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F u l l
C i r c l e
U p r i g h t
Fit the Full Circle to a Bridge Without Wheels
Warning! Only a professional repair-person should attempt this installation.
If you have not installed wheels before, please practice on a scrap bridge.
Fishman will not be responsible for damages due to improper installation.
Preliminary
NOTE: In this method we describe how to center the wheels precisely within the
taper of the bridge. We like the way the pickup performs when it is exactly
centered in the leg.
Many repair-people prefer to install the wheels perpendicular to the tailpiece
side of the bridge and parallel to the top of the instrument. This is also
acceptable, but the pickup's performance may be somewhat less predictable.
Fit the bridge to the bass before you install the wheels. Note that the wheel with
the white wire belongs under the E string.
We've had a lot of people ask if there is a tonal difference between "threads up"
or "threads down" position for the pickup. The answer is yes, there is a subtle
difference:
When you mount the Full Circle "threads down", the hot side of the pickup
faces the strings. This translates to more defined articulation and attack, with
a slight emphasis on the 'string' sound. (Illustration D)
When you mount the Full Circle "threads up", the hot side of the pickup faces
the body of the bass. You'll get a bit more woody acoustic tone this way, with
a rounded attack and less "edge" . (Illustration D)
Threads Down
Threads Up
Illustration D
Layout the Bridge
Refer to Illustration E
The pickup will work best when the wheel is precisely centered in the leg. To
do this, carefully layout the appropriate lines ahead of time. You will be
drawing lines on the side of the bridge that faces the fingerboard.
1. Use the line implied by the outside of each leg to make parallel vertical lines
down to each foot. (line A)
Option 1: Threads down into the feet:
Make a mark on each leg no less than 1-1/4" (31.75 mm) from the
bottom of line A.
Line up a straight edge on the marks and pencil in a horizontal line on
each leg (line B).
To accommodate the thickness of the wheel, make a parallel set of lines
(line C) 3/8" (9.5mm) below line B.
Option 2: Threads up into the legs
Make a mark on each leg no less than 21/32" (16.66 mm) from the
bottom of line A.
Use a straight edge on the marks and pencil in a horizontal line on each
leg (line B).
To accommodate the thickness of the wheel, make a parallel set of lines
(line C) 3/8" (9.5mm) above line B.
B a s s
P i c k u p
2. Find the center of line B on the face of each leg. From these points make
perpendicular lines down to the foot ("D"). Continue across the bottom of
the foot. ("E")
3. Turn the bridge sideways make a vertical line, centered through the taper of
the bridge (line F). Go back to line B and continue it across the thickness of
the bridge, perpendicular to line F (both legs).
4. Finally, center a line (G) across the bottom length of each foot.
Drill the Legs and Cut off the Feet
Precision is crucial here. Use a drill press and a band saw or table saw for
these procedures.
Make a jig that will allow you to clamp the bridge and align your layout marks
for the drill. Two pieces of 3/4" Plywood or MDF fastened at 90 degrees will
do the job. You will use a countersink, a #9 (5mm) drill bit and the appropriate
tap for this procedure (1/4-20 or 6mm). To simplify the job, we recommend
that you use a so called "extension" tap with a long reduced diameter shank.
Your drill jig should hold the bridge firmly. Line up the bridge (and shim if
necessary) so that lines D & F are centered with and parallel to the drill bit.
Double sided carpet tape makes an excellent temporary clamp for the bridge
while you drill.
Option 1:Threads down (into feet)
Start each hole with a single flute countersink. Drill the holes for the posts
with a #9 (5 mm) tap drill. Drill to a depth of no less than 1-3/4" (44.45
mm).
If you have an "extension tap", use it now to tap the threads to a depth of
1" (25.4 mm) into the feet. If you don't have an extension tap, wait until
you cut off the feet to tap out the threads. In these cases, start the tap from
the top of the foot.
Before you cut off the feet, line up the "B" lines on the legs so they are
parallel to the saw blade. Place the side of the bridge that faces the tailpiece
down towards the table. Line F must be perpendicular to the blade or the
wheels will not align properly. If necessary, shim up the bridge to make line
B parallel and line F perpendicular to the saw blade. Double sided carpet
tape makes an excellent temporary clamp while you cut.
After you cut off the feet, enlarge the holes in the legs to 1/4" (6.4mm)
diameter.
Option 2: Threads up (into legs)
Start a hole in one foot with a single flute countersink. Then use a #9 (5
mm) tap drill to plunge the hole in one leg to a depth of at least 2" (50.8
mm).
With the bridge still held in position from the first hole, enlarge it to 1/4"
(6.4mm) diameter, to a depth of 1" (25.4mm). Repeat this entire procedure
for the other leg.
Tap the appropriate threads into the legs. If you have an "extension tap",
you will be able to thread all the way into the bottom of the hole. If you don't
have an "extension tap", the threads won't reach completely into the legs.
This is not a problem; you can go back and finish tapping the threads after
you cut off the feet. But try to at least get the tap started into the upper part
of the legs. This will ensure good thread alignment when you finish tapping
after the feet are cut off.
Before you cut off the feet, line up the "B" lines on the legs so they are
parallel to the saw blade. Place the side of the bridge that faces the tailpiece
down towards the table. Line F must be perpendicular to the blade or the
wheels will not align properly. If necessary, shim up the bridge. Double
sided carpet tape makes an excellent temporary clamp while you cut.
Fit the Wheels
Once you have cut off the feet, fit the wheels with the bridge off of the bass.
The hot side of the pickup should lay absolutely flat against the bridge, with no
gaps or voids. If necessary, sand the wood flat at the contact point and/or
increase the depth/diameter of hole before installing the bridge on the bass.
(illustration A)
Setup
Once the wheels are mounted and the bass is tuned up, thread the white wire through one of the wing holes in the bridge and hold it in place with one of the
neoprene plugs from the kit. (illustration B)
Fasten the output jack behind the bridge and between two adjacent pairs of strings. Then fasten the RCA plug into the back of the output jack.
3/8"
(9.5 mm)
No Less Than
Line B
1 - 1/4" (31.75 mm)
Line C
Line A
C
Line D
Threads into Feet
Line C
3/8"
C
(9.5 mm)
No Less Than
Line B
21/32"" (16.66 mm)
D
Line D
A
Line A
Threads into Legs
Illustration E
B
Line F
A
D
B
Line D
Line E
Line G
Line F
F
T
ISHMAN
RANSDUCERS
340-D Fordham Road Wilmington MA 01887 USA
Phone 978-988-9199 • Fax 978-988-0770
www.fishman.com
D
G
E
I
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NC
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