BW Broadcast DSPXtra-FM Operational Manual
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BW Broadcast DSPXtra-FM Operational Manual

Rms leveller broadcast audio processor
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DSPXtra
incorporating the
RMS Leveller
Broadcast Audio Processor
Operational Manual
Version 2.30
www.bwbroadcast.com

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Summary of Contents for BW Broadcast DSPXtra-FM

  • Page 1 DSPXtra incorporating the RMS Leveller Broadcast Audio Processor Operational Manual Version 2.30 www.bwbroadcast.com...

  • Page 2: Table Of Contents

    Processing block diagram User levels The DSPXtra-FM menu system overview The menu structure Processing parameters Setting up the processing on the DSPXtra-FM Getting the sound that you want Managing presets Factory presets Remote control of the DSPXtra-FM Remote trigger port...

  • Page 3: Warranty

    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.

  • Page 4: Safety Instructions

    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. Page 4 BW Broadcast Technical Manual...
  • Page 5 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. Page 5 BW Broadcast Technical Manual...

  • Page 6: Forward

    X represents many things. DSPX was born. 18 months later and it was time for a more advanced model. We bring you, the DSPXtra-FM. The Xtra is the result of continued research and development and the inclusion of the award winning Ariane RMS leveller con- cept from TransLanTech sound of New York city.

  • Page 7: Introduction To The Dspx Tra-Fm

    Using the latest multi-band DSP technology the DSPXtra-FM offers a versatile and powerful tool in creating a loud punchy on-air presence. The DSPXtra-FM 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 DSPXtra-FM to produce similar results to other processors in the market but in a simpler more cost effective way.

  • Page 8: Dspxtra-Fm Connections

    Connections...

  • Page 9: Dspxtra-Fm Meters

    SAVE PRESET ENTER NEW PASSCODE U1=BASS FACE 3779 U2=ROUND FACE U3=CLASSICAL 3 DONE NAME PRESET U2 dSPX EtErS MY PRESET 3 DONE The DSPXtra has several hundred LEDS that provide ‘always on’ instant IO and processing metering. INPUT ARIANE LEVELER L IMITERS OUTPUT CLIP...

  • Page 10: Dspxtra-Fm Status Leds

    The DSPXtra-FM front panel contains three status LEDS. HOLD CLIP CLIP REMOTE: Indicates that the DSPXtra-FM is currently talking to a remote computer. This will flash DSPX REMOTE during an update of the firmware or remote control with the remote control application.

  • Page 11: Quickstart

    UICk 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.

  • Page 12: An Introduction To Audio Processing

    ntrOdUCtIOn UdIO rOCESSInG 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.

  • Page 13: Ariane Multiband Leveller

    EChnICaL and thE hILOSOPhICaL aCkGrOUnd OF rIanE IGItaL UdIO EvELLEr (Or, Why Automatic Level Control Doesn’t Have to be Processing’s Weak Link!) What is Levelling? Levelling is the automatic process of reducing the long-term dynamic variations in level of an audio source. Also called Automatic Gain Control or, AGC.
  • Page 14 tions create the ‘flavour’ of the sound, and help distinguish, for example, a flute from an oboe. Details ‘live’ in the fast variations that are mostly confined to the peaks, so preserving the fast variations while making level correc- tions only relatively slowly maintains this audio flavour. In the overall scheme of audio processing, the less we rely upon fast peak control and the more we rely upon slow average control, the more life-like our audio will be.
  • Page 15 range of control is usually less than 15 dB, but for the purpose of a modern AGC this range is too ‘limited.’ A “Feedforward” (or “open loop”) detector analyses the signal before the variable gain element and creates a con- trol signal that can accurately mirror level variations in the incoming audio.

  • Page 16: Source Material Quality

    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 DSPXtra-FM 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.

  • Page 17: The Dspxtra-Fm And Its Processing Structure

    IM distortion if over driven resulting in a packed, busy sound. The DSPXtra-FM 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 DSPXtra-FM 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.
  • Page 18 Distortion controlled clippers (PEAK CONTROL PATH 1) The DSPXtra-FM 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.

  • Page 19: Processing Block Diagram

    Block Diagram...

