Silver 4Bmini User manual

SILVER Audio Processor 4Bmini User’s manual
Page 1/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
USER’S MANUAL
Silver Audio Processor 4Bmini
Broadcast Audio Processor
Operational Manual
Version 1.3/ 2007-08

SILVER Audio Processor 4Bmini User’s manual
Page 2/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
Table of Contents
Safety Instructions ____________________________________________________________________________3
Introduction to the SILVER Audio Processor 4Bmini ________________________________________________5
Silver Audio Processor 4Bmini rear and front panel ________________________________________________6
SILVER Audio Processor 4Bmini Jumper Settings__________________________________________________7
SILVER Audio Processor 4Bmini metering ________________________________________________________8
Introduction to Audio Processing ________________________________________________________________9
The SILVER Audio Processor 4Bmini and Its Processing Structure __________________________________10
THE PROCESSING PATH _______________________________________________________________________10
MENU OVERVIEW ____________________________________________________________________________12
Setting up the Processing on the SILVER Audio Processor 4Bmini___________________________________16
Getting the Sound You Want ___________________________________________________________________21
Managing Presets (front panel control) __________________________________________________________24
Factory Presets ______________________________________________________________________________25
Remote Control Of The SILVER Audio Processor 4Bmini ___________________________________________26
Remote Trigger Port __________________________________________________________________________33
Specifications _______________________________________________________________________________36

SILVER Audio Processor 4Bmini User’s manual
Page 3/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
Safety Instructions
CAUTION: To reduce the risk of electrical shock, do not remove the cover.
No user serviceable parts inside. Refer servicing to qualified personnel.
WARNING: To reduce the risk of fire or electrical shock, do not expose this appliance to rain or moisture.
This symbol, wherever it appears, alerts you to the presence of uninsulated dangerous voltage
inside the enclosure—voltage that may be sufficient to constitute a risk of shock.
This symbol, wherever it appears, alerts you to important operating and maintenance instructions
in the accompanying literature. Read the manual.
DETAILED SAFETY INSTRUCTIONS:
All the safety and operation instructions should be read before the appliance is operated.
Retain Instructions:
The safety and operating instructions should be retained for future reference.
Heed Warnings:
All warnings on the appliance and in the operating instructions should be adhered to.
Follow instructions:
All operation and user instructions should be followed.
Water and Moisture:
The appliance should not be used near water (e.g. near a bathtub, washbowl, kitchen sink, laundry tub, in a wet
basement, or near a swimming pool etc.).
The appliance should not be exposed to dripping or splashing and objects filled with liquids should not be placed on
the appliance.
Ventilation:
The appliance should be situated so that its location or position does not interfere with its proper ventilation. For
example, the appliance should not be situated on a bed, sofa rug, or similar surface that may block the ventilation
openings, or placed in a built-in installation, such as a bookcase or cabinet that may impede the flow of air through
the ventilation openings.
Heat:
The appliance should be situated away from heat sources such as radiators, heat registers, stoves, or other
appliance (including amplifiers) that produce heat.
Power Source:
The appliance should be connected to a power supply only of the type described in the operating instructions or as
marked on the appliance.
Grounding or Polarization:
Precautions should be taken so that the grounding or polarization means of an appliance is not defeated.

SILVER Audio Processor 4Bmini User’s manual
Page 4/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
Power-Cord Protection:
Power supply cords should be routed so that they are not likely to be walked on or pinched by items placed upon or
against them, paying particular attention to cords and plugs, convenience receptacles and the point where they exit
from the appliance.
Cleaning:
The appliance should be cleaned only as recommended by the manufacturer.
Non-use Periods:
The power cord of the appliance should be unplugged from the outlet when left unused for a long period of
Object and Liquid Entry:
Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through openings.
Damage Requiring Service:
The appliance should be serviced by qualified service personnel when:
- The power supply cord or the plug has been damaged; or
- Objects have fallen, or liquid has been spilled into the appliance; or
- The appliance has been exposed to rain; or
- The appliance does not appear to operate normally or exhibits a marked change in performance; or
- The appliance has been dropped, or the enclosure damaged.
Servicing:
The user should not attempt to service the appliance beyond that is described in the Operating Instructions.
All other servicing should be referred to qualified service personnel.
CE CONFORMANCE: This device complies with the requirements of the EEC Council
Directives: 9 /68/EEC (CE Marking); 7 /2 /EEC (Safety – low voltage directive);
89/ 6/EEC (electromagnetic compatibility).
Conformity is declared to those standards: EN 0081-1,EN 0082-1.
WARNING: This equipment generates, uses, and can radiate radio frequency energy.
If not installed and used in accordance with the instructions in this manual it may cause
interference to radio communications. It has been tested and found to comply with the
limits for a Class A computing device (pursuant to subpart J of Part 1 FCCRules), designed to provide
reasonable protection against such interference when operated in a commercial environment. Operation
of this equipment in a residential area is likely to cause interference, at which case, the user, at his own
expense, will be required to take whatever measures may be required to correct the interference.
CANADA WARNING:
This digital apparatus does not exceed the Class A limits for radio noise emissions set out in the Radio
Interference Regulations of the Canadian Department of Communications.
Le présent appareil numérique n'émet pas de bruits radioélectriques dépassant les limites applicables
aux brouillages radioélectriques édictés par le ministère des Communications du Canada.

