Today I tuned a Yamaha U1E, its free service. In the high register, its very unstable. Finally, I break the G7-G7# string. I have to order string to replace.

I have some questions:
1. What no. is this string?

2. The strings in upper octaves has not visible difference. Does the string diameter difference is so little that human eye can't not distinguish it?

3. Mostly likely will place order China. I don't sure where is the string made, even they said its made in German. Does the string quality makes huge difference?


Edit:
The price of string is :
US$20/Kg

Thanks in advance.

I found vandaking . com has a set of 1/3lb wires. Can anyone tell me how long is 1/3lb of piano wire? 1 lb roll a little expensive than 1/3lb, should 1lb rolls better.

I found ebay has assortment of 13 wires for USD18.5. Each wire just sufficient for one note(may be 2/3 note).

I do not rebuild piano, nor replace string for a whole piano. I just use it to replace broken string during tuning service.

Thanks.

You need to measure the wire with with a micrometer to measure the thickness. Some pianos have the size number printed on the piano.

If you are doing piano service, you need to have wire of each size on hand for these type of repairs.

Most catalogs list the amount of wire per pound or kg. it may be 50-100 meters or several hundred feet.

If you can determine the size you need, I will send you some. I have no idea how to ship it to you, however.

I'm almost certain that the U1 has the wire gauge printed on the bridge.

Watch out for the difference between american and asian wire gauges, they're a half size off. Use the micrometer.

The weight matters, not the diameter.

You can string up or down a half size with no problems. For a U1 in the high octave G would be 13.0 or 13.5
A 1/3 third lb coil would be plenty of material.

Dan Casdorph: Thank you. Always get support here, both technical, material and emotional. Shipping some feet of string to Hong Kong is too expensive. I would order a whole set of treble strings to economize shipping cost.

1lb/roll seems has better price. If bring along all 12 strings, it seems too heavy.

I am going to buy a micrometer now.

I can only buy a Vernier Caliper. The precision is 0.05mm, can't compare to a micrometer. I will buy a micrometer if this is not precise enough.

I measured the broken string, its 1mm diameter.
It's 0.04 inch. Equivalent to No. 17-1/2.

After new year holiday, try to buy a micrometer to double confirm it.

A caliper is not accurate enough. from your description, I expect the string to be between 13-14 wire size.

I will buy a micrometer after the long holiday. Its Chinese new year in the coming week. I believe it should be 13-14 wire size. I check the string size just want to find out why the string broken, my bad technique, bad luck or the piano's problem.

It is sometimes difficult to determine why a string breaks. Sometimes the string is defective, sometimes it is caused by rust, usually breaking at the becket, sometimes by too much hard playing, usually breaking at the pressure bar at the top of the speaking length, sometimes due to bad design, and sometimes by someone's bad technique.

I use a dial thickness gauge to measure strings. There are inexpensive ones available which are accurate enough.