DSPXtreme-FMHD Broadcast Audio Processor Operational Manual Version 1.30 www.bwbroadcast.
Table Of Contents Warranty 3 Safety 4 Introduction to the DSPX treme 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 processin
Introduction WARRANTY BW Broadcast warrants the mechanical and electronic components of this product to be free of defects in material and workmanship for a period of two (2) years from the original date of purchase, in accordance with the warranty 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.
Safety Instructions 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.
Safety Instructions Object and Liquid Entry: Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through openings.
Introduction To The 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.
Connections 7 ANALOGUE INPUTS DSPXtreme- F M ANALOGUE OUTPUTS SCA MPX 1 & 2 INPUT OUTPUTS MPX2 LEVEL ADJUST L R +/L -/R 2 +/L -/R 3 +/L -/R 4 AES / EBU OUTPUTS +20 +18 +16 +14 +12 +10 +8 +6 +4 +2 -0 -2 -4 -6 +/L -/R 1 GATE IDR +20 +18 +16 +14 +12 +10 +8 +6 +4 +2 -0 -2 -4 -6 GND LIFT dB ARIANE LEVELER GATE ID R dB -2 -4 -6 -8 -10 -12 -14 -16 -18 -20 -22 -24 HOLD 1 3 4 SYNC INPUT 2 L IMITERS 5 6 dB L R OUTPUT 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -15 -18 AES / EBU INPUT
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. Change from I/O metering and GR metering with this button 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.
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.
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.
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.
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.
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 production and mastering, ideal for giving CD’s that HOT sound.
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 maximum distortion control before being fed to the final clipper stages.
Block Diagram 15 DIGITAL ANALOG SRC A/D P.R.
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 MAS
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.
'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.
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 corresponds to 10 ms to 1000 ms on a semi-exponential scale.
'MID ATTACK' Controls the average attack rate of the B3 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. 'MID DECAY' Controls the average decay rate of the B3 look-ahead limiter. This defines the decay rate of the secondary time constant circuit.
Overdrive the main clipper to hear the effect of this control and then back the drive back down after the finesse control is set to your taste. '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. 'ITU LIMITER' Sets the threshold of the integrated ITU limiter or turns it off. When activated, the unit will comply with the ITU BS.
limiter will drastically reduce the loudness of your signal and should be used only if the regulations in your country require you to comply with ITU BS.412. Otherwise set this parameter to off. The thresholds are calibrated in dB relative to the ITU BS.412 reference. 'PILOT OUTPUT' This controls the 19KHz pilot output reference signal which is available on the DSPXtra-FM back panel. Options are enabled and disabled.
'DELAY COARSE' Adjusts the delay in seconds, from 0 s to 12 s in 0.1 s steps. 'DELAY MEDIUM' Adjusts the delay in miliseconds, from 0 ms to 99 ms in 1 ms steps. 'DELAY FINE' Adjusts the delay in samples, from 0 smps to 47 smps in 1 smps steps. The 'SCHEDULE' menu contains all the controls for the dayparting (REAL TIME CLOCK) preset switching. 'TIME' Sets the time and day of the DSPXtreme’s Real Time Clock. 'DAYPARTING ON/OFF: Enables or disables the scheduling.
Setting up the Processing on the DSPXtreme This section has more detailed information on setting up the DSPXtreme’s processing. High pass filter The high-pass filter has five selectable cut off frequencies and a bypass option. Most users will bypass the highpass stage but there are several cases where enabling the high-pass has an advantage. The first of those is stations that mainly play vinyl recordings.
The effects of time constant speeds AGC attacking and decaying with faster time constants AGC attacking and decaying with slower time constants in dB that the return to rest level is set at. Window gating is separate from the silence gating that we have been discussing in that it does not work on the amplitude of the audio, rather the peak to average ratio of the waveform and how the waveform is changing over time.
