Of course there is a Goldilocks impedance. At least there is a fairly narrow range of impedance that Goldilocks will find acceptable. Hammer selection comes after the fact and if is made more difficult if the impedance of the soundboard assembly deviates too far from her fairly fussy range of acceptability. The difficulties in hammer selection you describe are the direct result of an impedance match between strings and soundboard assembly that fall at the extremes of that range whether by intent, by mistake or by the ravages of time. Goldilocks would have been quite pleased with the impedance of that compression-crowned soundboard assembly back when it was initially put together at the factory—assuming all the starts were in line and the relative humidity levels in the factory were just right—but over time her ardor cooled as the stiffness component of the impedance equation changed through the compression set of the wood panel. Goldilocks might well have been pleased with the impedance of a soundboard assembly designed and built with a 30 mm tall bridge but decidedly unhappy with it when the factory—for reasons known only to themselves—end up with a 36 mm tall bridge on what is otherwise the same system. When we find a piano in a customer’s home with “killer-octave” problems it is almost always because the impedance balance between the string scale—which hasn’t changed subsequent to assembly—and the soundboard assembly which has changed for reasons now well understood. We can try to “fix” the problem with voicing—the most common approach—or by installing hammers of varying weight and density characteristics in an attempt to mask over this imbalance but this approach is rarely completely successful. At least not for long. Since the problem is an impedance imbalance between the string scale and the soundboard assembly a more logical approach is to do what we can to restore the impedance balance and bring it back to a range Goldilocks will find, if not “just right,” at least acceptable. And here it is good to understand just what kind of impedance recipe Goldilocks prefers. For some time now we have been reading about attempts to fix this impedance imbalance by adding weight to the system—I’ve tried it myself—but, of course, unless the system was originally designed or built with too little weight this has not been the problem and so adding weight has not been an effective tactic. Extra weight does change the impedance balance but Goldilocks doesn’t like how that weight affected the frequency balance in the tone envelope. She finds that putting a little stiffness back into the system by installing a couple of thin auxiliary ribs to be a somewhat more satisfying solution; the stiffness of the auxiliary ribs putting back some of the stiffness lost through compression set. So, yes, I’d say there definitely is an impedance balance that Goldilocks likes. She is pretty fussy with her likes and dislikes; we deviate from that balance at our peril and when we do one of the prices we pay is a system that is fussy about hammer selection. ddf Delwin D Fandrich Piano Design & Fabrication 6939 Foothill Court SW, Olympia, Washington 98512 USA Phone 360.515.0119 — Cell 360.388.6525 <mailto:del at fandrichpiano.com> del at fandrichpiano.com — <mailto:ddfandrich at gmail.com> ddfandrich at gmail.com From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of David Love Sent: Thursday, May 24, 2012 5:36 PM To: pianotech at ptg.org Subject: Re: [pianotech] [pianotech--Centering the bridge--was S&S something er other Not to spoil the party but there is no Goldilocks impedance. The hammer requirements will tell you a lot about the impedance characteristics of a particular design and there are a number of combinations that will work. Is it one that requires a Top-high strike weight Abel Performance hammer such as the Overs piano that I heard in Reno, or is it one that requires a light weight Ronsen Bacon felt hammer as I’ve also heard. The character of the particular hammer that is required for that belly with those impedance characteristics will push that piano in a particular tonal direction from which it can be difficult to change course without creating