ARX AFW-1 User manual

AFW-1 Owner's Manual v 1.3 CE ©1997 ARX®
AFW-1 Owner's Manual v 1.3 CE ©1997 ARX® 1
Anti-Feedback
Workstation
OWNER’S
MANUAL
AFW-1
ARX Systems Pty Ltd, PO Box 15,
Cheltenham, Victoria 3192, Australia
Phone: 03 - 9555 7859 Fax: 03 - 9555 6747
International Fax: [phone]
On the Web: http://www.arx.com.au
Email: [email protected]
12
INTERNATIONAL LIMITED WARRANTY
ARX Systems (ARX) warrants to the first purchaser of any ARX equipment that it is
free from defects in materials and workmanship under normal use and service.ARX’s
sole obligation under this warranty shall be to provide, without charge, parts and
labour necessary to remedy defects, if any, which appear within twelve (12) months
from date of purchase, and for a further twelve (12) months supply parts only.
This is our only warranty. It does not cover finish or appearance items, or if the
equipment has been, in ARX’s sole judgement:
•Subjected to misuse, abuse, negligence or accident;
•Repaired, worked on, or altered by persons not authorized by ARX;
•Connected, installed, adjusted or used for a purpose other than that for which
it was designed.
Some states do not allow the exclusion or limitation of incidental or consequential
damages so some of the above exclusions may not apply to you.This warranty gives
you and us specific legal rights and you may also have other rights which may apply.
Warranty Service Procedure
Should it become necessary to have your equipment serviced under the terms
of the warranty, please follow these steps:
1. Call your ARX distributor for a Return Authorization (RA) number;
2. Carefully repack the unit, in its original packaging where possible,
including a note with a description of the problem, and a copy of the
receipt showing date of purchase. Attach these to the actual unit
itself. Don’t forget to write your name and address clearly, and in-
clude a phone number where you can be contacted during normal
business hours. Make it easy for our service technicians to contact
you if they have a question. Also, use plenty of packing material -
better to be safe than sorry.
3. Send the unit freight prepaid to ARX Systems, at the address given
you with your RA number. We will pay the return freight when the
serviced unit is returned to you.
4. We strongly recommend you insure the package. We can’t fix it if it
gets lost! Send it by UPS, Fedex, or any similar service that can track
the package. Parcel Post is not recommended
If Warranty Registration Card is missing, please write to ARX in the country of
purchase, stating model and where purchased, or to ARX, PO Box 15, Cheltenham,
Victoria 3192, Australia.

AFW-1 Owner's Manual v 1.3 CE ©1997 ARX®
AFW-1 Owner's Manual v 1.3 CE ©1997 ARX®
2
This symbol indicates that a Slow Blow fuse is used in this equip-
ment. Replace with same type and value only
This symbol is intended to alert you to the presence of uninsulated
dangerous voltage within the product's enclosure that may be of
sufficient magnitude to constitute a risk of electric shock.
This symbol is intended to alert you to the presence of important
operating instructions contained in this owner's manual
WARNING SYMBOLS USED ON THIS EQUIPMENT
IMPORTANT - PLEASE READTHIS FIRST
This is a dual voltage unit. It is essential that you check that the voltage
on the fuseholder cover below the AC connector on the rear of the chassis
is set correctly before connecting it to AC power.
To change, pull fuseholder out and rotate 180o, then push in again. Do not
insert power cable into unit until voltage has been correctly set. Do not plug
power cable into AC power until voltage has been correctly set
THIS IS SET FOR
100 V AC TO 120 V
AC OPERATION
THIS IS SET FOR
220 V AC TO 240 V
AC OPERATION
Complieswith89/336/EECElectromagnetic
CompatibilityDirective,amendedby92/31/
EECand93/68/EEC andmeetsthe follow-
ing standards:EN 55013 : 1990, Sections
3.2and3.5EN55020:1988,Sections4.3,
5.4, 6.2, 7.0, 8.0.
11
Non-Volatile Memory
A complete record of the Anti Feedback filter settings is stored automatically in the
AFW-1 when you power down the system. Upon power-up, the system automati-
cally reloads the filters and returns them to the same position and depth as they
were when the power was turned off.
Filter Reset
If the sound system’s setup has changed, such as a different venue, change of equip-
ment, significant movement of microphones or speakers, or any other change that
would cause the feedback points to change, theAnti Feedback section must be reset.
Most Important The AFW-1 should not be RESET during a program. The system’s
master volume should always be set to a minimum volume before clearing the fil-
ters. Otherwise high volume feedback may occur, with potentially damaging re-
sults.
Bypass switches
The Active/Bypass switch under the SET ANTI FEEDBACK section of the front
panel will bypass the Anti Feedback, the Limiter control, and the Output level con-
trol, leaving just the EQ section active.