The coupling control controls the amount of audio that is fed from one bands detector into the neighbouring bands detector. The audio is fed from one bands detector through the coupling ratio control and then the highest level wins. For example, if we coupled band 2 to band 1 with a coupling of 50% we would ensure that the band 1 gain reduction could never decrease (less gain reduction) more than 6dB past the band 2 gain reduction.
you are free to experiment to get the bass sound you're after. Additionally, bass tune control allows control of the 'flavour' of the bass by adjusting various points in the bass dynamic control system. Xover The Xover in the DSPXtreme has five selectable frequencies per band split.. The band 1/2 split can be set to 80, 100, 125, 160 or 200 Hz. The band 2/3 split can be set to 400, 500, 650, 800 or 1000 Hz and the band 3/4 split can be set to 1100, 1400, 1800, 2250 or 2800 Hz.
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.
Unless you have a specific reason to turn it off we recommend a setting of around -32dB but this may need to be increased or decreased depending on drive levels into the limiter and how much effect you want the hold control to have on the audio. If set too low you will rob yourself off some loudness, if set too high you will lose some of the benefits of the mechanism by letting the limiter release too far before gating.
the bass-clipper. Band 3 and 4 serve the mid-clipper and band 5 and 6 serve the HF-clipper. Low pass, band pass and high pass filters are used respectively. The DSPXtreme 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.
delay monitor output from the DSPXtreme as a studio feed. 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.
more business and IM distortion would be introduced to the audio especially under higher levels of drive. If we were to flip the settings of the secondary time constants around to distribute most of the energy into the secondary time constant circuit we would see an improvement of audio quality at the expense of reduced volume due to the longer release time constants being used. As previously pointed out a balance is best and that balance will vary with each band of the look-ahead limiter.
some of the harmonics which might result in slight increase of overshoots, depending on how much composite clipping you are using. Therefore you might need to re-adjust the output level to keep modulation peaks below 75 kHz (100% modulation) when the filter is activated. Auditioning individual stages of the DSPXtreme processing When setting up the DSPXtreme it is sometimes useful to hear the effects of the adjustments on that particular processing stage.
Getting The Sound You Want While the DSPXtreme can help you obtain the sound that you want we must always take into account the limitations 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. For FM broadcast this is +/- 75 KHz for 100% modulation and for digital services, 0dBfs. The trade off in any audio processor is loudness vs. quality.
More CLARITY We can obtain extra clarity and quality in several ways. Multi-band AGC: Slow down the release times. Decrease the GATE thresholds allowing the release times to release less often. Increase the band and channel coupling ratios , letting each bands energy be restricted by its neighbour. Multi-band Limiters: Speed up the peak attack times, letting less through to the clippers. Slow down the release times of the average release time constants.
Bass clipper: (FM USE) Increase the multi-band clipper drive. Increase the bass clip level. Set the bass clip mode and shape to suit the tone of the bass you prefer. Look-ahead limiter: (DR USE) Increase the look-ahead limiter drive. Increase the band 1 look-ahead limiter attack time constant slowing down the attack of the secondary time constant circuit. Decrease the band 1 look-ahead limiter decay time constant speeding up the decay of the secondary time constant circuit.
Managing Presets (front panel control) The DSPXtreme has an assortment of factory presets and provision for 16 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 custom preset. The preset facilities of the DSPXtreme are accessed from the main screen by pressing the disc icon on the left side of the touch-screen. To enter preset menu, press the disc icon Selecting a preset.
Factory Presets The factory presets in the DSPXtreme 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. What is right for one market is not usually right for another. The staff at BW will be able to help you refine your sound further if none of the factory presets meet your requirement. Beta contains the following factory presets. PRESETS.
Remote Control Of The DSPXtreme In addition to the front panel LCD control system the DSPXtreme has a serial port and an ethernet/LAN port. These allow remote control of the DSPXtreme through a remote application program running on a windows based PC. The remote control program is available for download from www.bwbroadcast.
Remote application connection screen NET/LAN PORT The DSPXtreme is equipped with a NET/LAN port for ease of remote control, setup and monitoring. CONTROL OF THE DSPXtreme BY THE NET/LAN PORT If you wish to use the NET/LAN port to control the DSPXtreme follow the steps below 1. Connect a cat 5 cable to the RJ45 port on the DSPXtreme 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. 2. .
Remote application connected When the DSPXtreme is connected the LED’s will show activity and the main controls window should show processing controls, depending on what option is selected on the menu tree located to the left of the screen. The DSPXtreme remote control application has three windows. The left hand contains the navigation/preset window.
