BW Broadcast DSPXtreme-FMHD Quick start guide

DSPXtreme-FMHD
Broadcast Audio Processor
Operational Manual
Version 1.30
www.bwbroadcast.com

Table Of Contents
2
Table Of Contents
Warranty 3
Safety 4
Introduction to the DSPXtreme 6
DSPXtreme connections 7
DSPXtreme meters 8
Quickstart 10
An introduction to audio processing 11
Source material quality 12
Pre-emphasis 12
Low pass filtering and output levels 12
The DSPXtreme and its processing structure 13
The processing path 13
Processing block diagram 15
The DSPXtreme menu structure 16
Processing paramters 17
Setting up the processing on the DSPXtreme 24
Getting the sound that you want 34
Managing presets 37
Factory presets 38
Remote control of the DSPXtreme 39
Remote trigger port 45
Clock based control 46
Specifications 47
Preset Sheet Appendix A

Warranty
3
Warranty
BW Broadcast warrants the mechanical and electronic components of this product to be free of defects in mate-
rial and workmanship for a period of one (1) year from the original date of purchase, in accordance with the war-
ranty regulations described below. If the product shows any defects within the specified warranty period that are
not due to normal wear and tear and/or improper handling by the user, BW Broadcast shall, at its sole discretion,
either repair or replace the product.
If the warranty claim proves to be justified, the product will be returned to the user freight prepaid.
Warranty claims other than those indicated above are expressly excluded.
Return authorisation number
To obtain warranty service, the buyer (or his authorized dealer) must call BW Broadcast during normal business
hours BEFORE returning the product. All inquiries must be accompanied by a description of the problem. BW
Broadcast will then issue a return authorization number.
Subsequently, the product must be returned in its original shipping carton, together with the return authorization
number to the address indicated by BW Broadcast. Shipments without freight prepaid will not be accepted.
Warranty regulations
Warranty services will be furnished only if the product is accompanied by a copy of the original retail dealer’s
invoice. Any product deemed eligible for repair or replacement by BW Broadcast under the terms of this war-
ranty will be repaired or replaced within 30 days of receipt of the product at BW Broadcast.
If the product needs to be modified or adapted in order to comply with applicable technical or safety standards
on a national or local level, in any country which is not the country for which the product was originally devel-
oped and manufactured, this modification/adaptation shall not be considered a defect in materials or workman-
ship. The warranty does not cover any such modification/adaptation, irrespective of whether it was carried out
properly or not. Under the terms of this warranty, BW Broadcast shall not be held responsible for any cost result-
ing from such a modification/adaptation.
Free inspections and maintenance/repair work are expressly excluded from this warranty, in particular, if caused
by improper handling of the product by the user. This also applies to defects caused by normal wear and tear, in
particular, of faders, potentiometers, keys/buttons and similar parts.
Damages/defects caused by the following conditions are not covered by this warranty:
Misuse, neglect or failure to operate the unit in compliance with the instructions given in BW Broadcast user or
service manuals.
Connection or operation of the unit in any way that does not comply with the technical or safety regulations
applicable in the country where the product is used.
Damages/defects caused by force majeure or any other condition that is beyond the control of BW Broadcast.
Any repair or opening of the unit carried out by unauthorized personnel (user included) will void the warranty.
If an inspection of the product by BW Broadcast shows that the defect in question is not covered by the war-
ranty, the inspection costs are payable by the customer.
Products which do not meet the terms of this warranty will be repaired exclusively at the buyer’s expense. BW
Broadcast will inform the buyer of any such circumstance. If the buyer fails to submit a written repair order within
6 weeks after notification, BW Broadcast will return the unit C.O.D. with a separate invoice for freight and pack-
ing. Such costs will also be invoiced separately when the buyer has sent in a written repair order.
Warranty transferability
This warranty is extended exclusively to the original buyer (customer of retail dealer) and is not transferable to
anyone who may subsequently purchase this product. No other person (retail dealer, etc.) shall be entitled to
give any warranty promise on behalf of BW Broadcast.
Claims for damages
Failure of BW Broadcast to provide proper warranty service shall not entitle the buyer to claim (consequential)
damages. In no event shall the liability of BW Broadcast exceed the invoiced value of the product.
Other warranty rights and national law
This warranty does not exclude or limit the buyer’s statutory rights provided by national law, in particular, any
such rights against the seller that arise from a legally effective purchase contract. The warranty regulations men-
tioned herein are applicable unless they constitute an infringement of national warranty law.

Safety Instructions
4
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.
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
time.
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 mainte-
nance instructions in the accompanying
literature. Read the manual.
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.
Safety InStructIonS

Safety Instructions
5
Object and Liquid Entry:
Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through open-
ings.
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: 93/68/EEC (CE Marking); 73/23/EEC (Safety – low voltage directive);
2004/108/EC (electromagnetic compatibility). Conformity is declared to those standards:
EN50081-1, EN50082-1.
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 15 FCC Rules),
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 emis-
sions set out in the Radio Interference Regulations of the Canadian Department of Communications.
Le present appareil numerique n'emet pas de bruits radioelectriques depassant les limits applicables
aux brouillage radioelectrique edicte par le ministere des Communications de Canada.