  • Page 20: User Levels

    EvELS The DSPXtra-FM has the ability to restrict the use of some of the more advanced processing parameters by selecting a beginner mode. This mode control is located at the top level of the processing menu tree, the options being beginner and advanced.

  • Page 21: The Dspxtra-Fm Menu System Overview

    yStEM vErvIEW This section presents an overview of the four main menus and thier submenus and any parameters that are con- tained in them. INPUT: Contains all the controls that affect input selection, level control and signal conditioning. PROCESS: Contains all the controls that affect the processing. OUTPUT: Contains all the controls that affect output selection, level control and signal conditioning.

  • Page 22: The Menu Structure

    B3 DECAY (Advanced mode) trUCtUrE B4 ATTACK (Advanced mode) B4 DECAY (Advanced mode) USER LEVEL (Disables some menu options when beginner mode selected) MENU: INPUT MENU: CLIPPERS INPUT SOURCE MULTI-BAND CLIP DRIVE STEREO MODE BASS CLIP LEVEL ANALOG INPUT LEVEL BASS CLIP TYPE RIGHT TRIM BASS CLIP SHAPE (Advanced mode)

  • Page 23: Processing Parameters

    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 DSPXtra-FM. There are only sub-menus inside the 'PROCESS' menu. The submenus are laid out in the same configuration as the signal path through the DSPXtra-FM.
  • Page 24 The 'L+R' menu contains the controls for the L+R (SUM) section of the matrix mode of operation 'IDR Sets the range in dB of the window gating system. The processing will turn off while the audio is inside this window. The window can be set between 1 and 15dB. 'GATE' The gate function prevents 'suck-up' of noise during periods of silence or low level audio.
  • Page 25 Can help reduce multi-path when enabled. More on this in this manual. 'L-R RESTRICTION' couples the L-R control system to the L+R control system so that the L-R gain reduction can not increase any more than a certain dB above the L+R gain reduction. This prevents build up of an excessive amount of stereo content.
  • Page 26 ‘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.
  • Page 27 DSPXtra-FM 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.
  • Page 28 'MAIN CLIPPER DISTORTION CONTROL' Controls the distortion reduction effect of the distortion controller in the DSPXtra-FM'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.
  • Page 29 'PORT' Sets the port number of the LAN port. 'ABOUT' DSPXtra-FM version number and design credits. 'BOOTLOAD' This option is used to FLASH update the software and firmware inside the DSPXtra-FM. Further information on using this option is described in the documentation supplied with the upgrade.

  • Page 30: Setting Up The Processing On The Dspxtra-Fm

    This section has more detailed information on setting up the DSPXtra-FM’s processing. Because the DSPXtra-FM contains another product in its own right, the Ariane, we have decided to start with discussing that section of the processing and its setup. This also seems logical because it is the first part of the processing chain after the audio has been routed through the high pass and phase rotating filters which we will get out of the way below before moving on to the background, workings and setup of the Ariane.
  • Page 31 IDR or Instantaneous Dynamic Range, is the main setting to adjust the amount of control action you wish your Ariane to have. The IDR setting is the ‘size’ of the RMS energy window in the windowing-release system. As long as the short-term variations of the RMS energy in the audio remain within this range, the Ariane will stop making any changes to the gain in that band.

  • Page 32: Bass Enhancement

    The range is +/- 6dB. The multi-band limiters in the DSPXtra-FM 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.
  • Page 33 stant 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.
  • Page 34 The mixer The post limiters mixer in the DSPXtra-FM is not strictly a mixer but a band output level control where small EQ changes can be made. It has been called the mixer as most other processors have a mixer at this position and our VIRTUAL mixer does the same job.
  • Page 35 The DSPXtra-FM has several controls that relate to the multi-band clippers. The first is a drive control and is self explanatory. It is a ganged level control that works in conjunction with the mixer controls. The 0dB drive level is a reference point that we choose that drives the multi-band clippers at a level that will produce a competitive amount of loudness.
  • Page 36 Look-ahead limiter A look-ahead limiter is used in the DSPXtra-FM to provide peak control for the DR path of processing. This is not just a simple single band peak limiter. The DSPXtra-FM look-ahead limiter works in three bands to maximise the quality of the processing while minimalising audible artefacts.

