Tuning the Duplex (was ...Capo)

[Duplexdan@AOL.COM]

To J Kanter, Gordon and Colleagues interested in Duplex Tuning,

The entry on e-mail has a number of questions which are all directed to 
improving piano tone by tuning the duplex scale. Although I have never 
pretended to be an authority on the subject I am the inventor of the Duplex 
Slider, have a patent on a method, and do practice the art. I am familiar 
with all your questions having asked them of myself, and with your permission 
I'd like to share some of my answers to assist you.

The hammer and screwdriver method was the first "primitive" method used by 
the original tuners of the duplex scale in the Steinway Factory. I know that, 
because I know and have had extensive conversations with the tuners and 
stringers who were descendants of the original technicians of the factory. By 
the way, it was a few of these technicians who helped me develop the method 
that we now have at our disposal.

This method was useful as long as Steinway was manufacturing the plates as 
well as the innards. Back in the days of yore the adjustment of the duplex 
bridges was usually minor because of the integrity of the matchup between the 
plate and the board and bridge assembly. However, since the pre WWII days I 
have found that the placement of the duplex bridges has become less exact and 
requires a bit more attention if the duplex scale is to be in tune with the 
scale of the speaking length and still adhere to Steinway's principles as 
explained in his patent 126848.

Therefore I invented the Duplex Slider to facilitate the procedure. You can 
find out more about the tool and the procedure on my website 
Singingtone@AOL.com,

In the live video you will notice that the first step is to ascertain if the 
duplex needs tuning, whether it is sharp or flat. Then I absolutely lower the 
tension of the strings on each duplex harmonic bridge before I move it 
because the down bearing is too much to allow perpendicular movement of the 
bridge under the strings by tapping it with any sort of tool, in my 
experience. I lower the tension a bit less than a quarter turn of the tuning 
lever.

As far as the muting felt is concerned, I have found that certain 
manufacturers insert it in duplex sections simply because they do not either 
know how to, or care to , tune the duplex scale. In many pianos that have 
come out since Steinway invented the feature, such as Fazioli, and the new M 
& H you will not find a felt strip in these instruments, but I am sure you 
will be delighted to listen to the perfection of the tuning of the duplex 
scale compared to the speaking lengths.

Hope this has been helpful.

Dan Franklin
Singing Tone
Duplexdan@aol.com