[pianotech] Helping out a GH-1

Mon Sep 27 20:33:58 MDT 2010

Barbara,

As others have already written—as a retro-fit the four lowest unisons are changed to bi-chords. For the piano Ryan mentioned the wire specifications were

            B -27               core = 1.050 mm; wrap = 1.76 mm
            C -28               core = 1.050 mm; wrap = 1.66 mm
            C#-29             core = 1.050 mm; wrap = 1.56 mm
            D -30              core = 1.050 mm; wrap = 1.47 mm

Or as close to these numbers as your string maker can come. You’ll have to furnish the lengths from the hitchpins to the start of the wrap and from the hitchpins to the end of the wrap. Most string makers will work from a measure from the hitchpin to the speaking length bridge pin and from the hitchpin to the agraffe.

It’s best if you also change D#-31 and E-32 to 1.100 mm wire and change F-33 and F#-34 to 1.050 mm wire. I did not do this on the piano Ryan described but if your owner is really picky it will help. Of course, if they were really picky they wouldn’t have purchased this particular piano.

I don’t recall just how much mass I put under the tail of the bridge. Probably about 100 grams. I usually take two or three weights of different sizes and pick that makes it sound least bad.

You might also try putting an auxiliary rib down there in place of the weight. This is my current practice. In this piano you might try something about 400 mm long and 25 mm by 25 mm. Given a straight feather this should end up at around 65 to 75 grams and the extra stiffness (in addition to the mass) helps.

Ideally, these pianos should get new soundboards and ribs along with a new tenor transition bridge—but that’s another story.

Small pianos can be designed and built with a fairly decent sound—but this wasn’t one of them. If you haven’t done so yet you might look at the article on small grands in Larry Fine’s Piano Buyer’s Guide (the latest edition—it’s available free online). Several of the 150 cm grands reviewed (including the two I designed for Young Chang) were judged to be quite nice musical instruments. Quite an improvement from the mediocre (at best) small grands of just a couple of decades back.

ddf

Delwin D Fandrich

Piano Design & Fabrication

620 South Tower Avenue

Centralia, Washington 98531 USA

del at fandrichpiano.com

ddfandrich at gmail.com
Phone  360.736.7563

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Barbara Richmond
Sent: Monday, September 27, 2010 12:42 PM
To: pianotech
Subject: [pianotech] Helping out a GH-1

Hey,

How many unisons at the bottom of the tenor section of a Yamaha GH-1 have you replaced with wound strings to improve the sound and tuning stability? 

And, did you replace the agraffe and damper felt, or will the original damper felt work if you string through the outside holes of the 3-hole agraffe?

 I think someone told me once (or twice), but I can't seem to find the information...

Thanks,

Barbara Richmond, RPT
near Peoria, Illinois

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