  • Page 37: Composite Clipper

    -0.5 to 2dB. Here at BW Broadcast we prefer to use the multi-band and final clipper to generate the required amount of loud- ness because composite clipping introduces stereo crosstalk. When we do use the composite clipper we prefer to use small amounts of no more than 1dB.

  • Page 38: Getting The Sound That You Want

    OUnd While the DSPXtra-FM can help you obtain the sound that you want we must always take into account the limita- tions presented to us by the transmission channel. The biggest problem we have is the maximum peak level that can be handled by that transmission channel.
  • Page 39 MODIFYING LOTS OF THE PARAMETERS. IF YOU ARE ADJUSTING ONLY A COUPLE FROM THE ABOVE SUGGESTIONS THEN YOU PROBABLY HAVE A BIT MORE LEE-WAY. IT IS VERY EASY TO LOSE YOUR WAY ONCE YOU START 'CRANKING' LOTS OF DIFFERENT SETTINGS. More CLARITY We can obtain extra clarity and quality in several ways.
  • Page 40 Multi-band Limiters: Increase the band 1 and band 2 limiter drive . Slow down the peak attack time for bands 1 and/or 2, letting more through to the clippers. Speed up the release time of the average release time constant of those bands. Slow down the band 1 and band 2 average attack time so that the peak time constant dominates the control signal providing faster control.
  • Page 41 This must be done carefully to avoid problems such as multi-path when the DSPXtra-FM is processing for FM broadcast. The sophisticated controls in the Ariane section of the DSPXtra-FM are more than capable of handling this problem, if set correctly. To increase stereo (spatial) energy, make sure the Ariane is operating in matrix mode.

  • Page 42: Managing Presets

    FrOnt PanEL COntrOL The DSPXtra-FM has an assortment of factory presets and provision for 8 user ones. While the factory presets may not suit your tastes you will generally find one that serves as a good starting point in creating your own cus- tom preset.

  • Page 43: Factory Presets

    aCtOry rESEtS The factory presets in the DSPXtra are not supposed to be de facto standards by any means but are starting points for you to create your own user presets. It is impossible to create presets that will suit every format and market.
  • Page 44 F15 HOT ROCK MA More aggressive version of ROCK preset. Louder and a bit more alive. Matrix mode in the Ariane F16 HOT ROCK ST More aggressive version of ROCK preset. Louder and a bit more alive. Stereo mode in the Ariane F17 HOT ST Nice EQ of bass and HF provide a good starting point for 80’s formats.

  • Page 45: Remote Control Of The Dspxtra-Fm

    DSPXtra-FM controller understands. This is trans- parent to the user but as far as the DSPXtra-FM is concerned the USB port is a serial device. The remote con- trol application on your computer will select the USB device through a virtual comm port driver (VCP) which is a driver that you will need to install on your computer in order to connect to the DSPXtra-FM over USB.
  • Page 46 If you wish to use the NET/LAN port to control the DSPXtra-FM follow the steps below 1. Connect a cat 5 cable to the RJ45 port on the DSPXtra-FM and plug this into your network hub/switch. A Xover cable can be used to connect directly to a PC if you don’t have a switch or hub.
  • Page 47 The DSPXtra-FM contains two levels of password control, a high level password which blocks access to all areas of the DSPXtra-FM and an ‘Output’ level password that allows access to all areas of the DSPXtra-FM except the output menus that contain the output mode and level settings. The ‘Output’ level password could be given to programme controllers to adjust the processing knowing that the transmission will remain compliant as there is no way for the user to adjust the peak output level of the DSPXtra-FM.
  • Page 48 Understanding the preset list The preset list contains all of the presets contained in the DSPXtra-FM. The user presets are prefixed U1 to U8 and the factory presets from F1 onwards. You may need to use the scroll arrows to view all of them as they won't all fit in the window at one time.
  • Page 49 'on air'. The exception to this is when the default preset is being overridden by a daypart or remote trigger. In this case the DSPXtra-FM will 'on air' the selected preset when the daypart or trigger hands back control to the default preset.
  • Page 50 There are three menu locations for controlling scheduling. The first location is shown in the screen shot below and it contains the ON/OFF and time setting control. The two menu locations below it access two banks of four dayparts which make up the 8 dayparts contained in the DSPXtra-FM. Scheduling On the daypart windows you have four dayparts.
  • Page 51 The dayparts can be layered so that one can override another. Let's say the default preset was U1:MAIN PRESET and this was on the air all of the time. We want to change the preset from 7AM to 10AM every day of the week to F2:CHR and then from 10AM to 12PM we want U4:NEW PRESET and then back to F2:CHR until 5PM.

