• Ensoniq DP/4
  • Ensoniq DP/4
  • Ensoniq DP/4
  • Ensoniq DP/4

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Ensoniq DP/4

Parallel Effects Processor

Just four effect

When the price tag says £1000+, the concept of placing four individual effects processors in a single box has to add up to more than simply a saving of rack space. And where the Ensoniq DP/4 is concerned, it seems it does...

Multi-effects units are a bit like the Swiss army knives of sound processing. The attraction is that they pack so many gadgets into one box - but that's also their fundamental weakness. As anyone who's ever tried to use a Swiss army knife to spread butter and get a boy scout out of a horse's hoof simultaneously will testify, multi-FX units are often not too hot when it comes to doing several jobs at once.

Even the latest generation of simultaneous multi-FX units still won't allow you to apply, say, gated reverb to the drums while saving the chorus and delay just for the keyboard pads. Of course, that's not a problem if you're laying down different parts of an arrangement on tape, track by track. Just select the appropriate FX for each sound as you record. However, if you're one of the increasing number of people who now by-pass the faithful multi-tracker and build up songs on a sequencer instead (only committing themselves to tape at the last stage of the process with what is, in effect, a live stereo mix) what you need is either a stack of individual effects processors or something akin to a 'multitimbral' multi-effects unit. Which is where we unveil Ensoniq's DP/4 - the first multi-FX box which really does let you have your cake and eat it.

Imagine a rack of four separate, fully programmable 24-bit digital effects processors, each offering a choice of 44 of the most commonly used effects types, plus a few not-so-common ones, like vocoder.

Now imagine them linked up via a programmable, MIDI-controlled patch bay which not only handles the routing of the signals into the four processors, but allows the units to be connected together in virtually any combination. This includes processing four signals completely separately, or creating one giant effects box to process just one. What's more, unlike a real stack of separate boxes, all routing, processing and mixing is done entirely inside its squeaky clean, digital innards.

Finally, add a programmable sub-mixer to take care of the configuration and volume of the outputs. Now stick it all in a 2U rack-mountable box with 400 memories, half in ROM (ie, factory presets), the other half in RAM (user-programmable presets). This is the Ensoniq DP/4: RRP £1175. Its American creators call it a Parallel Processor. I'd describe it as the mother of all multi-processors.

First some external architecture... most of which you'll probably be able to discern from the photographs. The 1/4 inch jack sockets at the rear provide the inputs and outputs (four of each) - though Input 1 is duplicated on the front panel. This is primarily designed for guitarists using the DP/4 as an 'in line' effects unit, although it will in fact take virtually any low or high impedance source. Back at the back: there are some holes here for MIDI, footpedals and CV inputs and things, but we'll fall into those as we come to them.

Familiarising yourself with the internal architecture of the DP/4 involves getting to grips with a little thing Ensoniq call Configurations - not the Albanian entry for this year's Eurovision Song Contest, but a word which unlocks the mystery of the machine's operation.

It goes like this... Configuration settings determine the number of input sources that can be processed, how those sources are routed to the DP/4's four effects processing chips (which from now on we'll call units A, B, C & D), how those units are linked together, whether the end result is mono or stereo and (in some cases) the mix of dry and processed signal coming out at the other end. Most important of all, the choice of configuration determines exactly how many effects are simultaneously available to process each input. Basically, the more sounds you want to process at the same time, the less power you've got to play with.

Let's start with the four-source configuration mode and you'll soon catch on. This effectively sets up the DP/4 as four separate units, each able to process a mono voice/sound using one of the 100 '1-unit' presets. These are all variations of the 44 effect algorithms which form the basic building blocks of all the DP/4 effects.

While all four processors select from the same menu of 1-unit presets (half in ROM, half in RAM, remember), there's no restriction on what presets are loaded where. Because each unit is effectively based around its own chip, you can load the same effect into all four processors if you like, and what's more you'd be able to edit parameters independently for each of them.

Now on to three-source mode, where the DP/4 becomes three separate effects processors - a couple of single units (A & B) plus a double one (C/D). While A and B can still be loaded with any of the 100 1-unit presets, you can now load the C/D combination with any of the 100 2-unit effects (again equally split between ROM and RAM). With two exceptions, these presets are created from pairs of single algorithms linked together either in series (ie. one followed by the other), in parallel (ie. the signal going through both pairs simultaneously then linking up at the other end), or with the output from the second algorithm feeding back into the first.

The odd men out are a pitchshifter and a 3.3 second digital delay, which are not simply two single algorithms linked together, but use the processing power of two chips to create a single effect.

