Richard, I have not actually attempted this procedure myself, but I have run across it from time to time -- see, there really is very little new under the sun. Usually these things are in the form of wedges stuck in at various intervals. In no case have I found it to be particularly effective. Not even in an 1890's Steinway D. The usual giveaway is the lack of fundamental energy in the tone coupled with the lack of power. Those ribs are tapered (feathered) at their ends for a reason. You really do need to have a somewhat moveable diaphragm to produce sound energy. If you are still curious, I can only suggest that you do what I would do if I were curious about such a thing -- try it. Buy an old piano with a flat soundboard. That shouldn't be very hard or very expensive. Stare at it for a while, then cut some dowels -- or whatever -- and stick them in where it seems appropriate. Once you've determined that this isn't working you can take them back out and try the soundboard spring idea. These go directly behind the bridge. My most successful procedure -- and the least complicated, overall -- was to install a few blocks to the sides of the backposts centered right over the bridge. You'll want about 4 to 6 of them spaced along the length of the tenor bridge and one or two behind the bass bridge. Before these blocks go on there is a hole drilled through them with a T-nut pressed in from the soundboard side. A long bolt is run through with the head toward the outside. Double nut the ends of the bolts with large fender washers between the two nuts. This makes the spring adjustable. Felt the end of the bolt and washer assembly so the spring does not buzz. You will probably also want to fill the spring with some loose wool felt so it doesn't ring. You will want to choose springs that will exert about 50 to 100 lbs (22.5 to 45 kg) of force against the soundboard when they are compressed from about 1/4 to 1/3 of their maximum height. As I recall, the springs that I normally used were about 35 to 40 mm long (uncompressed). Put a small wood block on the soundboard for the spring to rest against along with a piece of hard felt or leather to cushion it. Bolt the blocks against the backposts and crank away. Start by compressing the springs -- all of them -- to about 90% of their uncompressed height and go for a listen. Then try some more, and listen again. Soon you'll get the idea if this is what you want and if they are doing any good. Or just making the thing less bad. I'm sure I've forgotten a few details in the above description, but I hope you get the idea. After you've played with them for a while you'll know if they are doing what you want. If they do, leave them. If you don't like them, you can always take them off and replace the soundboard, which is probably what you should have done in the first place. But you will have learned something in the process. Regards, Del Delwin D Fandrich Piano Designer & Builder Hoquiam, Washington USA E.mail: pianobuilders@olynet.com Web Site: http://pianobuilders.olynet.com/ ------------------------------------------------------------------- ----- Original Message ----- From: Richard Brekne <richardb@c2i.net> To: <pianotech@ptg.org> Sent: Thursday, December 02, 1999 12:19 PM Subject: Re: Soundboard backposts ?? > Del... As usual you are up to your informative best.. many thanks indeed. I had > no idea that anything like this had ever been serioiusly considered. Food for > thought as far as it goes. > > I am wondering about one thing tho.. You mention that solid posts would mean > that the strings would be required to move the back posts (beams) as well as the > sound board to produce any energy (sound). Just how big an effect would a few > square inches over the whole of the soundboard have ?? Wouldnt the rest of the > board be free to vibrate.... and wouldnt energy take the path of least > resistance ?? > > These are at least the jist of the arguments presented to me by my counterpart > in this discussion we had, (are still having..grin) And I am not informed...well > enough read, nor experienced to authoritivly counter these. If you have the > time... grin.. > > Thanks again Del.. > > Richard Brekne > I.C.P.T.G. N.P.T.F. > Grin.. Now Head Technician for the University of Bergen (patting myself on the > shoulder a bit) > Bergen, Norway > > > > Delwin D Fandrich wrote: > > > ----- Original Message ----- > > From: Richard Brekne <richardb@c2i.net> > > To: <pianotech@ptg.org> > > Sent: Wednesday, December 01, 1999 2:04 PM > > Subject: Soundboard backposts ?? > > > > > Hi list.. > > > > > > Got into a discussion today with another piano tech which prompted me to > > > put the following question to you experts out there. > > > > > > Given an old beater with a flat soundboard, perhaps a bit of negative > > > crown... What would the effect be of glueing in wood pieces between the > > > ribs and the back frame beams to force and hold the soundboard into a > > > artificial crown ?? > > > > > > sounds off the wall, I know... but I am curious to hear your responses. > > > > > > Richard Brekne > > > I.C.P.T.G. N.P.T.F. > > > Bergen, Norway > > > > ------------------------------------------------------------------------- > > > > Richard, > > > > Crown, by itself, is not the issue. It is the relationship between the > > strings and the soundboard. To function as a transducer, the soundboard > > must be able to move in response to the vibrating energy in the string. > > Putting a solid coupler between the backpost and the soundboard would > > (could) force a curve into the soundboard, but I'd hardly call it crown. > > Now the string will have to move both the soundboard and the backpost to > > create any sound energy. Backposts are often fairly difficult to move. > > > > Garold Beyer has replied with a reference to the old practice of installing > > springs between the backposts and the soundboard at strategic spots. This > > was a bit of a fad back in the mid 1960's and the early 1970's. Several > > rebuilders, myself included, had been experimenting with this notion from > > time to time. I installed these devices -- the best were 1957 Corvette > > progressively wound valve springs -- on several old upright and grand pianos > > with varying degrees of success. (Actually, there was nothing magic about > > 1957 Corvette valve springs. I had owned one and at one time had replaced > > the heads. I had a few of the old springs floating around.) > > > > The practice was eventually ridiculed out of existence by the more > > traditional and more "respected" members of the trade as being a > > non-professional repair, but I have come back to the idea several times over > > the years. I guess I am non-professional enough to wonder just what the > > dynamics of the process are. And to not worry overly much about what > > tradition thinks of some of my strange ideas. Were I doing the same type of > > rebuilding today that I did then I would probably still be experimenting > > with them. > > > > As for not being "professional," well, I put soundboard springs into the > > same category as all of the CA pinblock repairs I read about. And the same > > principle applies: Yes, the piano needs a new pinblock (soundboard), but for > > a nominal amount of money -- compared to a new pinblock (soundboard) -- this > > repair will effect some improvement and possibly postpone the inevitable for > > a few more years. It will not tune (sound) as well (good) as a properly > > remanufactured instrument, but it will be better than it was. And for a lot > > less money. > > > > Regards, > > > > Del > > Delwin D Fandrich > > Piano Designer & Builder > > Hoquiam, Washington USA > > E.mail: pianobuilders@olynet.com > > Web Site: http://pianobuilders.olynet.com/ > > > >
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