Interesting quote by Paolo. Here are some random quotes by piano builders
I worked in a shop and rebuilt the soundboard press for Dale.
You probably know Dale. His boards are rib crowned and glued in a dished caul and dried before installing for a compression crown. He also uses the finest Sitka spruce you can find. I thought his boards became too stiff. I liked the ethereal sound of some of his early boards. A board not so constrained will have a higher amplitude of movement and the computer model pooling frequency Paolo showed in the Fazioli class at the Salt Lake convention would intuitively be lower. Better smoother bass.
Dale always wondered why in a board of fine straight grain,, the bass corner board was a weak piece of spruce. He must have decided that was needed to free up the bass because I saw a recent board he did and the bass corner piece was just that cruddy spruce.
Also, tall skinny ribs were better than wide flat ribs. I find this to be true in pre WW1 uprights. The boards with tall ribs still have life.
Dale heard Steingreabber say Dale's piano sounded like his. Dale thought, funny I thought his piano sounded like mine. All I got was the synopsis of the short discussion. With the language barrier, what came back was,, Steingreabber said,, What do you do with the long bridge?
Right? He was indicating the bridge is a long rib that gets tied to and affects the structure. He uses sand to see the board vibration patterns. I don't know if he actually crowns his bridge.
I think,, the bridge should be crowned to some degree. To build a board with crown and then flatten it with a center ridge beam would seem to remove the ability of the board to move.
However, free wheeling is not a good thing and the reason for shock absorbers on a car. The board can move too much.
A board that moves too much is what I thought of Sauter's board at the piano store in Berkeley. The sound erupted on the jazz player. He had a hard time controlling the soft dinner jazz sound. Airplane designers, they use only a straight rib and the lightest construction. Sauter was there and said it compromises the wood strength to cut through the grain and crown the rib. They high tech glue their board in a dished caul for the crown.
I was asking about sound transmission of the glue,, He said epoxy would be like pouring lead into his board.
I took Nick G's class and found out why the board I modified in a Schimmel upright had a double boom. No back posts so I put in a cutoff bar and fish. Then I thinned the board down so it wasn't so stiff. When you hit it, it would boom and then wah whoom! Impedance feedback. That piano was too loud, I put wiekert felt hammers on it.,,,, Now that it has been there for 8 years,, it has mellowed. Sounds beautiful.
Boards seem to work in a variety of design and have different sound. It is trial and error.
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Keith Roberts
owner
Hathaway Pines CA
209-728-2163
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Original Message:
Sent: 09-19-2018 18:37
From: David Love
Subject: rib crown radius
Thanks Karl! I think there are long standing traditions, especially in Europe, about "trade secrets". Even while I was teaching this seminar people expressed some surprise that I was so willing to share with them how I did things.
While I don't intend to just hand over the spread sheets that I use and that took quite an effort to develop for soundboard design and action design and component matching and balancing and smooth weighting I probably will just give this stuff away at some point when I'm too tired to care. Not quite there but will be at some point.
Anyway Ill make those inquiries, thanks again for checking.
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David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 09-19-2018 18:03
From: Karl Roeder
Subject: rib crown radius
Mr. Love,
Thank you for making me look into this. My sources in NYC continued to assert a non crowned rib so I queried Hamburg. Mr. Hartwig Kalb Director of product services was kind enough to inform me that Hamburg does indeed crown their ribs. You should reach out to him and see if he is willing to give you the information you seek. It has always confused me why piano manufacturers hold this sort of thing in such secrecy. In the automotive industry for instance the manufacturers can't wait to tell you in minute detail about engineering and production advances they have made. If you can't get an answer from Steinway you might try asking Chris Maene in Belgium. He seems to be pretty well acquainted with the Hamburg factory and probably studied their designs and methods as he was working on his own.
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Karl Roeder
Pompano Beach FL
Original Message:
Sent: 09-17-2018 12:55
From: David Love
Subject: rib crown radius
Does anyone know for exactly what the rib crowning radius (or how much rise is cut into a 1 meter rib will suffice) for various piano builders who use crowned ribs: Hamburg Steinway, Bos, Fazioli, etc.
Not so much looking for speculation but rather if any one has any data that's reliable.
Thanks
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David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
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