An affordable, compact device gave guitarists everything they needed to stay in tune
The market for portable, battery-powered instrument tuners was pioneered by Korg, with its introduction of the WT-10 guitar and bass tuner in 1975. Though it wasn't as accurate as previous tuners, no one really cared. Mechanical strobe tuners, around since the 1930s, could be quite accurate, but they required wall power, cost a lot of money, and could weigh as much as 15 kilograms. So back in the day, many guitarists would simply use tuning forks, pitch pipes, pianos, or even records to tune their instruments. Some players were even content with simply having the strings in “relative tune"—in other words, being at the proper intervals from each other without bothering to make sure that the E string was vibrating at the proper absolute frequency. So when an electronic tuner came along, the issue wasn't a matter of how much more convenient it was; the issue was the difference between convenience and none whatsoever.
In comparison with wind and keyboard instruments, guitars are especially apt to drift out of tune, even during a performance. So guitarists in particular were delighted to have something simple they could bring on stage with them. The inaccuracy of the WT-10 wasn't too bad, but it was bad enough to inspire other companies to improve on it. One of those was Boss, which introduced the TU-12 chromatic tuner in 1983, a model that decades later is still occasionally referred to as an industry standard.
Boss claims that at its introduction, the TU-12 was the first automatic chromatic tuner. Let's unpack that. “Automatic" in this usage meant the device automatically sensed and displayed the current pitch as it was picked up via a cable from an electric guitar or, for an acoustic instrument, detected by an input microphone. (However, thanks to more recent inventions, the phrase “automatic guitar tuner" now generally refers to a device that is installed on a guitar's headstock and that physically turns the tuning pegs until one or more strings are in tune.)
The distinction between chromatic tuners and nonchromatic tuners is that a chromatic tuner can detect all 12 tones of a chromatic scale: not just CDEFGAB, but also the half tones: C-sharp, D-sharp, F-sharp, G-sharp, and A-sharp (or, if you prefer, D-flat, E-flat, G-flat, A-flat, and B-flat). Most nonchromatic guitar tuners, on the other hand, can tune only to the six specific notes in conventional guitar tuning: the strings in a typical six-string guitar are tuned to EADGBE. So the advantage of a chromatic tuner is that it can tune to the nearest semitone. If it detects a pitch close to A-sharp, it will tune for that note, rather than tuning for A or B. This scheme offers a few important advantages. One of them is that it allows guitarists to tune their guitars when playing with alternate string tunings; DGDGBD is only one example among many. The TU-12 offers both options—there's a chromatic as well as a nonchromatic mode.
The TU-12 has a lighted meter that shows how close the detected note is to the nearest tone or half tone, a tuning guide, and a built-in microphone for tuning acoustic instruments. Of course, as with other tuners, electric instruments can be plugged in. The tuner can run on batteries or wall current.
A nice and unusual feature of the TU-12 is that musicians can manually select the pitches they want to tune to. For guitarists this means being able to select which specific string they want to tune.
The TU-12 also has a setting for instruments with very high frequency ranges, like flutes and piccolos. And there's another setting for those with low frequency ranges, such as bass and baritone guitars.
Floor Model: The TU-12 guitar tuner fit snugly into the upper right corner of a popular pedalboard used by guitarists. Below it in the pedalboard are several foot-pedal controlled effects boxes. Photo: Boss
Not only was the TU-12 accurate, and not only did it have a list of features important to musicians, it is regarded as one of the most rugged tuners ever built. Rock stars like to complain about how grueling touring is, and no one really pays attention to such whining. But it's worth noting that stage equipment does in fact have to stand up to being banged, dropped, kicked, and doused repeatedly in alcoholic beverages. The Boss TU-12 has a reputation for standing up to all that abuse and remaining accurate.
Among the pro guitarists who have endorsed it in the past or were still using it as of 2019 are Steve Vai, The Edge (U2), Ace Frehley (Kiss), and John Squire (The Stone Roses).
Guitarists tend to include a tuner on the pedalboard, which is a rack mounted on the floor that holds all of the foot pedals that trigger different sound effects they use when they play. A feature that performing musicians wanted was the ability to mute their guitars completely so that the audience (and bandmates) didn't hear the guitar as it was being tuned during a performance. Eventually, Boss, Korg, Peterson and other tuner manufacturers introduced models that could mute the guitar while it was being tuned. Although players can simply turn down the volume knob on the guitar to use a tuner, the lack of a mute feature is the one thing that took the shine off the TU-12.
Boss still makes tuners, its lineup now spanning eight models. Over the years there were several follow-ons to the TU-12, including the TU-12H, which has an extended range, and the TU-12BW, for brass and woodwinds. The most recent successor, the TU-12EX, was introduced in 2009. It has an even greater range than the TU-12H—8½ octaves—allowing it to be used with pretty much any musical instrument. It also provides flat tuning, in which the guitar's lowest E string is actually tuned to E-flat, with the tuning of the other five strings adjusted accordingly. Flat tuning is favored by some guitarists and is said to be more accommodating to vocalists. The TU-12EX also has the Accu-Pitch feature, which emits a beep when the note played is in tune. With a retail price under US $100, the unit is not quite 15 centimeters long (six inches), weighs 142 grams (5 ounces), and can tune to within one-hundredth of a semitone, known as “1 cent."