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Heavy Metal Bass
German Made G.A. Pfretzschner Aluminum Bass
Mechanical Extension Installation
What began as a simple mechanical C extension
installation quickly turned on us. Here is a tip to whomever thinks they
can install one of these as a DIY project; we would suggest you make your own
bridge, from scratch, before ever attempting this.
Perhaps the first problem was the devise itself,
"The Horst Contra C Double Bass Machine" made by the J.A. Fullenwider
Manufacturing Company. This device was made in 1984 and had never been
installed. It was brought to us along with the bass for installation.
Once we began working, things started to go wrong.
The original wood piece, pictured in photo number
3 below, was warped. It was painted black so it was hard to tell what the
grain was doing (or the orientation of the cut of the wood). When we hit
it with a block plane to true it up it chipped out horridly (50/50 shot...we
lost). The cut of the wood was determined though to be not structurally
sound, so we decided right away to just make a piece ourselves. Using
nicely aged Big Leaf Maple from the Pacific Northwest we quickly made a new
piece and topped of the string surface with ebony.
The original screws were aluminum and after two
in a row broke, we decided to buy all new stainless steel screws.
The supplied directions said to screw the
extension into the scroll and the nut platform. We decided that a screw at
the nut was not aesthetically pleasing so we drilled a hole into the end grain
of the maple and ebony fingerboard and secured it in place with a brass pin.
We decided to secure the extension into the scroll as the directions indicated.
A thin metal band went around the column of the
mechanics and was to be secured to the body of the scroll or wood extension.
This metal piece needed to be bent to accommodate this scroll and metal fatigue
set in on the first bend breaking it. A wooden piece was made, a bit over
engineered at first, but then we artistically shaped it to mimic the fluting of
a scroll.
Many hours (too many in fact) were spent
adjusting the springs, pads and intonation. The springs needed to be hard
enough to set the finger levers back into place after depressing them, but not so hard to make them
unplayable. Also, the pads needed to be set to just the right
height; too high and tremendous finger pressure was needed to work the
mechanics, too low and the vibrating string would make contact and buzz.
The leather pads needed to be trimmed to meet the string surface of the
extension (this bass has a Rhomberg bevel). Intonation was the easiest
part of the adjustment.
At the end of the day we would give this project
a 9 out of 10 in difficulty. Our restoration luthier, Eric Roy, even said
he would rather graft another scroll than attempt this particular brand of
extension installation again! Little does Eric know Gary is going to have
him make a fingered extension for his Carcassi bass! At least that will be
all wood!
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