BassLines Tone Circuits Quick start guide

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Wiring Diagram for
Pickup Models:
Tone CircuitsTM
3-Band Bass EQ for Music Man® Bass
STC-3M3
STC-3M4
SMB-4DS
SMB-5S
SMB-4A & 4D
SMB-5A & 5D
The basic steps for installation include:
Proper operation depends on proper hookup of all connections; observe color codes and wire
locations carefully.
1. Remove any old pots that will not be used in this new installation.
2. Remove the two connectors (see Fig. 1) with the hookup wires and pots attached. Note that the
connector housings have been color coded blue and red in order to facilitate returning each
connector to its proper location after all other wiring has been completed. Avoid excessive bending
and flexing of the connections to the pots.
3. Carefully install the new pots in the proper locations.
5. Solder the remaining connections as indicated on the standard hookup diagram. The red wire
is +9V and is soldered to battery hot and insulated with shrink tubing or tape. The black wire
which connects the shells of all the potentiometers is soldered to the ground connection of the jack.
Battery black is connected to the ring terminal of the stereo output jack.
6. Double check all of your connections, then re-connect the two connectors to the circuit board
making sure to return them to the proper location.
7. Attach the preamp to the control cavity of your instrument using the Velcro™ strip provided. Be
sure there are no components from the circuit board that are touching the backs of the pots..
The installation of the Basslines™ Tone Circuit™ 3-band EQ system is a straightforward process requiring
minimal tools and reasonable proficiency in soldering and following wiring diagrams. If you are unsure
of your soldering ability or unfamiliar with basic electronic wiring methods, it is advisable to employ the
services of a competent tech.
The standard control configuration comes prewired. This is done to simplify installation. However,
additional wiring configurations are possible. Please check out basslines.com for more diagrams
and tech tips.
Fig. 1
What’s the difference?
The STC-3M3 and the STC-3M4 are exactly the
same preamp. The only difference is in the wiring
harness. The 3M4 has separated bass and treble
pots (for basses with four knobs), while the 3M3
has the bass and treble controls stacked onto a
concentric pot (for basses with three knobs). The
circuit boards are identical, and the harnesses
are interchangeable.
Music Man is a registered trademark of Ernie Ball, with which Seymour Duncan is not affiliated.
Passive Electronics
Installation
Not using an active preamp?
Visit basslines.com under
“Support” for passive Music
Man wiring options.
P/N 501040-110 Rev. C
Wiring for Pickup with Preamp

We’re not just pickups anymore. Seymour Duncan also makes super cool stompboxes. And our sister company,
D-TAR, is turning out some really hip products for serious acoustic guitarists (d-tar.com).
Visit basslines.com for additional wiring diagrams.
Series/Split/Parallel switching using a 3-way blade switch
Output Jack Hookup Detail
Slap Contour Adjustment
The switchable slap contour is preset at the factory but it can be fine-tuned to suit individual taste. It is possible to preset the amount of bass boost or mid-
range cut by adjusting the trimpots located on the circuit board (see Fig. 3).
Fig. 2
Fig. 3
Pickup Wiring: 4A, 4D, 5A, 5D