Introduction
6
IntroductIon tothe dSPXtreme
The BW Broadcast DSPXtreme is a new generation of digital audio signal processor that can be used to process
audio ready for FM and digital broadcasting such as HD Radio, DAB or internet radio.
Using the latest multi-band DSP technology the DSPXtreme offers a versatile and powerful tool in creating a loud
punchy on-air presence.
The DSPXtreme 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 DSPXtreme to
produce equvivalent results to other processors in the market but in a 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 DSPXtreme is driven by fast ARM7 and ARM9 micro-controllers which control an array of specialised ana-
logue and digital circuits. These include 24-bit A/D and D/A converters, analogue level control circuitry, 24 x 24
bit DSP's, an ethernet port, an RS232 port, a trigger port, two 3" TFT LCD screens (one of which is touch sensi-
tive), three sample rate converters, a headphone jack 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 pre-
sented to the RMS levelling block. The four band windowed RMS leveller corrects for input level variations and
also improves consistency. The output of the AGC feeds the EQ and bass enhancement sections before being
split into six bands by linear phase time aligned filters. The six bands are processed by dynamic audio limiters
on each band. The unique dual processing paths allow simultaneous processing for FM and digital radio. Look-
ahead limiting and 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 touch-screen control system and a separate metering screen, 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.
With superb specifications and big and loud on-air presence, the DSPXtreme is a clear winner.
Dynamic, fresh & innovative...
... The DSPXtreme

Connections
7
REMOTE
AES/EBU
EDIT
UP
LOAD
SAVE
DSPXtra
OUTPUT
PROCESS
INPUT
LI MITERS OUTPUT
ARIANE LEVELERINPUT
DSPXtra
100
90 80 70
60
50
40 30 20 10
PILOT
00
-3 -6 -9
-12 -15 -18 -21 -24 -27 -30 -33 -36
-39
-42
-1 -2 -3 -4 -5 -6 -7 -8 -9
-10 -11 -12 -15 -18
-6 -4 -2 -0
+2 +4 +6 +8
+10 +12 +14 +16 +18
GATE
CLIP GATE
+18 +16 +14 +12 +10 +8 +6
+4
+2 -0 -2 -4 -6
HOLD
-2 -4 -6 -8
-10 -12 -14 -16 -18 -20 -22 -24
HOLD -2 -4 -6 -8 -10 -12 -14 -16 -18 -20 -22 -24
123456
dB dB dB %
RL RL
MPX
+ / L - / R
IDR IDR
1 2 3 4
+ / L - / R + / L - / R + / L - / R
+20 +20
DSPXtreme back panel connections
DSPXtreme- F M
ANALOGUE
INPUTS
SCA
INPUT
MPX 1 & 2
OUTPUTS
PILOT
OUTPUT
SYNC
INPUT
AES / EBU
INPUT
RS232
&
TRIGGER PORT
LAN
PORT
GND
LIFT
MAINS POWER INPUTANALOGUE
OUTPUTS
AES / EBU
OUTPUTS
MPX2 LEVEL
ADJUST

Meters
8
dSPXtreme meterS
The DSPXtreme has a dedicated LCD screen on the left displaying instant IO and processing metering. You can
switch from processing metering to IO metering (and back) with the button located on the bottom-right side of
the touch-screen.
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 DSPXtreme. If we were to have used the same scale as the input
metering we would not see a lot of activity on the LED’s, with all of the LEDS on most of the time.
The multiplex output metering represents the composite outputs peak level. This is a representation of the out-
put 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 while a floating ‘peak hold’ dot
tracks the absolute value of the waveform
G/R metering - four band AGC
The gain reduction/boost meters show the gain reduction and gating status of the multi-band AGC stage. The
range shown is -6dB to +20dB in 2dB steps with GATE or HOLD indicated by red color of the meters.
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 or you are using the DSPX to process two seperate mono feeds.
GR meters
Change from I/O metering and GR metering with this button

Meters
9
G/R metering - six band limiter
The six band limiter displays gain reduction from 0dB to -24dB in 2dB 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 or you are using the DSPXtreme to process two separate mono
feeds.

