| Pickup Installation:
Fitting an undersaddle piezo pickup on a mandolin,
cittern, mandola or bouzouki
The piezo under-saddle transducer is the most
popular method of amplifying acoustic instruments.
This page outlines the component parts and modifications required
when fitting the Headway HE4/FEQ system on a Shippey cittern.
The method is very similar for the LR Baggs "Element"
and other under-saddle pickups with endpin preamps when installed
in instruments with a similar bridge design. |
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Piezo pickup components
Piezo cable pickup;
The piezo cable (at the bottom of the photo) sits in the bridge
saddle slot under the saddle.
The cable is 2.3mm in diameter, with an active length of 98mm.
Preamp and Enpin jack socket;
The preamp with onboard fixed EQ modifies the signal from the
piezo to produce a more natural tone at a suitable impedance.
The preamp components are inside the metal sleeve labelled 'Headway'.
The endpin jack accepts a 1/4" jack plug. Inserting the
jack plug switches the battery on. The socket also incorporates
a strap button.
Battery;
A 9 volt PP3 Alkaline battery powers the preamp. The battery
is held in a pouch which is velcro mounted inside the instrument
and is accessible through the soundhole. |
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Installation:
Please note that the pickup manufacturers
insist that installation is carried out by a qualified luthier/techniciann
for the warranty to be valid.
First, make sure that the bridge is in the
correct position and that the instrument plays perfectly in
tune.
I use masking tape to mark the bridge location before slackening
the strings.
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With the bridge removed, I'm
drilling a 3mm hole at the treble end of the saddle slot for
the piezo cable to pass out through the bottom of the bridge.
Note that the drill is angled so that the pickup
doesn't have to bend through too sharp an angle. The shielding
around the piezo cable can be damaged if it isn't handled carefully.
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Next a hole is drilled through
the soundboard.
I position the bridge (with the saddle removed)
and tension the strings sufficiently the hold the bridge firmly
in place whilst drilling.
It's a good idea to use a slightly smaller diameter
drill than the hole in the bridge, so that there is less chance
of the drill snagging .
Great care must be taken so that the drill doesn't grab
the bridge and rotate it. This could cause horrific damage to
the lacquer. |
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I pass a length of string or
wire through the hole in the soundboard and out through the
soundhole. Then the string is fastened to the end of the pickup
cable with tape, so that I can pull the pickup into place. |
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The battery holder is attached
to the top block with velcro, allowing relatively easy removal
for battery changing. |
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The piezo cable is passed through
the bridge.
The cable type of pickup senses vibrations from
all directions, so in addition to string vibration, it can also
pick-up vibrations from the soundboard via the bridge. This
helps achieve a more 'natural' amplified sound with some of
the particular instrument's character preserved. |
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Here I'm using a metal rod pushed
into the jack socket to guide the endpin jack into place.
The endpin jack needs a 12.5mm (1/2") diameter
hole in the endblock. I use a Fostner bit for this because it
cuts a clean hole and is easy to control. |
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The nut is tightened on the endpin
jack. The Allen key is used to stop it from rotating and twisting
the wires inside the instrument. |
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The bone saddle needs to be reduced
in height by 2.3mm to take account of the pickup and maintain
the same action.
Abrasive glued to a flat block helps to keep the bottom of the
saddle flat and square.
In order for the pickup to function properly,
it is critical that the bottom of the saddle and the saddle
slot in the bridge, are absolutely flat and that the saddle
slides freely (but is not loose) in the slot. |
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The wiring and preamp are hidden inside the instrument. The
only visible clues are the battery pack (visible through the
soundhole) and the endpin jack.
The advantages of the undersaddle pickup are its simplicity,
reliability, quality of sound and high resistance to feedback. |
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