Two source configuration mode gives you two of these 'double-effect' units (A/B and C/D), both of which can only be loaded with 2-unit presets. In one-source mode, the DP/4 links all four units together to create a single, awesome multi-effects processor. Here the units are again divided into the A/B, C/D pairs, but those pairs are now linked together in a number of ways. The result is 32 different chains of effects with the option of placing any algorithm into any part of the chain. This, in itself, sets the DP/4 apart from most other multi-processors where the order of the different effects types within the chain is often fixed, or at best limited.

Bringing the numbers up to 400 presets is a bank of what are called Configuration Presets. We've actually entered this area when setting up the DP/4's configuration modes. Normally, the units would effectively be empty and you'd then select presets to 'fill' them. But other configuration presets not only configure the DP/4 in either one, two, three or four source modes, but also load a set of effects and preset the various mix parameters.

One such preset, which actually represents the power of all four chips harnessed together, is the vocoder. In true MacArthur style we shall return to this later on.

Having learnt a little of the architecture of the unit, you should now begin to appreciate the DP/4's flexibility and perhaps also understand some of its (few) limitations. But of course, architecture doesn't sell effects processors (...and why should it - it doesn't even sell buildings), a fact which Ensoniq understand well.

So for those who simply want to turn on, tune up and try out, there's a quick route to auditioning the 400 presets using just one sound source.

But I warn you: putting the DP/4 through its paces can seriously damage your wealth.

The reverbs are beautifully smooth; the choruses are fat and rich; the flangers carry your plodding sequenced synth lines on rockets. Try out presets like 'Boom Room' (an instant John Bonham-iser of drum machines); 'Holy Ascend-DDL' (ideal for the bit where we go back 50 years to when Orson Welles hadn't yet learned to be a bastard); the '66 Car Radio' tunable speaker preset... And these are just the single algorithm models.

Turning to the 2-unit and 4-unit multi-FX and we've got presets like 'Synth Doppler' - a... well, doppler effect which sounds like your head does before you take aspirin. Or 'Science Lab', which combines a sine/noise generator with a phaser/delay to create an ideal accompaniment to a scene of Frankenstein discovering how to extract DNA from the cells of sausage skins.

These are just a handful of the more sensational effects which immediately caught my attention. And there are plenty more which will grab yours too.

That's not to say the DP/4 is all about wacky sounds. Most of them are, in fact, quite sensible - ie. both useful and usable. For example, many of the 2-unit presets have been designed for use with particular instruments and are named as such. So, for drums, we have presets like 'Drums X' (nonlinear reverb fed back through a large room reverb) and 'Drum Squasher' (large plate/EQ/compressor). For brass there's 'Trumpet Plate' (large plate/8-voice chorus) and 'Horn Verb' (small plate/large plate) and for vocals there's 'Vocal Magic' (Pitch Shift/DDL/Large Plate) and 'Backing Vox' Lush (Dual delay/8-voice chorus).

The same principle is followed through with the 4-unit presets, where you'll find effects combinations for just about every type of instrument - string sections, brass, vibes, bass, organ, plus vocals. For example, there are around 30 presets devoted to guitar, giving you everything from instant heavy metal lead to mellow jazz rhythm at the touch of a button. Among them are a couple of real gems - namely 'NY Studio' and 'LA Studio' - which give you an extremely sharp, yet laid back guitar sound while also adding a touch of class to keyboard-based guitar and plucked string type sounds as well.

Again, many of the configuration presets have been setup with a specific task in mind, such as processing a particular group of instruments or musicians. So, dialling up configuration preset 18 loads a 1-unit reverb preset into A, a 1-unit eight-voice chorus into B and a 2-unit EQ-chorus-delay/reverb preset into C/D. Hey presto! you've got a three source set-up for a drums, bass and (stereo) keyboard combo. Well that's the theory, anyway.

Other combinations cover vocals/guitar, strings/brass, guitar/bass, lead/backing vocals and so on. There are also some specifically designed for mixdowns, such as 'Albumizer EQ' which sets up the DP/4 as four exciters. Of course, their usefulness depends on whether you are using this particular combination of instruments/sounds. But as a short cut to setting up the unit for particular mixes they can be surprisingly helpful.

Among them you'll also find the vocoder - those briefly-fashionable items of late-Seventies/early Eighties hardware which are now enjoying something of a comeback thanks to their use on radio jingles and commercials. For anyone who only remembers them from the first time round and has forgotten what exactly they do, vocoders analyse the frequency spectrum from an incoming source (most commonly, speech from a microphone) then apply that to pitched sounds from a source like a synthesiser or sampler.

Most people never seemed to get beyond using them to create robotised speech, so you'd be forgiven for thinking this is all you can actually do with them. Suffice it to say that the version on the DP/4 is easy to set up and works well enough, so you should get beyond this stage with a little perseverance.