Quickstart
10
QuIck Start
1. Install the processor into the rack.
2. Connect AC power to the unit, and turn on the power.
3. Connect the analogue and / or digital audio inputs.
4. Select the analogue or digital input as the source of the processing with the 'INPUT SELECTION' parameter
which can be found in the 'INPUT' menu. Apply audio and observe the input meters. For analogue inputs, adjust
the 'INPUT’ menus 'INPUT LEVEL CONTROL' so that the input meters do not clip. We recommend setting the
mixing board or audio source to full level output (even clipping) prior to adjusting this control. This ensures that
the processor's A/D converter will not clip under any conditions.
fm uSe:
5. Select the pre-emphasis setting for your region (input menu). 75 µs for USA and 50 µs for Europe.
6. Connect the audio outputs as required and set the output level and de-emphasis settings for the analogue and
digital outputs to match any external links, stereo encoders, or transmitters that require left and right audio inputs
or an AES/EBU input. Make sure the output mode is set to FM for the output in question.
7. If you are using the MPX Output (preferred), navigate to the ‘STEREO’ menu and adjust the ‘MPX OUTPUT
LEVEL’ to match the transmitter (or link device) that follows the processir. Adjust for 100% modulation with audio.
8. Select a factory preset (see Managing presets).
dr uSe (daB/hd radIo/drm/fmeXtra/StreamInG):
5. Set the pre-emphasis setting to OFF from the input menu.
6. Connect the audio outputs as required and set the de-emphasis for the analogue and digital outputs to OFF,
MODE to DR and set the output levels for the analogue and digital outputs to match the equipment that the proc-
essor is connected to.
7. Select a factory preset (see Managing presets).
8. Navigate to the look-ahead menu and adjust the SHELF EQ control to suit. This sets the brightness of the DR
outputs sound.
dual uSe: fm + daB/hd radIo/drm/fmeXtra/StreamInG:
5. Select the FM pre-emphasis setting for your region (input menu). 75 µs for USA and 50 µs for Europe.
6. Connect the audio outputs as required and set the de-emphasis for the analogue and digital outputs to OFF,
MODE to DR and set the output levels for the analogue and/or digital outputs to match the DR equipment that
the processor is connected to (EG: codec/computer).
7. If you are using the MPX Output, (preferred) navigate to the ‘STEREO’ menu and adjust the MPX ‘LEVEL’
Output to match the transmitter (or link device) that follows the processor. If one of the analogue or digital out-
puts needs to feed another piece of equipment that cant take a composite MPX input then make sure you select
FM mode for that output with the appropriate de-emphasis setting to match the corresponding piece of a equip-
ment in the FM chain.
8. Select a factory preset (see Managing presets).
9. Navigate to the look-ahead menu and adjust the SHELF EQ control to suit. This sets the brightness of the DR
outputs sound.
NOTE: The front panel headphone jack connects to the analogue outputs so the sound may be excessively
bright if pre-emphasis is engaged and de-emphasis on the analogue outputs is set to off.

Introduction To Audio Processing
11
IntroductIon toaudIo 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 process-
ing 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 wave-
form, 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 wave-
form. 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 pro-
duce 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.
Look-ahead limiting
Often used instead of a clipper in systems that feed bit rate reducing audio codecs, look-ahead limiting exam-
ines the audio waveform and prepares a gain control signal in advance of the delayed audio waveform arriving.
This prevents overshoots while minimising distortion. A look-ahead limiter behaves in the same way as a soft
clipper. Competent look-ahead limiters will usually be of the multi-band variety.

Source Quality And Pre-emphasis
12
Source materIal QualIty
The DSPXtreme has the ability to substantially improve the quality of your ON-AIR broadcast. However the
DSPXtreme can only work with what you provide it. The best performance will be obtained when the DSPXtreme
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 DSPXtreme.
We strongly advise against the use of MP3's and other compressed audio formats for audio storage. If you must
use compressed audio we advise rates of 256 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 DSPXtreme can violate the frequency masking characteristics of the bit reduction process,
creating distortion that was inaudible prior to the DSPXtreme processing.
Pre-emPhaSIS
If you are using the DSPXtreme to process for FM broadcast you will need to enable the pre-emphasis filter in
the DSPXtreme. Even though your STL or transmitter may contain pre-emphasis we recommend disabling it, let-
ting the DSPXtreme handle the pre-emphasis for the transmission system. The DSPXtreme uses sophisticated
processing methods to limit the high frequency energy of the pre-emphasis curve while maintaining a 'bright'
sound. Using de-emphasis and then pre-emphasising again will only degrade performance and possibly casue
overshoots, resulting in lower average deviation.
The exception to the rule is when the DSPXtreme is feeding discrete left and right outs to a compressed audio
STL. Bit rate reduction codec's do not cope with pre-emphasis very gracefully and artifacts will be generated.
The best option in this case is to de-emphasise the output of the DSPXtreme prior to the STL system. At the
transmitter site the pre-emphasis can be enabled in the transmitter to restore the processed signal back to nor-
mal prior to transmission.
The best solution is always to locate the processor at the transmission site. This way overshoots are minimised
and quality is maintained.
fInal loWPaSS fIlterInG
The DSPXtreme has a built-in lowpass filter in the HD path, adjustable from 4kHz to 20kHz that limits the
amount of high-end spectrum and energy delivered to the codec. Codecs are especially sensitive at higher fre-
quencies, where most of the annoying artifacts like "metallic high-end", "phasing" or "squishing" occur. Reducing
the amount of high-end puts less stress on the codec and can lower the amount of codec-induced artifacts. The
actual setting will depend on the type of codec and the bitrate used. Lower bitrates require more audio informa-
tion to be thrown away by the codec, so lower filter settings would have to be employed to reduce artifacts. If
you're using higher bitrates, you can set lowpass filter more towards 20kHz without causing excessive artifacts.
As a rule, low pass filter frequency should be set at or below codec's half sample rate frequency (i.e. 15 kHz for
codec running at 32 kHz sample rate).
outPut level SettInG
DSPXtreme has an adjustable output level that can be set to drive subsequent equipment with full scale digital
audio level. However, caution should be made here if the following equipment using perceptual coding (codec)
does not take into account internal codec overshoots. Overshoots can occur in the codec when presented with
the tightly peak-controlled audio such as the one produced by DSPXtreme. If the codec does not provide head-
room internally, these overshoots would be clipped leading to increased distortion and artifacts. Therefore we
would advise setting the output level of the processor lower than 0.0 dBfs to leave the headroom in the trans-
mission system for codec overshoots. The actual output level setting would depend on the amount of codec
overshoot occurring in the system, which depends on the type of codec used and how aggressively you're
processing audio with DSPXtreme. Generally, codecs that use spectral band replication (SBR) technology (such
as HE-AAC (aacPlus), iBiquity HDC, etc.) have more overshoots than the codecs that don't.
If you're using DSPXtreme to process for HD Radio (IBOC), DAB+, DRM+ or web-streaming, a good starting
point to set the output level would be -2.0 dBfs. This would ensure maximum audio quality at the expense of
slightly reduced level (which the users can always compensate with volume control on their radios).

