This is difficult to explain, but I'm having trouble with the longitudal motion of the strings between F#3 & C4, with G#3,A3 being the worst, on my Estonia 190.

The piano makes a wonderful sound, except for these few notes and is only noticable when played in a solo line (no harmony) and at a loudness of mF and up.

We usually think of the string vibrating back and forth to make its frequency. This, "metalic twang," doesn't come from that. Rather,it takes a strong blow to excite the string enough, so a wave travels from strike point, to bridge and back. It lasts for 1, quarter second beat, but because of the purity of other strings around these, the problem is very noticable--especially when playing something like a Chopin run that goes through that section of the piano.

You hear, sweet, sweet, then twang, twang and back to sweet, sweet.

We can actually hear the sound go from the front of the piano, down the string to the bridge and come back up. But play softly, and there is no problem. There isn't enough energy to get the string to vibrate longitudially, and when there is, it disapates rapidly. It is heard immediately on striking the string, one beat, and is gone as the nasty sound travels down the string and back up.

Just to be clear, it isn't a tuning problem--the issue happens with each string of a tri-chord, it can't be voiced out, it isn't anything loose or not seated, but it can be made louder or softer, by changing where the string terminates. However, redesigning and building the bridge/scale at that point is not an option.

I thought it was just my piano, but I went up to Rick Balldasin's place and played many of his upper tier pianos and ALL, have the problem, somewhere in their scale. Mine just happens to be between f3-c4 and is exceptionally, "live."

The only other thing thought of that might take it down (or make it worse), is to use a different tensil strength string in that section. /but that will be a shot in the dark.

Has anyone run into this problem and/or have a solution or idea?. I don't expect it to go away, since other Estonia, Schimell, M&H, Steinway, even Fazoli have the problem, but if I could just get this one to not be so noticable, less live, it'd be okay.

What to do,what to do?

The information that I have read regarding L-mode vibrations have mostly been in regard to wound bass strings. (Harold Conklin of "The Five Lectures") and Jim Ellis new book "Longitudinal Modes in Piano Strings.
As L-mode vibrations are not affected by string tension it is easy enough to identify them while tuning - the L-mode will not change pitch as the string is tuned sharp or flat.
The quick fix proposed by Dr. Sanderson is to change the inharmonicity of the string. On wound bass strings this can be done by changing the exposed wire core lengths in the speaking length or wrap/core ratio - resulting in a string that matches tonally and power as well as forcing the L-mode higher or lower so it is not noticable.
On plain steel strings this will not be so easy as the only thing that can be changed is wire diameter. This will change the tone and power of the notes.
L-Modes are usually around the 15th partial - for f3 this would be close to e or e-flat 7 and c4 this would be b or b-flat 7. Are you certain that what you are hearing is L-mode?

How did you determine this? Have you tried every tuner, every possible voicing technique? How did you change where the string terminates?

sunslight, I am glad you started this thread, as longitudinal vibrations is something I've been thinking about. I believe I encounter the same thing on my M&H A, where there's a stretch of about 6 or so notes in my wound bass section where if I play an ostinato-type bass loudly, especially when I'm depressing the sustain pedal, I get twanging overtones. Like you, for me it only happens when playing loudly, and it usually only happens if I'm playing the note repeatedly in a short time. But when it does happen, it is annoying!

Techs: Are there certain brands of strings that are more or less susceptible to this? Would switching to Isaac strings minimize it?

Thanks for the input guys and gals.

This can sure be a problem.
Seems like its easier solved in the wound, than plain steel.

A few minutes ago, I was playing a Beethoven piece, that had arpeggiated, F#3, A3, C#. The A was accented. As soon as I struck it, there was the l-wave.
It last for only a fraction of a second, but it's really troublesome.

I'm pretty sure it's l-wave, and the partials I am hearing which clash into the inharmonicity are right where you say they should be--rats--I wish it were something else.