SILVER Audio Processor 4Bmini User’s manual
Page 5/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
Introduction to the SILVER Audio Processor 4Bmini
The AUDEMAT-AZTEC SILVER Audio Processor 4Bmini is a new generation of digital audio signal processor that
can be used to process audio ready for FM. Using the latest multi-band DSP technology the SILVER Audio Processor
4Bmini offers a versatile and powerful tool in creating a loud punchy on-air presence.
The SILVER Audio Processor 4Bmini has been designed and built from scratch using a new approach to the design
of a digital audio processor that incorporates the most up to date components. Cutting edge technologies allow the
SILVER Audio Processor 4Bmini to produce similar results to other processors in the market but in a simpler more
cost effective way. The advances we have made have allowed us to pass the savings on to our customers.
What's Under the Lid?
The SILVER Audio Processor 4Bmini is driven by a fast 8 bit micro-controller which controls an array of specialised
analogue and digital circuits: These include 24-bit A/D and D/A converters, analogue level control circuitry, 6 x 24 bit
DSP's, an Ethernet port, a trigger port, an RS232 port, an LCD screen and memory devices to hold the software and
firmware.
The Processing Architecture!
After input selection the 24-bit digital audio signal is passed through conditioning circuitry before being split to four
bands by linear phase time aligned filters. Each band is processed by multiband RMS leveller which corrects for input
level variations and also improves consistency. Each band is further processed by dynamic audio limiter. The
following distortion cancelling clipping ensures your signal is kept to a strict maximum while maintaining crystal clear
sound. A supersonic sample rate DSP stereo encoder provides MPX generation with fantastic stereo separation.
The easy to use front panel control system wit LCD afford the user with ease of use and setup.
Comprehensive control of every processing parameter is available to the user both from the front panel control
system and by remote (computer) control.
Dynamic, fresh & innovative...
... The SILVER Audio Processor 4Bmini

SILVER Audio Processor 4Bmini User’s manual
Page 6/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
Silver Audio Processor 4Bmini rear and front panel
Front panel :
Rear panel :
Status
LEDS
Control
knob
Soft
Ke
y
s
Mains power unit
Lan port
RS232 & Trigger port
AES/EBU Input
Pilot
Output
MPX
Output
SCA
Input
Analogue Input

SILVER Audio Processor 4Bmini User’s manual
Page 7/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
SILVER Audio Processor 4Bmini Jumper Settings
Setting input clip level
Setting input clip level is now configurable from the front panel. Level is now fully adjustable between 0 and 24dBu in
1dBu increments.
To do that, use the jogwhell and buttons. Select the INPUT menu and scroll to
find the ‘ANALOG LEVEL’ parameter. Select it and set the desired value. You
can check the current levels with the SILVER Audio Processor 4Bmini at any
time by displaying the metering screen (press the middle soft key on the front
panel).
Ground lift
The ground lift switch is now accessible without opening the unit. It is located on the rear panel, near the MPX output
(see picture below). It removes circuit ground from chassis ground. If you are experiencing hum or buzz in your audio,
you might want to move this jumper to the lifted position as indicated below the switch.
Ground Switch

