Honky-tonk piano

In music, the tack piano (sometimes referred to as jangle piano, junk piano, honky-tonk piano or harpsipiano) is a permanently altered version of an ordinary piano, in which tacks or nails are placed on the felt-padded hammers of the instrument at the point where the hammers hit the strings, giving the instrument a tinny, more percussive sound.

Perhaps this preparation attempts to emulate the sound of a poorly maintained piano: as the felt hammers age and compact through use they become hard and cause the piano to yield a similar sound. A piano tuner will use a tool consisting of a number of fine pins to open and loosen the striking surface of the hammers, called voicing, a precision job calling for a good ear and lots of experience.

Another method of achieving that "percussive" sound without using real tacks is through the use of lacquered hammers in the piano, like the Steinway Vertegrand piano popularized by Mrs Mills which resides at Abbey Road Studios.

A "honky-tonk" sound can be achieved by detuning one or more strings for each piano key, creating the characteristic "wah-wah" or beating effect of an out-of-tune piano.

Using tacks on a piano runs the risk that the tacks will be ejected from the hammers and can then become lodged in other parts of the mechanism. If the jammed mechanism is then forced by hitting the keys, parts of the action may be broken. More importantly, the holes created in the hammers by the tacks dramatically weaken the hammer felt (which is stretched at high tension over the hammer wood), and may permanently reduce the sound of the piano to dark mush once the tacks are removed.

A safer alternative to real tacks is a device called a mandolin rail. It is a curtain of felt hanging between the hammers and strings. The felt is slitted on the edge, and paper fasteners or paper clips attached. The device can be purchased commercially or built by hand, and ultimately causes the piano hammers to be worn away from repeated impacts with hard metal. Mandolin rails could regularly be found in home pianos at the turn of the 19th century, but were most popular in commercial coin-operated pianos.

Canadian pianist Glenn Gould experimented with a tack piano made especially for his use by Steinway, which he called a "harpsipiano" (a portmanteau of "harpsichord" and "piano"). It was intended to recreate (somewhat, at least) the sound of the harpsichord, but unlike a harpsichord, whose strings are plucked instead of struck, it could be readily placed amongst an orchestra and capable of dynamic expression as on a piano. Gould used it in a 1962 television broadcast in which he played Contrapunctus IV from Bach's Art of Fugue. One of the few occasions he conducted was while playing the harpsipiano: he directed Bach's Brandenburg concerto no.5 from the instrument and realized the continuo part of Bach's cantata Widerstehe doch der Sünde, BWV 54, in a 1960s television recording (now to be seen in The Glenn Gould Collection).

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