The first stroboscopic (strobe) tuner was produced by Conn back in the 1930’s. Mechanical strobe tuners use spinning translucent disc’s that spin at a given rate of pitch that is set by the user. These Discs’s have a printed circular pattern on them. Behind this disc is a series of lights or LED’s that flash (or strobe) at the same rate as the incoming signal. The difference between the rate of the disc spinning and the rate of the lights flashing create the optical illusion of movement. The more out of tune the incoming signal is compared to the correct pitch, the faster the disc appears to spin. When the disc and the incoming signal are the same, no movement is seen and that’s how you know you are in tune. It's really that simple but ingenious!These days, strobe tuning is accomplished not only with spinning disc but also with LED and LCD displays. Such examples of this are the Planets Waves Tru-Strobe and SOS tuners.
The SOS Tuner projects two opposing strobe (or rapidly flashing) LED’s onto the guitar string at the exact frequency at which the perfectly tuned string will vibrate. This then gives you a visible indication on the string itself as to whether the string is in tune or not: if the two lights are moving, the string needs to be adjusted to bring it in tune. If there is no movement, the string is properly tuned. Tuning the string simply involves projecting the desired pitch onto the string, plucking the string, and adjusting the string tension until the strobe lights stop moving. What's also great about this tuner is that since you are shine the light right on the string no input signal is needed. you could tune you guitar perfect while standing next to a running 747 (I don't recomend that you try this though!)
The Tru-Strobe Tuner works by displaying the interference between a reference frequency (or pitch) and the instrument’s signal input. Electronics in the tuner detect the pitch of the instruments signal and spins the ring of LED’s at the recognized pitch, “E” for example. The instruments signal then turns the tuner's whole ring of lights on and off as the string vibrates, and the optical interference creates the strobe or spinning effect. When the string's frequency matches the lights' spin rate, the image appears to stand still, indicating the string is perfectly in tune.No matter which style is used, strobe tuners will take you to the next level of tuning accuracy. This is critical when in the studio, on stage or setting up the intonation of your guitar. Next time you’re at a concert or your local repair shop look around and I’m sure you will find a strobe tuner in use.