Processing Structure
13
the dSPXtreme and ItS ProceSSInG Structure
The DSPXtreme broadcast audio processor can be used for processing audio prior to broadcast on FM and
digital radio services. Digital radio encompasses DAB, HD Radio (IBOC) and other radio based broadcasting as
well as internet radio, also known as streaming. The DSPXtreme can also be used effectively for audio post pro-
duction and mastering, ideal for giving CD’s that HOT sound. It is also possible to use the DSPXtreme for other
audio level control/equalization applications such as night clubs and bands. However, this manual will only be
referring to the use of the DSPXtreme for FM and digital radio processing.
Before we discuss the processing structure in full we would like to tell you a little about the final peak limiting
stages of the DSPXtreme. The DSPXtreme employs dual output paths for peak control. Your processing applica-
tion may need you to configure the DSPXtreme in a certain way. Selecting the wrong output path and or not con-
figuring the other settings that affect it may seriously downgrade your audio quality.
The first peak control path is known as 'FM' as it is typically used when processing signals for FM broadcast.
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 char-
acteristics 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 second peak control path is known as 'DR' (digital radio) and is the desired method of peak processing
when the output feeds a codec that employs ‘bit rate reduction compression techniques’. The 'DR' path employs
look-ahead limiting as opposed to clipping. Look-ahead limiting produces less artifacts than conventional clip-
ping, so will reproduce the original audio more accurately with less bits of digital information because it is not
wasting bits encoding non-audible clipping artifacts. Look-ahead limiting produces less harmonic distortion but
produces IM distortion if over driven resulting in a packed, busy sound.
The DSPXtreme can be configured so that each peak control path can be routed to either of the digital or ana-
logue outputs. The stereo encoder is always fed with the 'FM' path. One popular configuration for FM radio sta-
tions is to use the DSPXtreme to process their FM broadcast and to have the 'DR' path feed their digital radio
service or web stream, each service optimally processed for that medium. We suggest that digital radio services
always use the 'DR' path but you are free to experiment with both options.
the ProceSSInG Path
Input selection and conditioning
The DSPXtreme offers the user input selection, gain control and a selection from a range of stereo/mono
options. The audio is then routed through defeatable high pass, phase rotating and pre-emphasis filters.
A silence detector provides automatic primary to secondary input failure switching.
AGC xover
The DSPXtreme employs an adjustable gentle-slope digital IIR filtering to split the audio spectrum into 4
bands while maintaining sonic transparency.
Multi-band RMS leveller
For a transparent input levelling function, the DSPXtreme employs an RMS detected multi-band leveller. With
a windowing gating concept, this four band AGC improves consistency and presents a uniform audio signal to
the following stages.
Bass enhancement
The DSPXtreme offers three forms of bass enhancement:
1. A 12dB/Octave shelving filter with up to 12dB of gain.
2. Bass tune control.
3. A peaking filter that can be set to provide up to 6dB of gain on 1 of four frequencies with a choice of 4
Q's. This can be thought of as a simple bass parametric.
Limiter xover
The DSPXtreme employs fixed linear-phase time aligned digital FIR filtering to split the audio spectrum into 6
bands while maintaining sonic transparency.
Multi-band Limiters
Each band has its own dynamic peak limiter. Multiple time constant based detectors with built in adjustable
hold and delay functions significantly reduce distortion.