Preset window shown If you are not using dayparting or the external trigger port the default preset will always be the 'on air' preset and it will be marked in the preset list with a (DEF) which appends to the preset name. If the scheduler (dayparting) or the remote trigger interface has changed the preset the (DEF) marked preset may not be the one that is on the air. There are two additional identifiers to mark these occurrences. (DP) for Daypart and (TR) for remote trigger.
Loading presets from a PC This option will pop up the standard windows load dialog box. You can browse to and select a preset file to be loaded into the DSPXtreme. The preset location that is loaded is the currently highlighted (in blue) preset, not the one that is currently 'on-air' You can only load into a user preset. Preset icons SCHEDULING WITH THE REMOTE APPLICATION Using the menu tree to change the processing is quite simple and really doesn't need a lot of explanation.
by clicking down on the arrows until you reach the off option. If off is currently selected you can click up to rotate through the user and factory presets. The middle box contains the time and day that the daypart will start at. To select day, hour or minute click on the appropriate part of the box before using the up and down arrows. The day part of the time also has an ALL option. This means that the daypart will occur on every day.
MITERS OUTPUT HO LD -2 -4 -6 -8 -10 -12 -14 -16 -18 -20 -22 -24 4 5 dB 6 L 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -15 -18 REMOTE AES/EBU EDIT R DSPXtra INPUT PROCESS OUTPUT UP LOAD SAVE Remote Trigger Port 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.
Clock Based Control (Dayparting) 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. This is very useful on a multi-format radio station where one processing preset may not suit all of the formats of music that are broadcast.
Specifications Specifications apply for measurements from analog left/right input to stereo composite output and to FM analog left/right output. Measurements apply to FM mode of operation. Frequency Response (Bypass Mode): Follows standard 50µs or 75µs pre-emphasis curve ±0.10 dB, 2.0 Hz– 15 kHz. Analog left/right output and digital output can be user configured for flat or pre-emphasised output.
Filtering: RFI filtered. MPX output 1 Source Impedance: 10 Ohm Single-ended, floating over chassis ground. Load Impedance: 600 Ohm or greater. Maximum Output Level: +12.0 dBu (peak) software-controlled output level control. Minimum Output Level: 0 dBu (peak)Software-controlled output level control. Pilot Level: Adjustable from 6.0% to 12.0% and OFF, software controlled. Pilot Stability: 19 kHz, ±1 Hz (10 degrees to 40 degrees C).
DSPXtreme-FMHD v1 preset sheet Preset 1 Preset 2 Preset 3 Preset 4 INPUT SOURCE MODE ANALOG LEVEL INPUT FAIL HP FILTER PHASE ROTATOR PRE-EMPHASIS dBu dBu dBu dBu Hz Hz Hz Hz µs µs µs µs dB dB % % % dB dB % % % dB dB % % % dB dB % % % B1-2 B2-3 B3-4 Hz Hz Hz Hz Hz Hz Hz Hz Hz Hz Hz Hz DEEP BASS BASS TUNE BASS PEAK GAIN BASS PEAK FREQ BASS PEAK Q dB dB dB dB dB Hz dB Hz dB Hz dB Hz MASTER DRIVE dB dB dB dB DRIVE THRESHOLD LIMIT. ATTACK LIMIT. DECAY COMP. ATTACK COMP.
LIMIT. ATTACK LIMIT. DECAY COMP. ATTACK COMP. DECAY HOLD DELAY dB dB dB dB DRIVE THRESHOLD LIMIT. ATTACK LIMIT. DECAY COMP. ATTACK COMP. DECAY HOLD DELAY dB dB dB dB dB dB dB dB dB dB dB dB DRIVE THRESHOLD LIMIT. ATTACK LIMIT. DECAY COMP. ATTACK COMP. DECAY HOLD DELAY dB dB dB dB dB dB dB dB dB dB dB dB DRIVE THRESHOLD LIMIT. ATTACK LIMIT. DECAY COMP. ATTACK COMP.
STEREO LEVEL PILOT LEVEL PILOT PROTECTION ITU LIMITER 19kHz SYNC dBu % dBu % dBu % dBu % dBr dBr dBr dBr Preset Sheet 51
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