SILVER Audio Processor 4Bmini User’s manual
Page 8/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
SILVER Audio Processor 4Bmini metering
The SILVER Audio Processor 4Bmini metering is accessible at any time by pressing the middle soft key on the front
panel. It shows instant IO meters as well as all processing metering.
I/O metering
The input meters show the level of the input audio. The meters are ‘hooked in’ to the DSP code after the input level
selection and mode options.
The output meters represent the level in dB below full scale output. This output level is the peak output level of
the processing and has nothing to do with the actual output level set by the analogue and digital output level options.
The output meters show a smaller dynamic range compared to the input ones. This reflects the smaller dynamic
range of the audio once processed by the SILVER Audio Processor 4Bmini. If we were to have used the same scale
as the input metering we would not see a lot of activity on the bars.
The multiplex output metering represents the composite outputs peak level. This is a representation of the output
in relation to the peak composite level of the processing and not the actual level set by the multiplex output
level control.
The IO meters follows an approximation of the PPM level of the audio waveform.
Multi-band AGC
The first four gain reduction meters show the gain reduction of the multi-band AGC. The range shown is -21dB
to +21dB in dB steps.
There is only one meter per stereo channel and the value shown is the largest gain reduction of the left and right
channels. Under normal operation (with a stereo audio feed) this is fine but you may observe strange metering if
the channels are not very balanced in level.
Multi-band limiter
The second four gain reduction meters show the gain reduction of the multi-band limiter. The range shown is
0dB to -1 dB in 1dB steps.
There is only one meter per stereo channel and the value shown is the largest gain reduction of the left and right
channels. Under normal operation (with a stereo audio feed) this is fine but you may observe strange metering if
the channels are not very balanced in level.
STATUS LEDS
The SILVER Audio Processor 4Bmini front panel contains three status LEDS.
REMOTE: Indicates that the SILVER Audio Processor 4Bmini is currently talking to a remote computer. This will flash
during
an update of the firmware or remote control with the remote control application.
AES/EBU: Indicates the presence of a valid AES/EBU signal connected to the digital audio input of the
SILVER Audio Processor 4Bmini.
EDIT: Indicates that you are currently editing a parameter

SILVER Audio Processor 4Bmini User’s manual
Page 9/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
Introduction to Audio Processing
Most audio processors use a combination of compression, limiting and clipping to 'funnel' the dynamic range down,
reducing the peak to average ratio in each stage. A cascaded arrangement of compressor, limiter and clipper
produces the best results. The first stage of processing usually operates in a slow manner, the processing getting
progressively faster and more aggressive as the audio passes through the chain. The instantaneous peak clipper or
look-ahead limiter is the final stage of the chain and sets the final peak level.
The images below illustrate a section of audio as it passes through a typical audio processor.
The first image to the right is an unprocessed section of audio.
The images that follow represent compression of the input waveform,
followed by limiting and then finally peak clipping.
Compression
Compression reduces the dynamic range of the audio waveform slowly in
a manner similar to a trained operator riding the gain. Compression is usually
performed on the RMS level of the audio waveform and the ratio of compression
is usually adjustable. Compression is usually gated to prevent gain riding and
suck-up of noise during silence or quiet periods.
Limiting
Limiting is a faster form of compression that employs faster time constants and
higher ratios to produce a denser sound while controlling peaks based upon the
peak level of the audio waveform. Excessive limiting can create a busier packed
wall of sound effect.
Clipping
Clipping the audio waveform will not produce any audible side effects if performed
in moderation. Excessive clipping will produce a form of distortion that produces a
tearing or ripping sound. Clipping can also be used as an effective method of high
frequency peak control when used in conjunction with distortion controlling filtering.
Source material Quality
The SILVER Audio Processor 4Bmini has the ability to substantially improve the quality of your ON-AIR broadcast.
However the SILVER Audio Processor 4Bmini can only work with what you provide it. The best performance will be
obtained when the SILVER Audio Processor 4Bmini is fed with very clean source material. After dynamic multi-band
re-equalisation is performed, poor quality source material will sound poorer when processed with the SILVER Audio
Processor 4Bmini.
We strongly advise against the use of MP’s and other compressed audio formats for audio storage. If you must use
compressed audio we advise rates of 2 6 Kbps and higher. Linear formats are always to be preferred.
Compressed audio formats employ frequency masking data reduction techniques to reduce the bit-rate. Through
re-equalisation the SILVER Audio Processor 4Bmini can violate the frequency masking characteristics of the bit
reduction process,
creating distortion that was inaudible prior to the SILVER Audio Processor 4Bmini processing.
SILVER Audio Processor 4Bmini placement
We recommend that the SILVER Audio Processor 4Bmini be placed as close to transmitter as possible. Ideally
SILVER Audio Processor 4Bmini
should be connected directly to the transmitter. Composite studio to transmitter links may introduce additional
overshoots, therefore increasing peak level and reducing average modulation.

