Planet Waves SOS Guitar Tuner

It's hard not to like something that's inexpensive, tiny, accurate, and very useful. Which is probably why I like the Planet Waves S. O. S. ("strobe on string") tuner a whole lot.

In case you're wondering why I included a shot of the package and not just the product, that's because it's small. Really small. As in, about the size of an oversized pick. Yet this is a functional, useable guitar/bass tuner that weighs next to nothing and fits in your axe's case. Actually, you could fit dozens of these in a case, but I think you get the idea.

Of course, it's not a top-of-the-line Peterson strobe tuner: It's not chromatic, and only tunes E-A-D-G-B-E so if you're into alternate tunings, this is not the droid you're looking for. Still, the S. O. S. fulfills almost all of a guitarist's tuning needs, and despite the copy on the package that says it's only for guitar, I've had no trouble tuning 4-string electric bass as well (however, a version designed specifically for bass is also available for the same price).

How It Works

S. O. S. gets its name because it's a strobe-based tuner with two red LEDs. It has a thumbwheel on the top that selects among "off" and which of the six strings you want to tune. You choose the string, then pick it with the S. O. S. "pick" so that its two LEDs shine on the string. Unless your string is totally in tune, the reflection on your string from the two LEDs will pulsate—in other words, first you see the reflection from one LED, and then the other. This is because the LED frequencies are basically "beating" with the string.

As you tune the string, the LED reflections come closer to appearing to shine in unison. When they're 100% stabilized and don't appear to be moving at all, that means your string is in tune. You then tune successive strings until your entire guitar is in tune.

It's a little hard to see the reflections on the top E string because the string itself is thin, but it's still not hard to tune. One surprising aspect of the tuner is that tuning is very easy, as there's not the "jitter" you sometimes associate with tuners. Tuning in broad daylight is a little tough—you may need to shade the string in direct sunlight—but conversely, you can tune in a darkened room, and do so in total silence (aside from the sound of a vibrating string).

The S. O. S. tuner uses a single CR1620 battery; there's an auto-shutoff circuit so that if you forget to turn it off, it turns off anyway in about a minute. As to accuracy, Planet waves quotes ±0.4 cents and while I have no way of measuring that, suffice it to say that your guitar will sound in tune after you're done.

The only caveat I can think of is that the thumbwheel feels a little flimsy, and the S. O. S. is made out of plastic so you certainly wouldn't want to run over it with a PA stack. However, I would think that if you're even remotely careful, this little sucker will last quite some time.

Overall, this is a totally cool tuner that definitely delivers value for money. It's never far from my guitar, and as a result, my guitar is never far from a tuning touchup. Two thumbs up.

More info: www.planetwaves.com