Strange Octave-like Overtones

[trailerpark]

I have recently added a 2007 Fender USA P Bass to my collection. I am getting a really strange sound when I fret the 7th fret on the d string and to a lesser extent on the 5th fret. It sounds like I turned on a Octave effect. I am running through a Tech 21 and into a Hartke amp. I don't hear it at lower volumes but at concert volume it is very noticable. Has anyone ever had this happen? Any ideas what could be causing it? The bass is kind of a frankenstein. 2007 USA Highway One P Bass neck and a 2007 Fender standard P Bass string thru body. Thanks for the help.

[Stealth]

Two possibilities come to mind. One is that the string got twisted while you were pulling it taut from the bridge to the tuners, the other is that the pickups are too high and are creating too much magnetic pull on the strings.

[phatbass]

Originally Posted by Stealth

the pickups are too high and are creating too much magnetic pull on the strings.

This would be my first thing to check...

[pilotjones]

That's a dead spot. It's not the usual "no sustain" full dead spot, but rather the kind that produces what I believe is called a "wolf tone."

The mechanism is the same though, coincidence of the position of a resonant antinode of the neck with the position of the fret used to produce that frequency, or multiple thereof.

The attempt to cure it would be the same as trying to fix a dead spot, which you can search on.