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Taurus TM-2 Preamp Install (With Photos)

This is a step-through process of installing a Taurus TM-2 preamp. You can read more about the TM-2 here for further information to get specifications – but let’s get to what you clicked on this for – a step-through on installing it! 🙂

Before we begin we need to source the tools required to complete the install. The Taurus TM-2 requires some soldering so a sufficient soldering iron, 60/40 Rosin Core solder, black & red wire of appropriate gauge (if needed), heat shrink tubing, Digital Multimeter, and a good pair of small diagonal cutting pliers is a good idea to have on hand or source from a friend.

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We start by carefully removing the control plate and pick guard on this particular Jazz bass, and place the screws for re-install in a safe location. I choose to place the screws inside a piece of cellophane from a cigarette pack and seal it shut to prevent them from being lost.

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The wiring attached to the controls on our control plate is carefully removed using the diagonal cutting pliers and carefully set aside.

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Fitment is going to be tight for this particular installation since this Jazz bass does not have a battery box. To aid in fitment and allow the use of 4-controls on a Jazz bass control plate the output jack had to be relocated out the side. To prevent any further alterations to the exterior body the decision to mount the battery hidden under the pick guard was chosen. I chose the following location and made the decision to remove enough material here to recess the battery low enough to be concealed under the pick guard.

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Now that our battery location and jack situation have been sorted out we can begin by removing the controls from control plate. Set aside the controls for future use if you choose to go back to your original control configuration or just to serve as backups if something ever fails.

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We now begin a basic test fit to ensure that the controls once mounted to the control plate will fit in the top routed control cavity.

The controls from Left to Right are:

  • Master Volume Push/Pull Active Passive
  • Blend
  • Treble
  • Bass

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The fit is not exact and does require some removal of material from the control cavity. The modular connector plugs for the ribbon cable, size of the p.c board mounted to the potentiometers, and location of the potentiometer all prevent this from being an easy install. Since this particular bass did not come equipped with a battery box I chose to remove the shelf between the control cavity and the neck pickup. The pick guard covers the modification for the battery location. A Dremel rotary tool with sanding drum cylinders was used to remove the material and prevent any finish chipping with the aid of blue painters tape.

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The control plate is bolted and used to scribe the shape onto tape. From here 1/8” (3mm) into the scribe line is marked every 1cm with a straight edge with the marks orthogonal (90 degrees) to the scribe line.

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The material is carefully removed and checked periodically with the controls mounted on the board for fitment. Multiple test fits are required to ensure the smallest amount of material is removed.

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The master volume control presents the greatest issue with the screw holes not lining up perfectly with the control plate. More delicate removal of material is handled until the fit and alignment is precise.

The total amount of material during removal is best emphasized here.

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Once fitment is achieved, the cavity is smooth with sandpaper moving up in consistency until it is smooth to the touch and no ridges can be felt. (Please Note: The pickups were removed during all material removal to ensure no damage to any wiring. They were periodically re-fit and left unscrewed to test how the controls fit with wiring).

The control cavity is shielded to conceal most of the work handled during removal.

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All wiring is pre-tinned including the pickup leads, output jack wiring, and battery clip wiring.

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From here the soldering is straight forward and the wiring diagram supplied includes all the necessary details. Once we have all the connections soldered we mount them to the control plate and carefully screw them in.

Final test fit is made and the ground from the control plate and each individual controls to the strings and bridge is tested with a multimeter. The multimeter is a handy tool to diagnose any wiring issues once already assembled should there be any.

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At this point it may be a good time to start cleaning the instrument thoroughly, aside from blowing the dust out of everything. I chose to polish and wax the finish on top before installing the pick guard. From here we install the pick guard and continue cleaning until we are at the end. The pickup height is re-set and the instrument tuned before plugging in and finally testing it out. It Works!

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4 thoughts on “Taurus TM-2 Preamp Install (With Photos)”

  1. To be honest I haven’t had much time to get a complete feel for it. Once I have some free time to assess the preamp and possibly put a video together I will lend my insight on the preamp. Based on the design I wish there was an option for stacked treble/bass, so a midrange control would be an option. With this requiring modification to run the jack out the side and having 4 knobs, I feel the control orientation would be better suited to Master Volume (Active/Passive Switch) – Blend – Treble/Bass Stack – Mid (or Mid Push Pull for Frequency selection, or a Mid/Mid Sweep). The lack of customization for a 4 control configuration is slightly dissapointing even with modular connectors. I would also say that the connections for the pickups and battery leads could be better suited for screw terminals to fully build on the modular based wiring approach. The ribbon cable is there to connect the modules, but the rest isn’t Size wise a screw terminal could be fit quite easily, though modifying the board is not something I would suggest. The soldering is straightforward and the instructions and support are definitely adequate for the install. Saying that it is an easy install is something I would put the brakes on as folks perception may lead them to believe that this is a drop in replacement for their bass. Sometimes this may be true, but sometimes not. They provide dimensions of each control which is definitely helpful for those planning ahead. I’ll report more when the time presents itself.
    C.H

    Reply

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