SOUTHAMPTON, Pa. — The Knabe baby grand did a cartwheel and landed on its back, legs poking into the air. A Lester upright thudded onto its side with a final groan of strings, a death-rattling chord. After 10 pianos were dumped, a small yellow loader with a claw in front scuttled in like a vicious beetle, crushing keyboards, soundboards and cases into a pile.


The site, a trash-transfer station in this town 20 miles north of Philadelphia, is just one place where pianos go to die. This kind of scene has become increasingly common.


The value of used pianos, especially uprights, has plummeted in recent years. So instead of selling them to a neighbor, donating them to a church or just passing them along to a relative, owners are far more likely to discard them, technicians, movers and dealers say. Piano movers are making regular runs to the dump, becoming adept at dismantling instruments, selling parts to artists, even burning them for firewood.


“We bust them up with a sledgehammer,” said Jeffrey Harrington, the owner of Harrington Moving & Storage in Maplewood, N.J.


Pianos consist of hundreds of pounds of metal, wood and intricate machinery able to channel Bach, Mozart and Beethoven, along with honky-tonk, “Happy Birthday” and holiday tunes. It is strange to think of them as disposable as tissues. Yet economic and cultural forces have made many used pianos, with the exception of Steinways and a few other high-end brands, prone to being jettisoned.


With thousands of moving parts, pianos are expensive to repair, requiring long hours of labor by skilled technicians whose numbers are diminishing. Excellent digital pianos and portable keyboards can cost as little as several hundred dollars. Low-end imported pianos have improved remarkably in quality and can be had for under $3,000.


“Instead of spending hundreds or thousands to repair an old piano, you can buy a new one made in China that’s just as good, or you can buy a digital one that doesn’t need tuning and has all kinds of bells and whistles,” said Larry Fine, the editor and publisher of Acoustic & Digital Piano Buyer, the industry bible.


Used pianos abound on Web sites like eBay, driving prices down and making it difficult to sell Grandma’s old upright. With moving costs of several hundred dollars, even giving a piano away can be expensive. Abandonment often becomes the only option, especially for heirs dealing with a relative’s property.


Many pianos are also dying of old age. In the late 19th and early 20th centuries, before radio and recordings, pianos were the main source of music, even entertainment, in the home. They were a middle-class must-have.


So from 1900 to 1930, the golden age of piano making, American factories churned out millions of them. Nearly 365,000 were sold at the peak, in 1910, according to the National Piano Manufacturers Association. (In 2011, 41,000 were sold, along with 120,000 digital pianos and 1.1 million keyboards, according to Music Trades magazine.)


The average life span rarely exceeds 80 years, piano technicians say. That’s a lot of pianos now reaching the end of the line.


Piano dealers also blame other changes in society for a lack of demand in the used-piano market: cuts in music education in schools, competition for practice time from other pursuits, a drop in spending on home furnishings with the fall of the housing market.


Whatever the reason, people in the piano world agree that disposals are mounting.


O’Mara Meehan Piano Movers said it takes 5 to 10 pianos a month to the debris transfer site here. The company was founded in 1874 by the great-grandfather of the brothers Bryan and Charles T. O’Mara Jr.


Bryan O’Mara and an employee, James A. Fox, drove their truck into a hangarlike structure one day last week. Inside the truck were six uprights and four grands. Several came from the Philadelphia school system and one from a retirement home. “This was Mrs. Dombrowski’s from New Hope,” Mr. O’Mara said, patting the Knabe.


Mr. O’Mara and Mr. Fox pushed them off the back of the truck one by one. The top of an upright popped off when it landed. Mr. Fox tossed amputated piano legs and a pedal mechanism. Sprayers from above sent out a swirl of dust-settling mist, adding to the surreal atmosphere.