Robair Report: 500 Series and Eurorack--A Call for Stricter Standards

While manufacturers have gone to great lengths to make computer peripherals plug-and-play, there is still a lot to be done in the hardware realm. Two modular formats, in particular—500 Series audio

Gino Robair

While manufacturers have gone to great lengths to make computer peripherals plug-and-play, there is still a lot to be done in the hardware realm. Two modular formats, in particular—500 Series audio products and Eurorack synth modules—are showing such explosive growth that it has led to a gold-rush mentality. As a result, there is a glut of products, an increasing number of which are designed carelessly and, at times, border on being dangerously incompatible.

I’ve been hearing complaints about 500 Series module and rack incompatibilities for years now, but I got an earful of stories while attending Sweetwater’s GearFest in June. I’m spec’ing out a front-end for my home studio, and because a number of module manufactures were attending the event, I went through my list of questions with each of the designers.

My final question was always, “Which rack and power supply do you recommend?” expecting a long list of pros and cons about each chassis. All but one designer said simply: Purple. By this they meant the Purple Audio Sweet Ten, a 10-space chassis and power supply that, they explained, sounded and performed the best.

Ironically, Sweetwater doesn’t carry it.

A major factor that was given for suggesting the Sweet Ten had to do with the increasing number of modules that do not conform to the “standardization and consistency guidelines” of the VPR Alliance created by API Audio. That’s because when one of the modules from these designers goes into a rack with an out-of-spec module and there is an issue (such as added noise, power issues, complete system failure), their module might be blamed, even though their own design conforms to API’s spec and is on the list of VPR-approved products. Apparently, this hasn’t been an issue with owners of the Sweet Ten chassis, though it’s just one reason why module developers like it.

Similarly, the API rep told me that they get phone calls when someone puts a rogue module into an API rack and there’s a problem. According to API, the VPR program “provides complete design specifications for manufacturers interested in producing third-party modules that physically fit and electronically conform to API’s rack specifications.” However, several of the module designers complained that the spec was “too loose” (I heard that specific phrase twice), which they believe has led to compatibility problems with some of the modules that have been brought to market. Yet it is often the guys who play by the rules who receive the brunt of the negative feedback.

Similar problems have arisen in the modular synth world, especially in the Eurorack format. While the huge variety of products is welcome, the range in design and build quality is too wide. One of the most common problems is the orientation of the ribbon cable that connects a module to the power bus board. Often user-error is the issue (plugging the module in upside down), but I own several modules that are wired improperly. We should be way beyond that by now. At the very least, the modular community needs to agree on a mandatory requirement that keyed connectors are used at the end of power ribbons, with the red stripe indicating -12. Imagine if you couldn’t trust the wiring of a MIDI DIN plug?

The people buying Eurorack gear tend to be less savvy about the technology than 500 Series buyers because the entry cost of the synth modules is so low. Often, they’ll buy the cheapest power supply and rack they can find and then connect as many modules with the coolest faceplates that they can, completely ignoring the operational manuals. When the system fails to work properly, who do they blame?

This came up in a recent conversation with Eric Barbour, owner of Metasonix and world-renowned tube specialist. He told me that, when the uninformed consumer tries to power a rack of his tube-based modules using an underpowered system, he gets the irate call. “Our modules do pull more current, but usually it’s not a problem, unless they try to use a really cheap power supply,” Barbour told me in a recent email. “All of the R-series Eurorack modules need 150-200 mA from both +12 and -12. Some of the newer DSP-based modules on the market also require a lot of power, usually at 5 volts.” He suggests that serious users purchase the Monorocket cabinet that is designed to handle Metasonix modules, which also provides more than enough power for other Eurorack products. Retailers should offer this level of advice, as well.

Clearly API did the pro-audio industry and its customers a big service by forming VPR. But based on the feedback I’ve heard from respected designers, the guidelines need to go further and involve a lot more of the development community, in the same way that manufacturers got together to hammer out the MIDI spec three decades ago. Both formats would benefit from greater standardization, because at the rate they’re selling, these products will be around for a long time.

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