[Ned Milburn]

Okay.... here we go...

12 string guitars require precision setup of nut slots to ensure best playability. Nut slots are simple to cut.... Simple to screw up... Hard to get ideal.

The neck bow (truss) needs to be adjusted ideal.

The saddle needs to be ideal.

I set up a 12 string lower than the standard 6 string, because of the extra string tension. So, usually about 1.75mm (.070") on high E and about 2.15 (.085" aprx). Slightly flatter bow than a 6 string...

Now, if you are having muffled notes, it could be: nut slots poorly cut, saddle peak poorly cut, fret problems (loose/high-low/hump, etc).

A setup alone will not correct problems with the fret-work.

MOST guitars do not have the nuts cut deeply enough from the factory.

MOST guitars come with a saddle that is higher than necessary from the factory.

MOST guitars end up with too much neck bow (even if adjusted correctly at factory), as the tension loads and bow grows. Once the wood/truss have stabilized, there will be less movement.

Hope this helps.