I am fairly certain it isn't a tuning/other problem. A regional rep of the guild is working on it with me. He can't figure it out either. We've tried all we can think of, but maybe there are other ideas out there.

The problem occurs which each, individual string, contrary to what was said, we were able to tune it out, by dropping the string a full-step! But tuning, sharp/flat, anywhere near the right freq., makes no difference--the sound is there.

We've strip mutted the entire piano, and still any one of the group of strings, on a hard blow, sets up the wave. It's sort of link "bo--n--k" and off, with the "n" being when it hits the bridge at the back of the piano.

We voiced the hammer, many times. All that was accomplished was to change its voice and loudness, but it had no effect on the "bonk." We took hammers about the same size, from good notes and substituted them a bad one--no diff.

We raised and lowered the strings, so they fit the hammers and groves perfectly, as well as are well-seated against the bridge pins. We whacked the bridge pins to make sure they are solid.

Here's how I found out, changing the length of the string, fixed the problem:

I found that by releasing the damper and plucking along the string length, rather vigorusly, obviously, the pitch would change, but then there would be places where the l-wave noise (if that's what it is) would be very loud. I could pluck up and down the string=no noise, no noise, there it is, no noise, no noise, there it is.

(if it were a tuning problem, I'd expect to not hear it when all the strings except the one being worked on are muted. If a voicing problem, voicing should have had some effect as well as switching out hammers--but nada.)

Back to how I found out changing the length of the string had an effect:
while plucking toward the bridge pin, the "bonk, twang" sound sound got varied very litte or got louder; plucking, actually deflecting the string away from the bridge pin, the it became almost clean. So, deflecting into the bridge pin made the string a bit shorter & the problem worse, while plucking away from it, strecthed the string and the problem just about went away.

--and too, if it were the hammers, plucking would not reproduce the problem--or at least I don't think it would.

So, how do we fix it?

I haven't a clue, especially since it's occurs on individual, unwound strings.

Plucking and deflecting the string (elongating it) away from the bridge pin, showed that if a string was about 1/8 inch longer, there wouldn't be a problem.

Or, if there was some way to "un-liven" that section of the piano, when playing loudly, that would do it too. Except then, the volume of sound wouldn't match the rest of the piano.

Like I mentioned, I tried many upper-tier pianos and it happend on all, it's just that on this one the problem is especially loud and noticable, because of where it is. --oh, there is some of it in the bass too, but I expect and can live with that. But being in the strings about a 5th down then up to C4, is a bad place for L-waves.

From what's said, I guess changing these strings for ones with less stiffness, won't make any difference?

I thought about wrapping yarn around the string and pulling that tight against the agraffe or bridge, but that'd make the string shorter, and from experimentation, it needs to be longer--or just not use those note, or never play them loudly in a melodic passage.

--also tried was keeping one string tuned, and detuning by a few cents, up/down the other two, had no effect--except an out-of-tune unison, still with the L-wave.

So, L-wave experts, the question then is how to get rid of or at least lessen l-waves, especially problematic with them being produced on unwound strings in the middle of the piano.

(I have an idea, the answer's going to be "live with it," but I'm hoping for better.)

Gene Nelson:
"L-Modes are usually around the 15th partial - for f3 this would be close to e or e-flat 7 and c4 this would be b or b-flat 7. Are you certain that what you are hearing is L-mode?"

Sunslight:
"We've strip mutted the entire piano, and still any one of the group of strings, on a hard blow, sets up the wave. It's sort of link "bo--n--k" and off, with the "n" being when it hits the bridge at the back of the piano."

My comment: These statements suggest that there are two different unwanted sounds being described there. "L-modes" are odd-numbered partials that make a note sound harsh. This is what Gene is referring to. Sunslight's description sounds to me like what technicians usually call false beats.

Of course it is impossible to ascertain exactly what is being described here without actually hearing the unwanted sounds. But "l-mode" sounds are not at all the same thing as false beats and the approaches to remedying them are very different.

