Robert Estrin - piano expert

What is Duplex Scaling?

Learn about this interesting piano technology

In this video, Robert talks about "Duplex Scaling" and why it is an important feature of piano technology.

Released on August 10, 2016

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DISCLAIMER: The views and the opinions expressed in this video are those of the author and do not necessarily reflect the views of Virtual Sheet Music and its employees.

Video Transcription

Hi, this is Robert Estrin at and, with a great viewer question, "What is duplex scaling?" Have you ever heard this term before? Perhaps you went shopping for a piano and some salesman told you, "Oh you've got to have duplex scaling." As soon as you hear it you figure, "Boy, I guess I better have that." Well, what is it and do you really need it?

We're going to cover that today. First off, exactly what is duplex scaling? Duplex scaling, simply, is a tone enhancement system that's used in some pianos to make a longer tone life. How does this work? Well, on a piano you have what's called the "speaking length of the string." That's the part of the string that's free to vibrate. So, when you play a note on the piano the string from this point to this point is vibrating. Above here, oftentimes below and above the speaking length of the string is muted out with felt, because that part of the string isn't vibrating and could cause clangorous sounds that are not complementary to the tone of the piano.

Duplex scaling uses a technology with what are called "aliquots", which precisely terminate the strings at lengths that produce pitches to that are complementary to the pitch that is being played. So, if you are playing a C, for example, on this piano with duplex scaling, the aliquot over here terminates the string, so you get well, I played the wrong string there, but you'll get the same pitch for all three strings an octave and a fifth above, which is one of the overtones of C, thereby extending the length and beauty of the tone by enhancing it with those overtones. Just as when you push the pedal on the piano, the damper pedal, you get an echoey effect. This part of the string, that isn't actually even hit with a hammer, sympathetically vibrates, adding to the richness and length of the tone. So, that's the rear duplex.

Some pianos like this one also have a front duplex, so this part of the string. Notice it's the same pitch as what I'm playing, but I'm not actually plucking the part of the string that's hit with a hammer. In fact, this bar here terminates the string so that this is a separate area of vibration. So all of this, and this, and this is all free to vibrate on this piano with front and rear duplex, giving a longer tone-life.

Now, is duplex scaling necessary? Well, no actually, because there are many different ways of accomplishing scale design on a piano. But a piano that has a good true duplex that's tuned to allow for these vibrations can get a richness so they sustain enhancement up to the tone.

Thanks so much for joining me, Robert Estrin here at and
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Comments, Questions, Requests:

Gib Rogers on October 4, 2016 @5:53 am PST
Having never heard of Duplex Scaling, this was somewhat confusing. Sorry. Maybe I need to study this feature more. Thanks!!
Oluwaseun Collins on August 12, 2016 @4:05 am PST
Wao, nice to know this. Thanks.
Fulvia * VSM MEMBER * on August 10, 2016 @6:24 am PST
Thank you, great explanation.
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