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Introduction
This page contains some general hints for setting up the processor. The guide is about MBL9 as the other processors have an inferior sound.(Better ears than mine may have a different opinion). MBL18 probably sound better than the nine band processors.
Basic Setup
This is a simple guide to setting up the processor using the supplied presets.
The factory presets (Factory Format) can be found in the top left window. Click on the buttons in the title bar to toggle through the various options. The first part of the name indicates the type of broadcasting Sonos 4 is being used for. 'digital_' is typically for internet streaming.'fm50_' is for FM broadcasting using 50us pre-emphasis. 'fm75_' is for FM broadcasting using 75us pre-emphasis. For FM broadcasting there are 'low latency' options for enabling off air monitoring while speaking.
The rest of the name gives an indication of how hard the processor is being driven. Mostly users will select 'loud'.
If you have not already got the sound coming through from the sound card input then you can select to use the sound card through the 'Factory Settings'. (Toggle through the top left window as explained above until the title bar shows 'Factory Settings').
The input level should be adjusted until the AGC indicates 0 with a typical input. This gives about 20dB of headroom on the sound card input.
If you are driving an FM transmitter from the discrete left and right outputs then you may have to add de-emphasis if your transmitter applies pre-emphasis. Also the transmitter may have a built in limiter. In this case the input level needs to be adjusted so that the level is just below the limiting threshold. It is best if any limiting and pre-emphasis in the transmitter is disabled. The de-emphasis control is found through the bottom left control window. Select Pre-Emph>De-Emph.The control will appear the the bottom right window. Select 50us or 75us. The value depends upon the pre-emphasis value applied in the transmitter.
If you are driving a transmitter with a stereo multiplex signal then it is only necessary to adjust the level to set the deviation. Use the left output to drive the MPX input of the transmitter.
Advanced Setup
This is run down of the full range of features available in MBL9. This guide details the features from input to output. Some controls are marked as an expert option. Expert is defined as somebody with acute hearing and an understanding of how the various controls affect the sound.
There are four stages of parametric equalization available. This is switched off by default to save CPU processing power.
A visual representation of the EQ sections frequency response is shown in the 'Meters' window. This made visible by clicking on the left button in the top right 'Meters' window.
Adjusting the EQ is an expert option.
Found under Controls>Input>Failsafe is a control for setting up a fail over source should the main feed fail. The left series of buttons select what source will be switched to during a failure. Typically this is the 'Player' running a repeating playlist. The central buttons enable or disable fail over with an option to test the failure source. The right hand buttons adjust how quickly the fail over switches over.
Controls>Input>LPF accesses the control for selecting the input and output low pass filter. It is marked by broadcasting type. FM has a 15kHz cut off. AMW is the wide band am filter. Cut off frequency is about 8kHz. AMN is the narrow band AM frequency. Cut off frequency is about 4kHz.
For SCA broadcasting the low pass filter should be set to AMW.
Controls>Input>HPF accesses the control for setting the input high pass filter. The usual option for FM broadcasting is 20Hz. AM broadcasters may use a higher value to reduce the bass to balance the lack of high frequencies. Use f the control in this way is an expert control.
Controls>Input>Mono should be set to mono for AM & SCA broadcasting.
Controls>Input>Phase Rotator is used to reduce asymmetry in speech waveforms. This increases the loudness of speech.
If the multiband filers are set to a non linear phase option the the filters will tent to break up asymmetry without the use of a phase rotator.
Controls>Input>Stereo Widener is a FFT based stereo image widener. It cannot be used if the processor is being used in low latency mode.
Controls>Input>Stereo Enhance is a clone of the Stereo Maxx stereo enhancer. Search online for Stereo Maxx manual that contains details of the adjustments available.
Adjustment other than switching in on or off is an expert control.
Controls>Input>Stereo Enhance Alt is a simple L-R enhancer. The L-R enhance signal is passed through a variable delay line.
Adjustment other than switching in on or off is an expert control.
Controls>Sp/Mu Detector Enable is used to enable the speech music detector. By itself this control does not affect the sound.
Under Controls>EQ>Sp/Mu is a control for controlling bypassing EQ when either speech or music is detected. The usual setting is 'On Speech' so that the EQ sections are bypassed when speech is detected.
