Test Drive: The Ensoniq DP/4 Parallel Effects Processor

Since there are four effects "units" in the DP/4, any combination of four of the above algorithms can be used simultaneously. (Doesn't that come out to over 1,600 different combinations?) Furthermore, you'll notice that many of the algorithms contain two and three effects. So, it is possible to get quite a few effects going at once, and the four 24-bit DSP chips in the unit provide ample processing power to cleanly handle the task.

The other three algorithms require a little more processing power than one effect unit can provide. Two of them are "2 Unit" algorithms. They are "Pitch Shift 2U" and "3.3 Second DDL 2U." By the way, DDL refers to digital delay, and the algorithm above does indeed provide 3.3 seconds of delay. In fact, the DP/4 can be configured to provide a maximum delay time of 6.4 seconds using all four effects units.

The final algorithm requires four processing units. This 4-Unit algorithm is the Vocoder, and yes, it works and sounds like the real thing. Hooking up the vocoder is simple. Input a mike into input 1 on the rear (or front) panel and a synthesizer into input 2, then select the vocoder algorithm. The unit analyzes the signal from the mike and uses this analysis to control the sounds from the synthesizer. There are several parameters available to fine tune the characteristics of the vocoder, and it worked well for us, not only with a synthesizer plugged into channel 2, but with an electric guitar as well. In fact, we used a CD of sweeper effects in place of the synth and guitar audio and got some very interesting vocal effects.

The 2-Unit algorithms mentioned above are stored in "2-Unit Presets." The 2-Unit Presets of the DP/4 account for another 100 of the 400 presets, most of which are a combination of two of the 1-Unit algorithms. There are also 100 "4-Unit Presets" which consist of four separate "1-Unit" algorithms placed in series and/or parallel with each other.

So...you have all these algorithms and presets to choose from, and four effects boxes you can plug them into. And, you can connect these four effects boxes together to process a single input! You can use just two of them, or you can use just three. You can use the DP/4 as four separate mono effects processors, or you can use it as two completely independent stereo processors. You can configure the unit as two mono processors and one stereo processor to process three separate source signals. These various configurations are achieved with an internal "patch bay." This is accessed with the Config button which selects Config Presets. These Config(uration) Presets account for the last 100 of the 400 presets in the DP/4 and contain the previously mentioned 88 presets that are "hidden" by the factory. (The Vocoder algorithm uses all four effects units and needs a specific input/output configuration, so it is also stored in a Config Preset.) It is these Config Presets that determine how the signals are routed -- how many input channels are used and how the effects units are connected to each other. If you plug three separate signals into three inputs, a specific Config Preset must be used to accommodate those three sources. Likewise, if you want to use all four effects units to process just one input, you have to tell the machine that is how you want things done.

Comments (4)

This comment was minimized by the moderator on the site

Great article, even several decades later !
Well it's 2020, and I just bought a DP/4 for $200 USD.
I decided to sell my TC Fireworx ($500), and replace it with Ensoniq's DP/4.
Almost 30 yrs later, the DP/4 remains to be one of the best multi effects processors made ever.
This article was so insightful, I saved it as a PDF for future reference.
Thanks !

This comment was minimized by the moderator on the site

Thanks, Daniel. That's a good price for this box. I actually still have this very unit. It's right behind me, plugged in, turned on, and has my Strat plugged into it. I don't think I have any other gear that has lasted this long. Every aspect of it still works flawlessly. Enjoy it!

Jerry Vigil
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I keep it around just for the organ patches.Send a mediocre mono organ track in, and you get a very convincing, wide, and moving organ with Leslie. I use the jazz guitar patch also. The others sound pretty dated, but can be modified easily enough.

Mine has recently developed an issue where after being on for 20 minutes or more produces a fairly loud mid-frequency noise, and the effect signal is no longer present.

Bud Martin
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I always hear engineers talking about "replacing the caps" in old equipment to get them back to good working condition. If your unit has had a lot of on time, that might be all it needs. Sometimes you can see a bad cap. That's when it's an easy fix. Otherwise, it's a bigger task.

Jerry Vigil
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