One‑Unit Preset Banks.

Once you've sorted out the differences between the vaious Preset types, editing the DP/2 is rather like editing any other late '90s hi‑tech musical device: scroll through the parameter list attached to each Preset (see 'Editing Parameters' box for fuller details of what you can change), and alter the values as you see fit. You'll probably find yourself working exclusively with the 200 Config Presets, since effects can be fully edited within a Config, and here you have access to the comprehensive routing system. One point to keep in mind is that there is no real way of accessing basic algorithms. When customising the two effects 'units' within a Config Preset, you don't start with two algorithms, but with two one‑Unit Presets.

I've suggested that you make regular reference to the manuals, and with good reason, because the DP/2 is confusing, and the manuals are exceedingly thorough. In fact, they're too thorough for my liking — the constant repetition of basic operational points, using exactly the same chunks of text, may be useful to the novice, but a little variation in language would have been more than welcome.


Operational eccentricity aside, the first thing you notice when trying to bungle your way through the operating system is that nothing seems to make the DP/2 sound bad — it simply exudes quality, warmth and lushness, helping you to produce involving and musically relevant treatments with virtually no effort. Noise doesn't intrude too much (except in the expected places, such as amp simulations and guitar distortion and fuzz), and let's not forget the sheer number of effects Presets provided by the DP/4 — 600 in all, 300 of which you can use to store your own edits.

It's impossible to pick out any favourite effects — this review would end up being a commentary on most of the factory settings — but if you like your choruses lush, your reverbs realistic, and your distortion grungy, you'll find something of use inside the DP/2. Reverb is a touchy subject for many people, and the algorithms provided here are as suitable for critical vocal work as they are for adding a wash to synths; they have a produced, glossy, yet natural feel that takes the hard work out of singing with headphones. Some factory settings tended to accentuate plosives and sibilants, but a little tweaking sorted these small problems out.

We at SOS approve of vocoders in general, hence the Two‑Unit Vocoder algorithm presented here is a welcome addition, although the way it eats up all the processing power available is a little disappointing. It doesn't seem to have quite as many parameters as the vocoder provided by Boss on their SE70, but the end result is pretty fine nonetheless. Other welcome (non‑effect) algorithms include a guitar tuner and a signal/noise generator — the latter is actually used in combination with other effects to create some wild sound effects.

Pitch‑shifting is an effect that is nearly always included in modern multi‑effects units, and it's nearly always useable only in small amounts. However, the DP/2's pitch‑shifting is actually quite good, especially the Two‑Unit pitch‑shift algorithm, which unfortunately uses up all the available processing power. It has a metallic edge, but the delay is minimal and the quality quite good.

It's possible to pick on one algorithm that's not so hot, and that's the so‑called Vocal Remover. This is a sophisticated filter that applies all sorts of fancy processing to the incoming signal. The result is that on most material, the lead vocal, and often any lead instruments, fade away into the distance. You can hear them, but only just. The trouble is that the rest of the track tends to be unpleasantly affected as well — it's a bit like listening to a track through a thick wall.

If you want to make the DP/2 stretch a little further in the studio, note that the dual in, dual mono output option means that you could use individual effects as 'insert' processors during tracking. The various EQ, compressor and filter options are all of sufficient quality that they introduce no compromises. For example: I set up a Two‑Source Config with dual mono outs that allowed me to compress a vocal during recording, while providing an independent headphone mix with (mono) reverb. So, a little lateral thought and a bit of customisation goes a long way with the DP/2.


While there's no doubt that the DP/2's effects are of a high quality and are extremely editable, I can't help wondering whether Ensoniq couldn't have made their new machine easier to use. Admittedly, the DP/4 and DP/4+ have a similar complexity, but when there are four independent effects units to patch together, such complexity is more acceptable. Perhaps Ensoniq could have given the DP/2 a simpler memory structure, with all memory locations becoming Config Presets and routing data then an integrated part of every Preset. Certainly, most DP/2 users will find themselves working exclusively with the two Banks of Config Presets.

Apart from my misgivings about the operating system, whose complexities can, however, be mastered given regular access to the manuals, the DP/2 is highly recommended. For a little over half the price of a DP/4+, you get a little more than half a DP/4+'s power, with a wonderfully smooth, 'produced' sound quality, Two‑Unit versatility, and some useful studio processors to boot. Although it does have some direct competition at its price of £799 (Digitech's TSR24S, reviewed in SOS October, comes immediately to mind) the DP/2 certainly has enough character to hold its own in the marketplace.


