Magazine Archive

Home -> Magazines -> Issues -> Articles in this issue -> View

Four Play

Ensoniq DP/4 Parallel Effects Processor

It's flexible, it's powerful, and it comes with a pretty hefty price tag. Paul White finds out whether Ensoniq's first foray into the world of stand-alone effects delivers enough bang for the buck. Additional research by Derek Johnson.

I have to admit that when I unpack an effects unit and find a manual about the size of the local Yellow Pages, I begin to feel uneasy. This sense of unease was in no way dissipated when I opened the manual and found that it was written entirely in English — I was rather hoping that there would have been at least 11 different translations in there, with the English version making up only the first 20 pages or so. But the Ensoniq DP/4 is no ordinary multi-effects unit, and some degree of literary assistance is definitely in order. It transpires that, (electronically if not physically), the DP/4 is made up of four separate effects units, each with its own audio input, which can be used independently or combined in a variety of series/parallel configurations, enabling the unit to produce some extremely rich and complex effects. There is a 4-output internal digital mixing system to combine the four effects units; on most occasions, the effects might be mixed to a single stereo pair of outputs, but with this system you also have the opportunity to route the internal effects to two stereo pairs, or to four individual mono outputs if the occasion demands.

With few exceptions, the four effects sections, or Units as Ensoniq like to call them, can make use of any of the 40 available effects algorithms, and as these include specific guitar-related effects, the DP/4 is by no means limited to the keyboard player or studio owner.

Before progressing further, it's also important to note that in this quantity-before-quality age, Ensoniq have done their utmost to provide clean, professional-quality sound from this unit. The internal processing system is 24-bit, while the input and output converters are 16-bit, yielding an 18kHz audio bandwidth and a dynamic range of 96dB.

By way of styling, the 2U DP/4 is neat and uncluttered, but it doesn't have the visual panache of some Japanese units. There is a large data entry knob, a 32-character liquid crystal display, and refreshingly few buttons. Eight rotary knobs provide control over the input and output levels of the unit, and there's a pair of red/green LEDs above each input control which function as simple input level meters.

In addition to the LCD, there is a 2-digit LED display, which shows patch numbers, or parameter values during editing. Under the display are several buttons: Write/Copy; Cancel/Undo; left and right parameter select arrows: Select; Edit; and System/MIDI. The four effects modules have their own selection buttons, plus associated yellow and red status LEDs, while nestling adjacent to these is the Config button, instrumental in deciding how audio is routed between the four effects modules.

For the benefit of the lone guitarist, there's a front-panel jack which feeds directly into input 1. All other audio connections are found around the back. The four inputs and outputs are on quarter-inch, unbalanced jacks, and there are three MIDI sockets, a footswitch socket, and a CV pedal socket.

There are 400 memory locations in the DP/4, 200 factory presets, and 200 user memories. These latter 200 come filled with duplicates of the factory presets, which is sensible, as these often provide a good starting point for editing. The factory settings can be recalled at any time, and reappear whenever the machine is initialised.


In common parlance, the effects created by the DP/4 are built around algorithms, chunks of computer code that define an effect (or in some cases, combination of effects) and the parameters which can be varied to alter that effect. For example, a reverb effect would be based around a reverb algorithm. There are 46 algorithms altogether and, depending on which one is selected, you have access to between 14 and 31 parameters.

Because there are four effects Units within the DP/4, and because these can be connected in many different ways, the business of defining an effect preset is not as straightforward as with a conventional effect device. The most comprehensive form of preset is the Configuration Preset, which holds information as to how the four effects units are connected to each other and to the audio inputs and outputs — what effect algorithms are loaded into the four Units and the parameter values for those effects. The input and output levels are not stored as part of a configuration and have to be set manually.

Moving down the programming hierarchy we come to the Four Unit Preset; this relates to the algorithm loaded into the four Units, along with their parameters, but it does not specify how the four units are connected. Below this are One Unit and Two Unit Presets, which work just like the Four Unit Preset but for pairs of Units or individual Units. This means we have four different types of preset to work with, and the DP/4's memory is equally divided between them: There are 50 of each type in the factory preset bank, and you can store 50 of each as user presets. Obviously, the simpler Unit presets can be combined in different ways to produce different Configuration Presets.

When you power up the DP/4 for the first time, only 12 of the most commonly used Config Presets are available — an attempt to break the new user in gently. The remaining 88 presets can be invoked via the System/MIDI mode.


I stated at the outset that the individual Units could, by and large, make use of the available algorithms in an unrestricted manner. The exceptions to this come when you select an effect which needs a lot of processing power; the DP/4 deals with this by using the processing power of two or more Units to create the more complex effects. The PitchShift 2U and 3.3 Sec Delay algorithms both use two processing Units, while the power-mad Vocoder commandeers all four. The remaining effects fall into familiar categories, the most obvious being reverberation. On offer are: 'straight' reverbs, a couple of reversed reverbs, a gated effect and three non-linear reverbs. The obligatory delay department sports four delays: multi-tap, dual, tempo and EQ-DDL with LFO.

