For decades, piano tuners have been muting off strings of bichords and trichords so they could tune a single string to the correct pitch, and then tune the unisons after.

Some would tune all the single strings first and then clean up the unisons at the end, collect their pay, and leave.

The problem was, how could they be sure their unisons were really that good? They left before they could really test them.

The solution was "Open Unison Tuning".

Simply put, you tune all the strings of a bichord or trichord before moving on - using the quality of that note to tune other notes. In this way it was easy to find drifters or unisons that needed fixing. 

The final product was better.

The main reason I didn't adopt this single string open unison tuning technique was that there was too much mute movements and it was too difficult to insert the wedge mute between two strings of the same note; too many mutes falling in the action.

Once I discovered double string unison, that problem was solved. There was always enough room for the mute between two notes, and the mute movements were cut more than half.

Watch the lessons to learn about the many other benefits of DSU.