Processing Structure
14
Mixer
The six bands are 'virtually' mixed together at this stage. In truth, the six bands have become three. The
three bands are fed off into the two peak processing paths.
Distortion controlled clippers (PEAK CONTROL PATH 1)
The DSPXtreme clipping algorithms peak limit (clip) and linear phase filter the audio in three bands for maxi-
mum distortion control before being fed to the final clipper stages.
Look-ahead limiter (PEAK CONTROL PATH 2)
The DSPXtreme look-ahead limiter is one of the most sophisticated available in a broadcast processor.
Processing is performed in three bands for maximum transparency and clarity. A cut shelving filter is provided
to compensate for the effect of pre-emphasis when the DSPXtreme is used to process FM signals at the
same time.
Delay
The DSPXtreme has an adjustable time delay for the MPX output that can be optionally selected for the ana-
log and digital outputs as well. Delay should only be used if you're simulcasting analog FM and HD Radio
(IBOC) and want synchronisation between these two transmission for perfect blends in the receiver. Separate
menu allows adjustment of the delay up to 11 seconds, with coarse, medium and sample-accurate fine con-
trol. If you're not using HD Radio and transmitting only analog FM, leave the delay controls at 0 settings.
Output selection, processing and routing
The DSPXtreme allows the user to select where each processing path is routed to and provides output level
controls. There are four choices for digital outputs to choose from - FM path, delayed FM path, DR path and
monitor. For analog outputs the options are FM path, delayed FM path, same as AES2 and monitor.
The monitor output is a lower latency (delay) path that bypasses the final clipper stages and reduces delay
by more than 4 ms. This can be used to help with talent (DJ's) who can not get to grips with the delay of the
main processing path. This output if selected should only be used as a studio monitor signal and should not
be used ‘on the air’ as the peak clipping stage in the monitor processing path is not over-sampled or anti-ali-
ased.
A de-emphasis option is provided on both the analogue and digital outputs. The digital output sample rate
can also be configured to a variety of settings.
The analog and MPX outputs will be affected by the ITU limiter, if it is engaged. The purpose of this limiter is
to comply with the ITU BS.412 standard. The standard calls for limiting of the power of the composite signal
being broadcast. When activated, the ITU limiter will drastically reduce the loudness of your signal.
Stereo encoder
The DSPXtreme's DSP stereo encoder takes its inputs from the FM path of peak processing. The audio fed
to the stereo encoder does not pass through any de-emphasis circuits and is always delayed by the amount
set in the Delay menu. 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.

Block Diagram
15
ANALOG
DIGITAL
A/D
SRC
HPF
INPUT
LPF
BPF BPF HPF
P.R.
BASS
SHELF
BASS PEAK
PRE
LOW
LIM
LMID
LIM
HMID
LIM
MB LIM
MID
LIM
LPF
BASS CLIP
BPF
MID CLIP
HPF
HF CLIP
N-1
DELAY
ATTACK RELEASE
LOOKAHEAD
SOFT HARD
N-1
DELAY
ATTACK RELEASE
LOOKAHEAD (DR MODE)
N-1
DELAY
ATTACK RELEASE
N-1
DELAY
ATTACK RELEASE
LPF
15
19
OUTPUT MPX
PILOT OUT
D/A
MPX
COMP
CLIP PILOT
SCA IN
MPX OUT
DSPXtreme PROCESSING BLOCK DIAGRAM
MON
DR Delayed FM
FM
LOW
AGC
MID1
AGC
HIGH
AGC
MB AGC
LPF
BPF BPF HPF
MID2
AGC
SHIGH
LIM
HIGH
LIM
BPF BPF
LPF
FAT
SLIM
LPF
MED
N-1
DELAY
MON
AES2 Delayed FM
FM
DE
ANALOG
D/A
DIGITAL 2
SRC
DE
DIGITAL 1
SRC
DE SYNC
MON
AES2 Delayed FM
FM
ITU
LIMIT

