WE HAVE SPENT so many years staring at the tiny displays of the typical effects unit that we can be forgiven in assuming that is the only way to control our effects. Although there were a few MIDIots that used a computer and MIDI interface to enlarge their window into the world of algorithms, the rest of us developed a knack for using nudge buttons and parameters knobs. We also resign ourselves to either spend serious money for a high-end unit or using phone jacks and 16-bit converters as normal connections to our mixers.
Power Technology has developed an effects system that sidesteps not only the limitations of the typical rackmount processor, but also the limitations of the DSP architecture that powers most of the current units on the market. Unlike the other effects processors, the DSP/FX is a card that is inserted into the ISA-bus of a PC. Thankfully, it doesn't suffer from the limitations commonly associated with internal cards in computers because all the audio functions remain on the card. The connection to the computer is simply there to provide the virtual front-panel interface for the unit. This allows the DSP/FX to maintain high-quality audio in spite of the noisy and clumsy (for audio) internal workings of the IBM compatible computer. The result is a device producing effects that are excellent in both sound quality and user interface.
The DSP/FX provides a visual interface that is extremely easy to use and shows everything you need to know about the parameters in a single glance. The ability to bring a software-based user interface onto the computer screen allows the designers at Power Technology to focus on visualizing the parameters with the full power of a VGA display instead of simple text and graphics of an LCD in the front panel of a device. By using the mouse and keyboard, it is easy to adjust the parameters, and the graphics display the results as the changes happen. The computer also simplifies the storage and recall of presets. Users will be able to add new effects algorithms or download other users presets from the internet and immediately try them out on their processor. Power Technology has developed a scheme for upgrading that will allow users to receive the new Plug-Ins via the internet or on disk.
The Studio System version (as reviewed) includes the full set of effects, reverberation, echo/delay, flanging, chorusing, and pitch shifting. All these effects were supplied with a wide range of useful factory presets and, of course, the number of user presets are unlimited. Parameters are well chosen and provide a useful range of control that is deeply enhanced by the visual feedback of the graphic display. The graphic display incorporates sensible metaphors for each parameter that allows you to see, in a single glance all of the settings of even the most complex preset.
Note that most current effects processors use a 24-bit fixed point DSP to manipulate the audio. This seems sufficient considering we can be happy with the quality of 20-bit audio. However, as signal levels decrease, such as with reverb tails, a fixed-point DSP begins using less and less of its 24-bit path to represent the signal. This results in a signal path that can often be far less than 24-bits -- a detail that is most noticeable in the tail-out of the effect as the processing approaches the noise floor. The audible result is a grungy distorted sound to the very low-level audio signal.
The DSP/FX employs a new Texas Instruments TMS320C32 32-bit floating-point DSP to increase the dynamic range of the audio ( the floating-point always uses all 32-bits to represent the signal value) in order to eliminate the low-level distortion common in effects that depend on considerable regeneration, such as reverb and echo. The result is especially noticeable in longer reverb settings, where the sound decays smoothly and cleanly. There is also a notable lack of stuttering or pitch to the reverb. I found that it was easy to create a recital hall for piano tracks or a cathedral for a choir. The small room settings were able to create a convincing ambiance for a jazz trio that gave the impression of small, smoky room without any of the hollow tube quality common to small room settings in lesser reverberation units. The DSP/FX is also capable of true stereo reverberation (input panning affects the early and late reflection localization) available in only a couple of other reverb units on the market.
The Brightness of the reverb can easily be adjusted with the high-frequency decay control. (I would also like to have control over the relative decay rates of the mid and, specially the low frequencies.) I found the density (diffusion) control to be far too subtle and would prefer far more diffuse reverberation for some applications. I also experienced some noise from on-board I/O when the DSP/FX card was too near the video card in the computer, and some of the reverberation (room liveliness) settings had a tendency to cause low-level oscillation when left without an input signal.
The DSP/FX echoes remained clear and even intelligible after seconds of regeneration. They are so good that you can use them with a little regeneration to create small rooms for background vocal tracks or blending horn sections. The chorusing and flanging are excellent and hearken back to the days of a finger on the reel of an Ampex AG-440. The visual interface provides not only a reference during adjustment, but allows you to remember (visually) which range of settings were suitable to a particular guitar style or drum track. The quality of the chorusing and flanging allows even excessive settings to work without obscuring the original instrument. The pitch-change algorithm sounds clean, however I had difficulty losing the slight vibrato quality.
The unit offers MIDI control over all parameters for each module. This allows control over the unit even when it is buried behind other Windows applications. By assigning a MIDI switch, access is even gained to the parameters in the edit page, such as the reverb; early and late decay; or density. With sufficient MIDI controllers, you can remotely access all the onscreen parameter. The DSP/FX is compatible with any CS-10. It only took a few minutes to set up my Lexicon MRC (MIDI Remote Control) to achieve hardware fader/push-button control over the most important parameters. MIDI control requires a MIDI interface (not included) for your PC or Windows application that can produce controller (such as Cakewalk or SoftMC) and offers potential for automation control over the effects. The clearly written and well-organized manual includes a complete listing of the MIDI control values.
The DSP/FX is part of an open-ended system. An optional AES/EBU and S/PDIF daughterboard for digital I/O is available as well as a rackmount 2-channel 20-bit A/D-D/A converter with AES/EBU S/PDIF I/O's. The ease of installation should allow even the less adventurous computer-owners to stick the basic system in a PC and be up and running as quickly as they can get the cover back on. The ISA card is typical of the high-quality versions of other PC products, with easily accessible address switches and clear instructions for setting them. Many PC users cringe at the thought of adding a board into their computer based on previous experience. Thankfully, the DSP/FX wasn't even a problem to install in my fully loaded Pentium. No conflicts, no software problems, and it runs fine in Win95 (although it is a 16-bit 3.xx program).
The DSP/FX ships with a large number of presets for each of the 5 Plug-In modules, and will probably increase as the user base grows. The size of the preset files are very small (between 400 and 1400 bytes), and therefore practically unlimited in number. The DSP/FX is a powerful DSP engine, and we can look forward to many other applications for this hardware. The 32-bit DSP coupled with Power Technology's smart visual interface concepts should prove to be an interesting combination.
Applications: Very high-quality reverberation, echo,
flanging, chorusing, and pitch-shift effects for studio applications.
Summary: An effective device capable of clean and
dense reverb and time-and-pitch-shifting effects with a unique
interface that brings all parameters into view at a glance.
Strengths: Excellent true stereo effects; very low
noise floor; hugely expandable while still very easy to use;
software support for multiple DSP-cards.
Weakness: Requires a PC host that will typically
have a noisy fan; currently limited to one effect per DSP-card; may
require careful PC slot selection to avoid internal noise when
using on-board analog I/O.
Wade McGregor is a senior consultant for Barron Kennedy Lysun &
Associates, an acoustical consulting firm based in Vancouver, BC.