other sound-shaping features. The op amps used must be of a low-power design to optimize battery life, a design restriction that limits the dynamic range of the circuit. The active circuitry may contain audio filters, which reduce the dynamic range and mildly distort certain ranges. High-output active pickup systems also have an effect on an amplifier's input circuit. Stereo and multiple pickups with individual outputs Rickenbacker was the first manufacturer to market stereo instruments (guitars and basses). Their proprietary "Ric-O-Sound" circuitry has two separate output jacks, allowing the musician to send each pickup to its own audio chain (effects device, amplifier, mix console input). Teisco produced a guitar with a stereo option. Teisco divided the two sections in the upper three strings and the lower three strings for each individual output. The Gittler guitar was a limited production guitar with six pickups, one for each string. Gibson created the HD.6X Pro guitar that captures a separate signal for each individual string and sends them to an onboard analog/digital converter, then out of the guitar via Ethernet cable. See also Contact microphone Electric lamellophone Electric sitar Humbucker Instrument amplifier Lipstick pickup List of electronics topics Magnetic circuit Nominal impedance Preamplifier Reverberation Single coil Transformer Lace Sensor Notes References Tillman, Donald (2002). Response Effects of Guitar Pickup Position and Width Wheeler, Tom (1992). American Guitars: an illustrated history. Harper. New York External links Guitar Pickup Simulation Properties of Magnetic Materials (chapter) Basic Electric Guitar Circuits - Pickups What Makes A Good Or Bad Guitar Pickup How Guitar Cable Capacitance Affects the Tone of Guitar Pickups How a pickup works from the National High Magnetic Field Laboratory Musical instrument parts and accessories