Menu Structure
16
AES1 OUTPUT LEVEL
AES2 OUTPUT LEVEL
AES1 RATE
AES2 RATE
AES1 DE-EMPHASIS
AES2 DE-EMPHASIS
MENU: STEREO
LEVEL
PILOT LEVEL
PILOT PROTECTION
ITU LIMITER
19K REFERENCE OUT
MENU : DELAY
DELAY COURSE (s)
DELAY MEDIUM (ms)
DELAY FINE (samples)
MENU: SCHEDULE (X) REPRESENTS 0-7
TIME
DAYPARTING ON/OFF
TIME CALIBRATION
DAYPARTS 1-4
DP(X) ON/OFF
DP(X) START TIME
DP(X) TIME ON (LENGTH)
DAYPARTS 5-8
DP(X) ON/OFF
DP(X) START TIME
DP(X) TIME ON (LENGTH)
MENU: SYSTEM
TRIGGER PORT
REMOTE SOURCE
MENU: LAN CONFIG
IP ADDRESS
DEFAULT GATEWAY
SUBNET MASK
MAC ADDRESS
PORT NUMBER
MENU: ABOUT
VERSION
CONCEPT
HARDWARE
CTRL SYS.
PROCESSING
BOOTLOAD
menu Structure
MENU: INPUT
INPUT SOURCE
STEREO MODE
ANALOG INPUT LEVEL
RIGHT TRIM
INPUT FAIL SWITCH
HIGH PASS FILTER
PHASE ROTATOR
PRE-EMPHASIS
MENU: PROCESS
USER LEVEL
MENU: MULTI-BAND AGC
AGC ON/OFF
WINDOW GATING
GATE
B1<2 COUPLE
B3>4 COUPLE
CHANNEL COUPLE
MENUS: BAND 1-4
ATTACK
RELEASE
MENU: XOVER
B1-2 XOVER
B2-3 XOVER
B3-4 XOVER
MENU: ENHANCE
DEEP BASS
BASS TUNE
BASS PEAK GAIN
BASS PEAK FREQ
BASS PEAK Q
MENU: MULTI-BAND LIMITER
MASTER LIMITER DRIVE
MENUS: BANDS 1-6
DRIVE
THRESHOLD
LIMITER ATTACK
LIMITER DECAY
COMPRESSOR ATTACK
COMPRESSOR DECAY
HOLD
DELAY
MENU: MIXER
B1 MIX LEVEL
B2 MIX LEVEL
B3 MIX LEVEL
B4 MIX LEVEL
B5 MIX LEVEL
B6 MIX LEVEL
MENU: LOOKAHEAD LIMITER
DRIVE
SHELF EQ
LOW ATTACK
LOW DECAY
MID ATTACK
MID DECAY
HIGH ATTACK
HIGH DECAY
MENU: CLIPPER
MULTI-BAND CLIP DRIVE
BASS CLIP LEVEL
BASS CLIP TYPE
BASS CLIP SHAPE
MID CLIP LEVEL
HF CLIP LEVEL
HF CLIPPING
MAIN CLIP DRIVE
COMPOSITE CLIP
ADVNACED:
MAIN CLIP DISTORTION CONTROL
MAIN CLIP FINESSE
OVERSHOOT CONTROL
ITU LIMITER
MENU: OUTPUT
MENU: ANALOG
OUTPUT LEVEL
MODE
DE-EMPHASIS
HEADPHONE LEVEL
MENU: DIGITAL
AES1 MODE
AES2 MODE

Processing Parameters
17
ProceSSInG ParameterS
User Level: This parameter allows you to select between beginner and advanced modes. Beginner mode
restricts access to certain menus and controls.
The 'INPUT' menu contains all of the options and parameters 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.
Input Mode: This parameter allows you to select different mono options as well as the default Stereo option.
There is also the ability to swap the left/right channels.
Analogue Input A/D Clip Level: Allows you to set the analogue input level with reference to the
DSPXtreme's A/D converter clip celeing. This would normally be set to +24dBu if driving the DSPXtreme
from professional audio equipment. This would translate to the wide-band AGC being driven to 12dB gain
reduction by a 0VU (+4dBu) audio signal. If the input level is low, you may decrease this parameter to bring
the level up and reduce signal-to-noise ratio. Make sure that the input audio meters NEVER show clipping
under any conditions.
Right Trim: This parameter allows you to adjust the right channels gain in small increments to BALANCE
out any small gain discrepancies between the left and right channels. The range is +/- 3dB.
Input Fail Switch: This parameter allows you to turn on the silence detection system and specify a silence
time. When enabled this parameter will switch the input source from the primary to the secondary source
when a predetermined length of silence occurs.
High pass filter: This parameter allows you to select from a variety of high pass filters. You can select from
20Hz, 30Hz, 40Hz, 50Hz and 60Hz. You also have the ability to bypass the high pass filter with the 'OFF'
option. The high pass filter can be used to reduce rumble on vinyl or can be effective in removing low fre-
quency energy that could otherwise cause carrier shift (AFC LOOP) problems in older FM transmitters. We
suggest you leave the high pass filter off unless you have a reason to turn it on.
Phase Rotator: This parameter if enabled will help to reduce vocal distortion in aggressive presets by reduc-
ing asymmetry in the voice which would otherwise put more workload on the clipping stages. We recommend
enabling this option if you want competitive loudness; otherwise leave it off as the phase rotation process
does colour the sound slightly, although this coloration is often used for artistic effect.
Pre-emphasis: This parameter allows you to activate pre-emphasis when the DSPXtreme is being used to
process for FM broadcast. The available options are 50 µs, 75 µs and OFF.
The 'PROCESS' menu allows access to all of the processing blocks that make up the DSPXtreme. There
are only sub-menus inside the 'PROCESS' menu. The submenus are laid out in the same configuration
as the signal path through the DSPXtreme.
The multi-band AGC in the DSPXtreme like any automatic gain control device is designed to correct input
level fluctuations and provide a consistent level to the other DSPXtreme processing blocks that follow it. The
AGC in the DSPXtreme is designed to operate in an undetectable, unobtrusive manner similar to a trained
operator controlling a mixing desk.
'AGC BYPASS' If you will be using an outboard AGC or if a processor is placed on the other side of an
studio-to-transmitter link with the AGC unit being used in front of the link, AGC in DSPXtreme can be
bypass in order to avoid "figthing" with the preceeding AGC.
'WINDOW GATING' A separate gating control from the silence gate, the window gate slows down the
attack and decay rates when the audio waveforms level has not moved outside of a pre-defined window,
set by the window gating control. The window can be set between 1 and 6dB or the gate function can be
disabled by setting the control to OFF. The window gating prevents unnecessary gain control when the
audio waveform is already well defined or having a low peak to average ratio. The window gating also
allows faster rates to be used without the audible effects normally associated with the faster rates.

