Tone Merchants TBX Jazz Bass Wiring HarnessTone Merchants TBX Jazz Bass Wiring Harness TBX Jazz 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