Under Controls>AGC2>AGC2 Sp/Mu and Controls>AGC3>AGC3 Sp/Mu is a control that when speech is detected the bass and high frequency bands gain is set to the mid band value. This disables the EQ effect of the AGC when speech is present.
The speech/music detector has a meter that discriminates between music and speech at its centre point.
Controls>AGC>AGC Type controls which of the three AGC sections to use. The default value is '2 Band'.
Controls>AGC>AGC Gate controls the gating threshold for all three AGC sections. If you are broadcasting high dynamic range material then the threshold may need reducing to a void quiet passages causing the AGC to gate and reduce the level as the AGC returns to its centre value of zero.
The remainder of this guide to the AGC will concentrate on the two band AGC.
Controls>AGC2 Drive is an attenuator to adjust the level entering the AGC section. When using the processor with the sound card as input then this control should be set to maximum. Level should then be adjusted externally. Either with the sound card mixer application or externally to the computer in the mixing desk.
Controls>AGC2 Bass Threshold controls the bass band threshold relative to the mid/high band. This is an expert control.
Controls>AGC2 Rate controls the speed at which the AGC responds to level changes in the audio signal.This should be slow with the multiband limiter handling step changes in amplitude of the audio signal. A value of 17 18 or 19 is the normal range of values that should be used.
Controls>AGC2 Max Boost are two controls the maximum boost that the AGC section can apply to the signal. The default value of 10 is recommended. For maximum AGC range set these controls to 20.
The next two controls affect the smoothing of the AGC side chain signal. The smoothing is a simple RC circuit that is only operative when the unsmoothed signal is within a window relative to the smoothed signal. When the unsmoothed value is outside the window the AGC side chain is driven directly by the unsmoothed value. The default values for these controls is normally adequate. These controls are for experts.
Controls>AGC Link is the control that sets how much boost that can be applied to the bass band relative to the mid/high band.
Controls>AGC2 Sp/Mu is a control that is only active when speech is detected by the speech music detector. When speech is detected the bass band gain is locked to the same value as the mid/high band.
Controls>AGC2 Bass XOver controls the bass crossover frequency in the two band AGC. The default value is 150Hz. This is an expert control.
Controls>Multiband>MB Filter has a selection of band splitting filters. The default value is 3rd Butter. The splitting filters are made up from third order butterworth low pass and high pass filters. The 5th Butter extends this to fifth order butterworth filters. The 1st BPF uses simple first order band pass filters. This option is not recommended because it can create audible distortion from the clipper. The Lin Phase option uses linear phase filters. This introduces too much delay for the processor to be used in low latency mode. Some people claim that linear phase filters sound better.
Controls>Multiband>MB Mono Bass puts the two bass bands into mono. This is to reduce L-R energy when using FM stereo multiplex encoding. Lower L-R energy reduces multipath distortion. The default value is off as the effect is marginal because the bass is often centred so that the L-R bass energy is low anyway.
Controls>Multiband Compressor>MB Comp Enable for enabling the multiband compressor.
Controls>Multiband Compressor>MB Comp Drive controls how much overall compression is applied to the audio signal. More tends to increase the loudness of the sound.
Controls>Multiband Compressor>MB Comp Attack controls the attack time of each band. This is an expert control.
Controls>Multiband Compressor>MB Comp Release controls the release time of each band. This is an expert control.
Controls>Multiband Compressor>MB Comp Rest controls the value of gain reduction applied when the AGC Gate is active.
Controls>Multiband Compressor>MB Comp Slope controls the slope of compression. This is an expert control.
Controls>Multiband Compressor>MB Comp Thresholds controls the compression threshold for each band. This along with any EQ applied controls the overall balance of the sound. This is an expert control.
Controls>Multiband Limiter>MB Lim Enable enables the limiting section of the multiband.
Controls>Multiband Limiter>MB Lim Drive controls how much overall limiting is applied to the audio signal. More tends to increase the loudness of the sound.
Controls>Multiband Limiter>MB Lim Attack controls the attack time of each band. This is an expert control.
Controls>Multiband Limiter>MB Lim Release controls the release time of each band. This is an expert control.
Controls>Multiband Limiter>MB Lim Plat Drive controls how much effect the platform affects the gain reduction is each band of the multiband limiter. The platform is an AGC that is applied along with the normal gain reduction. This an expert control.
