Test Drive: The DigiTech DSP-256XL Multi Effects Processor

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by Jerry Vigil


This month's Test Drive puts us in the driver's seat of yet another effects box. The DigiTech DSP-256XL falls into that category of the affordable, yet powerful effects boxes that, like most under $500, are designed for the musician. Even so, as many of you know, these little musician's boxes are jam packed with high quality effects perfectly suited for radio production with price tags that don't put your GM into cardiac arrest.

The primary features of the 256XL include 128 fixed factory presets, 128 programmable slots, up to four effects at once, twenty-six different effect configurations, and full MIDI capability. You get reverb effects, chorusing/flanging, parametric EQ, graphic EQ, and a not too often seen 4-tap delay.

Aside from its clean sound and numerous useable presets, perhaps the most impressive aspect of the 256XL is its ease of operation. When a program is selected, the 2-line, 16-character per line LCD display shows the program title on the top line and the effect configuration in use on the bottom line. PROGRAM UP/DOWN buttons scroll through the 256 memory slots in the unit, and if you hold the UP or DOWN button in, the unit shifts into a "fast scroll" mode for quick selection of any program (or adjustment of any parameter). In radio production, probably the most used parameter of an effects box is the wet to dry MIX parameter. If you're the type that doesn't care to get into the parameters of an effect and shop around for the MIX parameter before you make an adjustment, you'll appreciate the MIX control knob on the right side of the front panel. If you're looking for an effect for a voice track, let's say, just set the MIX level to 12 o'clock (or 50%) and start moving through the different programs as you input the voice track. When you find one you like, it's immediately on line and you don't have to enter any "edit" mode to adjust the mix. The other two knobs next to the MIX control are INPUT and OUTPUT level controls.

Now, should you want to edit the program, that too is quick and simple. The two PROGRAM UP/DOWN buttons mentioned above are dedicated to program selection. Similarly, separate PARAMETER buttons are dedicated to program editing. There are two UP/DOWN PARAMETER buttons and two LEFT/RIGHT PARAMETER buttons. The LEFT/RIGHT buttons are used to select the parameter you wish to edit. The UP/DOWN PARAMETER buttons increase or decrease that parameter's value accordingly. As you step through the various parameters, the entire top line of the display is dedicated to describing the parameter; so there is limited use of abbreviations which tend to confuse the novice effects editor. The bottom line of the display is reserved for the value of the parameter, and again, limited use of abbreviations helps to shorten the learning curve.

Once changes have been made to a program, the COMPARE button can be pressed to compare the edited program with the original. If you like what you hear, press the STORE button. You are given the option to store the edited program in the current position or to any of the other 128 user slots. The STORE button is also used to simply copy an existing program to another place in user memory. Once again, storing and moving programs is very easy, and the LCD display kindly guides you along the way with prompts such as "Storing," and "Copying." When you're just playing around with a program's parameters and then decide to go to another program, the unit will remind you that you've changed the program by giving you the option to save the changes before you go to the next program.

DigiTech's 128 factory programs are stored in locations 129-256. User locations 1-128 come from the factory with copies of programs 129-256 in them, and these programs can be edited or completely removed. We thought it was nice of DigiTech to put the user locations at 1-128 instead of at the other end. This way, all your favorite programs, whether they be factory programs or ones you create, can be at locations 1 through 10, for example, making the program number easier to remember than, let's say, 129 or 233!

Of course, all program titles can be edited. One small time-saver is to have some preset programs like "Joe's Reverb" and "Mary's Reverb" which indicate various reverb settings for staff announcers; or "Club Spot Echo" for that just right amount of delay and feedback for your next last minute club spot; or "Telephone EQ" to quickly get your mike to sound like a telephone without having to go through all the EQ adjustments every time you need it.

This takes us to program creation. Let's say you want to create a program called "Club Spot Delay" with some delay, feedback, and reverb. First, go to a program number (between 1 and 128) where you want the program to be stored. Let's use program number 20. If a program already exists there, press the TITLE button to change the name to "Club Spot Delay." When you're through, press the TITLE button again. The unit goes back to the program select mode with the new title in the display. Next, press the RIGHT PARAMETER button. The display now says, "CONFIGURATION:" with whatever configuration was originally in position 20 on the second line. Using the UP/DOWN PARAMETER buttons, scroll through the 26 effect configurations until you come to one with reverb and delay. In this case, we'll pick the "Delay+Hall+Mixer" configuration. At this point, the program is basically written. Now, just press the LEFT/RIGHT PARAMETER buttons to scroll through the various parameters and adjust your delay time, feedback, and reverb effects to your liking. When done, press STORE twice and presto! You're an official digital multi-effects processor programmer!

In the example above, you may have noticed that "Mixer" was part of the configuration used. This is in most of the 26 available configurations. "Mixer" represents a set of parameters that let you separately adjust the internal reverb and delay levels of the program. While the MIX knob on the front panel adjusts the mix of dry signal to wet, this internal, sub-mixer adjusts the level of an effect with respect to the other effects in the configuration. This mixer also lets you set the left/right balance of the particular effect.

