Have you ever looked at a sound system drive rack you've designed, seen a DP226, and wondered why such a powerful DSP drive unit was lacking the short step (or large leap) of complex computer code that could transform it into a powerful insert device? Well, guess what: the newest product released from British manufacturer XTA Electronics is a shocker — not another drive system unit, as the DP-series has always been, but a potent processing device designed for use in the insert channel, with brand-new software. The XTA DP324 DSP Dynamics Processor is referred to in the XTA literature and labeled SIDD — an acronym for Seriously Intelligent Digital Dynamics.

The single-rack space unit sports the blue brushed-aluminum front panel, as does the rest of the DP line from XTA — quality craftsmanship that is a pleasure to touch and that holds securely when mounted in a rack. The standard 2 × 24-character backlit LCD screen shows user data like all other DP units, and the buttons and knobs are very similar to those on the DP226.

Technical specifications are as follows: SIDD incorporates 40-bit (yes, 40-bit) internal data path with a dynamic range of >110dB, 20Hz-20kHz unweighted, with a frequency response of +1/2dB 20Hz-20kHz. Distortion is <.02%@1kHz, +18dBm. Minimum delay (inherent delay due to A/D and D/A conversions) 21µS, maximum available delay of 300mS. Two electronically balanced (transformer optional) XLR inputs with 10k• resistance are mated with four electronically balanced outputs (one each main out and auxiliary out for each input, again with transformers optional) with 600• load and maximum output level of +20dBm at 600•. AES-EBU I/O is an optional interface for users who are already working in the digital realm. SIDD also incorporates remote communications and control via MIDI, RS-232 via nine-pin DEE connector, and RS485 via XLR3 in and out. A standard IEC cable is provided for operation from 60-250VAC @50/60Hz.

So what does it do? It provides the user with lots of dynamics and equalization. Each of SIDD's linkable channels features a six-band parametric EQ; a noise gate/expander with a click-removing, look-ahead feature, and high and low-pass filters plus two bands of parametric for sidechaining; a compressor with two bands of sidechain EQ, variable knee, look-ahead, and dynamic EQ; a delay line that can be routed to the main or aux outputs; a brickwall limiter also with sidechain EQ; and a harmonics generator to simulate valve characteristics and emulate the vintage or esoteric compressors that have been known to creep into FOH racks.

Like the DP series, SIDD comes complete with PC platform controlling software (or simply download it or other information from the XTA website, www.xta.co.uk). Unfortunately, it is entirely different software than AudioCore, the easy, intuitive freeware that controls all the DP200-series drive processors. One CPU running both SIDD and AudioCore software can still control all the parameters of your XTA gear, but not simultaneously; you have to close one program and open the other to do so. Once in the software, the user can make immediate adjustments, and the software provides an easy way to create settings rather than relying on the front-panel controls. On several traveling events, however, I operated the unit solely via the front panel controls with some level of success.

It should be noted that for bidirectional communication, RS232 should be utilized to the top (master) unit, as MIDI provides only one-way communication from CPU to SIDD device. For additional units, use short XLR-3 cables connected to the RS-485 for the following (slave) units. AudioCore-controlled units on the same network will be ignored by SIDD and vice versa, so that the drive and insert processing has something of a separate-but-equal status.

SIDD has a nicely thought-out, well-written manual authored by Waring Hayes. Those who have experienced too many poorly translated illegible tomes can prepare to rejoice; this one is intelligently written in the mother tongue with lots of pretty pictures, color closeup screen shots, and useful information that you will love. Simply put, the time and effort put into the documentation is quite impressive. Open the title page to find a single-sheet quick reference guide — ideal for photocopying and pasting to the inside of one's road box or show binder. This sheet provides information about accessing menus and sub-menus and provides button descriptions and data. The 76-page manual features a comprehensive table of contents, while sections feature complete instructions and explanations with footnotes, cross references, helpful visual references, and appendices.

SIDD gets up and running after a user-defined initial boot-up time. Seven-step LED bar graphs show input and output level, and each section of the dynamic processing also features a varied number of LEDs to show how much of the processing is being used. The front-panel controls are somewhat intuitive where menus are not; after a quick look at the manual, users should be able to get started right away. The different divisions of processing can be quickly accessed, bypassed, or engaged for adjustment. After my initial introduction to the device, I took it to the studio to start listening to it in a controlled environment. Right away, I noticed the subtle, particular sound of the device and its smooth control when inserted on a channel, first on an SM58, then on an Earthworks TC40k omni condenser. I dialed in an alternative setting with heavy compression and limiting, then switched over to a Sennheiser MKE-2 Red Dot and listened to several different settings on each mic in turn. I then bypassed the compressor and limiter and started experimenting with the EQ and gate/expansion functions, again testing each mic in turn on each different ratio and threshold.