The Active/Bypass switch under the SET SYSTEM section is a true hardwire bypass
for the complete unit, and connects the inputs directly to the outputs, bypassing all
circuitry.
FBX Feedback Exterminator is a Registered Trademark of Sabine, Inc, and is the brand name of its line of automatic
feedback controllers.Covered by US Patent No.5,245,665, Australian Patent No. 653,736, and Canadian patent No.
2,066,624-2.Other patentspending.ARX ® isaRegisteredTrademark of ARXSystemsPty Ltd.Allothertrademarks
are the property of ARX Systems.
ARX policy is one of continuous improvement, and therefore designs may change without notice.However, unless
otherwise stated, specifications will always equal or exceed those previously given.

AFW-1 Owner's Manual v 1.3 CE ©1997 ARX®
AFW-1 Owner's Manual v 1.3 CE ©1997 ARX® 3
Introduction
Thank you for choosing this ARX AFW-1 Anti-Feedback Workstation. It’s a
great product, and we hope you enjoy using it as much as we enjoyed creat-
ing it. As with all ARX equipment, it has undergone extensive factory cali-
bration and ‘burn in’ before shipping. Since it involves a few radical depar-
tures from the normal way that we think of equalizers, for continued trouble
free use please familiarise yourself with the contents of this manual before
using the AFW-1 Anti-Feedback Workstation.
About the AFW-1
Tuning a live sound system, whether it’s a concert or a conference or all
points in between, is a complex procedure at the best of times! Stopping
feedback is only a part of it - you still need to adjust the actual sound of the
system in the room.
In the ideal world you’d have an equalizer to set the system curve, some-
thing to eliminate feedback, and something else to keep the system level
under control.
So, we’d like to introduce you to the ARX contribution to the ideal world -
the all-new ARX AFW-1 Anti Feedback Workstation. A single channel unit
incorporating a 30 band graphic equalizer, a smooth sounding peak limiter,
and onboard genuine Sabine FBX Feedback Exterminator circuitry.
Want total control over everything? You’ve got it.
Want automatic feedback locating and suppressing? You’ve got that too.
Want a safety valve that’ll keep your system in one piece? You’ve got that as
well. All integrated into one 2 RU package, all designed to work with each
other, and with you.
If the system is in a fixed installation, simply power everything down when
you’ve finished. The AFW-1 remembers your anti-feedback settings next
time it is used - there’s no need to reset the circuit when it is turned back on.
The ARX AFW-1 Anti Feedback Workstation has an application for every
mode of live audio: Monitors, Front of House, Church installations, TV au-
dience monitors, Conferences; in fact, anywhere there’s a live microphone,
there’s a need for the AFW-1.
In the next few pages you’ll discover how to set up your AFW-1, where to
use it, and how to get the most out of it.
Please take the time to read this manual. If you can’t wait, then go straight
to Page 4 and at least read the Quick Reference Guide. It’ll get you started.
10
Setting up the AFW-1
Setting up the AFW-1 correctly requires that certain steps are taken, in a particular
order. Technical people may call this the System Initializing Procedure, but we’ll just
call it Setup.
1. To install the AFW-1 in a sound system, connect it wherever a Graphic EQ
would go. For example, between the Mixing console and the Power amps. If
you are using multiple AFW-1’s in a monitor rig, then connect one between
each monitor send and crossover/amplifier
2. Place the speakers and microphones in the positions where they will be used
during the performance. Don’t place the microphones facing into the speakers!
3. Turn on the system
4. Set the Limiter Threshold at -10dB. The process of setting up the AFW-1 will
induce feedback rings, and the limiter will keep these from damaging the
system
5. Check that the Anti Feedback ACTIVE and Unit ACTIVE switches are pressed
IN and not Bypassed
6. Adjust the EQ section of the AFW-1 to set the system curve that you want. DO
NOT NOTCH FOR FEEDBACK. The EQ sliders should form a smooth curve
7. Set the channel levels on the console at the performance level. Reduce mixing
console master levels
8. Press and hold down the switch marked ‘PRESS AND HOLD FOR 4 SECONDS
TO RESET’ on the front of the AFW-1 for 4 seconds to clear out filters set
previously.
9. Place the AFW-1 in the active mode by releasing RESET. This procedure is
required to set the FIXED filters on the system’s resonating frequencies
10. SLOWLY bring up the console’s master sliders until feedback starts to occur.
The AFW-1 will detect and quickly remove it
11. Continue slowly raising the system master volume until the system is just over
the level required for the performance. Now back off the master volume
slightly so the system is not on the brink of another feedback point
12. The AFW-1 is now ready for use. It will lock these fixed filters on the feedback
frequencies, and leave a further 3 filters ‘floating’, to pull out any other
feedback during the performance if it occurs
13. Reset the Limiter at say, +3dB, or the maximum safe level of your system
14. The Clip LED may flash on transients - this is normal. But if it is lit continually,
then the level through the unit is too high and should be reduced. To do this,
bring down the master faders on the console a little, and bring up the output
gain of the AFW-1 by the same amount. Perhaps you have the Limiter set too
low, so it’s continually on. Or you could try increasing the crossover output
slightly. You could also make sure the amplifiers are on their maximum level.