SILVER Audio Processor 4Bmini User’s manual
Page 10/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
The SILVER Audio Processor 4Bmini and Its Processing
Structure
The SILVER Audio Processor 4Bmini broadcast audio processor is intended to be used for processing audio prior to
broadcast on FM.
Before we discuss the processing structure in full we would like to tell you a little about the final peak limiting stage of
the SILVER Audio Processor 4Bmini. It employs distortion controlled clippers to limit the peaks of the signal.
Distortion controlled clipping is the best method for preserving as much high frequency energy as possible, important
when the high frequency loss characteristics of the FM broadcast de-emphasis curve is taking into account. Distortion
controlled clipping produces harmonic distortion which if used moderately can produce a sizzling bright sound but can
result in a ripping or tearing sound if used excessively (overdriven).
THE PROCESSING PATH
Input selection and conditioning
The SILVER Audio Processor 4Bmini offers the user input selection (analog or digital input) and pre-emphasis
selection.
Bass enhancement
The SILVER Audio Processor 4Bmini offers a bass enhancement via peaking filter that can be set to provide up to
6dB of gain on one of four frequencies with a choice of 4 Q's. This can be thought of as a simple bass parametric.
Xover
The SILVER Audio Processor 4Bmini employs linear-phase time aligned digital FIR filtering to split the audio
spectrum into 4 bands while maintaining sonic transparency.
Multi-band AGC
The SILVER Audio Processor 4Bmini processes each band with RMS based levellers. Each bands gain control
processing function can be configured in different manners to provide different effects. Adjustable timing constants,
drive and gating afford the user with full control of this important re-equalisation stage of the processor.
Multi-band limiters
Each band has its own dynamic peak limiter. Multiple time constant based detectors are fully adjustable as well as
input drives.
Mixer
The four bands are 'virtually' mixed together at this stage, allowing overall EQ adjustment.
Bass clipper
The SILVER Audio Processor 4Bmini peak limits (clips) and linear phase filters the low frequencies before being fed
to the final clipper stages.
Distortion controlled clipper
The SILVER Audio Processor 4Bmini main clipper uses sophisticated algorithms to produce tightly peak controlled
output and maximum distortion control.
Stereo encoder
The SILVER Audio Processor 4Bmini's DSP stereo encoder takes its inputs after peak processing. The stereo
encoder is highly over-sampled and offers superb stereo performance. A composite clipping function is provided for
those who wish to use it.

SILVER Audio Processor 4Bmini User’s manual
Page 11/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
SILVER Audio Processor 4Bmini
PROCESSING BLOCK DIAGRAM

SILVER Audio Processor 4Bmini User’s manual
Page 12/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
MENU OVERVIEW
This section presents an overview of the four main menus and
their submenus and any parameters that are contained within them.
INPUT: Contains controls that affect input selection and preemphasis.
PROCESS: Contains all the controls that affect the processing.
From here you can fine-tune your sound.
STEREO: Contains all the controls that affect MPX output.
SCHEDULE: Contains all the real time clock controls for
switching presets (Dayparting).
SYSTEM: Contains all the system controls (non processing)
such as remote control and security.
SOFTKEYS: The SILVER Audio Processor 4Bmini has three context sensitive
soft keys that help access commonly used features. These
intuitive softkeys are primarily designed to aid in the selection,
loading and saving of presets, as well as displaying the
metering screen. More information on the softkey functions
are contained in the appropriate sections of this manual.

SILVER Audio Processor 4Bmini User’s manual
Page 13/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
The 'INPUT' menu contains options relating to the control and conditioning of the audio inputs.
Source This parameter allows you to select the between the analog and digital inputs as the source for the
processing.
Pre-emphasis: This parameter allows you to activate pre-emphasis when the SILVER Audio Processor
4Bminiis being used to process for FM broadcast. The available options are 50uS, 75uS and OFF
The 'PROCESS' menu allows access to all of the processing blocks that make up the SILVER Audio
Processor 4Bmini. There are only sub-menus inside the 'PROCESS' menu. The submenus are laid out in the
same configuration as the signal path through the SILVER Audio Processor 4Bmini.
The 'ENHANCE' menu contains the low frequency peaking bass equalizer which is used to provide bass
enhancement and help overcome the bass reduction effect of multi-band compression. Four frequencies,
amplitudes and Q's are provided giving you 64 different bass curves to select from. Frequencies selectable: 60Hz,
76Hz, 95Hz and 120Hz. Q's selectable: 0.4, 1, 2 and 4. Gains selectable: 0, 1.5dB, 3dB, 4.5dB, 6dB
The ‘MULTI-BAND AGC’ is designed to re-equalize the program material and create a consistent tonal balance
while maintaining a consistent output level based on the RMS level of the program material.
‘B1-4’
‘DRIVE’ Controls the drive into the AGC. 0dB drive corresponds to a gain reduction of 0dB, the midway
point. The drive can be increased or decreased by up to 12dB. You may need to increase the
drive a little as you go up through the bands to compensate for the fact that music has less energy in
the higher frequency spectrum compared to low frequencies.
‘ATTACK’ Controls the attack rate of the AGC, The time the AGC takes to respond to an increase of
input level. The attack time can be varied between 1 and 10 which corresponds to 100mS to 10S on
a semi-exponential scale.
‘DECAY’ Controls the release/decay rate of the AGC, the time the AGC takes to respond to a decrease of
input level. The DECAY time can be varied between 1 and 10 which corresponds to
100mS to 30S on a semi-exponential scale.
‘GATE THRESHOLD’ The gate function prevents ‘suck-up’ of noise during periods of silence or low
level audio. The level can be adjusted to turn on when the input drops to a level from -20dB to -40dB.
The gate can also be switched off or forced on. The gate when turned on will cause the gain reduction to
move towards the resting 0dB level
The 'MULTI-BAND LIMITERS' peak limit each of the bands to prevent distortion in the processors clipping peak
control system.
‘MASTERLIMITERDRIVE’ Sets the drive into the multi-band limiter. This control allows a +/- 6dB
adjustment.
'B1-4'
'DRIVE' Controls the drive into the limiter. The drive can be increased or decreased by up to 12dB.
'PEAK ATTACK' Controls the attack rate of the limiter, the time the limiter takes to respond to an increase
of input level. The attack time can be varied between 1 and 10 which corresponds to 1mS to 200mS on a
semi-exponential scale.