After getting a good feel for the processing on different mics, I put SIDD in line after a Valvotronics TFE2 (tube front end) custom mic preamplifier, then sent the output to ProTools along with a direct split from the TFE2 to record a set of comparison test tracks. By looking at the digital representation of the waveform, I noticed that the box was actually doing a little more than I had expected. When I blended the original signal with the processed signal, I experienced some subtle phase problems due to the inherent delay of the multiple conversions. For studio vocals that will receive a nice vocal effect like a plate, delay, or reverb, it would go unnoticed, but classical or pristine recordings are probably not the best prospects for this device. For theatre productions, this inherent delay would be considered part of the analysis, tuning, and correction of the room and system, so it would likely be of little consequence.

Having played with SIDD enough to know the controls well and have a strong sense of what settings work how well on what mics and with different styles, I set out to try SIDD on a few live events. The results were aggravating. I was able to use the unit very successfully on an industrial, but I had mixed results on a music network show, and I completely failed in an attempt to make a great processing setting on the electric bass for a recording of the punk band Green Day.

Normally I either adore or detest a new product, but this time I walk the line. I like the features and the product in general, but I feel some resentment and frustration as a designer and engineer. I am upset that I had difficulty making SIDD sound good even after an initial learning curve. But perhaps my biggest dislike is the overall sound of the box; even when completely bypassed, it does not sound the same as when the insert patch is disabled. Even after matching levels within a fraction of a dB, there was a significant change in timbre as well as delay (due to the inherent delay of the unit) to the original signal, until the 324 was taken out of line. With omni lavalier mics, this was made even more readily apparent in the change of the quality of the background noise. In some instances, this would be ideal, but for designers like me, the open, natural sound of an MKE-2 is the whole reason for choosing that specific microphone.

But because XTA and Group One feel the unit has a lot of potential in the theatre, I decided to ask someone who had used it in that setting. Still scratching my head over my great experience in the studio and my less-than-stellar trials in the field, I contacted Wallace Flores, the production sound engineer on Broadway's Rocky Horror Show. Though far from a standard musical — with its loud rock band, pop score, and interactive audience participation — it still uses the same omni lavaliers commonly found on Broadway and plays in a thrust house with a complex sound system. Flores has one of the first SIDD units made available for Broadway; sound designer Richard Fitzgerald specified for the show.

Flores, it turns out, is a fan. “It's a great little box,” he says. He has one SIDD inserted on two channels for actor Lea Delaria's two vocal mics, a handheld RF Vega in the first act for the character Eddie, and as Dr. Scott in the second act on an RF lavalier mic. “[Delaria] has such a large dynamic range, and the 324 really is extremely quiet in the way it compresses.”

Flores has yet to use all of the functions available on each channel. “I'm using three out of the four: limiting, compression and dynamic EQ,” he says. “I'm not doing anything extreme with her vocals, but to me it's quite subtle in the way that it works; you're not even aware that it's compressing. We had tried other compressors on her voice before. When we tried [SIDD], the artist and the director didn't know what the change was, but they said they liked the sound they heard in the house — a very clean, clear sound quality, not at all like experiencing a ton of gain reduction.

“You can actually set it so you don't notice any of it working at all,” he continues. “That's the beauty of the unit: I can start it with a subtle compression, and then once I pass a certain point with the knee adjustment, the compression will increase. That's when I discovered it was really cool, you know the knee is pulling the dynamic range back but don't hear the unit pull back.”

Flores thought that my problems with SIDD stemmed from faceplate adjustment and lack of trial-and-error time. He also agrees the software interface is an important part of SIDD. “You should really take the time with the computer to see what's happening,” he says. “It's easier to get around through the software than the faceplate itself. But since the first day after we set it up, I've been doing all of my changes through the faceplate, which is rather easy to navigate once you have an idea what function is located where.

“If you're going to put it in a show,” Flores warns me, “do it when you have time, like during tech, so that a designer can set up the levels and go wild — or not, as you need — with the unit. Have an opportunity to hear the subtleties of the machine and really dial somebody in properly,” he coaches. “Because it's a new box, it should be allotted the proper amount of time to be discovered and played with. It's not a box you want to just throw in someplace, which would be a complete disservice to it. Remember, it's not only a compressor, a gate, or an expander. Take the time to actually appreciate the thing.” [I curse his honesty, very quietly. Live shows and recordings don't always have such luxuries. Oh well.]

“I think it's a great box,” he concludes. “Everybody I've spoken to or shown the unit thinks it's very slick; they're amazed at what it does.” I mention to him that SIDD has a very specific sound, slightly coloring the source signal, and he agrees. “To me, the sound of the unit is not offensive, I can hear the difference in headphones when I have the mic in my hand during sound check, but onstage with 14 other radio mics, you can't tell and you don't know the difference, except that you hear the improvement.”

So, there you have it: one thumb way up, one thumb wavering. My advice: Make sure to get a demo before you buy a rack of them. It's a useful tool, but one I'm still a little vary of. I'm sure I'll use SIDD again, but next time in more careful and controlled situations.