Delwin and others,
Have you ever considered using high pressure inflatable air tubes for the
soundboard spring idea?
-Mike Jorgensen
Delwin D Fandrich wrote:
> 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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