Maintaining the original configuration is a worthy goal but more complicated and there are many things to consider, not the least of which is whether the original was worth copying. On many pianos it's not. For example, older Mason Hamlin action ratios are often way to high for the hammers they used and the actions are sluggish and difficult to play. Vintage pianos, depending on the vintage, often went through different iterations, some successful some not so much. Also, soundboards can change over time (if you are keeping the original) and a hammer that may have been ok on the original soundboard may no longer be on a belly that now has lower impedance characteristics. When installing new soundboards, even using "original designs", the outcomes may vary from the original in terms of impedance and require a somewhat different hammer than was on the original.
Steinway is probably the best example of the difficulties of sticking with original designs. The original bellies were very light and the original hammers were too. It's typical to find hammers from pianos prior to 1937 (when they switched from German felt to "other" felt) to find bass hammers weighing only 8 grams. That was due to lower density felts along with lightweight moldings. These hammers were very trim in their profile and the felt was quite soft. You will be hard pressed (no pun intended) to find a hammer that duplicates the qualities of those original hammers both in density and weight. No hammers produced by either Abel, Renner, or Steinway come close to those original hammers when considering all of those characteristics. The lightweight hammers produced by Abel and Renner are much denser and have a very different response. Lightweight hammers that are hard produce something quite unpleasant. The Steinway hammer (current) is also different both in weight, density, felt type and spring response. Ronsen comes the closest in being able to produce the characteristics of the original hammers of that period but even there a lightweight set of hammers from them will still produce, when tapered fully, bass hammers that are 9 - 9.5 grams. If you choose a lightweight hammer from Abel or Renner the voicing required will render a very different tonal response. In part that's because needled felt compresses and decompresses differently than softer felt that is relatively undisturbed by the intrusion of needles. The spectrum produced will be different as a function of the difference in spring response.
If you choose a hammer that is somewhat heavier then the tonal response will also be different, especially on an older soundboard that is more reactive at impact. You will have to tone down the attack sound and in so doing, combined with the increased mass, you will filter out more high partial energy from the strings than you will with a lighter and trimmer hammer. More whump but a reduced partial spectrum. The piano will tend toi sound duller and without clarity.
That brings us to the action performance. The original actions on Steinways with ratios at 6+ were designed for very lightweight hammers. As we know, action performance in terms of inertia (the most important aspect) comes from a combination of hammer mass and action ratio more than anything else. If you end up increasing the hammer weight by even one gram you will throw that relationship out of balance (if you're trying to duplicate the original). You can compensate for static touch weight by adding lead but the inertia will be higher with our without the extra lead. To duplicate action performance you will need to reduce the action ratio. By how much? It depends on the difference in the new hammer weights and what the original action ratio was (they do vary) and your final target.
Does lowering the action ratio to accommodate a heavier hammer change the action dynamics? If you believe, as I do, that the performance characteristics are mostly driven by inertia then the answer is no. Does changing the action ratio itself change the tone? I don't think so. At least not the tonal spectrum. Changing the action ratio changes the speed at which the hammer travels relative to the key. In a 6:1 ratio if the key travels at 10 mm per second then the hammer travels at 60 mm per second. If you lower then action ratio to 5:1 then that 10 mm per second key travel will produce a hammer velocity of 50 mm per second. That can have an effect on perceived power *initially* but I think pianists compensate for that pretty effortlessly just as they do when actuation the key from different positions for and aft (which also effectively changes the action ratio).
So if you are planning to change the hammers and along with it the strike weight then you would do best to change the action ratio to accompany that. Assuming that the key leads were smoothed and placed properly, and assuming that you had a smooth strike weight curve, then changing the hammer weight with a corresponding change in the action ratio would produce no changes in the required key lead pattern (of course those are a lot of assumptions but you catch my drift).
Therefore, while the idea of adhering to the original may have merit, in practice there are many other considerations and sticking to the original design on principle may not make the most sense, ultimately.
My approach, and I think this is the best approach, is to chose the hammer for tonal reasons first. Tone is number one. That includes hammer type, felt, weight, etc. Once you've determined the hammer and weight curve that suits the piano best then establish the action ratio to produce the inertia level that you want. I outlined how to do that simply in another posting recently. Whether you do that by changing the knuckle hanging position or capstan position or both I think is not that important. The ratio is the ratio and I'm not convinced that it really matters how you get there with one possible exception. Short knuckle hangings with heavy hammers may produce more let off friction at the knuckle. I've not really been able to quantify that but I have reason to think that might be the case.
I agree with DS that letting the balance weight float a bit is *probably* best if you have to chose something. Smooth strike weight, smooth FW first. If slight variations in the executions produce different ARs that yield different BWs then usually it's not that big of a problem. The other alternative is to produce a smooth SW and then target a uniform BW by letting the FWs float away from a smooth curve. I've done that too and, honestly, I don't really think it's a problem either way.
The main limiting factor on ARs is what your tolerance is for regulation and key dip.
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David Love RPT
www.davidlovepianos.comdavidlovepianos@comcast.net415 407 8320
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Original Message:
Sent: 05-15-2018 11:23
From: Dennis Johnson
Subject: Key Leads
Hi all-
With great respect for the wisdom represented in this discussion, I humbly suggest that it seems a bit presumptive of us to re-design historic old gems from 100 + years ago with action ratios and hammers they were not intended for. Granted, there are plenty of venues where big and powerful reign supreme but I hope we can leave room to respect and restore a great pianos heritage. Especially, since we have available now appropriate matches to the original layout. Instrument making history is littered with examples of people who completely re-designed classic old beauties to suit modern tastes- and in the long run something was lost. It's not right or wrong here, I hope I make that clear. In these situations I offer customers the option of "modernizing" or "restoring". For homes and non-piano teaching studios they usually choose the later, in a performance venue I'd recommend the former.
I totally agree with setting front weights as a scale design feature of the piano. That is a worthy goal indeed. My impression is that it used to be more like that.
best, and thanks........
Dennis Johnson
St Olaf College
Original Message------
Dear Floyd et al,
You are reading me correctly! It is my firm belief that Front Weights should be scaled as a design feature of the piano. Some day manufacturers will realize this and produce pianos with scaled front weights. In the mean time we have to take on the challenge of sorting out the key lead messes that result from the archaic down weight method.
Once the front weights are established then all focus is on the hammer weight - as measured with the strike weight method. When front weights are codified then the Balance Weight becomes an indicator of ratio and the associated inertia and dynamic playing forces. Let the chips fall. The balance weights will be within a reasonable range of evenness.
There will be cases when the Strike Weight tests out to be very low which can have tonal issues. Very light hammers need to be softer with a deeper gradient of density. The tone may be beautiful but it will lack energy. Voicing up is not the solution. Light hammers have less capacity for lacquer. You can see this in pianos miked for jazz. With light hammers the mike signal is weaker even though the voicing is right. You can hear it when you step back and listen. The tone of light hammers typically won't fill a big room and will have trouble keeping in balance with ensemble. The solution is to reconfigure to a lower ratio which allows higher hammer weights. This requires special skills - Moving capstan lines, wippen heels, tweaking arc geometry, center pin elevations, spreads, knuckle core radii, balance rail points.
Thank you Floyd!
David Stanwood
Floyd wrote:
>What I think I hear you saying here is:
- Establish your front weight
- Negotiate between hammer strike weight curve and action ratio to get in the right ballpark for balance weight
- Establish a smooth hammer strike weight curve
- Let the chips fall where they may in terms of balance weight variability.
>Am I reading you correctly?