As to the why...please keep in mind this is all hypothetical. The reason I started messing with bridge pins, front back row spacing, and materials, is that the impedance model of soundboard disfunction, around notes 45-55 simply does not describe, to me, the totality of the system. All pianos, regardless of soundboard shape, grands and uprights, which have seriously different soundboard shapes, exhibit the same tendency to break up or have lousy sustain in this area.
I started to question whether the natural frequency of the pins themselves, were participating in the tonal breakup that happens in this frequency range, as the tonal challenge seems to be frequency thing. It is true, from the impedance model, that the density of soundboard modes in that frequency range, are extremely dense. This means it could be impossible to avoid an impedance match, regardless of the board design. (Impedance matches of driving frequency and board modes are to be avoided as they will be explosive sounding.) So I started to examine whether the mode densities were an unavoidable gottcha or whether some other vector might help mitigate the effect of mode density in this area.
I started to question whether the frequency response of the pin's material could be involved, to some degree, in the tonal challenge in this area. Titanium will have a different natural frequency in the pin material itself, because it has a different composition than steel, The thought was to offset the pin's frequency a bit. I don't know whether my hypothesis holds up, regarding the tonal breakup, and pin frequency. Tonally it appears to be different, but the area is still tonally challenged.
Stainless has been used, but the stainless is too hard, and the termination becomes quite noisy, as in M&H current iterations of stainless terminations, even after they started using a softer alloy of stainless. Titanium retains the stiffness of steel, but is quite soft...close to aluminum's hardness. So there will be a different filtering of partials because of the makeup of the termination material.
As to why the hard pins are so noisy, we are flailing in the dark. It could be, as Ed Mcmorrow hypothesizes, that the hard pins do not let the string machine a groove to anchor them during vibration, whereas softer materials would allow that self machining. It could be the softer materials do not let longitudinal modes propagate past the pin. Explanations are pure guesses, at this point. But I do know, having experimented with Ed's FTDS of the last 5 or 6 years, there is something going on that is not completely explained by the impedance models. My trebles, and especially high trebles are really nice and getting better, the more I work various parts of the system other than the board. I'm getting outstanding high trebles and lower trebles with old boards that should not be perfoming this well according to the impedance model.
Also involved in experiments is front back spacing of the pins, 8mm at 13 degree offset in the high treble, 10mm at 13 degree offset throughout the rest of the piano, including the bass. This all by itself is, as far as how my tonal results are trending. I think is buying some very nice tonal improvements.
As well, as Ed Sutton mentioned above, with Sauter's ebony caps, the choice of cap will filter partials differently. Will Truitt has been doing a raft of experimentation on this front, but I will let him discuss his work, if he chooses to. I will say, that Will's work turned me on to both the bridge pin/cap/pin orientation line of thought last year. I stopped by his shop to listen to some of the pin configurations he was experimenting with. I expected to hear no difference between configurations (he had laid out 4 or 5 different configurations right next t each other on a tenor section). I was floored by the fact that each iteration has its own signature...I didn't necessarily like them all, but, without a doubt each configuration had a signature.
So at this point, my thinking is that the termination on the bridge, which is an absolutely horrible termination to begin with, has a lot more to do with piano tonal signatures and dysfunction, than the impedance model, which prioritizes soundboard ribbing and panel design, will have us believe.
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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Original Message:
Sent: 11-08-2020 08:59
From: Peter Grey
Subject: Titanium Bridge Pins
So my question is:
WHY does titanium benefit the application here? (IOW what's actually going on?)
Also (okay more than one question), what grade(s) of titanium alloy is being experimented with (as there are several)?
Pwg
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Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com
Original Message:
Sent: 11-08-2020 08:44
From: Ed Sutton
Subject: Titanium Bridge Pins
Jim-
Vis a vis "experiment," perhaps you'd consider alternating steel and titanium unisons for part of the high treble to check for audible difference, assuming you could replace the lesser pins after the test tunings showed the difference.
Incidentally, the clearest high treble I've heard was in a Sauter concert grand, which included lots of titanium parts and an ebony bridge cap in the treble.
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Ed Sutton
ed440@me.com
(980) 254-7413
Original Message:
Sent: 11-07-2020 17:36
From: Jim Ialeggio
Subject: Titanium Bridge Pins
Yes, there is a good shot some "dowel pins" are produced in all kinds of lengths and diameters. In fact, if you look at Michael Spreeman's pics on his website, the pins he's using look very much like dowel pins. I chose to make my own for my first experiment. If I continue, and it pans out, I will talk to those titanium specialty suppliers about making a run. The other choice would be to hve a local screw machine shop make them out of wire for me. But personally I'm still in the R&D phase, so by hook or by crook works for now.
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
Original Message:
Sent: 11-07-2020 15:53
From: Steven Rosenthal
Subject: Titanium Bridge Pins
Perhaps you've already searched this out but there are makers of such pins.
i.e. http://www.alliedtitanium.com/products/fasteners/springpins/vupdc_Results.php?Search.x=19&Search.y=6&Search=Search&S_UCatalogue=204&S_UMeasurementSystem=1&S_UGrade=5&S_UMaterial=1
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Steven Rosenthal
Honolulu HI
808-521-7129
Original Message:
Sent: 11-07-2020 11:29
From: John Zeiner
Subject: Titanium Bridge Pins
Be careful if grinding.
Titanium is classified as a combustible metal because it is easy to ignite. As with all metals, fine dust-like particles of titanium will ignite more readily than solid blocks. ... Titanium fires cannot be put out with water or carbon dioxide.
John
Original Message:
Sent: 11/6/2020 10:31:00 PM
From: Chris Chernobieff
Subject: Titanium Bridge Pins
Received my titanium wire yesterday. Thanks for the tip Jim.
So i tried two ways to cut it. First was using a cut off wheel on my grinder. It was kinda neat seeing the bright white sparks. Next i tried just using bolt cutters and that worked very well. Neat stuff, cant wait to try them out.
-chris
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Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720
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