SILVER Audio Processor 4Bmini User’s manual
Page 14/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
'PEAK DECAY' Controls the peak release/decay rate of the limiter, the time the limiter takes to respond to
a decrease of input level. The DECAY time can be varied between 1 and 10 which corresponds to 10mS to
1000mS on a semi-exponential scale.
'AVG ATTACK' Controls the average attack rate of the limiter.This control is a modifier control that
scales from the peak attack control. The attack time can be varied between 1 and 10 which correspond to
peak attack time / 2 to peak attack time / 1000 on a semi-exponential scale. The AVGattack control
determines the dynamics of the dual time constant system and how control is shared between the peak
and average circuits.
'AVG DECAY' Controls the average release/decay rate of the limiter, the time the limiter takes to respond
to a decrease of input level. The DECAY time can be varied between 1 and 10 which corresponds to
200mS to 000mS on a semi-exponential scale.
'MIXER' menu. Each band can be adjusted over a small range to provide small EQ changes. These controls are
limited in range to prevent excessive drive into the peak clipping stages and excess distortion being introduced.
BAND1MIX: - dB to + dB of level adjustment is available.
BAND2MIX: - dB to + dB of level adjustment is available.
BAND3MIX: - dB to + dB of level adjustment is available.
BAND4MIX: - dB to + dB of level adjustment is available.
The 'CLIPPER' menu contains the clipping controls that form the final peak limiting stages of the Silver Audio
Processor 4Bmini.
'BASSCLIP' Controls the clip level of the mix of Bands 1 and 2. The clip level range is -6dB to 0dB
referenced to the main clippers output level.
'HFCLIPPLING' This control redistributes high frequency peak control between the limiters and the HF
clipper. The range is 0 to 17 with 0 equating to full control by the limiters and higher numbers producing
less control by the limiters on a frequency dependent basis, leaving control by the HF clipper. This control is
similar to a variable de-emphasis control in the limiters side-chain control signals.
'MAIN CLIP DRIVE' Controls the drive into the main output clipper that defines the systems peak clipping
ceiling. Adjustable over a -6dB to +6dB range.
'MAIN CLIPPER HARDNESS' Another distortion controlling mechanism that helps to reduce IMD in the
final clipper. The range is 1 to 10 with 10 producing the least distortion control. A setting of 10 effectively
bypasses this control.
'OVERSHOOT CONTROL' Controls how much the main clipper will pass overshoots to the composite
clipper. The range of overshoot control is 1 to 10 with lower numbers allowing more overshoots through
to the composite clipper.
'COMPOSITE CLIP Controls the drive into the composite clipper which effectively sets the amount of
composite clipping. The range of composite clipping is -0. dB to +2dB.
The 'STEREO' menu contains all of the controls relevant to the DSP stereo encoder that generates the
multiplex signal.
'LEVEL' Controls the output level of the composite MPX output. Range is 0dBu to +12dBU
'PILOT LEVEL' This parameter sets the level of the composite signals 19 Khz pilot tone. The adjustable
range is 6% to 12% and an OFF setting for mono applications.
'PILOT OUTPUT' This controls the 19KHz pilot output reference signal which is available on the SILVER
Audio Processor 4Bmini back panel. Options are enabled and disabled

