Sound Offset Spacer

for classical guitars (nylon string)
fitting scale: 640-650mm


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S.O.S improves the intonation at each fret and easy installation to your instruments.
We only insert the S.O.S next to the nut between the fingerboard and the strings.
We develop S.O.S. to fit most of major instruments like dreadnought size guitars or classic, etc.
It is designed and based on MTS theory (Patent no. 4383272) and made in Japan.

S.O.S. Sound Offset Spacer Q&A

S.O.S. general questions

What is MTS theory?

MTS is an ultimate guitar tuning system based on the laws of physics. All fretted instruments have fatal problem. That is, when player pressed the strings at the fret, the string tension is up and tone will be a little bit sharp, though the frets are set on the correct position. Inventor, Mr. Minehara researched and derived one formula to calculate the corrected (offset) value from string material, guitar scale and string height.

What is the material of S.O.S.?


Each fret pitch will be improved with S.O.S.?

S.O.S. improves the pitch from nut to 12th fret area. If you need to improve high fret area (over 12th fret), you need to adjust saddle. But S.O.S. doesn’t cover. You can consider to install custom MTS adjustment.

Can I change the string gauge?

Yes, you can. Even if changing the gauge, but same string material, S.O.S. works well.

How is the effect, if open tuning or down tuning?

Usually, tension is getting lower, pitch gap is getting bigger. S.O.S. under down tuning will still improve the pitch better than normal condition.

Using capo, do I need re-tuning?

After setting S.O.S, each pitch will be improved already. So basically, no need to re-tune after setting capo.

Any sound character changing with S.O.S installation?

Sound character depends on the materials which are constructed of the instruments. S.O.S material is bakelite not bone, so it effects to change the character a little bit.

Questions for installation

Can I install S.O.S for short scale guitars?

We designed each S.O.S to fit major instruments. And advise suitable scale length on catalog. Please check your instrument’s scale if S.O.S fits or not. If the scale doesn’t fit, S.O.S can’t work well to improve the pitch.

How to do, if original nut height is too much and space is available between string and S.O.S?

If the nut height is too much, there is 2 solutions. One is making nut string slot deeper till strings set on S.O.S. In this case, if you take out S.O.S, the string height will be lower and may have buzzing. So we reccomend to test with spacer tape (0.1mm thickness x 3pcs, included) and make S.O.S height higher and after checking S.O.S works well, you adjust the nut slot deeper.
If you want to keep the original nut condition, you should make S.O.S height higher than nut slot.
Please use the spacer tape and adjust S.O.S height. If the height is not enough, we advise you to use thin plastic sheet and glue to S.O.S to make suitable height. But Nut side height will be higher than S.O.S target, S.O.S pitch improvement will be less.

Does S.O.S work for any kind of guitars (ukuleles)?

S.O.S offset value is caluculated from string material, string scale and string height. So if your instrument is longer scale or shorter scale than S.O.S target, or installed different material strings, S.O.S can’t work well.

Question for ukulele

S.O.S for ukulele fits low-G or High-G or both?

You can use our S.O.S for both low-G and high-G string.

Is the S.O.S. for the Tenor Ukuleles available?

There are only 2 type for the soprano and concert.

Can we use the S.O.S for any type of the ukulele?

The corrected value of the S.O.S is calculated from string material, guitar scale and string height. Please refer the fitting size above. There are 2 material type of S.O.S to fit for the nylon and nylgut.