Correcting False Beats in treble notes

Posted by: Mark Weisgram

Correcting False Beats in treble notes - 09/23/07 03:04 PM

I have a piano that I like the sound of A LOT. It is a 1931 Starr Remington..... not the most highly regarded piano perhaps, but it has "something" that a lot of pianos I have played do not have - great tone.

The piano tunes fine in the lower octaves but there are definitey some squirely false beats in the treble. I have seen a of other uprights that have them too, and I would like to find out what I could do to help this situation.

A tuner recently told me to reposition the strings on the upper bridge and also possibly re tension the bridge screws.

I would be curious to know how others deal with this. I wasn't able to find another post in the past year or so that deals with this issue.

Mark
Posted by: Supply

Re: Correcting False Beats in treble notes - 09/23/07 03:31 PM

A certain amount of falseness can be found in most pianos. Generally, better pianos have fewer problems of ths sort, or at least they are less pronounced. It is not surprising that a Depression-Era MOR upright has a noticeable problem. Normally in such a case, we would just live with it, and tune to make it sound as good as it can.

False beats are either caused by the imperfections in string wire, or, more often, problems at the termination points. Agraffes and V bars can cause strange effects if they are grooved, worn or incorrectly shaped. But most often, false beats originate at the bridge. Incorrectly notched and pinned bridges, and loose or flagpoling bridge pins are obvious problem spots. Removing the pins and replacing them with new ones which are driven in with epoxy can help. Some techs report good results using CA glue.

The thorough way to address all these issues is to restring, and take the time to examine and recondition all the terminations.

This is definitely out of the realm of the do-it-yourselfer.
Posted by: Keith Roberts

Re: Correcting False Beats in treble notes - 09/23/07 03:43 PM

Grab the bridge pin with pliers and rotate it 120* or drive it in further. Seat the string.
Move the strings sideways at the capo bar to clean the edges of the groove in the capo bar.
Tune
Make sure all three string are in the same plane and parallel to the hammer rail. This is similar to leveling strings in a grand.
Retune.
Now block the hammer lightly to the strings and pluck to see which ones are open. Either relevel your string or sand a little felt off the appropriate part of the hammer.
Posted by: BDB

Re: Correcting False Beats in treble notes - 09/23/07 04:32 PM

False beats are not as common as it first may appear. First of all, make sure they are actually false beats. Listen to each string with the rest muted. Secondly, if the piano has not been tuned often, and has been flat, get it to pitch and wait for a while. False beats due to kinks in the wire usually disappear as the kinks stretch out.

The false beat will be higher and weaker than the string's actual pitch. Learn to distinguish between them.
Posted by: Supply

Re: Correcting False Beats in treble notes - 09/23/07 05:07 PM

 Quote:
Originally posted by BDB:
The false beat will be higher and weaker than the string's actual pitch. Learn to distinguish between them.
Can you explain that?
Whe I tune in the treble, and I am tuning an A at say 1760 Hz, the false beats I usually hear in one string are 1, 2, 3, or 4 Hz.
Posted by: BDB

Re: Correcting False Beats in treble notes - 09/23/07 05:13 PM

If a kink in the wire is causing a false beat, it is because the kink is causing a vibration on a shorter length of the string, which will be higher than the actual pitch of the string. The beat is the difference between the fundamental pitch and the pitch that results from the kink.
Posted by: Supply

Re: Correcting False Beats in treble notes - 09/23/07 07:10 PM

 Quote:
Originally posted by BDB:
The beat is the difference between the fundamental pitch and the pitch that results from the kink.
OK, we're on the same page. Your first post was unclear and perhaps misleading. The beat we hear clearly has a very low frequency.
Posted by: BDB

Re: Correcting False Beats in treble notes - 09/23/07 07:47 PM

Just careless writing, I am afraid.
Posted by: Tom Tuner

Re: Correcting False Beats in treble notes - 09/24/07 06:46 PM

Kinks don't produce beats. The string is producing beats because it is vibrating at two different frquencies. The beat is slow because it is the difference between them.. This usually means the string is not touching the bridge pin at the same place it touches the edge of the bridge notch. Below about the top 2 or 2 1/2 octaves you don't notice beats because the difference is an inconsequential fraction of the speaking length. Try pushing the string down the pin. Often you can see it move or hear it click into place.

Tom Tuner
Posted by: pianoexcellence

Re: Correcting False Beats in treble notes - 09/24/07 06:57 PM

 Quote:
Originally posted by Tom Tuner:
Kinks don't produce beats. The string is producing beats because it is vibrating at two different frquencies. The beat is slow because it is the difference between them.. This usually means the string is not touching the bridge pin at the same place it touches the edge of the bridge notch. Below about the top 2 or 2 1/2 octaves you don't notice beats because the difference is an inconsequential fraction of the speaking length. Try pushing the string down the pin. Often you can see it move or hear it click into place.

