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I am not familiar with the scaling of the modern Bechsteins. I am, however, familiar with the propensity of some of their plates to self-destruction. (In my earlier years I foolishly tried to repair one of these plates. An exercise in futility if ever there was one.) For the most part this was a metallurgical problem confined to the early 20th century. There is also some evidence of a area of strain caused by the way the pinblock is fitted, but I think the jury is still out on that. Perhaps there are some jurors on the list??? In any case I’ve not heard much of the problem in pianos built in the last half-century or so. But, perhaps we just don’t see enough of them here in the upper left hand corner.

Del

DEl,

Do you know how the German Steinways compare to the American Steinways in terms of scaling tension? I have an American S&S B with German wire. Has the use of German wire rather than S&S's wire ( Mapes I believe) changed the scaling of my piano? I always thought one should use the thinnest wire possible for a given pitch. I guess the result would be a lower tension and less inharmonicity, although I know you have said you don't concern yourself with the IH.

I have read a lot lot about low tension and high tension scales. What about the middle ground? Are there medium tension scales? Are they a nice compromise between the sound of the Estonia and Yamaha?

Lawrence

The only Hamburg Steinway pianos I've evaluated (and that's not been many) have had scaling very similar to the U.S. counterparts. But I'm probably not the best person to be asking.

And it's not that I don't concern myself with inharmonicity, we just don't hear it. While I don't pay much attention to the absolute value of inharmonicity I do pay attention to how it progresses through the scale. This progression, or curve, must be smooth and consistent, especially across the scale (plate) breaks for a nicely balanced tuning curve.

Del

Del & MarkS,

Last year when I visited the Bechstein factory, I talked to an engineer about the plate cracking problem in some of the older vintage pianos. He indicated that there were two problems that caused a decrease in the plate's compression strength. The plate manufacturer changed its iron ore supplier. The new supplier's ore had too high a silica content. The plate manufacturer, at about the same time, modified its casting procedure, allowing the plates to cool down too rapidly which aggravated the problem. It took a while for the problem to surface and for the causes to be identified and corrected. I think we're talking older Bechsteins here ... ones built in the 1880 - 1910 timeframe. Bechsteins made after 1910 don't have plate problems.

The reason that this issue pops up occasionally is because of the high demand for these older instruments. My impression is that vintage Bechsteins and Steinways are the two most most desirable and popular rebuild candidates in Europe, with Blüthner and other top tier manufacturers coming in a distant third. At least that's my impression from having shopped pianos in Germany for a couple of years. An older Bechstein that has been properly rebuilt is a wonderful piano. You just don't get that kind of sound out of today's modern pianos.

Some time ago, I read a thread on the PTG site about a technique that's been tried in Europe to repair these stress fractures. I think it was a welding technique, but I don't remember for sure. Some rebuilders had positive comments about it though.

JP

Plates usually crack from improper design or improper casting technique, rather than lack of strength. I once tried smashing a plate from an old upright and couldn't do it.

I recently worked on a 1927 Bechstein E one day, and a 1990 Bechstein C a day apart. I couldn't help but notice how similar the sound of them was, despite the obviously improved scale of the newer one. I have to admit that I prefer other manufacturers, though.

That sounds about right. These plates definitely had a metallurgical problem. While the affected pianos themselves are gradually being removed from the gene pool their reputation lives on.

The cooling rate of gray iron can be a tricky problem both to identify and then to resolve. Contemporary iron foundries tend to ignore this in setting up their patterns and molds. In times past all kinds of heat sinks would be used to hold heat and reduce the cooling rate in various areas but I’ve not seen the technique used in recent years. I had to redesign the capo tastro bar in the Walter 190 plate for this reason — the original bar was some wider and created a cooling rate differential at the intersection between it and the longitudinal struts that caused the latter to crack as the casting cooled. Since the foundry was unable to control the cooling rate at this area — At the time quite unwilling. Both ownership and management have changed since then and they would be a lot more interested in trying to make it work nowadays. — I redesigned the capo tastro bar, reducing its mass and making the cooling rate of the two areas more uniform thus preventing the buildup of the internal tension stress that was causing the problem.

Gray iron castings are generally specified by the mechanical results desired rather than by the metallurgy involved. We can specify the general grade of iron to be poured — Piano plates today are generally poured using Grade 30 iron. That is, it has a test tensile strength of about 30,000 lbs/in2, but the real results are highly dependent on the physical characteristic of the pattern, the mold and the pour.

