action ratios

[Richard Brekne]

Stéphane Collin wrote

1st Post:
Hi Richard, David, Bill, etc.

I've been following the thread with much interest.
May I ask an innocent but pragmatic question (I think related to this topic) ?
More than often, I encounter this problem when rebuilding Bechstein pianos : I get the sound right,
I get the touch feel ok, but the whole instrument always happens to be difficult to control, as the
dynamic output switches too quickly from PP to mF (I mean :  the dynamic shades are not progressive
enough.  Very soft playing is fantastic, very loud also, but progressively crossing from soft to
loud happens to be difficult to control, as sound gets loud too quickly, which is musically not
desirable at all).

2nd Post:
Hello Richard.

Here are my measurings on my latest Bechstein model B (2 m).

<<< I took the liberty of condensing and adding BW and Friction. I also figured FW based on assumed WW of 18 and that your R is more or less representative >>>>

KR =  0.576,  WW 18 (assumed for conveince), Ratio 5.1(Manually taken)

note   DW    UW    SW   -->  BW    Fricton    FW
C-3   60      40       8.4          50        10         3.2
C-2   60      39       8.4          49.5     10.5      3.7
C-1   63      47       8.9          55         8         0.9
C0    62      39       8.3          50.5     11.5      2.3
C1    57      36       7.3          46.5     10.5      1.2
C2    56      35       6.5          45.5     10.5     -1.9
C3     56     32       5.8          44        12        -3.9

Richard replys

Now as I said, I would be really hesitant to start talking about attributing the problem you relate in your origional post to needling question, which is why I requested this information. Lets take a look at what you have (we have to assume this is all fairly dependable data)

The SW's you give are close to the lowest on the Stanwood graphs until you get to C2 where they approach the dividing line between lights and mediums, which means they are feathers more or less. ( Ed McMorrow would love this :) ) Combined with a ratio usually associated with the opposite SW situation its easy to understand that there would be little or no leads in the keys.

Before going on I'd like to point out that if you do have lots more lead then the table above results in, then something is wrong with your measurements.  In that case please visit the following website for a review of how Stanwood measurments are taken : http://www.stanwoodpiano.com/SW-HWstandards3.pdf

That being said. If all this IS more or less correct then your description of the dynamic output doesnt suprise me a bit. I would also expect that the dynamic range is quite narrow and might contribute significantly to the problem. I have two reasons right off the bat for this thinking. 1st, such light hammers have in my opinion been shown (Ever since Ed McMorrow made their use "famous") to yeild a narrow dynamic range.  Secondly you have such enormous amounts of leverage throwing those featherweights up there
that going from light to hard is bound to be an extremely short jump. While its true in my opinion that you should be able to excercise a high degree of control while playing pianismo (due to the slow hammer speed to key speed relationship inherent in low action ratios), it will take nearly nothing to force that hammer up to nearly full speed.

So my solution would be to address these ratio, SW and FW issues before whipping out my needling tool. Probably (after making sure top action spread is good) would shoot for my own starting point of Top medium SW's, 5.7 - 5.6 ratio, and FW's  to Stanwoods Maximums.

One other question... since you give such a low ratio for play. What is your key dip,  blow distance, and letoff distance ?

Thats my reading anyways.

RicB