Digital Effects Processing System
By Dave Tosti-Lane
One imagined advantage of the digital revolution is the ease with which we can manipulate our manifestations of aural delight within the magical digital audio workstation. I say "imagined advantage" since, typically, we consign a reasonable amount of cash and an enormous amount of time (or is that an enormous amount of cash and a completely unreasonable amount of time?) to the hardware and software we thought we needed to reach digital nirvana, only to discover that there are at least a few holes in the emperor's new clothes.
A particularly exposed and sensitive spot is often discovered as we come to the battle between number of tracks and amount of effects processing. We find that we can indeed apply effects to the tracks in our editor, but that we can only apply so much before we start having to limit the number of tracks playing, or do our processing ofline. There are many fine programs that allow the resources of the CPU to be applied to effects processing, and they often do an excellent job, but there is no substitute for being able to hear an effect in real time, while it is a part of the mix we are producing; and the only real way to effectively do that is to have hardware DSP to take the load off of the CPU of the host machine.
As I have four systems running SAW and SAW Plus software, and another running Spectral's Producer and Studio Tracks XP, I was intrigued to hear about the DSPFX system from Power Technology. The system provides quality 32-bit floating-point processing that can be patched into your editor via either analog or digital connections. In addition, the folks at Power Technology are working with both Innovative Quality Software and Spectral Inc. to develop links to allow the DSPFX processors to work with SAW Plus as a plug-in, and to be accessible internally within the Studio Tracks XP software.
Many otherwise sanguine audio professionals have been known to become somewhat unhinged in the process of adding components to their computers. I have even heard some wonder aloud why the difficulty of installation seems directly proportional to the effectiveness of the gear. Power Technology has created a rather clear exception to this so-called rule: I was checking out the sounds within 30 minutes of opening my door to FedEx.
For this review I installed a pair of DSPFX cards, with their AES/EBU daughter cards attached, in a Pentium 100 system already loaded with a Spectral Prisma Digital Audio card, a Digital Audio Labs CardD+ sound card, an MQX-32 MIDI/SMPTE card, and an ISA network card, along with PCI cards for video and SCSI. This is, to say the least, a fairly full house. I had some concern that getting all this up and running would become a complex process, but I was pleasantly surprised.
During the setup process, you are asked to indicate how many cards you have installed, and to enter the address for each. You will find a separate icon for each in the DSPFX folder when the installation is complete. Because the real work of handling the audio is done entirely on the cards, the front end of the control software does not take much in the way of resources, so it is no problem to run multiple instances of the DSPFX control program along with a digital editor on the same computer.
Power Technology Note: Prices have changed. Please see current price list.
The basis of the DSPFX system is the ISA bus DSPFX card ($749, includes one plug-in FX module), which provides A/D-D/A conversion using the Crystal Semiconductor 16-bit delta sigma converter, and Texas Instruments' TMS320C32 32-bit floating point DSP.
Each card sports four -10dB (ref. 1.0V) unbalanced 1/4-inch phone connectors for stereo input/output, and a standard 9-pin jack that is only used when the optional processor card is added. There is also a proprietary connector on the back of the card that will allow interconnection of multiple DSPFX cards internally for enhanced operations:
· Adding the AES/EBU /S/PDIF Digital Interface daughter card ($250) extends the flexibility of the DSPFX card by adding digital in/out on the supplied interconnect cable. The daughter card attaches to the DSPFX card and does not take up an additional slot, nor does it exceed the maximum width specified for ISA bus devices.
· The external DSPFX AES/EBU 20-bit A/D-D/A Converter ($549) is a 1U rackmounted converter providing 20-bit A/D-D/A conversion, and balanced +4dB (ref. 0.775V) "pro" level inputs and outputs.
The DSPFX MIDI Controller ($699) is an external surface that provides a tactile interface to the functions of the DSPFX system. It is functionally identical to the JLCooper CS-102 and can be used to control other MIDI applications as well.
· The FX PACK (Price TBA) is a modular (2U) rack-mount system configured with up to four of the DSPFX cards. It connects via either Ethernet or serial connection to either a PC or a Mac, and does not require a card to be mounted inside the computer, making it ideal for laptop applications.