And if you don't like what you get, it's time for DIY. The DP/4 is a programmer's heaven... or hell, depending on how you look at it. There are an average of 15 parameters per algorithm to wrestle with (most of the reverbs, for example, are based around a complex route map involving no less than 22 separate parameters!) plus, of course, further options when it comes to linking algorithms together to create 2-unit and 4-unit patches. Nothing if not comprehensive!

Incidentally, if you run out of space in the internal memory for your own programs, the DP/4 will happily dump any or all of its RAM presets via MIDI. Which brings us neatly around to the MIDI spec sheet, which as you might expect for a piece of gear aimed at the world and his producer, is pretty comprehensive. Each of the four individual processors can receive patch changes and volume (MIDI controller 7) information on a separate (programmable) MIDI channel. A fifth MIDI channel needs to be set up to access Configuration presets.

The user also has complete control over the MIDI mapping ie. defining exactly which preset is selected by each MIDI program change number - useful for matching the presets to patches on a synthesiser for example. The performance editing facilities also allow real time control over various parameters of each preset - not just via MIDI, but through a number of other devices as well.

You can define up to eight system controllers for the system as a whole, and since the DP/4 supports the full range of MIDI channel controllers, the choice of control via MIDI is pretty wide.

But the DP/4 also supports good old-fashioned foot-pedals as well as control voltage devices - basically anything that produces a 0.5 CV output. This could be a foot-pedal like Ensoniq's own CVP-1, or you could dust off your old analogue synths and use them.

You can then build them into the parameters for each individual preset. Any two controllers can be used to modulate any two parameters in the algorithm - the choice is entirely yours. The minimum and maximum values of that parameter can then be defined and, when you press the pedal, move the pitch bend wheel, or send appropriate control information from a MIDI sequencer, lo and behold, the particular parameter value will alter.

A simple example might be a sampled piano, where you could use the higher MIDI notes to shorten the reverb decay for a more realistic sound. Used in conjunction with MIDI sequencers the facility could offer you a number of pseudo-automated mixdown facilities controlling mutes, fades or panning.

Finally, for live work I should mention the DP/4's song facility which allows you to chain up to five presets together in up to 20 songs. You can then step through them via a footswitch.

Is the DP/4 the future of multi-processing? Well, we'll have to see if other manufacturers follow suit. I suspect they might; the DP/4 is too good an idea not to catch on. It's versatile, it's easy to use, it sounds good... and it's got knobs on. Most importantly, the DP/4 is one of those rare beasts where the whole adds up to more than the sum of the parts. Unlike other multi-processors, its main strength lies in the very fact that it all happens to be in the one box.

Because you can try out any combination of effects you like, just with the press of a few buttons, I think it actually inspires you to be more creative than if you were experimenting with a real stack of separate effects units and a patchbay.


Price: £1175 incl. VAT

More from: Sound Technology PLC (Contact Details)

Of course, there's the price. £1175 is not exactly the sort of cash you keep in the shoebox under your bed, yet when you think of the DP/4 in terms of its individual components, it does represent excellent value for money. Hear it and then decide. You may not agree with me that this is the mother of all multi-FX processors, but you'd still have to concede it's one mother of a unit. Ask mother to buy you one.

Effects Extra

It's worth looking at a couple of the more unusual/creative effects in depth. For example, tempo delay is a useful algorithm for setting up multi-tap delays for a specific musical context. Here, delay time is defined in terms of notes: 1/32, 1/16 triplet, 1/16 dotted, 1/8 triplet and so on, up to 1/2 notes. The space between repeats is then controlled according to tempo parameters, using either the DP/4's internal clock (50-250 BPM), MIDI clocks or by tapping out the tempo via a footswitch.

The 3.3 second delay mentioned in the text incorporates an instant replay feature where you can record and then loop passages up. It's no substitute for a sampler, but you can get some interesting rhythmic effects out of it.

And it's fairly easy to use live since you can set up a footswitch to toggle between loop record and loop play. Also worth a mention is the expander, which features a trigger mask function that can be used to extract a click track from drum tracks.

The Effects

11 types of reverb (including rooms, plates, reverse and gated); four types of delay (including multi-tap and stereo); chorus, vibrato, auto-panner, flanger and tremolo (all of which include EQ and delay facilities); phaser/DDL; eight voice chorus; straight flanger; three pitchshifters; distortion; three guitar amp and three speaker simulators (including a highly convincing rotating Leslie cabinet); compressor, three expanders (one inversed); de-esser; ducker/gate; rumble filter; parametric EQ; an exciter; and last but not least a sine wave/noise generator. Phew! Give that man some air...

Also featuring gear in this article

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The World About Us

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Intrinsic Technology Slam

Music Technology - Copyright: Music Maker Publications (UK), Future Publishing.


Music Technology - Oct 1992


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