Processing Parameters
18
'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 level set by the RTR LEVEL control and to move towards that level at the rate set by
the RTR speed control.
'B1<B2 COUPLING' Sets the amount of coupling between the band 2 gain reduction system and the
band 1 gain reduction system. This is adjustable from 0dB to 15dB with an option for no coupling (OFF)
This coupling is uni-directional, band 2 into 1.
'B3<B4 COUPLING' Sets the amount of coupling between the band 3 gain reduction system and the
band 4 gain reduction system. This is adjustable from 0dB to 15dB with an option for no coupling (OFF)
This coupling is uni-directional, band 3 into 4.
'CHANNEL COUPLING' Couples the Left channel control system to the Right channel control system
so that the either channels gain reduction can not increase any more than a certain dB above the other
channel gain reduction, helping to preserve stereo balance. This is adjustable from 0dB to 15dB with an
option for no coupling (OFF).
'B1-4'
'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 100 ms to 30 s 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 100
ms to 30 s on a semi-exponential scale.
'XOVER' menu provides the user with another tool in creating their sonic signature.
'B1-2 XOVER' Sets the B1-2 Xover point to one of five frequencies.
'B2-3 XOVER' Sets the B2-3 Xover point to one of five frequencies.
'B3-4 XOVER' Sets the B3-4 Xover point to one of five frequencies.
The 'ENHANCE' menu contains the low frequency enhancement filters which are used to provide bass
enhancement and help overcome the bass reduction effect of multi-band compression.
‘DEEP BASS’ A 12dB/octave shelving bass equalizer that provides between 0 and 12dB of bass boost.
Use this control with caution as too much low frequency bass boost can cause loss of mid-bass because
the very low frequency bass, often inaudible on many receivers dominates the gain reduction of the
BAND 1 AGC and limiter. A setting of 6dB is a good compromise and starting point.
'BASS TUNE' Adjusts multiple points in the dynamics control system, allowing you to control the 'flavour'
of the bass.
‘PEAKING BASS EQUALIZER’ 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.
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 xover that generates the six bands of
audio. This control allows a +/- 6dB adjustment.
'B1-6'
'DRIVE' Controls the drive into the limiter. The drive can be increased or decreased by up to 12dB.
'THRESHOLD' Sets the limiter threshold. If audio is below threshold, there will be no gain reduction.
Audio signals that go above will be attenuated. Threshold level can be varied between -6dB to +6dB

