LR Baggs iBeam Onboard - Manual (Page 7)

flush on the guitar side's surface.
1. Once the bezel has been formed, drop it into the existing cutout and screw
the 4 provided screws into the holes until they protrude into the guitar about
1/16”. Do not enlarge the holes in the guitar! If you enlarge the holes, the
screws will not be able to hold the bezel in place to position the preamp.
2. Plug the pickup and strapjack harness into the end of the preamp.
3. Insert a battery into the battery compartment (observe polarity!) and push
the battery compartment into the unit until it click-locks into place. Insert the
preamp into the guitar through the sound hole and place it into the opening
in the bezel from inside of the guitar. Wiggle it around until the screw ends
find the corresponding slots in the chassis. Center the preamp laterally (along
the length of the side) in the bezel and start the screws into the plastic. Hold
the preamp firmly against the side so that it does not “walk” as you tighten the
screws. Before you tighten the screws completely, be sure that the battery
compartment does not bind against the bezel when you open and close the
compartment.
Do not overtighten the screws! This will cause the bezel ends to lift from the
side. Excess overtightening may even cause the screws to cut through the
bezel. It is helpful to watch the edge of the bezel as you tighten; stop when it
seats nicely against the wood.
4. Secure the wires inside of the guitar with the self-stick wire platforms
provided.
1 1 . U S E R ' S G U I D E
11.1 Controls:
Caution: Do not remove the battery from the preamp while plugged in!
1. Phase Button: This inverts the frequency phase (see section 11.3).
2. Battery Access and Battery Gauge Light: Depress and release the upper
panel to access the battery compartment. When the battery light dims, it will
be necessary to replace the battery.
3. Volume Slider: This adjusts the preamp volume.
4. Garrett Null Notch Filter: This knob is used to cancel guitar body resonance
feedback (see section 11.4).
5. Treble and Bass Controls: These sliders adjust the level of high and low
frequency output.
11.2. Preamp Gain Trim: The gain control is located on the back side of the
preamp. It is factory-set to average levels. You may turn this trimmer with a
small screwdriver if you’d like your output to be louder or quieter.
How to tell if you’ve gone too far: if you hear distortion, it’s too high; turn it
down. If you hear hiss, it’s too low; turn it up.
11.3 Phase: Phase is a time relationship between two vibrating objects, in this
case a guitar and a speaker. The phase relationship between the speaker and
the guitar at feedback frequencies will vary with the distance between the
guitar and the loudspeaker. Depending on the phase determined by the
distance between the guitar and the speaker these frequencies will either
reinforce (add) or cancel (subtract).
If you’ve ever backed away from a loud monitor to keep your guitar under
control (thinking that increasing the distance would reduce the loudness) you
were actually altering the phase relationship between your guitar and the
speaker at that feedback frequency. What you intuitively did was to move your
guitar from “in phase” with the monitor to “out of phase” at that frequency. It
was this change in phase that was responsible for the reduction or elimination
of feedback, not the lowering of volume due to moving away. Moving towards
the monitor may have been just as effective.
fig. 11
1
2
3
4
5
click-lock batter y
access -- press to
release
g u i t a r
s p e a k e r
fig. 12
c o m b i n e d g u i t a r / s p e a k e r
fig. 13: phase addition