My dual-source system with external dual-channel preamp does not work

Applies to the Trinity Systems, Bass Master Pro, Bass Master Rockabilly, PowerMix Pure XT

If there is a malfunction, the first step is to isolate exactly which part is causing the malfunction. There are several possibilities:

  • transducer
  • the stereo jack
  • the stereo cable between instrument and preamp
  • the output cable from preamp to amp
  • loose wiring or insufficient installation of pickups
  • the preamp

Switch out all connection cables (stereo cable and output cable) to test if one of the cables is faulty.

With the PowerMix Pure XT, please check if the strap knob on the endpin jack is screwed in all the way. If in doubt, simply remove it for the testing.

If the stereo cable tests fine, test the pickup systems individually without going through the preamp:

  1. Insert a working mono cable into the stereo jack on the instrument and connect it to an amp.
  2. If the stereo jack produces an intermittened signal when you wiggle the plug, it is probably worn out and needs to be replaced.
  3. You should hear one pickup at a time in passive mode. See the label on your preamp to determine which pickup on the ring terminal and which pickup is on the tip terminal.
  4. Start with the pickup on the tip terminal by pushing the mono cable all the way into the jack. Test if the signal is clear or if it has a problem. Of course it will be quieter, as compared to connecting it via the preamp.
  5. When the plug is partially pulled out of the stereo jack by about 1/4 inch, the pickup connected to the ring terminal (see box label) will be heard. It needs some trial and error to find the exact spot in the jack.

Unfortunately, a mic cannot be tested without the power supply of the preamp.

With upright bass systems especially, it also could be a mechanical problem like a loose pickup or a pickup cable that is not properly taped down or secured.

If all this checks fine, the problem comes down to the preamp. The preamps are very reliable and usually do not develop malfuctions. However, the battery clip can wear out over time and may need to be replaced.

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