Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Short sustained sound of Boston GP 193

I regularly tune a Boston GP 193. I also did a full day service on it, including hammer shaping, mating and voicing. The action works very well.
The main problem is the overall short sustain of the grand. A recording of a concert was done a week ago and I could listen to it. There are no tuning problems or so, it simply sounds like a fortepiano. The sound is somehow smothered.
Sitting in front of the grand this problem is not so obvious. Maybe the room is a little too big for the Boston, but I think that it not the problem.
I rechecked the bedding of the key frame, it seems to be ok. From d5- g6 I had to put in some felts to mute the instrusive ringing from the NSL on about 8 notes, which rubs a little power of course but is surely not the culprit of the poor sounding instrument.
I tried to add some resilience to the shaped hammers by doing deep shoulder needling, nothing helps to open up the nasal, thin tone. It is like there is no "body" in the tone. Especially in the bass and the notes up from d5 to c7.
I also tried to change the position of the action back and forth. It seems to already have the best place. Every change in position weakens the tone even more.

Replacing hammers is not an option at this time, so I have to find a solution with the given circumstances. Any help is really appreciated. If it's helpful I could post an excrept of the concert.

Toni

Can you check the downbearing?

Measure the downbearing and soundboard crown on various sections of the piano and see what you get.

I will do that. I did not do it, because the grand is not older than 15 years.

If the problem is on the recording but not at the piano, I would suspect the recording.

Toni,

When looking at the crown, pay particular attention to whether the amount of crown is CONSISTENT across the board. It helps to have a little wedge shaped gauge with lines drawn across it to determine relative gaps in the thread, as well as a light up near the board to see things better.

What you are looking for is not simply the existence of crown, but rather the possibility of excess compression from downbearing in various places. The most important place to look is directly under the bridge, since that is where the pressure is coming from. If for example you notice that there is plenty of crown under the 'free' area of the board, but significantly less directly under the bridge, that is an indication of excessive pressure from above (downbearing). A worst case scenario is to have crown in the free part, and zero or almost zero under the bridge (we call this "oil canning"). This is a tone killer, and if you find it inconsistently (more here, less there) that indicates either very uneven downbearing from the start, OR various compression areas in the board due to grain orientation/flexibility issues, OR both.

If you find generally consistent crown pretty much all over the center and under the bridge, that is a good thing and downbearing could probably be eliminated from the picture (unless of course there is no downbearing...not good).

Question: when the piano goes out of tune does it do so predictably and somewhat evenly, or are there spots that seem to go kind of wild?

Also, I would like to suggest that you do some research into "riblets" as discussed by the Fandrich brothers. Judicious usage of these can do some pretty amazing things.

Pwg

The recording was made with a Tascam DR-100MKII. I have also tried it at home, the results are not really satisfying (with piano recording). So there is some truth in it.
But also when listening directly to the sound, it is still not satisfying.

The piano goes out of tune as followed: the bass section drops by about 2Hz. The treble is quite stable. The midrange are detuned because of the right string (drops a few cents). Mostly stays on pitch, even during this very cold and dry winter.

I don't understand the text you wrote about the gauge. I speak German and a little English, maybe you could write it in easier words, Peter? Thanks a lot

Your written English is quite good!

So, to look at the crown underneath in the soundboard, use a piece of fine thread that will span the entire width of the board. Pick a spot pretty much in the middle area of the board. You want to stretch the thread all the way across the underside of the board from edge to edge. I like to tape both ends to the board so I can use both hands for the next step. It needs to be tight abd strsight, no sagging of the thread. Duct tape works quite well to hold it in place.

Now, using a flashlight, look at the center portion of the thread. There should be gap between the thread and the soundboard indicating positive crown. (BTW you need to do this on the flat area of the board between the ribs, thread not hanging up on notebooks or anything else that might be in the way). How much gap? It depends, but if the piano is pretty new, you should probably see at least 1/8" or 4-5mm.

I have to go right at this moment but I will finish this later.

Pwg

Before you bother with any esoteric measurements, try plucking some of the strings and see if they seem normal or not compared to other pianos.

OK I'm back. A couple of typos in the last post: thread needs to be tight and straight, and not hanging up on any nosebolts or anything else that might be in the way.

As far as just how much crown there should be...the amount is really not critical as long as it is relatively even throughout the center area of the board. The gauge I was talking about is simply a very small wedge (1"-2" long, 1/4" wide, tapered from 0" to 1/4" or so). Draw pencil lines across it about 1/4" apart. use this between the thread and the board to visually gauge approximately how much crown exists in various areas. Pay particular attention to right under the bridge. If you see that the gap between thread and board reduces dramatically right under the bridge, that indicates that there is probably too much pressure being exerted by the strings in downbearing. A little bit of change here is OK but if it is alot, especially if it reduces to near zero, that is a "red flag" that there is way too much downbearing in that area of the board. Now move the thread to another part of the board and repeat this procedure. You are trying to get a visual sense of how much downbearing pressure exists and where. Look all over using the wedge tool to measure differences.