The reverb types available are Hall, Room, Gated Reverb, and Reverse Reverb. The basic reverb parameters are there as well as several parameters used for very fine tuning of the reverb such as Accent Envelope, Normalized Room Volume, Normalized Reflectivity, Subsequent Reverb Diffusion, etc.. (It's a good thing you don't have to know what these do, let alone use them!) You even get a Reverb Filter parameter to select a "Bright," "Soft," or "Warm" reverb. All in all, it's safe to say that the reverb programs of the 256XL are not only very versatile, but they rival the warmth and smoothness of those found in higher dollar boxes.

The delay programs have a maximum delay time of .75 or 1.5 seconds depending upon the configuration used. The 4-tap delay is basically four separate delays tied to the same input and going to the same output. Several interesting effects can be generated with the tap delay, and each tap can be positioned anywhere in the stereo spectrum with a delay range from zero to 1.5 seconds. If 99% delay feedback doesn't put you in a long enough loop, a "Repeat Hold" setting on the delay feedback parameter will do the job.

The modulation effects of the 256XL include chorusing and flanging. The usual parameters are available -- Speed, Depth, Chorus Delay, Flange Feedback, Flange Delay, etc..

There are two types of EQ in the unit. A 9-band graphic equalizer provides EQ from 63 Hz to 16 kHz at pre-set center frequencies and bandwidths. The range of the 3-band parametric EQ is from 100 Hz to 12.8 kHz. Bandwidths are fixed, and frequencies can be cut or boosted up to 12 dB.

A major advantage of the 256XL's simultaneous effects feature is that the different configurations are already built for you. There's no need to go into the edit mode and select each effect individually and put them together when you want to create a program. As mentioned, there are 26 different, pre-programmed configurations. They are: 1) Stereo Chorus, 2) Stereo Flange, 3) Stereo Delay, 4) 4-Tap Delay, 5) Ultimate Reverb, 6) Room Simulator, 7) Gated Reverb, 8) Reverse Reverb, 9) Parametric EQ, 10) Graphic EQ, 11) Para+Delay+Mixer, 12) Para+Chorus+Mixer, 13) Chorus+Room+Mixer, 14) Delay+Room+Mixer, 15) Chorus+Hall+Mixer, 16) Delay+Hall+Mixer, 17) EQ+Gated+Mixer, 18) EQ+Reverse+Mixer, 19) Para+Cho+Dly+Mix, 20) Para+Fla+Dly+Mix, 21) Cho+Dly+Room+Mix, 22) Fla+Dly+Room+Mix, 23) Cho+Dly+Hall+Mix, 24) Fla+Dly+Hall+Mix, 25) EQ+Chor+4Tap+Mix, and 26) EQ+Flan+4Tap+Mix.

You'll note that the latter configurations contain the most effects. While "Mix" refers to the internal mixer section, it is not really an effect as we know it. The "fourth" simultaneous effect available is actually a low-pass filter with a cut-off frequency adjustable from 100 Hz to 18 kHz.

The UTILITY button is where the MIDI capabilities are accessed. We didn't check out every parameter of all 128 factory programs, but it appears that every parameter you could possibly want to control via MIDI is accessible and assignable to any controller. The UTILITY button also accesses the LCD contrast control and the system reset function which erases all the user programs. To the right of the UTILITY button is the BYPASS button. A BYPASS LED on the LCD display indicates the bypass status.

Is the frequency response a full 20 Hz to 20 kHz? You bet! These days, nobody in their right mind is going to make a box that doesn't have full 20-20 response, that is unless they plan to sell it for under fifty dollars. The signal-to-noise ratio is 88 dB. The A/D converter is 16-bit. THD is less than .08% at 1 kHz. The LCD display includes an OVERFLOW LED which lights to indicate too much internal gain, plus you get a 4-LED bargraph to indicate input levels. The DigiTech DSP-256XL takes up one 19-inch rack space. Quarter-inch TSR jacks on the rear panel accommodate balanced and unbalanced stereo ins and outs. Two quarter-inch TSR footswitch jacks on the rear panel accept standard footswitches or the DigiTech FS-300 pedal, and pedal functions can be programmed via the UTILITY function.

At a list price of $439, the DigiTech DSP-256XL easily falls into the category of affordable, quality, digital multi-effects processors. As with most "stereo" effects boxes in this price range, you don't get true stereo processing which required two independent effects chains. The summed signal of the stereo inputs is applied to the effects chain. The effects at the output are stereo, but the "dry" signal you mix with the stereo effects is a mono mix of the stereo input. Still, for most applications in radio production, particularly with voice tracks, this is not a hindrance.

You don't get a pitch shifter or a compressor. You don't get a "distortion" algorithm, and you don't get a built in sampler. But if you're looking for top notch reverb and delays with chorusing, flanging, and EQ to boot, the DSP-256XL fits the bill. The exceptional, user-friendly layout and operation also gets a candy bar. When it comes to quality effects that are simple to access and manipulate, the 256XL is like a salesman that gets his copy in on time. They're both rare and a pleasure to work with!

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