Archive for the ‘Regulation’ Category

I am replacing the bushings on my piano keys. The piano is a 1928 Lester Grand. Today I am checking the level of the keybed. As I view the wood of the keybed, there are many clues that can help me learn the history of the piano, what has happened to it over the years of its life, and the impact the keyframe has had upon the wood. I have placed photos on this page, and very large photos on another site, so you can see what I am looking at here in the shop. Below, the keyframe (containing the action and the keys) have been removed. I am sitting on the bench looking into the piano. The wood you see is called the keybed.

Photo A: Keybed Left

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D is the edge of a water mark. So is E. F and G are indentations in the wood. C is an area that has several watermarks. B (upper left) is the word area where the back of the keyframe meets the keybed. A (far left) is a discoloration in the hardwood frame of the keybed.

A close up of areas F and G is shown below.

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Interesting? What would have caused these indentations? They are not equidistant, so I’ll assume they were made by single blows to the keybed by an instrument. They are all similar depth, so I’ll assume the same force was used in each blow. I also notice a darker color to the interior of the marks which matches the color on the very front edge, and towards the upper portion of the photo. If  a light coat of varnish was applied to the keybed, it was applied after the indentations were made. If true, then the indentations were made prior to the varnishing step, which would be a final step in the construction of the keybed. Therefore, the tool which was used to make the indentation would be among the tools that are used prior to the completion of the keybed. the edge of a chisel would make a mark like this. Also the claws of a hammer.  Why were these marks made though? How odd!

Photo B – Keybed right

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At H (bottom left) the indentations continue and form a pretty straight line. They are not as deep. F is a stain with a dark residue. D is a drop of something resembling the varnish found on the piano and at the very right edge of the keybed. C is a stain which conforms to the shape of a rectangle. A is a watermark. B is where the keybed meets the keyframe. At C then, a contained rested on the piano for a short period of time. The bottom of the container was either wet with a liquid prior to being placed on the keybed, or it contained a liquid which caused condensation on the container which leaked onto the keybed, or the container itself has a small leak, or for some other reason. Area C is under the pinblock, which would not be an ideal area to place a container that was being used to complete a step in the construction of the piano. it may not have been a container – it may have been a piece of cardboard or paper.  It may have been placed there to get it out of the way temporarily, or as a rest for the varnish brush. There is enough wear to the wood on the right side that I remain curious to know if at least the frame of the keybed was varnished.

I will inspect the keys and pinblock to see if there are any watermarks which line up with the watermarks on the keybed. This will tell me more about how the watermarks were made.

Photo C: Keybed center

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Again, you can see the long line of indentations at B toward the bottom of the photo. Area A (top center) is where the keybed meets the keyframe.  The remainder of the marks were shown in the other photos.

I determined that the keybed is level by using a level. A good flashlight was used to project light under the edge of the level to see if any light was able to move under the bottom of the level. The surface of the keybed is smooth to the touch.

It is tempting to light sand the surface to make it more attractive to the eye. However, sanding will not increase its functionality, but it will alter the appearance and make it more difficult to identify any existing marks in the wood – which may later be useful in identifying clues that may not seem important at this time. Sanding the keybed only eliminates evidence that may later prove to be helpful troubleshooting a future problem. The keybed is level, so there is no reason to alter its surface. I can proceed with the rebushing of the keys.

The Point of the Exercise

The piano technician views your piano differently than you do. Every single mark on your piano, inside or out, is potentially evidence that might be helpful in determining why a problem exists, what can be done to repair the problem, how the problem originated, how the piano has been cared for over the years, and what conditions have had an impact on the piano.

I will post links to the larger photos after I built the HTML page necessary to display them. Then I will post links here.

Until then, enjoy your day.

Piano

The tone of your piano can be changed by voicing the hammers. In this blog I want to give an overview of how a hammer is voiced and how you can determine if a piano needs to be voiced. I will also explain what a “strike line” is and how old hammers cancel out important harmonics when they strike the string.

Getting to Know Your Piano

Look inside your grand, or lift the top and gaze into the upright piano, and you will notice that the bass section of strings is separated from the treble section. The scale design of all pianos employs an overstrung bass section; meaning the bass strings are set above the treble strings diagonally. Where the bass section ends and the treble begins is called the break. At this point, you may notice that several of the first treble strings have a copper winding, similar to the bass strings. It is believed that by wrapping the first several strings in the treble section that a smoother tonal transition can occur as one plays through the break area from the bass to the treble section and vice versa. Similarly, when chords are played such that notes from both sections are used, the desire is to have the same quality of tone throughout the chord. Play a scale from the bass through the treble section at the break and see if you can hear a difference in the tone quality.
Good Tone is the Goal

The break serves as a visual example of how tone changes. It is not as easy to hear subtle differences between hammers. Your treble section may be bright while the bass section is dull and lifeless. Any combination involving two or more notes is possible. Each note has a different tone quality. The object of voicing is to make the tone quality as similar as possible throughout the piano.  Hammer voicing is the direct method of altering the tone of a piano wire.

