Tone Merchants TBX P Bass Wiring HarnessTone Merchants TBX P Bass Wiring Harness TBX P Bass Wiring Harness complete with genuine Fender TBX tone pot. This is the Tone Merchants modern take on the classic 1980s TBX wiring made famous by Duff McKagan of Guns n Roses. Traditional tone pots give you a range from 1 10. A TBX tone pot will give you a treble and bass boost while remaining a completely passive instrument. Your standard tone control goes from 1 5 and from 6 10 is where the TBX kicks