How to Make a Mandolin Pickup
A musical instrument pickup, or transducer, "picks up" mechanical vibration and converts it into an electrical signal. In a piezo-electric transducer, mechanical vibrations cause a crystal element to produce a signal. This type of pickup typically produces a more accurate picture of an instrument's high frequency information than a magnetic pickup and is well suited to the mandolin. Rather than start from scratch, a simple way to make a piezo transducer is to affix an audio output cable to an existing electronic piezo buzzer sold in many electronics supply stores.
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Things You'll Need
- Mini piezo buzzer element, such as Radio Shack Part #273-064
- Sharp knife
- Wire cutter (optional)
- Poster putty or double-sided tape
- 15-25 watt soldering iron
- Rosin core solder
- Tin snips (optional)
- Audio cable: two-conductor, shielded
- 1/4-inch audio output jack
Instructions
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Preparing the Piezo Element
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1
Cut or pry the plastic case away with a knife, taking care not to damage the brass and ceramic element inside.
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2
Pry the element from the backing material carefully. It is held in place with a small amount of glue. The thin layers of materials must remain in contact for the pickup to function.
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3
Make a note of the point at which each wire was attached, then remove the black and red leads with a soldering iron. Leave the two solder points on the element. The point where the red lead was attached is the signal. The black wire contact point is the ground.
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4
The element can be used as is, or it can be trimmed with tin snips to any desired shape and size, provided that the layers of the element are not separated.
Attaching the Output Cable
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5
If necessary, use a wire cutter or knife to expose the ends of the audio cable wires for soldering. Solder a length of the signal wire to the signal contact on the element. Repeat this step with the ground wire.
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6
Solder the signal and ground wires to their respective contact points on an output jack.
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Test by plugging into an instrument amplifier. If no sound is produced, check for loose solder connections.
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8
Place the piezo transducer near or on the instrument's bridge, where the initial energy from a plucked string is transferred to the body. The pickup works equally well placed inside or outside of the instrument. For temporary mounting, poster putty or double-sided tape can be used. The main consideration for their long-term use on the outside of an instrument is aesthetic; the putty or tape could mar some finishes over time.
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Tips & Warnings
Experiment with pickup placement at various points on the instrument's body.
Experiment with output jack placement.
Electrical signals from piezo pickups often benefit from being buffered by an electronic preamplifier.
This modification assumes that the user is familiar with electric soldering irons and their safety precautions.
When considering whether to mount the pickup permanently, it is important to consider an instrument's monetary value and actual playing conditions before making any permanent modifications.
References
Resources
- Photo Credit background instrument image by robert mobley from Fotolia.com