Processing Parameters
19
in 0.5dB steps.
'LIMITER 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 1 ms to
200 ms on a semi-exponential scale.
'LIMITER 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 corre-
sponds to 10 ms to 1000 ms on a semi-exponential scale.
'COMPRESSOR 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.
'COMPRESSOR 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 200 ms to 5000 ms on a semi-exponential scale.
'HOLD THRESHOLD' The HOLD function prevents 'suck-up' of noise and helps reduce IM distortion
by allowing the limiter to rest 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 HOLD can also be switched off.
'DELAY' This function provides a delay before the peak decay circuit is activated. This can be used
to reduce distortion when faster release time constants are employed by reducing the gain hunting
between neighbouring transients. The range available is 1 ms - 500 ms 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. A solo mode is provided to aid in the setting up of parameters.
BAND 1 MIX: -3dB to +3dB of level adjustment is available.
BAND 2 MIX: -3dB to +3dB of level adjustment is available.
BAND 3 MIX: -3dB to +3dB of level adjustment is available.
BAND 4 MIX: -3dB to +3dB of level adjustment is available.
BAND 5 MIX: -3dB to +3dB of level adjustment is available.
BAND 6 MIX: -3dB to +3dB of level adjustment is available.
The 'LOOKAHEAD' menu contains the controls that affect the look-ahead limiter which serves as the peak
limiting method for the DR mode of operation.
'DRIVE' Controls the drive into the look-ahead limiter.
'SHELF EQ' A high frequency shelving filter with a variable cut response. Adjustable over a range of 0-17
which corresponds to a cut of 0dB to -17dB measured at 15 KHz. This low-pass shelving filter is used to
compensate for the effects of pre-emphasis when the DSPXtreme has pre-emphasis enabled (FM appli-
cations). The shelf control can also be used to tame high frequency energy when the box is configured
for DR applications and no pre-emphasis is enabled.
'LP FILTER' A high frequency filter adjustable over a range of 4-20 kHz. This control can be used to tame
the artifacts of subsequent perceptal coding, especially when used with very low bitrates.
'LOW ATTACK' Controls the average attack rate of the B1-2 look-ahead limiter. This defines the energy
distributed into the secondary time constant circuit. The attack time can be varied between 1 and 10
which corresponds to 10 ms to 2000 ms on a semi-exponential scale.
'LOW DECAY' Controls the average decay rate of the B1-2 look-ahead limiter. This defines the decay
rate of the secondary time constant circuit. The decay time can be varied between 1 and 10 which corre-
sponds to 10 ms to 2000 ms on a semi-exponential scale.

Processing Parameters
20
'MID ATTACK' Controls the average attack rate of the B3 look-ahead limiter. This defines the energy dis-
tributed into the secondary time constant circuit. The attack time can be varied between 1 and 10 which
corresponds to 10 ms to 2000 ms on a semi-exponential scale.
'MID DECAY' Controls the average decay rate of the B3 look-ahead limiter. This defines the decay rate of
the secondary time constant circuit. The decay time can be varied between 1 and 10 which corresponds
to 10 ms to 2000 ms on a semi-exponential scale.
'HIGH ATTACK' Controls the average attack rate of the B4 look-ahead limiter. This defines the energy
distributed into the secondary time constant circuit. The attack time can be varied between 1 and 10
which corresponds to 10 ms to 2000 ms on a semi-exponential scale.
'HIGH DECAY' Controls the average decay rate of the B4 look-ahead limiter. This defines the decay rate
of the secondary time constant circuit. The decay time can be varied between 1 and 10 which corre-
sponds to 10 ms to 2000 ms on a semi-exponential scale.
The 'CLIPPER' menu contains the clipping controls that form the final peak limiting stages of the
DSPXtreme’s FM mode of operation.
'MULTI-BAND CLIP DRIVE' Controls the drive into the multi-band clippers that precede the main clipper.
Adjustable over a -6dB to +6dB range.
'BASS CLIP LEVEL' 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.
'BASS CLIP TYPE' Controls the action of the bass clipper. Hard provides maximum punch by using
the filtered harmonics of the clipped bass signal to create the illusion of more bass. Soft employs look-
ahead techniques to dynamically control the bass clip level. This creates a more natural soft clip action
which may be preferred for some formats. The soft clip option can raise the bass to 100% modulation as
opposed to the hard option which does not allow bass to exceed the bass clip threshold. The soft option
will add almost 5 ms extra delay to the audio path.
'BASS CLIP SHAPE' Controls the shape of the bass clip transition. Fat is square topped traditional hard
clipping and med and slim smooth out the clipping transition slightly and help reduce distortion a little.
'MID CLIP LEVEL' Controls the clip level of band 3. The clip level range is -12dB to 0dB referenced to
the main clippers output level.
'HF CLIP LEVEL' Controls the clip level of band 4. The clip level range is -12dB to 0dB referenced to the
main clippers output level.
'HF CLIPPLING' This control redistributes high frequency peak control between the six band limiters and
the HF clipper. The range is 0 to 17 with 0 equating to full control by the limiters and higher numbers pro-
ducing 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.
'COMPOSITE CLIP Controls the drive into the composite clipper which effectively sets the amount of
composite clipping. The range of composite clipping is -0.5dB to +2dB.
The 'ADVANCE' menu contains the controls that fine tune final clipping
'MAIN CLIPPER DISTORTION CONTROL' Controls the distortion reduction effect of the distortion
controller in the DSPXtreme's back-end clipping system. The range of multi-band clipping control is
1 to 10. Setting this control to 1 virtually defeats the mechanism, while higher numbers will progres-
sively make the mechanism work on reducing the distortion and keeping the clarity and cleanliness of
your on-air sound.
'MAIN CLIPPER FINESSE' Another distortion controlling mechanism that helps to reduce IMD in
the final clipper. The range is 1-10 with 10 producing the most distortion control. A setting of 1 effec-
tively bypasses this control and makes the clipper perform similar to the one on V1. This control is
very subtle and may not appear to do a lot on some program material while a lot on others. HINT: