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Tune-o-matic (also abbreviated to TOM) is a fixed bridge for electric guitars, designed by Gibson and introduced in 1954 in Gibson Les Paul Custom guitar. In 1955, it was also used on Gibson Les Paul Gold Top, and then, gradually was accepted as a standard on almost all Gibson fixed bridge guitars, except budget series.

Contents 1 Function 2 Construction 3 Varieties 4 Spelling 5 External links

Guitar strings, especially steel strings, are not ideal vibrators. Generally the thicker the string, the shorter the effective length, i.e. the length of string involved in producing sound, as opposed to the length between the nut and the bridge. Many guitar designs with fixed bridges have the bridge slanted or stepped so that the distance from nut to bridge is larger for thick strings. The Tune-o-matic extends this idea to make the distance adjustable, within limits, for all the strings.

The most common way of determining correct adjustment for a string is to compare the note at the 12th fret with the harmonic at the same position. The two should be as close as possible.

The Tune-o-matic bridge consists of 2 adjustable posts that are screwed into guitar body, and a bar between these posts. The bar has 6 saddles, one per string. When fully assembled, each string is passed through a saddle and the saddle thus "marks" the end of the vibrating string. Each saddle can be adjusted (moved back and forward) with a screw to control intonation. To prevent saddles from falling out of the bridge when no strings are installed, most models usually hold the saddles with retainer wires.

After the saddles, each string is passed to the tailpiece. Some guitars have a stopbar to hold strings, others have "strings through the body" construction, thus holding the string by whole body.

The Tune-o-matic bridge is not absolutely flat and standard Gibson Tune-o-matic bridges have a 12" radius. Ideally, the radius should match the radius of fretboard for the most comfortable playing experience.

Since its invention, lots of varieties of the Tune-o-matic construction emerged, both different versions by Gibson itself and by other companies.

• Standard Tune-o-matic is the first version that appeared in 1954. It used slim posts, but it lacked slots for adjustment with screwdriver. The only way to adjust was using a thumbwheel that was accessible only after loosening strings, i.e. adjusting bridge height required retuning of the whole guitar.

• Modern Tune-o-matic is the second version. It featured a much larger post with a threaded pot. It could be adjusted using a flathead screwdriver instead of a thumbwheel, but the posts were too large to be used in Fender guitars - it required drilling to install.

• Refined standard Tune-o-matic is the third version of the Tune-o-matic. It featured both slim posts (as in "standard" version) and screwdriver adjustment (as in "modern" one).

There are multiple widely known Tune-o-matic models that differ in the following parameters:

Model	1st-to-6th distance, mm	Between posts, mm	Post, diameter × length, mm	Thumbwheel diameter, mm	Saddles, mm
					width	height	thickness	hole
Gibson BR-010, ABR-1 ("Vintage")	52	73.8	M4×30	15	8.8	6.5	3.0	M3
Gotoh GE-103B[1]	52	74	M4×30	18	8.8	8.0	3.0	M2.5
Gibson BR-030 ("Nashville")	51.6	74.3	M3.9×25.1	11	8.8	10.0	2.55	M3

There's no general consensus on "proper" capitalization of bridge name. Gibson official site usually spells it as "Tune-o-matic"[2], while "Tune-o-Matic" and "Tune-O-Matic" are frequently used in advertising and promotional material.

• Tune-o-matic guide on Jag-stang.com site.
• An overview of Tune-o-matic systems and replacements parts by K.T.S Titanium Section