SILVER Audio Processor 4Bmini User’s manual
Page 15/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
The 'SCHEDULE' menu contains all the controls for the dayparting (REAL TIME CLOCK) preset switching.
'TIME' Sets the time and day of the SILVER Audio Processor 4Bmini’s Real Time Clock.
'DAYPARTING ON/OFF Enables or disables the scheduling.
'DP(X) ON/OFF' Enables or disables an individual daypart schedule.
'DP(X)' Sets the preset to switch to when this daypart is triggered.
'DP(X) START' Sets the start time day and time of the daypart. There is also an ‘ALL days’ option.
'DP(X) LENGTH' Sets the length in minutes that the daypart will run for.
The 'SYSTEM' menu contains all the system controls (non processing) such as remote control and security
'LCD CONTRAST' Sets the contrast of the front panel LCD screen. The range is 0 to 2
'TRIGGER PORT' This enables or disables the rear panel trigger (remote) port. The options are enabled
and disabled. More information is available in the trigger port section of this manual.
'CODE LOCK' This enables or disables the security code lock. The options are enabled and disabled. More
information is available in the code lock section of this manual.
'OUTPUT LOCK' This enables or disables the output code lock. The options are enabled and disabled.
More information is available in the code lock section of this manual.
'REMOTE SOURCE' This selects the serial or the NET/LAN port as the remote control method. The default
option is Off.
The 'LAN CONFIG' menu contains the controls relevant to the LAN/NET port.
'IP' Sets the IP address of the LAN port
'DG' Sets the default gateway of the LAN port
'SM Sets the subnet mask of the LAN port
'MA1' Sets the first half of the MAC address of the LAN port
'MA2' Sets the second half of the MAC address of the LAN port
'PORT' Sets the port number of the LAN port
'ABOUT' SILVER Audio Processor 4Bmini version number and design credits.
'BOOTLOAD' This option is used to FLASH update the software and firmware inside the SILVER Audio
Processor 4Bmini.
Further information on using this option is described in the documentation supplied with the upgrade.

SILVER Audio Processor 4Bmini User’s manual
Page 16/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
Setting up the Processing on the SILVER Audio Processor
4Bmini
This section has more detailed information on setting up the SILVER Audio Processor 4Bmini’s processing.
Bass enhancement
The frequency contouring effect of multi-band audio processors often leaves the bass lacking a little. The summation
of the bands tends to give a boost to the presence frequencies and leaves the bass sounding a little thin. This effect
can be compensated somewhat by enhancing the bass prior to multi-band processing.
The SILVER Audio Processor 4Bmini has a pseudo parametric style bass equalizer control that allows you to sweet
tune the bass. Four frequencies, amplitudes and Q's are provided giving you 64 different bass curves to select from.
Frequencies selectable: 60Hz, 76Hz, 95Hz and 120Hz. Q's selectable: 0.4, 1, 2 and 4. Gains selectable: 0, 1.5dB,
3dB, 4.5dB, 6dB. A starting setting of 95Hz, Q of 1 and gain of 4.5dB warms the bass up quite nicely but you are free
to experiment to get the bass sound you're after.
Multi-band AGC
The multi-band AGC in the SILVER Audio Processor 4Bmini employs an RMS based level detector for superior
performance. This enables the SILVER Audio Processor 4Bmini to control input level variations based on the true
loudness of the input waveform unlike other simpler average responding peak detectors used in other digital audio
processors. When you couple the advanced detector with the user adjustable and hidden intelligent controls you
really do have a powerful levelling tool.
The Multi-band AGC stage of the Silver Audio Processor 4Bmini-FM has two main functions.
1. To re-equalise the program material to provide a consistent tonal balance and sonic signature.
2. To prevent excessive limiting by the following peak limiter stages.
Because of the RMS based level detectors the multi-band AGC can re-equalise the sound in a more natural manner
than the peak limiter stages which use peak detectors. As the human ear works on average loudness rather than
peak level the re-equalised audio will sound more natural when dynamic range reduction is performed by RMS based
level detectors.
Because the peak to average ratio of the program material can be quite wide it is still necessary to control the peaks
of the audio with the multi-band limiters but unlike most other audio processors the bulk of the work has been
performed by the multi-band AGC and the limiters can be fed with a more controlled level allowing them to operate in
their sweet spot.
Over the course of the next few pages we have included several scope shots clearly illustrating the input and output
of the single band AGC together with the AGC control signal. The effect of the control signal is clearly evident on the
output audio waveform. These scope shots help to visually illustrate the concepts under discussion.
The multi-band AGC stage is designed so that a 0VU input level to the processor will drive the multi-band AGC to the
midway resting level of 0dB.
Individual drive controls are provided as a way of equalizing the audio before processing. This can be used to add a
touch of more presence or bass. Keep in mind that the mutli-band AGC by it's very nature will tend to compensate
any cut or boost you make here.