  • A/D‑D/A Converter: 16‑bit
  • Sampling Frequency: 32kHz
  • Internal Processing: 24‑bit
  • Input: 2 quarter‑inch balanced jacks
  • Output: 2 quarter‑inch balanced jacks
  • Frequency Response: 20Hz‑16kHz
  • Signal to Noise Ratio: 90dB
  • Preset Memory: 100 user/100 ROM 1‑Unit Presets; 100 User/100 ROM 2‑Unit Presets; 100 User/100 ROM Configuration Presets.

Those Algorithms In Full:


  • 8‑voice Chorus
  • ADSR Envelope Generator
  • Chorus‑Reverb
  • Compressor‑Distortion‑Flanger‑Reverb
  • De‑Esser
  • Digital Tube Amp
  • Distortion‑Chorus‑Reverb
  • Distortion‑Rotary‑Reverb
  • Dual Delay
  • Ducker/Gate
  • Dynamic Tube Amp
  • EQ‑Chorus‑Delay
  • EQ‑Compressor
  • EQ‑Delay with LFO
  • EQ‑Flanger‑Delay
  • EQ‑Gate
  • EQ‑Panner‑Delay
  • EQ‑Tremolo‑Delay
  • EQ‑Vibrato‑Delay
  • Expander
  • Fast Pitch Shift
  • Flanger
  • Flanger‑Reverb
  • Fuzz Box
  • Gated Reverb
  • Guitar Amp 1, 2, 3, 4
  • Hall Reverb
  • Inverse Expander
  • Keyed Expander
  • Large Plate
  • Large Room Reverb
  • Multi‑tap Delay
  • Non‑linear Reverb 1, 2, 3
  • Parametric EQ
  • Phaser‑Delay
  • Phaser‑Reverb
  • Pitch Shift‑Delay
  • Pitch Shifter
  • Plate‑Chorus
  • Reverse Reverb 1, 2
  • Rotating Speaker
  • Rumble Filter
  • Sine/Noise Generator
  • Small Plate
  • Small Room Reverb
  • Speaker Cabinet
  • Tempo Delay
  • Tunable Speaker 1, 2
  • Van Der Pol Filter
  • VCF‑Distortion 1, 2
  • Vocal Remover
  • Wah‑Distortion‑Reverb
  • No Effect


  • 3.6 Second Delay
  • Guitar Tuner
  • Pitch Shift
  • Vocoder

Editing Parameters

Ensoniq have managed to cram rather a lot into their algorithms, yet there are never more than 31 parameters per algorithm. I guess they really made them count. As an example, here is the parameter list for the Distortion‑Rotary‑Reverb algorithm: Mix; Volume; Reverb Mix; Pre‑distortion Low Pass frequency; Distortion Level In; Distortion Level Out; Post‑distortion VCF frequency; Post‑distortion VCF resonance; Distortion Mix; Rotor Speed; Slow; Fast; Rotating Speaker Inertia; Tremolo Depth Slow; Tremolo Depth Fast; Vibrato Depth Slow; Vibrator Depth Fast; Rotating Speaker Mix; Rotating Speaker Stereo Spread; Reverb Decay; Reverb HF Damping.

There are also eight parameters for selecting the two modulation sources and destination, along with their minimum and maximum parameter ranges.


The MIDI side of the DP/2 is comprehensive and sophisticated. For a start, it operates on no less than four MIDI channels at once. This is necessary since the unit is capable of accessing three separate program change tables, plus a separate MIDI controllers channel. One MIDI channel is used to select a Config, while two more channels (and program change tables) are used to select One‑Unit effects (from the One‑Unit Presets Banks) within a Config.

The DP/2 has plenty to offer by way of real‑time control via MIDI (on the MIDI controllers channel) or through plugging in up to four footswitches and a volume pedal. You can define eight system controllers to be used as modulation sources, which can then be assigned to any two parameters in an effect — so you could easily control reverb decay time with velocity, for example. Controller sources can be any MIDI controller, velocity, note number, pitchbend or aftertouch, the volume pedal, or any of the footswitches connected to the DP/2.

The DP/4+ In Brief

The DP/4 was reviewed in SOS back in October 1992 (and in sister magazine Recording Musician in August 1992). The recently unveiled DP/4+ adds a number of significant features:

  • 54 algorithms, to the DP/4's 46.
  • A combined Neutrik XLR/quarter‑inch front panel input with signal gain switch.
  • Headphone socket on front panel with output mute button for soloing mix in headphones.
  • Two dual footswitches at the rear.


  • Excellent effects, with something for almost everyone.
  • Useful studio processors, such as EQ and compression.
  • Usable as one mega multi‑effects or two independent units.


  • Complicated.
  • Large, external PSU.
  • Only one pair of stereo outs.


The sound quality of the DP/2 is beyond reproach and the factory presets are useful and imaginative, making it a good studio all‑rounder. However, the operating system could be a lot more straightforward.