problems. Not all of those differences are to found in the scaling either. What are those differences? I think they are manifested in the quality of the attack sound itself as well as the relationship between the attack and sustain part of the tonal envelope. For example, the piano that requires a light weight Ronsen Bacon felt hammer will not easily (if at all) achieve a sharp attack. The hammer simply won’t produce it, not without altering it considerably and possibly with other negative consequences owing to the particular character of the belly that drove you to select that hammer in the first place. I do agree with Del in one important point that he brought up. Pianos with compromised killer octave sections will benefit most from lighter weight hammers, not too much felt over the core (my addition) and not too hard. With the low impedance soundboard already filtering out the high frequencies you don’t need the additional filtering that a heavy and or soft hammer provides by virtue of extending the hammer string contact time. Trying to drive the board harder to get more out of it usually backfires with something just uglier. Obviously this conversation has wandered around a lot but it’s all been good. I’ll take my name out of the subject line now without risk of screwing up the thread too much as would happen in the new HL system—ok, let’s not go there… David Love www.davidlovepianos.com From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Dale Erwin Sent: Thursday, May 24, 2012 4:18 PM To: pianotech at ptg.org Subject: Re: [pianotech] David Love--Centeringthe bridge--was S&S something er other So I want Goldilocks impedance? :) Dale Erwin... RPT Mason & Hamlin/Steinway/U.S pianos <http://www.Erwinspiano.com> www.Erwinspiano.com 209-577-8397 -----Original Message----- From: Delwin D Fandrich < <mailto:del at fandrichpiano.com> del at fandrichpiano.com> To: pianotech < <mailto:pianotech at ptg.org> pianotech at ptg.org> Sent: Thu, May 24, 2012 3:02 pm Subject: Re: [pianotech] David Love--Centeringthe bridge--was S&S something er other You got it; not too high, not to low … just right. And the right balance between mass and stiffness. ddf Delwin D Fandrich Piano Design & Fabrication 6939 Foothill Court SW, Olympia, Washington 98512 USA Phone 360.515.0119 — Cell 360.388.6525 <mailto:del at fandrichpiano.com> del at fandrichpiano.com — <mailto:ddfandrich at gmail.com> ddfandrich at gmail.com From: <mailto:pianotech-bounces at ptg.org> pianotech-bounces at ptg.org [ <mailto:pianotech-bounces at ptg.org?> mailto:pianotech-bounces at ptg.org] On Behalf Of Gene Nelson Sent: Thursday, May 24, 2012 2:54 PM To: <mailto:pianotech at ptg.org> pianotech at ptg.org Subject: Re: [pianotech] David Love--Centeringthe bridge--was S&S something er other _____ The best we can do is to make that area of the soundboard scale as efficient as possible and keep the hammers as light as possible. Which, of course, means it is generally counter-productive to put heavier and harder hammers on a piano with a killer octave problem an attempt to increase “power.” ***An efficient soundboard scale would mean that impedance is not too low or too high? Gene Delwin D Fandrich Piano Design & Fabrication 6939 Foothill Court SW, Olympia, Washington 98512 USA Phone 360.515.0119 — Cell 360.388.6525 <mailto:del at fandrichpiano.com> del at fandrichpiano.com — <mailto:ddfandrich at gmail.com> ddfandrich at gmail.com From: <mailto:pianotech-bounces at ptg.org> pianotech-bounces at ptg.org <mailto:[mailto:pianotech-bounces at ptg.org]> [mailto:pianotech-bounces at ptg.org] On Behalf Of Gene Nelson Sent: Thursday, May 24, 2012 1:50 PM To: <mailto:pianotech at ptg.org> pianotech at ptg.org Subject: Re: [pianotech] David Love--Centeringthe bridge--was S&S something er other Ok – hammer knock – the noise I hear if I mute the strings and listen to a hammer blow. _____ From: <mailto:pianotech-bounces at ptg.org> pianotech-bounces at ptg.org <mailto:%5bmailto:pianotech-bounces at ptg.org%5d> [mailto:pianotech-bounces at ptg.org] On Behalf Of Delwin D Fandrich Sent: Thursday, May 24, 2012 1:39 PM To: <mailto:pianotech at ptg.org> pianotech at ptg.org Subject: Re: [pianotech]David