Test Drive: The PreSonus DCP-8 Eight Channel Dynamics Processor

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by Jerry Vigil

The DCP-8 8-channel dynamics processor is one of a new breed of processing boxes created in response to the growing use of digital 8-track recorders. In the analog world, you strive to maintain high recording levels in order to keep the noise floor down and efficiently use the available dynamic range. In the digital world, keeping recording levels high increases the "resolution" of the recording by using more bits in each sample, and again, the available dynamic range is efficiently used. But digital recorders are far less forgiving when levels exceed the limits. Digital distortion is not pretty. Enter the DCP-8, the first product from PreSonus Audio Electronics (list $999). The DCP-8 delivers eight independent compressor/limiters that can eliminate those nasty peaks in the red. You also get eight noise gates, eight mutes, and eight level controls. If you're using one of the popular 8-track digital recorders (Alesis ADAT, Tascam DA-88, etc.), the DCP-8 was designed for you. Even if you're one of the poor souls still using an analog 8-track, the DCP-8 can clean up and improve the quality of your work. But putting the DCP-8 between your console buss outputs and recorder inputs is not the only application of this versatile box.

The DCP-8 is very simple to install and use. The rear panel provides eight inputs and eight outputs on 1/4-inch TRS jacks, balanced or unbalanced. There's a port for the optional MB-8 meter bridge, the second and most recent product from this new company. Since you don't get any metering on the DCP-8, the MB-8 is a nice option, providing metering for both input signals and gain reduction using sixteen 10-element bar graphs in a single rack-space unit (list $399). MIDI IN, THRU, and OUT connectors provide MIDI control of all DCP-8 parameters and turn the DCP-8 into much more than meets the eye, as we'll look at later. The A/C power connector wraps up the rear panel.

All processing in the DCP-8 is done in the analog domain, but the processors are controlled by a microprocessor--like most digital effects boxes these days. As a result, you find three buttons on the front panel not normally found on dynamics processors: LOAD, STORE, and NAME. These familiar functions perform as you'd expect. Up to one hundred "audio scenes" can be stored in the DCP-8's memory. The current program number is displayed in the large red LED Program display. The 16-character by 2-line backlit LCD display shows the program name, when in the program LOAD, STORE, and NAME functions, and displays other information when other functions are active. Press the CHANNEL/PROGRAM UP and DOWN buttons to select a new audio scene then press LOAD to recall that program. Press STORE to store a scene, and press NAME to edit the program name. (Green LEDs on the buttons turn red to show which function is active.) You don't get a set of factory presets--that wouldn't make much sense--you simply get one hundred locations in which to store your own settings. All parameters in each program are set to factory defaults with "User Program" as the default name.

Part of the simplicity of the DCP-8 is that there are only two adjustable parameters for the compressor. Press the COMPRESSOR button to adjust the Compressor Threshold (from -50dB to +20dB). Press the RATIO button to adjust the ratio. Ratio settings are from 1:1 to LIMIT, which is one notch past 20:1. The VALUE knob is used to make the adjustment. The CHANNEL/PROGRAM UP and DOWN buttons are used to select the channel you wish to adjust. Compressor attack and release times are not user adjustable. The attack time is 200us and the release time is "program dependent."

Press the GATE button to set the noise gate on any channel anywhere from -90dB to +20dB. Press the GATE button again to put the gate in Bypass mode for that channel. (This Bypass function applies to the Compressor Threshold and Ratio functions as well.) The gate attack time is preset at 100us and provides 85dB attenuation.

Press the MUTE button to mute individual channels. The numbers 1 through 8 are displayed on the LCD display. Use the UP/DOWN buttons to move the cursor to the desired channel. Press the MUTE button to mute the selected channel. The channel number on the display changes to "M" to indicate that the channel is muted.

Press the LEVEL button to adjust individual channel outputs from -85dB to +20dB. When the DCP-8 is connected between console buss outputs and recorder inputs, you might not need to access this function at all since you can control levels from the console. However, if you're using a great deal of compression, boosting the level from this function is handy. But the real power of the Level controls of the DCP-8 is when the unit is connected between your tape outputs and console tape inputs, during mixdown mode. If you have a MIDI control panel and sequencer, MIDI signals can be recorded and sent to the DCP-8 to provide automated mixing. Can your compressor/limiter do that? Furthermore, automation doesn't stop with level control. All the DCP-8's parameters are MIDI controllable. Mutes can be automated. Compressor settings can be automated. And, of course, MIDI program change commands can switch between audio scenes instantly.

Press the SOLO button to mute all channels except the currently selected channel. This is helpful when the DCP-8 is used during a mixdown. When the Solo function is active, pressing the CHANNEL/PROGRAM UP/DOWN button lets you select other channels in the solo mode.

Press the SETUP button to access the DCP-8's system configuration mode. There are four sub-menus here: MIDI Setup, Group Setup, Link Setup, and Output Setup. The MIDI Setup menu sets MIDI transmit and receive channels and sets Program Change and Controller Change transmit and receive to ON and/or OFF.

