A Different Way to Label

August 31, 2012

Changing the Standard for Identifying 7.1 Surround Wires

 
Anthony Grimani (agrimani@pmiltd.com) is
president of Performance Media Industries, with offices in Novato and San Anselmo, CA.
I ran into a common problem on an install the other day. It was a great system: cool room, nice gear. The installation team had wrapped up and was headed out the door to another job; it was my turn to configure, debug, tune, and calibrate everything I could think of. I flipped on the surround processor’s internal speaker test noise to get a rough idea of what I was in for. The left channel came on. Center channel, check. Right channel...was coming from behind me. Oh. Oops. Hey, wait! Installation team! Don’t leave yet…

After a few minutes of pecking around, we found the problem. The wire for the back-left speaker was connected to the right speaker output of the amplifier. How could this happen? When labeling the wires, the technician had used the terminology “LR” for the left-rear speaker. However, the “L” and “R” were on separate labels, and the “L” had come off. Now there were two wires–the other being the right speaker–with a single “R” on them. You see how things went off the rails from there. In the end, it took three of us about 30 minutes to solve the whole thing (the integrator spent the entire time apologizing to me). That’s 30 minutes I could have been calibrating, 30 minutes the technician could have been on another job, and 30 minutes the integrator could have been selling another system. One-and-half manhours wasted because of a silly little label.

There’s a Better Solution

We seriously need a simple new standardized convention for labeling each one of our 7.1 channels. Labels may seem like a small and insignificant thing on the surface, but my recent experience demonstrates how important they can become. So, here is what I’m proposing.

First, let’s call them “front,” “side,” and “back” channels. Fronts go in front of you, sides go to your side, and backs go to your back. Simple. I know it’s popular to call them surrounds and rears, but all the speakers that aren’t fronts are technically surrounds, and my example above shows why it’s a bad idea to use an “R” for rear. I’ll also give “height” an honorable mention, because I’m starting to see that pop up in a few places.

Next, how do we differentiate left and right for the fronts, sides, and backs? Use upper case for the fronts and lower case extensions for the sides and backs. This looks like Sl, and Sr for the side-left and side-right channel respectively. In fact, I’d argue that you don’t even need a “front” designation; they’re just the L, C, and R. That way you know a wire with an upper “L” is the left, not a side left or back left speaker–even if a label gets torn.

 
Figure 1: This new 7.1 home theater wire labeling convention is easy for installers and technicians to remember. It’s robust in the event labels get damaged. It’s also short and easy for manufacturers to print on the back of amplifiers and receivers
What About Subwoofers?

We should not start their labels with “S” for fear of mistaking them for sides. So let’s use “W” for “subWoofer.” Also, by now you should know that you should be using at least four subs these days. It’s been pretty well demonstrated that four at the wall midpoints, or more typically corners, (vastly more ergonomic with only slightly lower performance) is the way to go. That means you will have at least four wires coming in labeled “W.” It may not matter for some systems where the subs are fed the same signals. However, I like to split the feeds up to trim levels and delays separately during calibration and eek every last bit of performance out of the room. (This is not recommended unless you have experience doing this sort of thing and a lot of sophisticated test gear to back you up.) I say we start with “W1” in the front-left corner, and then go clockwise around the room with “W2,” “W3,” and “W4.” See Figure 1 for a graphical form of what I’m talking about.

This convention is easy for installers and technicians to remember. It’s robust in the event labels get damaged. It’s also short and easy for manufacturers to print on the back of amplifiers and receivers. This convention applies to speaker connections, as well as any line level interconnects between the surround processor and amplifiers or perhaps an old disc player with analog outputs.

The point here is to use a simple convention to save time and money. I don’t have to track down problems, technicians don’t have to undo beautiful wiring, and so on. Let’s all agree to a convention, stick to it, and be happy!

Chase Walton contributed to this column.

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