Bob, We don't have any specs from the factory for damper spring tension. But it is normally rather high, as you have found. Most modern uprights seem to be made this way, but the USTs do seem especially strong to me as well. This changes from one piano to the next somewhat, not because the springs are set differently, but because the damper lever angle changes a little from one piano to the next. Upright damper spring tensions tend to change a lot as they are compressed - so your measurement at one position will be quite different at another. The spring size changes in Kawai uprights at about G4, and this does cause complaints sometimes about the touch in the middle of the keyboard. I have weakened the tenor springs to smooth the tension change using my Hart spring tool. You can get a smooth progression just by feel, if you are careful about it. If you want to be extra precise with the spring adjustment, you can put the action in a cradle, lay it back so the dampers are facing up, and use key weights on the dampers to check the tension. Just create an even increase in tension down through the tenor, and leave the low bass octave as it is from the factory. If you weaken the springs, you will most likely need to do some damper adjustment. If you send a short report about this to Mark or me at Kawai, it would be very helpful. Include the serial number, and any findings from your adjustment process. A report from a college technician, with serial number remember, can have some real impact. dmannino at kawaius.com mwisner at kawaius.com Thanks. Don Mannino ----- Original Message ----- From: BobDavis88 at aol.com To: pianotech at ptg.org Sent: Friday, March 06, 2009 10:26 AM Subject: [pianotech] Kawai UST-9 damper springs I am setting up a new Kawai UST-9 at a college. The piano sounds great, but the users complained about a heavy touch. It's the damper springs. I measured the spring tension with a Correx gauge, and in the bass it's just over 100 (!!) grams. This means the key downweight goes from around 50 without dampers to over 100 grams when the dampers engage. I'm going to weaken them, but I wondered if there is a standard for this. Does anyone regularly measure this, and is there a range that works? Don Mannino, if you're there, does the factory have a standard for this? I remember your talking about damper springs lately, but I can't find the email. Thanks, Bob Davis ------------------------------------------------------------------------------ Need a job? Find employment help in your area. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech_ptg.org/attachments/20090307/f34eb39d/attachment.html>
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