Or you may have too little system for the sound pressure level you want in too
big a room. That’s one thing we can’t fix!

AFW-1 Owner's Manual v 1.3 CE ©1997 ARX®
AFW-1 Owner's Manual v 1.3 CE ©1997 ARX®
4
AFW-1 QUICK REFERENCE GUIDE
If you can’t wait to use the AFW-1, at least read this page first!
1. To install the AFW-1 in a sound system, connect it wherever a
Graphic EQ would go. For example, between the Mixing console and
the Power amps
2. Connect up and position the speakers and microphones where they
will be used during the performance. Don’t place the microphones
facing into the speakers!
3. Set the Limiter Threshold at -10dB
4. Check that the Anti Feedback ACTIVE and Unit ACTIVE switches
are pressed IN and not Bypassed
5. Adjust the EQ section of the AFW-1 to set the system curve that you
want. DO NOT NOTCH FOR FEEDBACK. The EQ sliders should
form a smooth curve.
6. Set the channel levels on the console at the performance level. Reduce
mixing console master levels
7. Press the switch marked ‘PRESS AND HOLD FOR 4 SECONDS TO
RESET’ on the front of the AFW-1 for 4 seconds
8. SLOWLY bring up the console’s master faders until feedback starts to
occur. The AFW-1 will detect and quickly remove it.
9. Continue increasing the master level until the required volume level
is reached
10. The AFW-1 is now ready for use. It will lock these feedback
frequencies, and leave a further 3 filters ‘floating’, to pull out any
other feedback during the performance if required
11. Reset the Limiter at +3dB or the maximum safe level of your system
12. The Clip LED may flash on transients - this is normal. But if it is lit
continually, then the level through the unit is too high and should be
reduced
13. The AFW-1 will remember its settings the next time it is turned on
and will not need resetting if the room or system has not changed.
14. For best results the unit should be reset if there has been any change
in the room or system that may change the feedback characteristics
15. Don’t reset the unit during the performance!
9
The result is that the overall program gain is increased 6 or more dB and provides
much clearer and more natural sounding speech and music. And since it is fully
automatic, no operator is required.
The digital filters inside theAFW-1 are switchable between 1/5th octave and 1/10th
octave. 1/5th is recommended for speech applications, such as conferences, speech-
es, etc, and 1/10th is recommended for music applications.
Before changing this switch, you must first power down the system. Then switch
the filter to the setting required. Power up the system again, and during its turn on
self test the AFW-1 will change the filter setting. The system should be RESET after
doing this, by following the Setup procedure detailed below.
About the Filters
The Anti Feedback section has two types of filters - fixed and dynamic.
Fixed filters retain their frequency center points in memory until the unit is reset by
the user. These filters are set in the AFW-1 initialization procedure by the strongest
resonating frequencies to provide the system’s gain before feedback.
Dynamic filters control intermittent feedback that comes and goes throughout the
performance, such as feedback from moving wireless microphones, getting too close
to speakers, monitors, that sort of thing. They are automatically reassigned to new
frequencies as feedback occurs on a first in - first out protocol.
The Anti Feedback section circuitry has a total of 9 filters; 6 fixed and 3 dynamic
filters. This has proven to be the best combination for most applications.
Where To Install The AFW-1 In The Signal Path.
The Limiter Section
The Peak Limiter in the AFW-1 has been included to let you set an absolute ceiling
on the output level.
Its attack and release times are program dependent and have been optimized to
appear as transparent to the ear as possible.
However, remember that it is a Limiter, and should be set at a level that coincides
with the onset of clipping in the system, where ideally it is not going to be active for
the bulk of the time.
TheAFW-1 can be placed anywhere
in the system that a line level signal
is available. However, best results
are obtained if it is placed last in the
chain before the power amplifiers.