SILVER Audio Processor 4Bmini User’s manual
Page 17/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
The attack and decay times of the AGC have a range of 1-10 and this corresponds to time constants of 100mS to
30S. We suggest an attack somewhere in the region of 3-4 and a decay setting of 1 or 2 positions higher than that.
Like most competent audio processors the AGC stages in the SILVER Audio Processor 4Bmini are gated.
This slows down the release time of the multi-band AGC when the program material drops below a certain level.
This prevents noise suck up and gain hunting from occurring during quiet periods or lulls in the audio. The SILVER
Audio Processor 4Bmini allows adjusting the gate level over a range of -20dB to -40dB.
This is the level at which the program material must fall below for the gate to become active. The gate level control
has two more options, OFF and ON. OFF is self explanatory and prevents the gate from having any effect. ON is
often referred to in this manual as ‘forced gating’ as it has the effect of switching the gate on at all times with any level
of program material. This option is used to bypass the AGC.
Under gated conditions, the gain reduction will slowly move to average gain the AGC had in the recent past. This
preserves the frequency balance of program material when multi-band AGC is gated.
Multi-band limiters
The multi-band limiter drive can be adjusted over a +/- 12dB range. Increasing the drive will increase the level of
limiting and with it on air loudness. Above a certain level of drive no more loudness will be obtained and all that will
happen is you will generate higher levels of IM distortion and the sound will take on a busy packed texture. You may
also observe higher levels of high frequency noise when the band 3 and 4 drives are increased. We don't usually find
much use for drives above +6dB but more may be required if other settings are adjusted to compensate. In any case,
observe the peak limiter meters for a good indication of how much drive to use. We don't recommend more than 9dB
of gain reduction especially on bands 2, 3 and 4. Gain reductions of 2-6dB are a good compromise between loudness
and quality.
The effects of gating
AGC attacking and decaying with gating
disabled
AGC attacking and decaying but with
g
atin
g

SILVER Audio Processor 4Bmini User’s manual
Page 18/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
The multi-band limiters in the SILVER Audio Processor 4Bmini are of the dual time constant variety. There is an
attack and decay to handle the peaks and an attack and decay to handle the average level of limiting. Understanding
how the two time constants interact is imperative if you want to make major changes to how each bands limiter
reacts. We have included some scope screen captures to illustrate things a little clearer. The peak and average
function can clearly be seen in the images.
Traditionally audio limiters have two time constants, an attack, the time is takes the limiter to respond to a signal
above the threshold and a decay or release which is the time is takes to respond to a drop in level. In a traditional
audio limiter the attack time is usually set to somewhere in the region of a few milliseconds and the decay time
considerably longer at somewhere in the hundreds of milliseconds. This is not the most optimum solution because
transients that last only a few milliseconds will reduce the level of the waveform for hundreds of milliseconds,
reducing loudness and creating audible pumping effects.
The solution is multiple time constants where one set of time constants can be set to handle the fast peaks and
another to handle the average level of limiting. Fast transients will release in a faster less noticeable way and won't
punch holes in the sound in a way that single time constant limiters can. The secondary slower time constant circuit
will not have much effect on the audio waveform when hit with a transient because the higher attack time, generally in
the hundreds of milliseconds will not allow a build up of energy. In the case of a sustained envelope of audio above
the threshold the multiple time constant will attack as normal with the peak time constant but the sustained energy will
also charge the secondary slower circuit. When the audio energy falls away and the circuit goes into release the peak
decay will dominate until it reaches a point where it hands over to the slower secondary time constant for a slower
rate of decay. The illustrations show this to good effect, where transients have a fast release but multiple or sustained
transients build up energy in the secondary circuit which acts as a platform for the peak to release to. The secondary
circuit's platform can be thought of as the average level of limiting. Having this fast peak responding circuit ride on top
of the average circuit creates many advantages, limiter transparency, less chance of pumping and greater loudness.
By setting the time constants appropriately we can have the multiple time constant based detectors work as peak
handling, average handling or the optimum setting of a balance of the two.
The peak attack time should be set to the desired attack time required from that limiter. The range is 1-10 which
corresponds to 1 to 200mS on an exponential scale. The peak decay time should be set to the desired peak decay
time required for transients. The range is 1-10 which corresponds to a decay time of 10 to 1000mS.
The average attack time is perhaps the most important control in the dual time constant detector as it sets the
balance between peak and average energy in the detector. With smaller numbers more energy is transferred into the
average circuit and a higher platform level is created so more time will be spent releasing at the slower average rate.
Higher numbers offer slower attack times for the averaging part of the detector and this has the effect of lowering the
average platform level and allowing the peak part of the circuit to dominate with its faster release times.
The average decay time can usually be viewed as the nominal release time of the detector, similar to a standard
single time constant limiters release time.
Limiter control signals response to tone bursts
Peak time constants dominating
control due to a very high setting
of average attack
Peak time constants dominating
to a lesser degree due to high
setting of average attack
Peak time constants dominating to a
much lesser degree due to a lower
setting of average attack

