Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Grand Pianos w/Ribs on Top of Soundboard, instead of back

[quote=Olek]The distance the bolt need to make to gain crown in the panel is incredibly small...[/quote]

I am aware of that. It's precisely this reason I think such a system, if it's going to work properly as intended, ought allow for *precision* movement, and precise locking and unlocking of the position, and not anything that introduces potential slop as with bent screws or screws unseated from their recess. Precision would be easy enough to incorporate in the design.

I'm also interested in why Del said it would not work as well with other boards. I think the basic idea is good and think good provisioning for some stiffness in the edges of the board and careful placement of pressure-receiving points would allow it work on other more lightly-ribbed board, since the required movement *is* so small.

Del, is it that you think a lighter board would simply compress under the additional downbearing as additional crown is induced?

I would fix that quote format issue above, except the system says "maximum time to edit has expired". (Two minutes??!!)

I didn't say "lighter" I said "less stiff". As in, more flexible. The adjustment feature depends on the parameter of the soundboard assembly being stiff enough to support crown in the middle -- along the bridge line. A more flexible system would simply bend.

It would be possible, of course, to build a soundboard assembly with equal stiffness and less mass.

ddf

I didn't say "lighter", I said "less stiff". There is a difference.

A conventional soundboard system is relatively flexible around its parameter. A mechanism such as this would simply bend the assembly and accomplish nothing.

The same problem exists with the notion of beveling the inner rim and belly rail to "form crown" or "support crown." The parameter of the assembly is so flexible that all that is accomplished is to introduce a warp in the assembly at the edge of the board just in from the inner rim.

ddf

I realized you'd said "less stiff" rather than "lighter" right after I hit "submit". (That's when I discovered the edit function wasn't working this morning.)



So you think it's essentially the same result discussed around and around at PTG's forum of what happens to a board with "compression crown"? I suppose my own mind wants to imagine that if a board were *just* stiff enough, Bauer's idea might work, but that just goes to the point you made earlier about if a board *is* stiff enough (and properly crowned by ribbing [or even lamination] in the first place, it's not going to need "adjustment".

What about if the board were made of something other than spruce, like carbon fiber, that might not compress and might not be as susceptible to uncontrolled warp?

I suppose what I'm interested in here is the concept of such a fine adjustment of crown as Bauer might have intended. It'd be interesting to be able to hear, in a single piano, the effect on tone, with an ability to change that one variable while all others remain the same.

While I know others are sort of playing around with the concept, I find the idea of carbon fiber boards most fascinating. I wonder if it can go further in to plate design and being used as a "string frame" as Del usually refers to it. A concert grand that doesn't weigh a half ton might be extremely feasible.

Richard Dain (Hurstwood Farm, England) has done just that. Google "Richard Dain." for all kinds of interesting places to go.

ddf

William Bauer was a very innovative piano thinker. His patents are available for reading online, which he makes his claims.
Also, I have some pics of the inside of the factory on my website that I got from a descedent of the finisher.
http://antiquepianoemporium.com/bauer-julius/

Oh...[snap]...that was interesting: even the upright was an innovative and creative design! This guy was good, IMHO...he was really good.

...so, I guess that is a double decker bridge?!? I'm really curious as to how that sounds!!! That looks like it might be functioning somewhat like a sound post in a violin...that is interesting, no? I don't really have a mental reference as to how to predict that kind of sound. Any ideas? If that indeed does work, then a double layered soundboard, using those kinds of wooden connections in holes through the top level of the soundboard, could be a possibility. Producing a high and a low functioning soundboard separately is much easier (i.e., what is good for the bass, is not for the treble).

Not everything was perfect in this design. That soundboard assembly is rather heavy and stiff as is the bridge assembly.

I don't have the scaling from my 9' JB in my computer (or, if it is, I can't find it) but as I recall the tensions were high even for a 9' piano. I lowered the tensions some to free up the system at the expense (probably) of some "power" but it improved the tone quality and the dynamic range. Since the piano was going into a private home the power loss -- if, indeed, there was one -- was of no consequence. The piano was still adequately loud for any mortal ears.

The two biggest problems with the overall design were cost and weight. This had to be one of the most expensive pianos in the world to build. And it weighed approximately twice as much as a more conventional grand of the same size.

ddf

I still have bad memories from putting that piano on its side in preparation for being picked up by the Baldwin truck. How did you talk me into that?

Estonia where building very stiff grand concert pianos too.
Everything seemed to be enlarged , up to hammer shanks at 136mm length

Forget string plane height ! the action had to be surelevated on wooden blocks in order to use 60 mm bore on meium hammers !

Lot of sustain, assurely, but the treble sloped own progressively to a somewhat non manipulable tone with very limited ynamics and more foundamental than partials

One of those 80's grands where owned by a Gallish pianist I know ,and put at work by the Buethner restoration workshop in ENgland, he told me they suppressed one rib on 2 +- (they probably made a new soundboard, an correcte the 250 mm string height)

You got even. During transit the piano tipped over and landed on top of my bicycle. Never saw a flatter bike....

ddf

Ouch!

I thought a bit more about the pictures of the double-decker upright bridge. It is intriguing: it probably gives the piano more acoustical ambience (i.e., the opposite of a clear focused percussive attack sound). For a home piano, this could have been a step in the right tonal direction.

However, I am guessing that if bridge-tilt is a real thing, then this probably one of the worst examples of something like that. No?

BTW, I haven't observed bridge tilts in pianos, but I've also never gone looking for it either. Has anyone actually measured this? Is there a method?

I'm still trying to figure out what I think the ideal side bearings at the bridge should be (i.e., the angles and length between). Not enough, at it can create falseness, too much...maybe bridge tilting gets worst?!? Bridge-tilt happens predictably with the string instruments--it makes sense it would/could happen with the piano as well.

Simply use a small thin metal ruler and you will see the most evident occurrences, where the slant on bridge surface is not enough anymore, and most down bearing is on the back.

It may be visible by eye, sometime, but also when measuring A49, less than 438 mm can only be due to tilt.
P
The main reason to keep pianos at pitch is there.

When pitch raising pianos that where low for years, the tone degrades clearly generally.

(as it get better when tuning from 444 to 442 for instance.

That's what I thought, as well. But in my 9' JB there was little, if any, bridge tilt.

I tend to think most of what we call "bridge tilt" is the result of soundboard deformation related to changes in EMC.

ddf