Radial Engineering Workhorse 5000 offers direct and summing outs.
A year ago at AES, the show seemed inundated with software plug-ins of every sort. This time around, the AES floor was teeming with analog processors, and many of the new debuts were modules — and new housings — made in the increasingly popular API 500 Series format. A good part of this stems from API co-founder Saul Walker, whose brilliant design some four decades ago for the API 550A equalizer (based on his discrete 2550 op amps and ingenious Proportional Q circuit) led to a highly prized classic that remains in production today.
There are numerous reasons why so many new products appeared sporting 5.25×1.5-inch front panels and rear 15-pin edge card connectors. Certainly, the ability to pack up to 11 modules in a single rack or desktop-style “lunchbox” makes sense for traveling engineers or any users who want to pack a maximum amount of analog gear into a convenient, customizable package for use as a front end to DAWs or digital consoles. On the manufacturing side, creating a product with minimal metal work, few or no I/O connectors, and sans power supply is an attractive incentive. Let's face it: No one enjoys designing power supplies.
After a little research, we uncovered more than 130 modules and housings in the 500 Series format, including preamps, equalizers, compressors, summing boxes, Dis and some that defy categorization. It's a huge selection by anyone's standards, and so far no one's built a digital processor in a 500 Series module, but give it time.
Parking the Cards
Unless you already have a console that supports 500 Series modules (such as API's Model 1608 or the Tree Audio 500), you'll need some sort of enclosure to provide I/O connections and supply the standard 130 mA to power each module. Enclosures vary from bare-bones, two-slot horizontal or vertical units to elaborate rack systems with onboard summing, mixing and monitoring (such as Radial Engineering's new Workhorse 5000) to small sidecar consoles, like the 8-channel Mark VIII console from Pete's Place Audio.
Once you've settled on a housing that meets your needs, the selection of modules should be fairly easy. However, there are a few products that vary enough from the original module spec to lead to a few caveats. Purple Audio's Moiyn 8×2 summing amp only functions when used in Purple's Sweet 10 rack. Radial Engineering's modules can be used in any 500-compatible application, but some offer additional features when used with the company's Workhorse 5000 rack, such as the tuner output function on the JDV-LB instrument preamp or the DI output jack on the PowerPre preamp. As an alternative, Speck's ASC-V EQ module has rear I/O and power connections so it can be used stand-alone in an enclosure.
Some modules, such as Buzz Audio's Elixir preamp, exceed the 130mA current draw, which may limit the number of Elixirs in some systems, depending on the design of the enclosure's power supply. A few modules have sidestepped the power issue by making 3-inch, double-width modules that combine the output of two slots, thus doubling the allotted power available to the module. This approach doesn't work for all designs, such as VSI Audio's tube compressor/preamp, which requires either a separate source to supply the 300-volt plate voltage or installation in a VSI-made housing.
A few years ago, in an attempt to standardize conformity within the 500 Series module realm, API started the VPR Alliance. Administered by API, VPR is a free approval process that verifies whether modules are fully compatible with its API Lunchbox and 500VPR rack units. A number of third-party manufacturers have opted to join VPR, although others have declined. Lack of a VPR stamp does not necessarily mean a product is unsatisfactory; but the fact that VPR exists at all indicates that users need to check manufacturer specs to make sure any module/enclosure under consideration is right for their needs.
Outside the Box
While not necessarily compatible with 500 Series products, modular systems are available from other manufacturers. SSL offers its Mynx system, which houses the company's X-Rack modules. Tonelux offers an array of modules for its 16-slot VRACK and full-on console systems. Tube-Tech just announced a new two-slot housing to complement its RM-8 8-slot rack and tube-based mic pre/EQ/compressor modules. And at AES, SPL debuted its RackPack 500, a rack housing for four 500 Series modules and four of its proprietary modules — mic pre's, Transient Designer, equalizers, TwinTube saturator and compressor.
Another option not mentioned so far is the D.I.Y. approach, and a number of manufacturers offer their gear in kit form, including Laz Electronic (compressors), Five Fish Studios (preamps) and Big Rack Audio (housings). And if you have an empty slot or two, several companies sell blank filler panels, although Big Rack Audio also offers panels custom-engraved with your studio logo. The charts that begin on page 26 survey the current state of the 500 Series world. The offerings are varied and plentiful, so you should have no problem configuring the ideal system for your productions.
George Petersen is Mix's executive editor.