Group Setup is a common automated mixer function. This function enables grouping several channel "faders" together so that adjusting the level of one channel of the group affects all the other channels in that group. Up to four groups can be programmed. Group information is stored and recalled for each program.

The Link Setup function is another function common with automated mixers. This function lets you link channels 1 and 2, 3 and 4, 5 and 6, and/or 7 and 8 with each other. When linked, adjustments to channel 1, let's say, will also apply to channel 2. The parameters affected are Compressor Threshold, Compressor Ratio, and Gate Threshold. If you want to link a pair of channels together so adjusting the level of one also affects the other, use the Group function. Link Setup information is also stored and recalled for each program.

The Output Setup function sets the output of each channel as either "nominal" or "-10dBV." When set to Nominal, the input level will match the output level. When set to -10dBV, the DCP-8 sets the output to -11.8dB which is the difference between a +4dBu system and a -10dBV or "line level" system. These settings are "global" and are not stored with individual programs.

With all these extra features, the DCP-8 is useful in a number of applications. Of course, as a level "guard" feeding your digital recorder, the DCP-8 is ideal. When used as a mixdown processor, it's even more fun. Let's say you've got a 2-voice spot with voice 1 on track 1 and voice 2 on track 2. Use the DCP-8's gates to silence the tracks when the other voice is speaking. Another example: during the mixdown, the voice track varies in level too much and gets buried by the music track in spots, then overwhelms the music in other spots. Compress the voice track during the mix with the DCP-8. If the unit is always in line between your 8-track outputs and console inputs, you'll find yourself doing a lot more dynamics processing simply because it's accessible without having to reach for patch cords, and, you've got EIGHT processors instead of just one...and they're all hooked up!

The ability to store settings is helpful in a mixdown configuration. This is especially true for musicians who want to store settings for particular songs. In radio production, it's less likely you would store settings for individual productions, but the DCP-8 can be used to store settings for various types of productions. You could have a program with settings just for promos--extra compression on voice tracks or music tracks or both. If the DCP-8 is used when recording tracks, you might have programs with compressor settings set to individual voice talents, not unlike having preset programs on a voice processor.

If you have a studio with an 8-track recorder with eight inputs and eight outputs, the DCP-8 can do a lot for you. Since radio production rarely involves recording more than two channels of audio at a time, the DCP-8 would probably be more useful during mixdowns. If your studio is MIDI equipped already, the DCP-8 can give you automated mixing easily and effectively. But the DCP-8 shouldn't be looked at as a box just for rooms with eight tracks feeding a console. In today's radio production rooms, digital workstations with internal mixing are quickly turning eight outputs into two. In these studios, the DCP-8 can be used as a bank of eight dynamics processors. How many times have you grabbed a patch cord and piped your studio telephone interface into a compressor to help control levels? With the DCP-8 in your studio, the phone could be wired directly to, let's say, channel 1 of the DCP-8, providing a dedicated compressor for the phone which is on line all the time and comes complete with a noise gate to mute line noise when the person on the other end isn't speaking. Take channels 2 and 3 and dedicate them to studio mics. Channels 4 and 5 could be Grouped and Linked as a stereo pair that processes the reel-to-reel deck that all dubs are made from. This could add consistency to all those agency dubs with levels varying from one extreme to the other. Channel 6 could be assigned to a network feed. Channels 7 and 8 could be another linked stereo pair used for mastering all productions to DAT or whatever.

Obviously, there are applications in other studios in the radio station. Talk formats could benefit from eight noise gates and compressor/limiters connected to the many mics found in on-air studios. Newsrooms with several network feeds and other audio sources can take advantage of the DCP-8's multiple ins and outs.

The DCP-8 can very effectively reduce tape hiss during mixdowns on an analog 8-track by using the noise gates on all channels. Set the gate thresholds so that tracks that have occasional sound effects or voice elements will mute until the effect or voice element appears.

The DCP-8 also makes it possible to perform a different type of compression during a mixdown. Most producers who compress on the mixdown send the entire stereo mix into a compressor and then to the mastering deck. Compressing all the tracks separately and simultaneously during the mix gives you the option to compress a voice track a little harder than you're compressing the music. Maybe a sound effect in the promo has too much dynamic range and doesn't stand out enough in the mix; the DCP-8 will let you compress it during the mixdown without affecting the other tracks. If you like lots of compression on your mixes, this is a very clean way to get it, with just the right amounts on the individual elements.

Once I realized the potential of having eight dynamics processors in the studio, I began to see the DCP-8 as much more than a level control device for a DA-88 or ADAT. As with many of today's high tech toys, the DCP-8 feels very much like the type of box whose applications will expand along with the user's imagination and his or her studio. Considering that this is one of the first boxes of its kind, and that the software version is version 1.0, I expect we'll see some exciting developments along the way. Imagine the DCP-8 with EQ on each channel!

Reported specs on the DCP-8 include signal to noise ratio at 92dB, THD+noise at 0.01%, and dynamic range >115dB.

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