SABINE FBX1200 Operations Instructions download pdf (Page 8)

TURBO MODE SETUP

The FBX2020-Plus incorporates TURBO mode setup, which is

indicated by a flashing red “CLIP” LED. This lightning-quick

setup feature cuts the time for FBX filter initialization to just a few

seconds, and it reduces the volume level of the feedback

during setup. The 2020Plus is set in TURBO mode at the

factory and automatically engages every time you press

RESET (resetting filters). The 2020Plus automatically re-

turns to normal program mode when the first dynamic 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.

WARNING: TURBO Mode will cause distortion in your audio

program — it is for setup only. You must follow the setup

procedure outlined in the previous section, and do not play

program during TURBO setup mode. Otherwise the 2020Plus

will clip, and filters may be set improperly. (Clip level is set to

the lowest level so the feedback clips quickly; therefore, your

program will also be clipped in TURBO mode. Be sure a dynamic

filter is set, and if one isn’t, press the LOCK FIXED button before

your program begins.) You’ll know the 2020Plus is in TURBO

mode if the red CLIP LED flashes when no other signal level

LEDs are lit.

You can manually override TURBO mode if necessary: Press

LOCK FIXED (the LOCK FIXED light will turn on), then press it

again. (LOCK FIXED light will go out).

MOBILE vs. STATIONARY

MICROPHONES

One significant advantage offered by the Sabine family of FBX

feedback eliminator products is their ability to adapt to chang-

ing acoustical relationships involving sound system compo-

nents and various user applications. One major source of

potential feedback problems arises in situations with wireless

microphones, when the user of the wireless mic is moving

around the stage/auditorium. As a microphone moves in a

sound space, with varying degrees of proximity to the speakers

and varying acoustic responses, feedback frequencies may

shift. In such a situation, feedback-free mobility may be more

important a concern than maximum system gain.

One method of setting FBX filters with mobile microphones is

to turn a microphone on and walk around to the various

possible microphone locations. At the same time, raise the

system gain and set the FBX filters one at a time.

In some situations, raising the number of dynamic filters

(versus fixed FBX filters) may allow a second layer of defense

against new feedback from new locations. However, in many

mobile microphone set ups, fixed FBX filters will protect against

feedback across the range of microphone mobility.

Q. Can I place the FBX in the mixer’s EQ loop?

A. Yes.

Q. Can I place the unit in the mixer effects loop?

A. Avoid this configuration. You can configure the system this way

only if each effects send of each mixer channel is set so that

all of the signal is routed completely through the effects loop.

You cannot mix dry signal with effects signal and still control

feedback.

Q. The signal input LEDs do not light. The unit will not catch

feedback. Why?

A. The unit is not in the signal path. Check the connections. Be

sure that the program is interrupted when the input is discon-

nected from the back of the unit.

Q. Can I mix balanced and unbalanced inputs and outputs?

A. Yes. An unbalanced input and balanced output is compatible.

However, a balanced input and unbalanced output may result

in a 6 dB loss of dynamic range, and the bypass function may

not operate correctly.

Q. Why does one of the FILTER ACTIVITY LEDs blink?

A. The last filter to be automatically updated blinks. During

normal operation, the blinking will move from filter to filter as

they are reset. This gives the user a visual confirmation that

the unit is responding to new feedback and is functioning

properly.

Q. Sometimes during the initial set-up, the first filter LED

will blink before any feedback has been introduced into

the system. Why?

A. The FBX will set a filter if the system has a hum. Check for bad

grounds. Try resetting the filters and/or the Ground switch on

the rear panel.

Q. Why does the FBX cause a noticeable hum?

A. It hums if the main power voltage drops significantly below

10% of the specified voltage. Check the A/C power mains.

Q. Why does my system sound thin and muffled?

A. Place the FBX in BYPASS MODE. If the system still sounds

thin, your problem is probably improper use of a graphic EQ.

If the problem is really the FBX, reinitialize the system.

Q. Why does my program sound clipped and distorted?

A. Make sure the FBX’s TURBO mode has turned off before your

program. Check the signal level ladder. If the red CLIP LED

lights with no other signal level LEDs lit, the FBX2020-Plus is

still in TURBO mode. TURBO mode turns off automatically

after the first dynamic filter is set, or you can turn it off manually

by pressing the LOCK FIXED button.

Q. Can I patch two FBX2020-Plus channels together for

twice the filters?

A. Yes; connect the output of the FBX2020Plus’s channel A to the

input of the 2020Plus’s channel B. Place the 2020Plus

between the output of the mixer and the input of a power amp,

and set up the channels sequentially. Bypass channel B while

setting up channel A, then lock channel A’s fixed filters (all

channel A’s filters should be fixed) by pressing channel A’s

LOCK FIXED button on the front panel after set-up.

Q. Why doesn't the FBX2020-Plus filter feedback immedi-

ately?

A. 1. Lower frequencies may take longer than higher ones.

2. Check input level of signal at the unit and reconfigure gain

so the signal level LED's on the unit light up.

3. It may be patched in an "effects loop", not directly in the

signal path.This WILL NOT WORK.

4. You may have used all 12 filters. Dynamic filters will

continue to operate by notching feedback frequencies as they

occur, but ultimately, gain will exceed filter capacity.

TROUBLESHOOTING TIPS

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SABINE FBX1200 Operations Instructions Page 8

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