Tack 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.

Lastly, 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.