Electronic Tuner - Types

Types

Most tuners contain a microphone and/or an input jack (for electric instruments such as electric guitar), circuitry for detecting the pitch, and some type of display (an analog needle, an LCD simulated image of a needle, LED lights, or a spinning translucent disk illuminated by a strobing backlight). Some tuners have an output, or through-put, so the tuner can be connected 'in-line' from an electric instrument to an amplifier or mixing console. While small tuners are usually battery powered, some tuners also have a jack for an optional AC power supply.

The waveform generated by a musical instrument is very complex, as it contains a number of harmonic partials, and it is constantly changing. For this reason the regular tuner must average a number of cycles of the note and use this average to drive its display. Any background noise from other musicians or harmonic overtones from the musical instrument can easily "confuse" the electronic tuner's attempt to "lock" onto the input frequency. This is why the needle or display on regular electronic tuners tends to waver when a pitch is played. Small movements of the needle, or LED, usually represent a tuning error of 1 cent. The typical accuracy of these types of tuners is around +/- 3 cents for quality needle tuners and +/- 9 cents for the most inexpensive LED tuners. Some companies offer one type of tuner (e.g. Behringer, Quick Time and Fender focus on inexpensive pocket-sized tuners), while other companies, such as Boss and Korg, sell a range of standard, pedal, and rack-mountable tuners at varying levels of quality and features.

"Clip-on" tuners attach with a spring-loaded clip to an instrument (commonly at the headstock of a guitar or scroll of a violin) and pick up vibrations, rather than using a microphone or input jack to sense the input frequency. The tuner then displays the pitch of the instrument's vibration on its large LCD. Clip-on tuners are less likely to be confused by background noise than a microphone-based tuner, because the clip-on tuners pick up the vibrations of the instrument directly from the body of the instrument. The pioneer of the clip-on tuner industry was the Intellitouch PT1 built by OnBoard Research Corporation.

The "String Master" tuner consists of a regular LED tuner where the electric instrument plugs into the unit's base with a 1/4" TRS cable, or an acoustic instrument via a microphone cable. The unit has a built-in motor which drives a string winder tool at the top to the unit. The unit is then placed over the tuning button of the machine head of the string to be tuned, and a note on the relevant string is played. The unit detects the input note and robotically corrects the pitch to a desired frequency by mechanically turning the tuner button to the correct position. It monitors the change in frequency until the "in tune" signal is given.

Some electric guitar tuners are fitted to the instrument itself, such as the Sabine AX3000 and the "NTune" device. The NTune consists of a switching potentiometer, a wiring harness, illuminated plastic display disc, a circuit board and a battery holder. The unit installs in place of an electric guitar's existing volume knob control. The unit functions as a regular volume knob when not in tuner mode. To operate the tuner, the player pulls the volume knob up. The tuner disconnects the guitar's output so the tuning process is not amplified. The lights on the illuminated ring, under the volume knob, indicate which note is being tuned. When the note is brought into tune a green "in tune" indicator light is illuminated. After tuning is complete the volume knob is pushed back down, disconnecting the tuner from the circuit and re-connecting the pickups to the output jack.

Gibson guitars released a model in 2008 called the "Robot Guitar". It is a customized version of either the Les Paul or SG model. The guitar is fitted with a special tailpiece, looking like a regular unit, with in-built sensors that pick up the frequency of the strings. There is an illuminated control knob with which the player can select different tuning options. The headstock is fitted with custom-built motorized machine heads that automatically tune the guitar. This system can assist the player to intonate the guitar when the unit is put into "intonation" mode, displaying how much adjustment the bridge requires with a system of flashing LEDs on the control knob.

The first automated guitar tuner was invented by JD Richard in 1982 while studying Electrical Engineering at the University of New Brunswick, New Brunswick Canada. This tuner was based on phase-locked-looped feedback design that listened to the frequency of the string and turned a stepper motor (with a 400/1 gear ratio) attached to the tuning peg of the guitar. This first design never went into production although the thesis paper can still be obtained at the university.