  • Page 52: Remote Trigger Port

    MITERS OUTPUT HO LD DSPXtra REMOTE INPUT LOAD PROCESS AES/EBU OUTPUT SAVE EDIT EMOtE rIGGEr The system menu contains the remote trigger port option from where it can be enabled or disabled. If enabled the remote trigger port on the processor allows you to select any of the first 8 user presets by pulling one of 8 pins on the trigger port socket low.

  • Page 53: Security Code Locks

    If unsuccessful you will be required to try again. If successful the DSPXtra ENTER PASSCODE DSPXtra-FM will allow you to re-confirm the code or change it. This is where you may want to change the fac- U1=BASS FACE INPUT tory default code if you have not already done so.

  • Page 54: Clock Based Control

    LOCk aSEd OntrOL ayPartInG Your processor contains a battery backed up real time clock that can maintain the current time and date even when the power has been removed. This allows users to switch between presets at specific times of the day or week.

  • Page 55: Specifications

    >20dBu AD Clipping Point than the best for your digital broadcast services, the Connectors DSPXtra-FM is your best choice. No other FM processor, 24 bit 48 Khz 128x oversampled A/D conversion at any price, has both a BW Broadcast six-band <0.01% THD...
  • Page 56 APPENDIX A Installing USB VCP Drivers To install the VCP drivers for the processor under Windows XP and XP SP1, follow the instructions below: If a device of the same type has been installed on your machine before and the drivers that are about to be installed are different from those installed already, the original drivers need to be uninstalled.
  • Page 57 Select “Install from a list or specific location (Advanced)” as shown below and then click “Next”. Select “Search for the best driver in these locations” and enter the file path in the combo-box (“C:\VCP Drivers” in the example below) or browse to it by clicking the browse button. Once the file path has been entered in the box, click next to proceed.
  • Page 58 The following screen will be displayed as Windows XP copies the required driver files. Windows should then display a message indicating that the installation was successful. Click “Finish” to complete the installation. This has installed the serial converter. The COM port emulation driver must be installed after this has completed.
  • Page 59 The following screen will be displayed as Windows XP copies the required driver files. After clicking “Finish”, the Found New Hardware Wizard will continue by installing the COM port emulation driver. The procedure is the same as that above for installing the serial converter driver.

  • Page 60: Preset Sheet

    DSPXtra-FM v2 preset sheet Preset 1 Preset 2 Preset 3 Preset 4 INPUT SOURCE MODE ANALOG LEVEL INPUT FAIL HP FILTER PHASE ROTATOR PRE-EMPHASIS µs µs µs µs PROCESS ARIANE MATRIX MODE GATE B1 RELEASE B2 RELEASE B3 RELEASE B4 RELEASE...
  • Page 61 THRESHOLD LIMIT. ATTACK LIMIT. DECAY COMP. ATTACK COMP. DECAY HOLD DELAY BAND 2 DRIVE THRESHOLD LIMIT. ATTACK LIMIT. DECAY COMP. ATTACK COMP. DECAY HOLD DELAY BAND 3 DRIVE THRESHOLD LIMIT. ATTACK LIMIT. DECAY COMP. ATTACK COMP. DECAY HOLD DELAY BAND 4 DRIVE THRESHOLD LIMIT.
  • Page 62 COMPOSITE CLIP ADVANCED MAIN CLIP DIST CTRL MAIN CLIP FINESSE OVERSHOOT CTRL ITU LIMITER LOOKAHEAD DRIVE SHELF EQ LOW ATTACK LOW DECAY MID ATTACK MID DECAY HIGH ATTACK HIGH DECAY OUTPUT STEREO LEVEL PILOT LEVEL PILOT PROTECTION ITU LIMITER 19kHz SYNC Preset Sheet...
  • Page 63 www.bwbroadcast.com...

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