An "oil-canned" soundboard is probably the worst situation you can have, that is where you show positive crown over in the bass string area of the board (towards the flat side of the piano) and showing zero or even negative crown right underneath the bridge. I highly doubt you will find this situation in the piano you have described, but it is important to look. Too much downbearing can kill the sustain by choking the soundboard and not allowing it to vibrate as intended.

Ideally you want to see reasonable consistency in the curve of the crown across the soundboard. A little compression under the bridge is good...alot...not so good. Again, the specific amount of crown is not all that important...the way it is distributed under the string load is important. I consider this observation to be more important than any measurements taken from the topside of the board. In fact I maintain that it is impossible to get a totally true measurement of the composite downbearing with the piano in its strung state. You cannot SEE everything that is going on with a downbearing gauge on the strings and the bridge. But you might as well look anyway.

So what do you do after taking these measurements and observations? Good question. It depends on what you find. I cannot go into all possible parameters here...too complicated.

Here though is a quick and simple test you can do to isolate where a problem may reside:

Pick a unison in the mid treble area. Mute two strings of the unison. Pluck the open string with a pick or your fingernail and listen to the sustain of the note. Now play the note with the key...listen and compare the volume and sustain time of the struck string vs. the plucked string. Do it several times to compare. If the plucked string sustains longer than the struck string, then that points to the hammer as the culprit. For some reason the hammer is impeding the vibration of the string (and you need to voice it for sustain). If it is the other way around and the struck string sounds better and longer than the plucked string, that tells you that the hammer is doing everything it can in the right way, but the soundboard is doing something to impede the sustain. Now do the same test on a few more notes higher and lower to get the sense of what's going on.

You may be able to correlate this with what you find in the crown. At any rate that is how I would go about trying to diagnose the situation. It is not foolproof but can reveal important information about the piano and what you can or cannot do with it.

I hope this is a little clearer. If not, let me know and I'll try again.

Pwg

Another suggestion: If you cannot fix it within what you expect the budget to be for repairs, do not diagnose it. In fact, do not even mention it to the powers that be. They may find the piano acceptable, and if you suggest that thousands of dollars worth of work need to be done on such a new piano, they will not be happy.

I care for a Boston 215. When new, the hammer flanges were way too tight causing some complaints about heaviness. Also the dealer had applied hammer hardener after delivery due to the treble being "dull", which made the most vocal user a little happier but not really satisfied. Much later I re-pinned the hammers to lighten the touch and the tone opened up quite a bit, too. Just another thing to check and consider.

Both Semipro Tech and Jeff make excellent points. Action centers can have a huge effect. Don't create problems for yourself if no one is complaining. If though you're just doing research to advance your own abilities, go ahead.

Pwg

I always try to keep it really simple. The first thing I would do is very very lightly seat the strings on the bridge with a vertical hammer shank by gently tapping just to the side of the bearing point of the string/ bridge pin. You would be surprised how often this brings up the tone. The criticism of this has been that tapping too strongly would damage the bridge. But gently setting them down is always a quick fix for tuning stability and tone. I tap both sets of bridge pins as well as right in front of the hitch pin. You will find that this often eliminates a lot of difficulty in rendering.

Thanks very much for all your advices. As soon as I have access to the grand again, I will do the measurements of the soundboard and the crown.
Till now there were no complaints about the sustain or the sound, and I did not say anything about it. It is just for me, to see if it is possible to improve the situation.
For me it is not satisfying how the grand sounds at this time, and as BDB mentioned, I don't say anything to people that they don't hear if my possibilities are limited because of money reasons.

I keep you informed as soon as possible.

Toni,

I just re-read your original post and noticed that you muted much of the NSL due to the ringing. I wanted to say that although this is an annoying problem, my experience has been that muting that area DOES in fact affect the sustain.

Are you familiar with PitchLock string couplers? If not, you should check them out. Although a major pain in the neck to install, they can be a much better solution to that duplex ringing. And by coupling the energy in the strings may very well improve the sustain too. They are an excellent voicing get tool to have in your kit.

Contact Scott Jones at www.pitchlock.com

Pwg

Thanks very much, Peter. I already thought about removing these felts again, but the ringing is so strong, that it is better with than without them. I heard about these couplers a year ago and I couldn't remember where to find them. Thanks very much for the information. It looks like they could be made easy myself (ordering fine things from America to Switzerland is unfortunately always very expensive)☹️. The videos of the couplers are interesting, especially for these bad sounding bass strings they could be a good thing and of course for the ringing, too.

I have to install three Dampp Chaser systems next week in the same building where the Boston is, so I will go there and have a look at it and do some measurements. Probably I can do some short videos of the sound in the different areas.

Best regards
Toni