It sounds like there is a harmonic you are not happy with. If you pluck on a string at various points, it will be an anti-node at the point you are plucking at, and that will make a given harmonic louder or softer, depending on where it is. This can be exacerbated by the room acoustics, in the same way that feedback occurs in a sound system. Defects in the strings can also be a problem. There is no duplex scaling on the notes that bother you, is there?

All waves travel along the length of the string, unless you only excite the string in the fundamental, which is not the case in a piano. At various points of the wave, it will look like:

| | ( ) | |
| ( | | ) |
( | | | | )

and repeat. (In case my lousy ASCII graphics confuse you, there is an anti-node that travels from the point that the hammer hits it up to the bridge, flips over, and back to the agraffe, where it flips over and goes back again. If you can find a Slinky, you can hang it at both ends of a room and pluck on it and see this happening. In this case, the point of excitation starts on the bottom of the left-hand image, and the anti-node travels up, flips over and back down as you move to the right through the six images. It may be difficult to interpret as such, especially if your computer handles fonts differently than mine, where it is difficult enough!)

Sunslight,

The speed of the pulse traveling back and forth from the agraffe to the bridge is directly related to the tension of the string.

I have measured the tension on the Estonia 190 in the area you describe and the tension is low.

It results in a pulse slow enough and slightly larger in amplitude that you can interrupt it with the right frequency of repetition of the key/note.

If you restring with a larger wire size you will raise the string tension and speed up the pulse, making it more difficult to interrupt.

There was some great high speed photography in Rochester last year that demonstrated this. Maybe someone here remembers the gentleman's name.

You will also change the tone quality of the note when you do this as well as the inharmonicity.

possibly for the better, depending on your taste.

Somewhere I posted the Estonia 190 info ...

Sunslight,

I just did a search and it was your thread back in January I posted on.

http://www.pianoworld.com/ubb/cgi-bin/ultimatebb.cgi?/topic/3/2407.html#

My response remains the same.

What ideas have you considered?

Here are a few ideas,

If changing the string length affects the noise, I would try pitch-locks (those staple things).

Perhaps also changing to a different alloy music wire (titanium?) may allow you to vary tension, also affecting the noise problem.

Furthermore, consider changing to a Wapin bridge to allow more transverse energy in the string.

Since the problem in this piano is in just a few adjacent notes, I wonder whether the noise is due to bad wire or less-than-ideal stringing (e.g. twisting of wire) on those notes. Restringing the bothersome section shouldn't be too big a deal for a perfectionist. Or putting some needles again into the appropriate hammers.

Since Sunslight also noticed this noise in other well-prepared, high-end pianos (at Rick Baldassin's, no less), he may have taken the first step to being able to accept that ALL pianos can have small idiosyncracies and irregularities of sound. Most musicians are able to focus positively on the useful and expressive characters of their instruments (most of which are far from as high in quality as the piano in question) rather than on the small flaws which are evident only under very restricted conditions while in a critical frame of mind.

One of the burdens of being a technician is that one can become hypersensitive to very small flaws in tuning and other sound characteristics in instruments. This can become a significant impediment to the enjoyment of music. Some reflection and psychological adjustment can be very useful: moving from the critical back to the creative mode.

Sunslight: keep in mind that this piano is not a very big one and that its dynamic range limit, particularly at high amplitude, will appear at certain points in the scale. Like at the lower end of the tenor bridge where you notice it. Also keep in mind that your piano plays and sounds great at soft levels of play. Many pianos cannot play well softly and that greatly limits them musically.

A last thought: I often wonder whether the post which begain this thread is an indication of poor communication between customer and technician. Certainly I do not feel comfortable making suggestions here which may be used to second-guess a competent tech who actually knows the piano in question.

Hi, Did you check if the string agraffe is absolutelly squared with the string -90º no more no less. it makes a huge effect is properly adjusted.
regards, zeH