Del

Del,
Were you aware of any performance changes in the piano, due to the different Capo bar?

Dan

No. Since we were unable to use any of the first sample plates it was impossible to tell.

Del

What would you have predicted the difference to be?

FWIW, I put a 25 lb bag of lead shot on top of the capo bar tonight, to see what would happen with more mass (and rather internally damped mass at that). It didn't seem to make an appreciable difference, in either sustain or tone.

Dan

Very slightly reduced sustain with the smaller bar.

Probably more measurable than discernable with the ear.

Del

[QUOTE]Originally posted by Dan M:
[QB] FWIW, I put a 25 lb bag of lead shot on top of the capo bar tonight, to see what would happen with more mass (and rather internally damped mass at that). It didn't seem to make an appreciable difference, in either sustain or tone.

Dan


Well, no, you wouldn't. A bag of lead shot is far too viscous. The added mass and/or stiffness would have to be part of the original structure. Or clamped and/or affixed so securely as to fool the original bar into thinking it was part of the original.

In any case the differences would be minor. I wasn’t broken-hearted to have to thin out the original design. It is still relatively thick.

Del

Probably what Bösendorfer is aiming at with their massive, removable capo bar. I don't notice much difference there, either. I'm sure that it doesn't rank very high on my infamous list of the top 1000 things that affect piano tone, of which maybe 30 or so are discernable!

Yes, probably. If it were all one casting the longitudinal struts would be cracking just behind the capo tastro bar.

A more effective method of stabilizing the capo tastro is that used by early Sohmers in which the capo tastro bar and the pinblock panel are connected as part of the casting. This technique effectively coupled the two together and added both stiffness and mass (through that coupling) to the capo tastro. This, by the way, was the inspiration behind the Baldwin string termination pieces used in the SF-10 and SD-10 pianos. A great idea not so well executed.

Del

Just a note: I read in Fenner's piano book that Bechstein is among the very few piano makers who use a very high inharmonicity scale. Now, if this is due to thicker strings, or shorter string, or lower tensions, or whatever combination of these, I don't know.
The particular sound usually associated with Bechstein pianos is ascribed, by Fenner, to this high inharmonicity. he considers that it gives a pleasant sound at moderate volume but a too harsh one at loud volumes.
Does any of this fit with your observations ? Did anybody here measure a Bechstein piano and could tell if it has indeed more inharmonicity than others?

On the Bechstein plate issue: I've heard a German restorer say that the plates of the old Bechstein grand plates that cracked had a design flaw: they were too thin in the pinblock/strut area, causing the cracks.
He didn't think the casting was at fault.
Hard to say where the truth lies though. i have a Bechstein V from 1887 with absolutey no sign of crack, so some of them must have been strong enough to survive ;-)

Calin

Just a minor note but - isn't it Capo D'astro?

The tone character (and the amount of inharmonicity) will be the result of either relatively short and/or relatively large diameter strings. That comes first. Inharmonicity is a result, not a cause.

Del

It's debatable. Ed Good has written about this in his book, “Giraffes, Black Dragons and Other Pianos.” Neither spelling has much going for it technically, but Capo d’Astro seems to me as much of a marketing label as anything else.

Del

The Bechstein that I spend the most time with these days is a concert grand from the 1920's, which was restrung sometime in the past 20 years. It certainly sounds fine at both loud and soft volumes, although I have to say that I prefer the Steinway D in the other room.

I'm not certain about the inharmonicity of it, but I don't think the fundamental is as strong on other pianos. As I have said earlier, recently I worked on a 1990 Bechstein C the day after working on this, and despite the obviously better scaling (the E has a real hockey stick bridge!), the characteristic sound was the same.

I have a theory about one aspect of the design that I think may be part of the sound. That is the relatively flat plate from the hitchpins to the rim. I've noticed weakness in the fundamental on a lot of pianos with this feature, and I think that it may be an important difference between the Yamaha CFIII, which I didn't think much of, and the CFIIIS, which I think is one of the best concert grands out there. The Grotrian-Steinweg this morning had a flat plate, and the same weak fundamental.

Lot's of people like that sound, so I can't say that it's necessarily worse, but it's not to my taste.