If you are using a 2 or 3 way or more
system, with an active crossover
before the amps, then naturally the
AFW-1 will go before the crossover

AFW-1 Owner's Manual v 1.3 CE ©1997 ARX®
AFW-1 Owner's Manual v 1.3 CE ©1997 ARX® 5
AFW-1 Specifications
Input Impedance
20 K Ohm Balanced
Output Impedance
300 Ohm Balanced
Nominal Operating Level
+4dB
Maximum Input Level
+20 dB
Maximum Output Level
+20 dB
Dynamic Range
110 dB
Signal to Noise Ratio
-90dB Unweighted
Distortion
0.01% @ 1 KHz, +4dB
Frequency Response
20 Hz to 20 KHz, 0.5 dB
Equalizer Filters
30 x 1/3rd octave Constant Q on standard
ISO frequencies
Equalizer Range
±10dB cut or boost
FBX Filters
6 fixed, 3 dynamic
FBX Filter Range
51Hz to 17 KHz
FBX Filter Width
Switchable 1/5th or 1/10th octave
FBX Filter Depth
0dB to -40dB
Peak Limiter Threshold
-10 dB to +10 dB, user variable
Limiter Status Metering
Amber LED: Limiter Active
AC requirements
90-120 or 220-240 VAC, 50-60Hz, 18 VA
Size 482 x 88 x 230 mm
19”W x 3½”H x 9”D
8
AFW-1 Reference Guide
Graphic Equalizers are great products, and are extremely useful tools for profes-
sional audio engineers. But, they do require a fair degree of knowledge to operate
them successfully.
Feedback Exterminators are great, too, because they automatically find frequencies
that are feeding back and pull them down. But, that’s all they do. You can’t tune the
system with them - for that, you need an equalizer, usually a Graphic Equalizer.
In the ARX AFW-1 Anti-Feedback Workstation, we’ve combined the two products
described above, to give users the best of both worlds. An equalizer, to tune the
sound of the room/system, and an FBXAnti Feedback to automatically pull out any
feedback.
And, as a very useful added bonus, we’ve included a smooth sounding Peak Limit-
er to ensure that the signal stays within the level that you decide.
So let’s work our way through the operation of the AFW-1, from start to finish.
The Equalizer Section
The EQ section of the AFW-1 has been designed without compromise as a totally
accurate professional third octave equalizer, with innovative ‘Constant Q’ circuitry.
Constant Q is a true WYSIWYG (WhatYou See Is What You Get) design concept that
allows far more accuracy in EQ control.
Its 30 smoothly damped, centre grounding sliders can be adjusted to give a maxi-
mum of 10dB cut or boost. The Q of the filter has been specifically optimised to
allow easy combining of the filters. This enables you to set up a musical, notch free
system curve.
Using the EQ section
The idea of the EQ section is to ‘tune’ the room to the system, and to ‘tweak’ the
response a little so that it sounds good. We’re not going to use it to notch out feed-
back - we’ve got the Anti Feedback section for that - but to adjust the overall sound
of the system so it doesn’t sound ‘boomy’ or ‘harsh’. So, play a tape or CD that
you’re very familiar with, and adjust the sliders on the EQ section so that the system
sounds ‘just right’.
Note that a little EQ is a lot, so use each fader gently. Avoid any sudden dips or
peaks - that’s not what it’s there for. The look of the sliders should resemble a smooth
curve. If you don’t need to move it, then leave it.
Avoid too much boost at lower frequencies. Very few systems can deliver much
response below 30 Hz, so it’s pointless pushing those sliders up. However 50 to
100Hz can often benefit from a little boost, as can 10KHz. Between those points it
should be a smooth succession of gentle curves.
The Anti Feedback section
The Anti Feedback section of the AFW-1 is essentially a computer controlled para-
metric equalizer which continuously searches for feedback. Once feedback is detect-
ed, it extinguishes the feedback automatically by inserting a very narrow notch fil-
ter directly on the feedback frequency, only as deep as necessary to control the feed-
back. It finds and eliminates feedback typically in less than one second.

AFW-1 Owner's Manual v 1.3 CE ©1997 ARX®
AFW-1 Owner's Manual v 1.3 CE ©1997 ARX®
6
Front Panel Controls
1. 30 smoothly damped, centre grounding sliders
per channel, on standard ISO frequencies
2. Reset control for Feedback Exterminator
circuitry
3. Clip LED indicates imminent clipping,
monitored at all vital stages throughout the
AFW-1
4. Active/Bypass switch for Feedback
Exterminator, Limiter and Output level
controls
5. Limiter Threshold and Limit LED
6. Hardwire Active/Bypass switch for unit
7. Power LED indicates AFW-1 is connected to
AC power
7
Rear Panel Connectors
1. Balanced Input TRS socket. Tip + HOT, Ring —
COLD, Sleeve GROUND
2. Balanced Input XLR type. Pin 2 + HOT, Pin 3 —
COLD, Pin 1 GROUND
3. Balanced Output XLR type (same wiring as Input)
4. Balanced Output TipRingSleeve jack socket (same
wiring as Input)
5. Feedback Exterminator filter width switch
6. Audio Ground Lift switch
7. IEC 3 pin AC connector and integral fuseholder.
RISK OF FIRE - Replace fuse with correct value
only: 90 - 120 V AC 1 amp, 220-240 V AC 0.5 amp.
Please also refer to voltage details on Page 2