Cy,
A Samick is likely to have had extra dense hammers to start with. Hence, the sound you describe is likely the result of voicing. What you describe about the surface felt conditions reinforces that idea, and also the notion that the voicing that was done was "stab" voicing: lots of rapid jabs, somewhat random in where they hit. This kind of stab voicing tends only to penetrate about 5 mm on average. The result is often what you describe: characterless, mellow tone, that doesn't "rise" as you play harder.
The inner felt is likely to be quite dense. If you needle deeply, 10 mm plus, you will release the bonding of the inner fibers, so that they will press outward. This will result in a brighter tone quality, at least to some extent. I
nsert a single long needle (10-12 mm) into several hammers in the shoulder area. Does the needle penetrate easily through the first 4 - 5 mm, then encounter a layer that is very difficult to penetrate? That would indicate my guess about stab voicing is correct. It may be, though, that the first step should be to file, fairly aggressively, taking off 1 - 2 mm of felt from the outside. Experiment, and see what happens.
For the deep needling to bring up the hammers, a good technique is to start in the lower shoulder (below 3 and 10 o'clock) and aim toward the crown and toward the core (an angle in that combination of directions). That way you are releasing inner compression without compromising outer tension, to the extent that is possible. A good tool for this is the ergonomic needle tool sold by pianoforte supply and Renner, with the curves for thumb and finger. It can let you do this on the shank side of the hammer (since it is short, and can be controlled). BTW, thanks to Terry Otake of Shigeru Kawai for this technique using this tool.
Fine surface sanding can give good attack brightness, and I have come to like the 15 and 9 micron 3M sanding film for that, though you can use 400, 600 and 1000-1500 grit wet of dry for the same basic results.
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Fred Sturm
University of New Mexico
http://fredsturm.net "When I smell a flower, I don't think about how it was cultivated. I like to listen to music the same way." -Federico Mompou
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Original Message:
Sent: 09-14-2014 10:18
From: Cy Shuster
Subject: Adding power and tone
Thanks, Kevin and David. I've taken Oorebeek's class, and he focuses mostly on preparing brand-new hammers (while these techniques should work on old hammers somewhat).
It's interesting to contrast the two answers: one is to harden the staple area to support the crown, and the other is to soften the staple area to allow tension to move up to the crown. Standard shoulder needling should reduce string contact time and increase power, too. I've done the binder clip trick on uprights, but hadn't thought about it for grands. The hammers are rather small overall; haven't measured weight.
Kevin, you gave one specific answer I was looking for: how effective one technique is over another. With a given time budget on a piano, I'm looking for a technique that's less time-consuming than deep-needling half of each hammer. I'm also guessing this is less effective on 30-year-old felt than on new felt.
And what about resurfacing the strike point? No one has chimed in with a vote for that approach.
I'm leaning toward a combined approach: lacquer for a big win, and then needling to even it out.
--Cy