SILVER Audio Processor 4Bmini User’s manual
Page 19/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
Limiter control signals response to program material
To recap, the peak attack time and average decay time play the same sort of role as that of a standard conventional
single time constant based limiter. The peak decay time sets the decay time for fast usually inaudible transients and
the average attack time sets the ratio of peak to average control and defines the position of the platform that the peak
circuit releases to.
The mixer
The post limiters mixer in the SILVER Audio Processor 4Bmini is not strictly a mixer but a band output level control
where small EQ changes can be made.
Be careful when making large EQ changes at this stage because there is no peak control prior to the clipping system.
It is easy to overload the clipping stages by setting these controls all to large positive values.
The control range for each band of +/- 3dB is purposely restricted for the above reasons.
Bass clipping
Most competent processors have a bass-clipper prior to the final clipper. The purpose of the bass-clipper is to keep
low frequency energy to a pre-determined level to allow for the summation of the other bands. Without the bass-
clipper the bass signal can push the mid and HF audio waveforms into the final clipper creating audible IM distortion,
the worst type of distortion. By restricting the bass to a certain level the mid and HF energy has its own reserved
space in the summated waveform and we reduce the likelihood of bass generated IM distortion.
The downside to bass clipping is you are restricting the bass to a lesser level than what it would be without it. The
upside is that moderate levels of bass clipping won't cause a large loss of bass loudness and should have minimal
audible artefacts.
When bass-clipper is being driven more aggressively you will start to notice generated distortion. This distortion can
be used to actually give the illusion of more bass, especially on smaller radios that are incapable of producing the
lower frequency fundamental bass waveform. This can be viewed as an upside of bass clipping. You need to decide
what level of bass clipping is acceptable to your format, both in creating room for summation from the other bands
and making the punch/distortion trade-off.
The final clipper
The final clipper, used in the FM processing path is a sophisticated highly over-sampled peak limiter that incorporates
distortion controlling techniques and has an embedded 15 kHz low-pass filter. This section of processing is the last
line of defence in the processing and is also the most critical part in the loudness/quality trade-off. While each of the
proceeding processing stages play a part in reducing the peak to average ratio of the audio waveform none has the
same effect on the peak to average ratio as the final clipper.
Peak time constants dominating
control due to a very high setting
of average attack
Peak time constants dominating
to a lesser degree due to a high
setting of average attack
Peak time constants dominating
to a much lesser degree due to a
lower setting of average attack

SILVER Audio Processor 4Bmini User’s manual
Page 20/38
Audemat-Aztec SA – Audemat-Aztec INC
web: www.audemat-aztec.com - e-mail: [e-mail]
Great care is needed in setting the final clipper drive control. This control needs to be adjusted carefully and only you
can make the decision on the balance between loudness and quality. As you increase the drive you will obviously
obtain more loudness but at the expense of distortion. There is a fine line between artistic distortion and distortion
that your listeners will find uncomfortable to listen to, especially for extended periods of time.
The final clipper now has an additional control to help reduce IMD distortion. This clipper hardness control is an
additional program dependent mechanism that helps to reduce distortion by analysing the level of IMD distortion and
dynamically adjusting time constants. The control is subtle and its range has been limited to restrict the amount of
control, preventing pumping and a loss of loudness which would undo what we want to use the clipper for which is
gaining loudness.
You may not notice the effect of this control on all program material. When adjusting the clipper hardness control we
recommend that you turn the final clipper drive up past the point that you have it set at. This will make the effect of
the hardness control much more obvious and allow you to find the setting that sounds best for your format. Once the
clipper hardness control is set you can back down the final clipper drive to the point that sounds best knowing that the
clipper hardness control has been set correctly to help keep the distortion down on difficult program material.
There's also an overshoot control for the clipper. Setting this control to lower numbers allows more overshoots
through to the composite clipper which trades off main clipper distortion for composite clipper distortion. Composite
clipper distortion can sound a touch nicer albeit at the expense of slight contamination of the output spectrum.
Composite clipper
The composite clipper in the SILVER Audio Processor 4Bmini's stereo encoder is highly over-sampled and allows
you to gain an extra dB or two of modulation loudness when using the multiplex output to drive your FM transmitter.
The range of the composite clipper is -0.5 to 2dB.
Here at AUDEMAT-AZTEC we prefer to use the final clipper to generate the required amount of loudness because
composite clipping introduces stereo crosstalk. When we do use the composite clipper we prefer to use small
amounts of no more than 1dB.
Auditioning individual stages of the SILVER Audio Processor 4Bmini processing
When setting up the SILVER Audio Processor 4Bmini it is sometimes useful to hear the effects of the adjustments on
that particular processing stage. By setting the other processing blocks up in a certain way you can make it easier to
hear the effects of the one you are adjusting.
For example, to listen to just the action of the multi-band limiters bypass the AGC stage and back down the multi-
band and final clipper drives. To hear just the clippers do the same back the drive down into the limiters to -6dB. You
can then up the drive into the clippers with the clipper drive controls and mixer controls to here just the clippers
working.