For the guitar player, there's a very effective VCF-Distortion for overdriven wah-wah and auto-wah effects, plus three guitar amp effects, two of which feature great tube emulations. There are also speaker simulations for DI recording, including a useful 'tunable speaker', which is ideal for creating special effects such as transistor radios or telephones.

The remaining effects comprise a wide variety of chorus treatments (including an eight-voice chorus), flangers, phasers, tremolo, pitch shifters, panners, a de-esser, a rumble filter, a ducker/gate, parametric EQ, a vocoder and a sine/noise generator. The latter is useful for creating sound effects when processed by the effects sections. Additionally, there are three kinds of expander, an EQ-Compressor and a Van Der Pol Filter, which produces an 'exciter' effect to brighten sounds, and particularly benefits plucked sounds.

Some of the basic algorithms are actually combination effects, where Chorus, Vibrato, Panner, Flanger and Tremolo are combined with pre-EQ and post-delay. Even in isolation, these can provide very usable effects, but things don't start to really hot up until you start to combine different things.


Configurations, as touched upon earlier, are simply the various ways in which the four effects Units can be patched together. If there is a negative aspect of this unit, it's that there are so many variables that you have to approach programming with a clear head. To this end, both the display system and the manual are very helpful, with clear, non-technical explanations of what's really taking place. It might be long-winded, but at least Ensoniq are keen to ensure that the user understands the DP/4 and what it can do.


The DP/4's MIDI implementation allows for realtime control of up to eight sources at once, from a choice of over 138. A CV pedal can also be used to control one parameter, though two might have been more in keeping with the general air of excess the DP/4 provides.

With 400 presets on board, some way of speeding up access to presets is desirable, the most straightforward manner being through the MIDI Program Change map which assigns presets to MIDI program change numbers. As ever, setting this up is long-winded, but it's not something you do every day. You can also step through presets with a single footswitch, or with Ensoniq's special dual footswitch which increments with one pedal and decrements with the other. In addition to an overall MIDI channel for the whole unit, each of the four effects can have a different MIDI channel. This way, each effect can be controlled in level over MIDI, using MIDI Controller 7.

"There is still a psychological price barrier at £1,000 for effects units, but for the user who wants to combine outstanding flexibility with professional sound quality, I feel the asking price for the DP/4 is very fair."

The MIDI implementation also allows timed delays to be measured against incoming MIDI clocks, which takes the grind out of working out rhythmic delays. There's a delay time choice of ordinary notes, dotted notes, and triplets from quarter up to 32nd notes.


What really strikes you about this unit when you first try it out is the sheer quality and depth of the effects, especially if you hapen to plug in a guitar. The reverb and chorus effects have a beautiful shimmering quality about them and just seem to hang in the air between the speakers, while the background noise level is exceptionally low. The musicality of the reverbs carries over to the remaining effects, with an overall natural quality and smoothness. Quite often a single effect (such as chorus or phasing) sounded so perfect that no further processing was necessary. The Eight Voice Chorus algorithm was a real treat for acoustic guitar, and it was hard to believe there was no reverb with the effect, so natural was the sound.

Overdriven guitar sounds or over-zealous flanging can get a touch noisy, but the noise gate will help to get rid of this (providing you are careful to set the threshold as low as possible, so as not to chop off any of the wanted sounds as they decay). The guitar overdrive effects are actually rather impressive, and, whilst they don't bear comparison with a real miked-up amp, they are nonetheless good and solid with none of that fizzy nonsense that some effects units provide.

The only effect that wasn't entirely satisfactory was the pitch shifter. This is better than most of the attempts found in budget units, but still tends to become 'lumpy' when any significant degree of shift is applied. It's not so bad when covered by the unshifted sound, or when smothered in effects, but if used in a position of too much prominence it creates that familiar, out-of-tune sound for which the performer invariably takes the blame.

The amp simulation sounds are a trifle artificial but, somehow, they still work exceptionally well, and the range of overdriven sounds that can be achieved is astonishing. Particularly nostalgic is the Hendrix distorted wah sound — and yes, I did play that riff! If you like Dire Straits' 'Money For Nothing' sound, that's in there too, while more subtle overdrive settings produce quite convincing blues sounds. But for me, the unit excels at producing those shimmery, complex guitar sounds that turn a simple chord into an entire musical statement.

It's also interesting to see how the unit handles changes from one effects patch to another — instead of a glitch or a sudden gap, the current effect is rapidly faded out and then the new one fades in after a short pause. It might have made more sense to leave the dry sound present during the changeover but, so long as you plan your change points with care, it shouldn't be too limiting.


Because the DP/4 is so versatile, it is hard to ascribe a character to it, other than to say that the sounds it produces are as rich as they are classy. Not all the effects are completely silent, as regards processing noise, but in general they are all quieter than we have come to expect from all but the most exotic studio processors. One moment the DP/4 is seducing you with ethereal reverts interlaced with sparkling modulation effects, while a moment later it's banging you over the head with a Marshall stack set to 11. The unit is also spectacularly versatile — one day you could be sharing it with your chums, one effect apiece, the next you could be hogging the lot to create really mammoth, self-indulgent effects. This thing does for self-restraint what Saddam Hussein did for lacemaking.