Tom Tuner [/b]
If it is moving up the pin, then chances are that there is a problem with downbearing. tapping the string down will likely be a short lived solution.

I just tuned a piano where the bridge pin and the notch were literally 1\8 of an inch apart on some of the notes. sometimes the problem is that When a string is struck, it vibrates on vertical and horizonatal planes, switching back and forth. Depending upon which plane it is on, it will consider the pin or the wood as it's termination. I tapped it down, and it lasted about 10 seconds. really the only thing to do is repair this horrible workmanship on the bridge.
Posted by: Tom Tuner

Re: Correcting False Beats in treble notes - 09/26/07 07:01 PM

True. If the soundboard has lost crown to the extent that the bridge is hanging from the strings, then there is a real problem. Ordinary false beats are not that extreme a case and the the "fix" is more durable since it it not directed at curing a major structural failure. Note that false beats most commonly occur on the left string.

Tom Tuner
Posted by: Supply

Re: Correcting False Beats in treble notes - 09/26/07 09:07 PM

 Quote:
Originally posted by Tom Tuner:
Note that false beats most commonly occur on the left string.
I don't share that experience. Middle, left, right, any permutation.
Posted by: michaelg

Re: Correcting False Beats in treble notes - 09/27/07 10:13 PM

I've found they do most commonly occur or are at least beating fastest on the left string in the treble.
Posted by: Mario Bruneau

Re: Correcting False Beats in treble notes - 09/27/07 10:55 PM

One of the reasons a string has false beat is due to the too much mooving it, I mean the pitch. So obviously the left string will have more beat because it is the one used to tune the octave and since octaves are more difficult to tune than unisons, the more times and bigger moovement the left string will get as opposed to the second and third string. My personnal trick is that on old pianos (the ones with more tunings was done) to automatically tune my octaves with the third string, the right string. Most of the time the left string will have false beats and the right string wont so at least, you don't "do your best" for the octaves. Your octaves are perfect and maybe the unisons are "do your best" but not both!

Excuse my poor english. I hope you get what I mean.
Posted by: Supply

Re: Correcting False Beats in treble notes - 09/28/07 03:11 AM

 Quote:
Originally posted by michaelg:
I've found they do most commonly occur or are at least beating fastest on the left string in the treble. [/b]
Ah, yes, but you also drive on the left side of the road in Ireland!
Posted by: Tom Tuner

Re: Correcting False Beats in treble notes - 09/28/07 05:53 PM

Strings will vibrate at all angles normal to length. The difference in length between that established by the pin and that by contact with the bridge are where the beat comes from. If the bridge is that badly notched or misdrilled for pins then correcting that is the only fix.
Otherwise it is likely that the piano always had beats because the stringer didn't seat the strings on the bridge, the factory tuners didn't notice or didn't have time to do anything about it, and ditto for dealer prep, if any. For these reasons cheap pianos have earned a reputation for having false beats.

Tom Tuner
Posted by: Anne Francis

Re: Correcting False Beats in treble notes - 09/28/07 11:49 PM

 Quote:
Originally posted by Mario Bruneau:
So obviously the left string will have more beat because it is the one used to tune the octave [/b]
Doesn't this depend on how you mute? i.e. if you use a strip you tune the center string first, if you use a Papps, same thing (if there's enough space to mute the side strings leaving the center string open like it was intended, otherwise you're shoving the mute between the center and right strings and tuning the left string first).
Posted by: Mario Bruneau

Re: Correcting False Beats in treble notes - 10/01/07 01:37 AM

Anne, I was talking about tuning octaves when the temperament is finished. False beats occure more often on the octaves above A440.
Posted by: Tom Tuner

Re: Correcting False Beats in treble notes - 10/02/07 07:28 PM

You can hear them up there because the the tiny difference in length becomes more significant a fraction of the speaking length the shorter the speaking length is. For longer strings it is too minute a fraction to cause an audible beat.

Tom Tuner
Posted by: BDB

Re: Correcting False Beats in treble notes - 10/02/07 07:41 PM

On the other hand, bass strings can have false beats from other causes, such as loose windings.
Posted by: Tom Tuner

Re: Correcting False Beats in treble notes - 10/04/07 02:41 PM

Yes, but those are usually called, "rattles".

Tom Tuner
Posted by: BDB

Re: Correcting False Beats in treble notes - 10/04/07 04:50 PM

Not necessarily.
Posted by: Mario Bruneau

Re: Correcting False Beats in treble notes - 01/04/10 06:55 PM

There is a lot of false beats on the bass side of poor pianos because of the notch cut not going through the diameter of the bridge pins.

Here is a photo a my Bl├╝thner 7' from 1893 which shows the precicion of the notch cut. The line passes through the diameter of the bridge pins.



Here is another photo of an Estonia with the bridges badly cut. Notice the red line I draw to show where the cut must have been.