The Piano Hammer

The hammer is made from compressed wool. It is shaped according to need and specification and a set of hammers is produced.  The quality of the wool and the production process are the first variables that affect the tone of the piano. Here is a link to the English version of the Abel piano hammer manufacturer. You can see how many types of hammers are produced.

How a Hammer is Voiced

The piano hammer is voiced by inserting a needle into the felt.  The type of tool used most often is shown below.

You can remove one or two of the prongs in order to vary the impact of the voicing tool.

The methods of voicing are numerous. Each technician has his/her own preference for how to voice a piano, but there are general guidelines that are easily accessible to all technicians. In general, the hammer is poked and prodded until it yields the desired tone quality.

How to Determine if Your Hammers Need To Be Voiced

There is a simple exercise you can perform that may help you determine if your piano hammers need to be voiced. Play any four chromatic notes as a single series of four sixteenth notes: 1-2-3-4. The first note will sound a little louder, which is natural. Start again on the next #2 note: 2-3-4-5. In the first example, the #1 note sounded louder. #2,3 & 4 should have sounded the same. In the second example, #2 will sound louder, with #3,4 & 5 sounding the same. #2 sounds the same in Ex. 1. It sounds louder in Ex.2 This is due to how we tend to accent a quartile of sixteenth notes. As a method though, you may hear one or two notes which are dramatically different in tone as you play up and down the keyboard.

Another way to find hammers that are too bright or dull in a piano is to play a short scale and listen intently.  Play the notes softly, play them louder. Get to know the tone of your piano by listening intently to the TONE, and screening out the PITCH of the note.

Okay, if you try that, you will soon appreciate how difficult it is to find hammers that need to be voiced — or — you may soon discover that the tone of your piano is in serious need of help.

Let us say that you try and try to find a note that does not sound right and you are unable to find one. That is good! Now you know that your piano has an “even tone”, and you also know how to demonstrate to someone why you know you are correct.

Older Pianos Are Usually Bright

As a piano ages the hammer felt compresses. The notes more often played (in the middle register) will be more compressed than notes that have not been played as often. Voicing the hammer separates the fibers in the hammer felt and can soften the sound. But in really old pianos, the hammers are probably so old that voicing will not help. You can consider getting new hammers.

Grooves in Hammer Crowns

Now look at the ends of the hammers and see if there are deep grooves in the crown area. If there are, try to visualize where the hammer is actually hitting the string.  In hammers with deep grooves, a larger area of the crown is striking the piano. In fact, the area may be so great that the hammer is dampening some important harmonics when the wire is struck. The area where a string is struck is matched to a node of the wire. A node is where the vibration of the wire is neutral.

The node is the exact point where a frequency is neutral. If you touch a string at that point when striking, the corresponding harmonic will NOT sound.

The best place for a piano wire to be struck would be on a node that produces an inferior harmonic, right?

Think about that for a moment….

Now look at your strings again. See how the distances vary and produce a harp-like line from end to end. But notice also that the hammers are in a straight line…

Here you can see the curvature of the harp. That is due to the necessity of aligning the hammers in order so that each will hit the desired NODE which terminates the undesired HARMONIC. That “line” is called the strike line, and it is the exact line where the hammers shall hit the string.

Makes sense, although you probably never thought about that before.

Follow me now….

If the striking point (node) is such an important point on a wire, can you see that it is very important to 1. hit it precisely and 2. NOT hit parts of the wire that are OUTSIDE that node?

And an old hammer does not do #1 and it does do #2. It does not hit a string precisely (because it is flattened on the crown) and it DOES hit parts of the wire outside the node area which effectively DAMPENS some of the harmonics of the wire.

Pretty cool, eh?

(Ed Note: Since writing this,  I have learned that the bass section strike point is significantly wider. The mid and high trebles are less forgiving. )

Reshaping Hammers

An old hammer can be reshaped by a technician to restore some of the tone to the piano. Flattened crowns have lost some wool, so you cannot reshape them over and over again. At some point, you will have to get a new set of hammers installed. But if your hammers are REALLY flat on the crown, reshaping can improve the tone.

Conclusion

So that is about it for this blog.  In part II (when I write it) I will show you more about how a hammer is voiced, in more detail.  You now have a way to see if your piano hammers need to be voiced. You can inspect your hammers and see if they need to be reshaped. You know about the strike line, and why the strings follow a contour. Most importantly, you know more about your instrument.

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