Of course this degree of sophistication comes at a price, but the best way to justify the cost is to keep telling yourself that there are really four effects units in the box and that, taken individually, they are really quite cost-effective; it works out at well under £300 a processor and you get an effects submixer thrown in.

Guitarists are well catered for when it comes to tonal choice. In this respect the nearest comparison I can make is with the Zoom 9030, which has a similar 'larger-than-life' character. The main difference is that the four effects in the DP/4 let you have more excess at any one time. Despite the unit's great suitability for guitar processing, its supreme flexibility makes it an impressive studio all-rounder, and it is equally at home adding reverb to drums and vocals or spicing up keyboard sounds. What's more, the overdrive section is second to none for creating those wailing pseudo-guitar synth sounds.

Operationally, the DP/4 offers a high degree of flexibility, but while editing individual effects Units within a Config Preset is relatively straightforward, it can be quite time consuming You certainly need to refer to the manual, at least for the first day or two, or you can get quite lost. I think Ensoniq have come up with a very versatile output arrangement, and though some users will bemoan the fact that there aren't a full eight outputs, being able to return four stereo effects via a single stereo pair is definitely the more elegant solution in the majority of applications.

Aside from the more conventional, but nevertheless beautifully implemented, effects, I appreciated the addition of a vocoder and the over-generous maximum reverb and delay decay times. It isn't often that you need to use these excessively long times, but at least they're there if you want them. The gate is also nicely unobtrusive when set properly, which means that even heavily overdriven sounds stay squeaky clean.

Of course there have to be some moans, and I must say I found the Select button a bit slow, while the Bypass buttons refuse to respond unless you hold them down for half a second or so. The unit is also, by its nature, fairly complicated and, though the individual programming steps are in themselves quite logical, setting up a complex configuration from scratch demands both time and undivided attention.

There is still a psychological price barrier at £1,000 for effects units, but for the user who wants to combine outstanding flexibility with professional sound quality, I feel the asking price for the DP/4 is very fair. Digital recording is now with us, and our perception of sound quality is rather more sophisticated than it was, say, five years ago. What was once acceptable now tends to sound noisy and a trifle bland, but I can guarantee that it will be a long time before you feel that way about the Ensoniq DP/4.

Further information

Ensoniq DP/4 £1,179 inc VAT.

Sound Technology plc, (Contact Details).


Small Room Reverb
Large Room Reverb
Hall Reverb
Small Plate
Large Plate
Reverse Reverb
Reverse Reverb 2
Gated Reverb
Non Lin Reverb
Non Lin Reverb 2
Non Lin Reverb 3
Multitap Delay
3.3 Second Delay (2U)
Dual Delay
Tempo Delay
VCF Distortion
Guitar Amp 1,2
Guitar Amp 3
Speaker Cabinet
Tunable Speaker
Rotating Speaker
8 Voice Chorus
Pitch Shifter
Pitch Shift 2U
Pitch Shift-DDL
Fast Pitch Shift
Keyed Expander
Inverse Expander
Rumble Filter
Parametric EQ
Van Der Pol Filter
Sine/Noise Generator
No Effect (Bypass)
Vocoder (4U)


01 Mix
02 Volume
03 Room Decay
04 Room Predelay Time
05 Room LF Decay Time
06 Room HF Damping
07 Room HF Bandwidth
08 Room Diffusion 1
09 Room Dffusion 2
10 Room Decay Definition
11 Room Detune Rate
12 Room Detune Depth
13 Room Primary Send
14 Room Ref 1 Time
15 Room Ref 1 Level
16 Room Ref 1 Send
17 Room Ref 2 Time
18 Room Ref 2 Level
19 Room Ref 2 Send
20 Position Balance (1)
21 Position Balance (2)
22 Position Balance (3)
23 Mod1 Source
24 Mod1 Destination Parameter
25 Mod1 Parameter Range Min
26 Mod1 Parameter Range Max
27 Mod2 Source
28 Mod2 Destination Parameter
29 Mod2 Parameter Range Min
30 Mod2 Parameter Range Max

Also featuring gear in this article

Previous Article in this issue

Shape Of Things To Come

Next article in this issue

Passport Master Tracks Pro 4

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 - Oct 1992

Gear in this article:

Studio FX > Ensoniq > DP/4

Gear Tags:

Digital FX

Previous article in this issue:

> Shape Of Things To Come

Next article in this issue:

> Passport Master Tracks Pro 4...

Help Support The Things You Love

mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.

If you value this resource, you can support this project - it really helps!

Donations for September 2021
Issues donated this month: 0

New issues that have been donated or scanned for us this month.

Funds donated this month: £18.00

All donations and support are gratefully appreciated - thank you.

Please Contribute to mu:zines by supplying magazines, scanning or donating funds. Thanks!

Monetary donations go towards site running costs, and the occasional coffee for me if there's anything left over!

Small Print

Terms of usePrivacy