When I play two notes simultaneously about mid-neck, say for example the 12th fret on the D string and the 10th on the G string as a chord, I hear a rattling noise coming from the neck. When I play any of these notes solely by itself, I don't hear it, though. Also no issues when playing any notes NOT around the 12th fret. I'm scared...
Rattles and buzzes will easily telegraph to an area different than their origination. Check everything including saddles, bridge, etc. If it is coming from the neck make sure you don't have a loosened truss rod adjusting nut.
Like Ken said, the wood can transfer the sound of a rattle throughout a guitar. I once had a rattle that I thought was coming from the neck of my '75 4001FL. After pulling out cleaning, bending and reinstalling the truss rods, it wasn't them. Then I thought maybe it was the toaster pickup cover rattling against the pickup, that wasn't it, wasn't a wire or the pickguard either. Turned out to be one of the mute assembly springs. I gave each of the springs a little stretch, no more rattle.
Had the same issue awhile back. Rattle from what seemed to be inside the neck when hitting a C at the 8th fret on the E string. A slight turn of the truss rods took care of it.
This issue hits home for me. I was absolutely convinced that I has a truss rod rattle issue, and it only showed up when I played a double-stop mid-neck.
When I play two notes simultaneously about mid-neck
really kicked it for me. I'm 99.9% sure that what you are hearing is the "back end" of one of the strings vibrating against the fingerboard. By back end, I mean the portion of the string that is closer to the nut. Try this: Play the double stop, let it ring, and then take your right hand and touch both strings (one at a time), below your fretting hand. Does it go away?
I'd bet $1,000 it does.
Sympathetic vibration. Just a natural issue that really isn't an issue.
Oh, and by the way: 12th fret on the D string and the 10th on the G string as a chord. Two notes do not constitute a chord. A minimum of three notes are required for a chord.
Can we have everything louder than everything else?
Aha! It DOES go away when I do what John proposes.
I also checked the mute assembly springs before that. That wasn't it. But I do have the same slight rattle on the C like Matt, though that's most probably another issue then. But so far so good, thanks guys.
Finger the C with a finger other than your index finger and use the index to also finger a note below the C, say a Bb or an A. Does the rattle go away? If not, a tweak of the bass rod might help or you may have a fret (above C) that slightly higher than the others. A good luthier could either tap it in or dress it slightly in a snap.
Can we have everything louder than everything else?
