• The TC-3B on-board preamp, like any low noise audio circuit, must be installed in a electrically shielded cavity.  Since this is a very important point to a  successful installation, we recommend the use of copper foil in order to provide the shielding.  There is also a special paint type for such purpose, that usually provide acceptable results.
   
• Always try to use a star-grounding connection type.  This means connecting all the wires that must be electrically grounded physically to the same grounding point, which must be electrically connected to the cavity shielding.  This procedure avoids “ground loops”, a common cause for noise generation.  It is also important to ground the instrument strings specially with passive pickups.  Please refer to the recommendation of the pickup manufacturer about string grounding.
   
• Potentiometers must have their bodies connected electrically to ground.  Anyway, since the installation of the preamp must be done in a shielded cavity, the pot will be already electrically connected to ground.  Because of that, DO NOT connect any wire to the pot body to ground it.  That would create an alternate path to ground that would make possible the appearance of ground loops that would eventually generate noise!
   
• The TC-3B on-board preamp can provide a considerable boost (and cut) of frequencies with the use of the bass, mid and treble controls.  Because of that, noisy pickups will have its inherent noise amplified when the controls are used at full boost.  Single coil pickups can be sometimes not adequate to be used in conjunction with on-board preamps if maximum EQ boost is desired.  All pickups, including humbucking models, must be shielded.  Humbuckers that have their coils connected in parallel are almost always less susceptible to capture external noises than the ones with their coils connected in series.  Take all this information into account when installing the TC-3B preamp.
   
• Power to the preamp can be obtained by the use of one or two 9V batteries.  There is no change in performance directly related to the increase of the supply tension.  What happens is an increase of the headroom capacity with the use of a 18V supply instead of 9V.  If you are using VERY HIGH output pickups (something like 1VRMS), an 18V supply will minimize the possibility of clipping especially when using the EQ controls at their full boost.

• A stereo type jack must be used in most cases.  This will allow the circuit to drain current only when the instrument plug is connected.  It is important that the cable uses a mono plug.  True stereo jacks with separate on-off contacts can also be used, but these units are harder to be obtained and will provide no added functionality than a standard stereo jack.
   
• An active/passive switch can be installed to bypass the preamp operation.  We provide an electrical diagram showing this option.  The preamp offers a larger than 1 gain, so the selection of the active operation by the switch will provide a boost when compared to the passive mode.  A DPDT toggle switch can be used, like the one available on push-pull pots or even standalone toggle switches.  It is important to notice that the circuit will always drain a small current from the battery even when operating in passive mode. 

• For the blend control plus  individual volume for the pickups configuration, use the potentiometer value recommended by the pickups manufacturer.  For the master volume a 25k, 50k, 250k or 500k pot can be used if the circuit is operating always in active mode (without switch) or a 250k or 500k pot if an active/passive switch is in use.  Always use an audio taper (log) device ("A" curve).
   
• On the electrical diagram it is displayed an optional capacitor to be installed in the input of the preamp itself.  Its purpose is to provide a slightly warmer sound by means of rolling off some of the high frequencies.  Its use is a matter of personal taste, and it's also strictly related with the pickups used.  Bear in mind that the use of this capacitor will reduce high-frequency noise but also will reduce the brilliancy of the sound.  The higher the value, the less brilliant the sound will be.  Typical values would range from 150 pF to 1500 pF, but any other value can be tried to achieve a desired result.  Always use non-polarized capacitor, like ceramic-disc units.
   
• Another choice to control the excess of high frequencies is to install a "TONE" potentiometer, as shown on the diagram.  The TONE potentiometer must be a 250k or 500k type (depending on the recommendation of the pickup manufacturer) and a log type ("A" curve) is known to work better, providing smoother control of the amount of treble attenuation.  This configuration is preferred by several top bass players, and it also provides the capability of working even in passive mode.  When using the TONE configuration, the optional capacitor described on the previous item is usually not used.  However, if the installer desires, both options can be installed together.
   
• A "MUTE" can be installed to silence the bass operation.  This option is showed in our main diagram.  A SPDT or DPDT toggle switch can be used for that purpose.  It is important to notice that the circuit will always drain a small current from the battery even when the MUTE switch is activated.
   
• The preamp is provided with all the connection wires in a size that will be long enough for most installations.  It is recommended that all the wires are kept with the minimum possible size, in order to prevent noise induction.  When installing, leave only a small amount of wire excess to facilitate future access to the circuit, and cut the remaining length.  It is also interesting to organize the wires inside the cavity with wire ties or similar, in order to provide a clean look and facilitate any future maintenance.
   
• When soldering the wires to the potentiometers, you must be fast.  Potentiometers are sensitive to excessive heat, and can be damaged.  Use a small soldering iron (20W or 25W) with solder wire appropriate to small electronic circuits.

For any other questions please contact us at support@tonechaser.com .

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