Basically the Planet Waves SOS guitar tuner feels like holding a massive guitar pick. It’s shape is a kind of curved triangle with a pair of red lights beaming out of a recess in one corner. The opposite edge has a wheel with the following numbers: 0, 1, 2, 3, 0, 4, 5, 6 corresponding to two off-settings and the guitar’s strings in common tuning. The entire unit appears to be made of plastic but seems thoughtfully designed and well made. It uses a common “hearing-aid” type battery.
When the string selection wheel is spun to a number other than 0 the two recessed red lights turn on. They look steady, but pick the corresponding string while hovering the tuner over it and you’ll quickly see a stroboscopic effect on the string itself. When the string is out of tune the two lights appear to be on rollers spinning in opposite directions. When the string comes into tune, the lights line up.
It takes almost no time at all to understand this effect, and with 5-10 minutes of messing around you can become quite proficient.
So how good is it?
Well, I’ve gotten fairly used to my little PROFILE PT-2700 clip-on tuner. It has difficulty locking on to the low E string, but if I use 12th harmonics all the way across I can get fairly close. Then I fine tune the relationships by ear.
This Planet Waves S.O.S. tuner, however, has no trouble fine tuning any string. Select the number on the wheel, pluck the string while you adjusting the tuning peg, and within seconds you’re spot on. It works best if you pluck very near the 12th fret because this is where the string vibrates the most. It’s very accurate.
Two things to consider. First, it doesn’t do alternative tunings very well. Second, if a string is way off the mark it can be a little more time consuming than a digital tuner that displays each note.
So my final thoughts are these… I wouldn’t want to use it to tune my strings for the first time out of the wrapper, but as a fine-tuner with very high accuracy once I’m in the general neighborhood, the Planet Waves SOS tuner is an extremely portable device and is very cool.