The DSPFX software is organized into plug-ins that are loaded into the FX software engine. Each instance of the DSPFX engine can currently have only one plug-in loaded at a time; future plans call for the ability to access multiple cards with a single instance. Included with each DSPFX card are an Auto-Panner plug-in, a tremolo plug-in, and one of six other available plug-ins which currently are: Graphic Reverb, Parametric EQ, Flanger, Chorus, Multi-Tap Delay and Pitch Shifter.
Each additional plug-in costs $179, though you can save quite a bit by buying the entire complement of plug-ins as the DSPFX card Studio System Plus for $1,099; or by buying the Studio System Upgrade Package, offering the full set of plug-ins for $350.
Note also that the software allows complete control from any MIDI application using MIDI controller Mapping, an application detailed in the well laid out user's Guide, or by using the very handy Power Technology DSPFX MIDI controller mentioned above.
The DSPFX software runs very well in both Windows 3.1 and Windows 95,on a 386 or better, through a 486 or Pentium is recommended. Minimum RAM requirements are 4 Megabytes for Win 3.1 and 8 MB for Windows 95 if you are running DSPFX alone; 8 and 16 Megs respectively would be advisable if you are also running an editor on the same computer. I easily ran two simultaneous instances of the software along with the Spectral interfaces on Windows 95 on a 100MHz Pentium with 16 Megabytes of RAM.
The DSPFX system is particularly well suited to working with a system like Spectral's Producer. With the AES/EBU in/out, I was able to connect the cards directly to the digital connections of my Spectral interface, and simply patch them into the send/return loop, eliminating the need for intermediate stages of A/D-D/A conversion, and its attendant introduction of delay.
As we make the transition from twiddling knobs to mousing about on a screen, it is comforting to see something that resembles our old tried and true equipment. Power Technology doesn't disappoint in this regard, but the product also includes a visual reference that is new. The designers realize that they had to invent a sort of visual short-hand for parameters of equipment that we've always thought of primarily in aural terms. I found the graphical representations of most of the plug-in modules quite suggestive of the action.
Probably the most obvious is the Parametric EQ, which was in late beta stage when I worked with it for this review but should be released by the time you read this.(Obviously, the curve shown in the figure is a bit aggressive to say the least, but it does get the idea of the display across.) Note that the left side of the display, you have controls for the parameters of band 6, with coarse and fine adjustments for the center frequency and Q, as well as an adjustment to set limits to the scale of adjustment (Maximum Boost/Cut). Beneath the knobs, which change color to match the color of the band being adjusted, are a bank of buttons that, among other things, allow you to call up or save user presets, bypass the effect being applied, compare the current settings with those immediately prior to the last adjustment, select different plug-ins, link left and right channels (or display and control either one individually) and call up one of five user-selectable Quick Pick presets. You can also access the help engine, or switch the controls above over to the high and low frequency shelving filters, which are also a part of the parametric EQ plug-in.
To the right of the display is the graphical representation and eight faders that control boost/cut in each of the eight bands of the Parametric EQ. Under the Settings button, you can also change the number of bands with selection from one to eight bands allowed. This makes it possible to build special EQ presets with restricted function. At the bottom of the display, you see meters for input and output.
In use, the EQ is exceptionally clean and quite natural sounding. It was possible to dial quickly into an area of the spectrum and apply the needed EQ (and no more). The range of Q adjustment is from 20 to 0.1, which takes you from quite narrow to quite broad bandwidth. Any of the filters can be swept over to double another, and one of the presets provided locates all eight bands at 60 Hz with narrow Q and deep cut. (I would hope this setting is not used too often before attempting to eliminate the source of the hum!)
The image used to represent the Graphic Reverb is also evocative, with the size of the room directly indicated by the size of the "box" in the display. The levels of early and late reflections (controlled by the two knobs at the right that appear when you click the more button) are indicated by the two small blue columns at the lower and upper right of the "room" in the display. Room Decay is indicated by the density of the color of the surface of the whole box, while the adjustment for high-frequency absorption is indicated by changing color density on the top and right side of the box. Stereo spread (which is reversible) is indicated by the position of the two arrows at the top of the image, while the density of the reverb is shown by the thickness of the line joining the arrows.
