Connect Corner
The ins and outs of multipin connector designs

By Peter Janis

The choices of multipin connectors is wide and varied.

The use of multipin connectors for live touring has become the norm, not the exception. But trying to make headway through the myriad of connectors that are used can sometimes cause confusion. Blame it on Whirlwind! Way back in the “dark ages” of the 1980s, Whirlwind introduced the concept of multipin connectors by adopting the 142-pin Cannon Mass connector. This hefty device was developed in Whitby, Ontario for use by the mining trades in Alberta. It had the distinct advantage of being hermaphroditic (half male, half female), allowing long cable lengths to be deployed and extended as mining pits grew. The rugged circular design and water-resistant O-ring combined to be well suited for use in harsh environments such as outdoor festivals.

DECIDING FACTORS

Several companies currently offer multipin connectors, most of which come from the military or aerospace industries. These include circular bayonet connectors, such as those made by Pro Co, Veam, Amphenol and their European counterparts, and square-block connectors from companies like Edac, Amp, Cannon and so on.

Making a decision on a multipin often comes down to standardizing the complete rental department. Often, even though one may not be enamored with a particular connector, changing over can be cost-prohibitive. Clair Bros., for example, was an early adopter of using a circular screw-on multipin connector for smaller snakes. Even though Clair might prefer changing to some of the newer bayonet-style connectors, it has so many of the older models that it’s not feasible to make the switch.

The difference in size between Veam (above) and Mass pins.

One of the most challenging decisions lays in selecting larger channel multipin connectors. For instance, the Mass connector is one of the most common in use today, and it’s a very good connector. However, because the Mass (W3 or W4) has very small pins, they are easily broken. And changing the pins is not for the faint of heart. The connector must be collapsed by removing a C-ring, and then the two “pucks” that hold the pins in place must be pulled apart. To do this, all wires must be removed and all solder cleaned off.

New generations of connectors, such as those pioneered by Veam and now manufactured by a variety of offshoot companies, allow individual pins to be removed and replaced. This makes the connector field-serviceable, and, for many, has been reason enough to switch. There have been attempts by a couple of companies to make a removable pin version of the Mass connector, but the diminutive size of the pin and density of the pin block have yielded varying degrees of success. As a result, when given the choice, most system designers opt for a larger pin size, which not only reduces opportunity for damage, but also ensures a greater contact surface area.

WHAT A RELIEF

Another key factor in determining the suitability of a multipin connector is the strain relief. For example, Edac and Elco make a good connector, but due to small cable openings and non-existent strain-relief, they are usually only used in fixed or semi-permanent installations. If absolutely necessary, a Kellems-style grip can be attached to the cable as a reasonable solution.

Taking apart the mass connector.

For larger multipin connectors, the choice comes down to either compression fittings or large Kellems grips. Kellems or “Chinese finger trap” stain-reliefs are generally considered the best options, however, keep in mind that they do cost significantly more. It’s a good idea to dab on some Locktite or even insert a locking screw so that the connector barrel does not loosen after use.Often, untrained hands will try to disconnect these connectors and turn the wrong section, which can cause undue strain on the fragile internal solder joints.

Unfortunately, there is no official standard wiring configuration currently in use on the market. Just because Whirlwind offers a standard pin-out, some of the major touring companies opt to use their own pin layouts, thereby making the Whirlwind approach incompatible.

The best guarantee for compatibility still comes down to a spare multipin-to-XLR panel or cable. Every sound company, recording and broadcasting truck is able to mate with another XLR. Therefore, it makes a lot of sense to simply outfit a snake system with a second XLR panel to allow cross-patching compatibility.

Peter Janis is president and managing director of CableTek Electronics, the parent company of Radial Engineering, Primacoustic and C-TEC. He is also chairman of the Vancouver AES Society.

MONTHYEAR Live Sound International