Love--Centeringthe bridge--was S&S something er other Plate “ring?” Or hammer knock? I don’t recall plate ringing being a problem. Hammer knock is—among other things—a function of hammer mass and density. If you design an acoustical system that is relatively more efficient you can then use hammers that are relatively lighter and still get good performance. The top twenty or twenty-five hammers in the Fandrich upright were 9 mm wide and used relatively thin moldings and a less than normal amount of felt. I don’t recall just how heavy the tenor/treble hammers were just now but they were the lightest hammers used on any production piano at the time. At the other end the bass hammers were 11 mm wide and the tenor hammers were 10 mm wide. This better blended the hammer mass curve through the bass-to-tenor transition. ddf Delwin D Fandrich Piano Design & Fabrication 6939 Foothill Court SW, Olympia, Washington 98512 USA Phone 360.515.0119 — Cell 360.388.6525 <mailto:del at fandrichpiano.com> del at fandrichpiano.com — <mailto:ddfandrich at gmail.com> ddfandrich at gmail.com From: <mailto:pianotech-bounces at ptg.org> pianotech-bounces at ptg.org <mailto:%5bmailto:pianotech-bounces at ptg.org%5d> [mailto:pianotech-bounces at ptg.org] On Behalf Of Gene Nelson Sent: Thursday, May 24, 2012 1:25 PM To: <mailto:pianotech at ptg.org> pianotech at ptg.org Subject: Re: [pianotech] David Love--Centeringthe bridge--was S&S something er other Did your treble design help eliminate or reduce or noticeably have any effect on plate ring? Especially in the top 5 or so notes? _____ From: <mailto:pianotech-bounces at ptg.org> pianotech-bounces at ptg.org <mailto:%5bmailto:pianotech-bounces at ptg.org%5d> [mailto:pianotech-bounces at ptg.org] On Behalf Of Delwin D Fandrich Sent: Thursday, May 24, 2012 1:14 PM To: <mailto:pianotech at ptg.org> pianotech at ptg.org Subject: Re: [pianotech] David Love--Centeringthe bridge--was S&S something er other Well, that is what most of this conversation has been about. At the time I was designing the 122 Fandrich vertical piano it seemed logical to me (and it still does) that it would be desirable to place the driving energy source of the vibrating diaphragm—i.e., the bridge—relatively close to the middle of the working part of the soundboard and its supporting ribs. The energy wave starts there and moves away from both sides of the bridge on across the soundboard to the mounting points and it seems a good idea that both arrive at more-or-less the same time. Since this was a new design and I could do anything I wanted I did so and was pleased with the results. It’s one of the best treble sections I’ve designed for any piano of any type. This was, to my knowledge, one of very few pianos that have been built with the treble section designed so the bridge could be placed relatively close to the center of the ribs. At least I can’t recall seeing any others. The physical construction of the grand piano makes it impossible and I don’t know of any upright piano designs that attempted it though there might well be some. As may be, I got a combination of power and sustain out of this design that was noticeably better than anything I’d done previously. And this with relatively light and un-juiced hammers. ddf Delwin D Fandrich Piano Design & Fabrication 6939 Foothill Court SW, Olympia, Washington 98512 USA Phone 360.515.0119 — Cell 360.388.6525 <mailto:del at fandrichpiano.com> del at fandrichpiano.com — <mailto:ddfandrich at gmail.com> ddfandrich at gmail.com From: <mailto:pianotech-bounces at ptg.org> pianotech-bounces at ptg.org <mailto:%5bmailto:pianotech-bounces at ptg.org%5d> [mailto:pianotech-bounces at ptg.org] On Behalf Of Gene Nelson Sent: Thursday, May 24, 2012 9:37 AM To: <mailto:pianotech at ptg.org> pianotech at ptg.org Subject: Re: [pianotech] David Love--Centering the bridge--was S&S something er other Yes indeed. Can you talk a bit about the treble bridge as well? Without your redesign work the bridge would also be located near the end of a rib – not so desirable up there. _____ -------------- next part -------------- An HTML attachment was scrubbed... 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