problem with the bass string!

Hi Everyone,

Has anyone encountered this problem before? I just tuned a Yamaha U3 and the age is about 30 plus to 40 years old but the condition is still quite good. when i tuned one of the keys in the bass (double strings: one hammerhead strike 2 copper strings) with my Yamaha Scope in unison, they sound very out of tune. That's strange. It should sound in tune when tune in unison. As a result, i purposely tune the 2 strings at different pitch (e.g. 10 cents apart), they turn out sounding better. What's wrong with this? Is it something wrong with the string or could it be due to the age of the piano? I have come across another similar problem before.

What's the best way to settle this problem?

Tune the bass strings by ear instead of machine.

First of all, the hammer is probably hitting two separate "notes" which is making it sound that way. That needs to be fixed if that is the case. Possibly repinning or, possibly tightening and spacing the flange alone with filing the hammer once that is done.

2ndly, one should never tune pianos only using a machine. Your ears should be trained to be able to know what is right and what is wrong. In this case, apparently, you cannot tell the difference enough to know so, you trust the machine instead of your ears. IF, the hammer is hitting two different notes, that is, the string on the note next to it, and you tune that note to what the machine says when that is not really the problem, you are asking for a broken wire or a horribly out of tune piano.

The bass strings may be coming close to the end of their life span, and the two strings are no longer sounding the same, i.e. their partial content is different. If you tune the fundamental to be in tune, the partials sound out of tune and vice versa. Probably time for new bass strings, all across the board, or at least both strings of the offending unison. No doubt it won't be long until other unisons follow suit.

Maybe one of the strings was replaced in the past instead of replacing both strings with a matched pair. I've seen this but you can usually see that one string is shinier than the other or the coil is ugly.

Jerry, I read this quite differently. It seems to me that the OP is trusting his ears and is just confused by his machine. He is trusting his ears enough to come up with an estimation that his machine is about 10cents off in the way it measures this note. Obviously there is some strange inharmonicity in one of these strings which the machine is measuring. But the OP certainly seems to be very able to hear where it should be and has corrected it thusly. He just seems to lack some confidence in disregarding the machine and trusting his judgement in the case of such anomalies.

HI Ando,

You could be right. I maybe mis-reading it. Tuning 2 strings 10 cents a part to make them match one another, is a very large difference. Either that decision is right, or, it is wrong. There is no gray area here.

I've encountered more than my fair share of false beats, strings that were mismatched and much more in the past 38 years of full time tuning.

In my opinion, if the OP could truly hear it with his ears, he would know the answer to the question. He would know if it was actually in tune or not without the machine or with guesswork.. It could still, possibly be something other than worn out wires etc. It could be a bobbling hammer or the one hammer could be hitting the wrong strings. We really don't know from here.

Could your scope be misreading the overtones? Often the etd's read the upper partials of the bass strings. A reading of 10% difference at the 3-4 partials of lower bass notes would not be a big surprise.

Bass bridges are often notched so that the bass bichords have equal lengths.

Straight bass bridges, cut straight cause bichords to be slightly unequal in length.
We accept that on a great many pianos.

Yamaha, back in the time of the piano the OP mentions, notched the bass bridge such that it accentuated the unequal length of the bichords. These are problematic when tuning the bichords.

Thank you everyone for your opinions! It seems that the bass strings are having the same color without one looks shinier than the other and the hammer is striking at the correct strings. I guess it could be due to the strings itself. I have encountered another similar problem in an old piano and this does not happen to new pianos.

One of the strings could be a replacement string. If that is the case then you will never get them to tune up equally.

Dan, I was just thinking that exact same thing myself. Good thought!

Agreed Jerry, I didn’t think of that until the OP mentioned the difference in colour of the two strings.

This was brought up by another Dan a few days back and we all missed it…here;

Yamaha bass strings are sounding dull and cardboard like (for lack of better term) often after only 5 years, I was told it possibly was due to their machine winding inclueding some sort of resin of the core.

Anyway trading them for a set of Hellerbass on a C5 C7 is a good idea and will allow for a nicer tone. (Thanks Gregor for your bankcheck !)

Check to see if it is the last pair of strings on the base bridge. I have found and also read on Piano World that this is a problem site. I've even checked it on a brand new small piano and noticed same effect.
As mentioned make certain that the hammer is touching both strings at the same instant.

Replace both strings and tune them aurally.