6
Where the FBX fits in your sound system
Place the FBX anywhere in the sound system that a graphic
equalizer might be used to control feedback. The most com-
mon place is between the output of the mixer and the input of
a power amp. In this position, the FBX can sense and eliminate
feedback occurring in any channel of the mixer. The FBX can
also be used on a mixer insert point.
A note about graphic equalizers
Graphic EQs are excellent for shaping sound, and they are fairly
simple to use. However, using one-octave-wide EQ filters to
control feedback invariably causes an unnecessary decrease
in the gain and fidelity of the program. It's easy to see that if
feedback occurs somewhere between the sliders, you will
have to pull one of those EQ sliders down pretty far to eliminate
feedback. That pulls out plenty of your program, too. On the
other hand, you'll get considerably more net gain and much
better sound quality if you use wide graphic EQ filters for tone
control and insist on narrow filters for feedback control.
If you use an equalizer, place the FBX after the EQ in the signal path.
Use the EQ’s controls to shape the tonal response of the sound
system, but DO NOT NOTCH FOR FEEDBACK.
Understanding FIXED & DYNAMIC filters
Before operating the FBX, you need to understand the
two types of FBX filters: FIXED and DYNAMIC. FIXED
FILTERS retain their frequency center-points until the
unit is reset by the user. The system’s gain before feedback is
limited primarily by the number of fixed filters; i.e., increasing the
number of fixed filters increases the system’s gain before
feedback. The FBX's DYNAMIC FILTERS control intermittent
feedback that comes and goes throughout the program. They are
!
R e a d
This
!
R e a d
This
continually reset automatically to different frequencies as new
feedback occurs during the program. For most applications, the
optimal setting is nine FIXED and three DYNAMIC FILTERS. This
is the factory default.
ClipGuard™ Adaptive Clip Level Control
Your FBX-1020 has a powerful new feature: Sabine's
patented ClipGuard™ adaptive clip level control. Until
Sabine invented ClipGuard™, engineers had to set
audio equipment input and output levels to a compromised
setting that allowed too much noise in quiet programs and
risked clipping during high-level programs. With ClipGuard™,
no front panel program level control is needed. It automatically
matches the FBX-1020 internal dynamic range to the constantly
changing program level and maintains unity gain. ClipGuard™
extends the effective dynamic range of your FBX-1020 from
100dB to 105dB!
ClipGuard™ incorporates TURBO mode setup, another new
feature. It cuts the time for FBX filter initialization to just a few
seconds, and it greatly reduces the volume level of the feedback
during setup. The FBX-1020 is set in TURBO mode at the
factory and automatically engages every time you
press RESET or SET TOTAL NO (to reset filters or set
total number of filters). The FBX-1020 automatically
returns to normal program mode when the first dy-
namic filter is set or when you press the front panel
LOCK FIXED button. ALL FILTER LEDS WILL CYCLE TO
INDICATE THE FBX IS ABOUT TO EXIT TURBO MODE.
FBX-1020 OPERATING INSTRUCTIONS
FBX Setup for Single Insert Point
Note: If you're using a mixer with unbalanced 1/4" outputs, you must
use standard unbalanced cables and connectors when connecting it
to the FBX. Similarly, if your mixer is wired for balanced 1/4" (Ring/Tip/
Sleeve) outputs, you must use that type of connector. If you don't, you
may experience a loss of gain when using the FBX.
FBX-1020
OUTPUT & INPUT
1/4" phone (ring)
1/4" phone (tip)
Mixer Input
Channel
TRS connector
High Z
Insert
Low Z
FBX Setup for Insert Send & Return
FBX-1020
OUTPUT & INPUT
Mixer Input
Channel
High Z
Insert
Send
Low Z
Insert
Return
Use 1/4" TRS plug for balanced sends/inserts
Use 1/4" TS plug for unbalanced sends/inserts
The FBX is designed for balanced output. If either side of the balanced output is grounded at any point, a 6 dB loss in dynamic range may occur
(+21dBV max. signal level unbal.; +27dBV max. signal level bal.).