That sounds a lot more awkward to remember than it is. Fact is, you will begin to easily associate these visual changes with the excellent quality reverb you will be hearing. I found the reverb to be especially good with the larger rooms modeled in the presets, but I've always been a sucker for the sound of a good cathedral reverb! The benefits of using full 32-bit processing really show in the reverb, which is smooth and completely free of artifacts. I did find myself wanting to have a more control over the EQ on the reverb, especially in terms of allowing different EQ tailoring on the early and late/left and right early reflections, but this is more in the way of wanting to make an excellent tool better than a complaint.
I can tell you that the Pitch Shift module is very unpopular with the cats in my house. Of course, I mean the four legged, furry ones, not the cool jazz variety. The real-time Pitch-Shift module is another clean, solid application of the quality DSP processing in this gear. Presets are quite effective, including a range of vocal and instrument Fatners, which use varying degrees of pitch shifting up and down then panned variously left and right to add "body" to the dry sound of the source. Once again, the graphics make a good deal of sense once you use the application a few times, and parameter values are listed below each control, but as the effects are created in real-time, you'll be adjusting to sound most of the time.
I used the Pitch-Shift module, along with the Reverb module, in preparing a set of comic "head bonks" for a theater production, using the sound of ping-pong balls hitting the table as a source. Quite remarkable what several trips through the pitch shifter, a bit of time stretching (in the Spectral system), and the application of stereo reverb can do to such an ordinary sound.
Each of the other effects currently available works in a similar way, with direct reading of the parameter value under knob, and with a graphic representation that manages to communicate what is being done in a minimum of space and clutter. I found all to be very high-quality, and would not hesitate to use them in any project. In fact, I managed to hang on to the units long enough to use them in several projects, and I'm going to have a hard time sending them back at the end of the evaluation.
Okay, so are there any down sides to the system? One, which will probably be addressed before too long, is the gradual disappearance of the ISA slot in recent computers. Most PCs on the market these days have only about three ISA slots, so you would be limited in the number of cards you could use, especially if your audio cards are also ISA. To a large measure, the existence of the FXPACK rack module mitigates this one, as with that option you would not need any cards in the computer to use the DSPFX. While a PCI version of the card is inevitable, it is not immediately forthcoming. Given the availability of cheap used 486 systems however, this may be less of a problem than it seems, as one could easily set up one of these machines to function as a DSPFX server.
Another issue is the current limitation of a single plug-in to a single card at a time. This can be vexing when you change plug-ins, as it takes some time for the cards to clear and then reinitialize with the new plug-in. The situation is likely to improve with the implementation of the internal physical connections between cards, and with a revision of the software to allow addressing more than one card at a time.
Finally, it takes a big monitor to be able to easily operate more than one instance of DSPFX and a DAW at the same time. On a 17-inch monitor there is a bit of overlapping that can be awkward when you are shuffling back and forth between the send/return levels on the DAW and the adjustments on the DSPFX panels. Two cures for this are a larger monitor (always a good thing anyway) and the use of the DSPFX controller, or another MIDI interface, which allows control of the software without the need to see all the controls.
One of the great things about Power Technology's concept is that the DSP engine is so completely programmable that what is an EQ at one moment can transformed into something completely different the next moment. This can save a good deal of patching and re-patching for the engineer, to say nothing of a good deal of schlepping heavy boxes around the studio. I had a chance to watch the development of the parametric EQ from early beta stage to shipping, and while the plug-in was working solidly from the first beta I loaded, it got consistently better, with more and more attention to detail, as each revision was loaded.
Power Technology is excited about the development of the DSPFX FXPACK, because it eliminates the need for a card within the computer, and expands the potential customer base to include both Macintosh and PC users for the first time.
Owners of DSPFX cards recently got a pleasant surprise when the company put the Tremolo and AutoPanner plug-ins up on their Web site for free download. I understand from talking with Mark Kaplan at Power Technology that the company hopes to provide this sort of extra service to their customers from time to time while they pursue development and marketing of major plug-ins for the future (the next major project is reportedly a compressor).
I'd have to say that the DSPFX system is a solid investment, and a solid addition to the
studio, with a value that appears to grow with each addition to the software.