Controls>Multiband Limiter>MB Lim Plat Attack is the rate at which the platform responds when increasing the platform gain reduction. This is an expert control.
Controls>Multiband Limiter>MB Lim Plat Release is the rate at which the platform responds when decreasing the platform gain reduction. This is an expert control.
Controls>Multiband Limiter>MB Lim Rest controls the gain reduction when the AGC gate is active.
Controls>Multiband Limiter>TC Mode. Smart reduces the release time when the density of the program material is higher. This is an expert control.
Controls>Multiband Limiter>MB Lim Thresholds controls the limiting threshold for each band. This along with any EQ applied controls the overall balance of the sound. This is an expert control.
Controls>Multiband Limiter>MB Look Ahead controls the look ahead delay line. The default value is Off as this increases delay in low latency operation. A typical value of 5ms will help when the audio signal suddenly increases in amplitude. This is an expert control.
The multiband clipper is not recommended and may well be removed in future releases.
Controls>Limiter>Lim Drive controls the overall limiting. The control should be set to only register a few dbs of gain reduction. The majority of gain reduction should be done in the multiband sections.
Controls>Limiter>Lim Rest controls the gain reduction applied when the AGC gate is active.
Controls>Limiter>Lim TC is the attack and release controls. This is an expert control.
Controls>Limiter>Lim Platform TC is the attack and release controls for the platform. This is an expert control.
Controls>Limiter>Lim Platform Drive is the drive control for the platform. This is an expert control.
Controls>Limiter>Lim TC Mode. Smart reduces the release time when the density of the program material is higher. This is an expert control.
Controls>Limiter>Lim Look Ahead controls the look ahead delay line. The default value is Off as this increases delay in low latency operation. A typical value of 10ms will help when the audio signal suddenly increases in amplitude. This is an expert control.
Controls>Limiter>Clip Drive is the final clipper drive control. It is the primary definer of how loud the processor is. The default value of plus two in combination with default values of attack/release in the limiter is about as loud as the processor will go without obvious distortion. This is an expert control.
Controls>Limiter>Clip Band Drives are individual clipper drives for altering the balance of the sound before final clipping. This is an expert control.
Controls>Limiter>Clip Mode. There are three modes. 'Purist' offers the lowest distortion while 'Loud' theoretically should be a bit louder. Hybrid is the old MBL4 way of clipping the high frequencies.
Controls>Pre-Emph>Pre-Emph is a switch for the various pre-emphasis options. Pre-emphasis is applied partially before the multiband section and after the final clipper.
Option '50' applies 50us zero with a pole at 25us.This creates a shelf before the multiband section with the remainder of the boost applied after the final clipper.
Option '50 Alt' is similar to the '50' option but the shelf pole is at 37us.
Option '75' applies a 75us zero followed by a 25us pole. This creates a shelf before the multiband section with the remainder of the boost applied after the final clipper.
Option '75 Alt' is like option '75' with the shelf pole at 37us.
These options apply exact pre-emphasis.
The following options '50+Bst' and '75+Bst' apply exact pre-emphasis before the multiband section with an arbitrary shelf boost after the final limiter. This scheme maximises high frequency boost. All the supplied presets use these options.
Options '150' and '225' are for use with the SCA generator found in the 'Sound Out' function. Setting the processor up for SCA operaton is for experts only.
Controls>Pre-Emph>Drive controls how much high frequency boost is applied when the pre-emphasis is set either to '50+Bst', '75+Bst', '150' and '225'.
Controls>Pre-Emph> HPF is for enabling a high pass filter on the boosted high frequency signal. When used it increases latency.
Controls>Pre-Emph> Clip Mode switches the clipping mode. A is theoretically lower distortion levels. B is the old MBL4 method of clipping.
Controls>Pre-Emph>De-Emph applies de-emphasis necessary for driving transmitters that have built in pre-emphasis.
The '50us LP' and '75us LP' are obsolete linear phase de-emphasis.
This page contains some general hints for setting up the processor. The guide is about MBL9 as the other processors have an inferior sound.(Better ears than mine may have a different opinion). MBL18 probably sound better than the nine band processors.
Basic Setup
This is a simple guide to setting up the processor using the supplied presets.
The factory presets (Factory Format) can be found in the top left window. Click on the buttons in the title bar to toggle through the various options. The first part of the name indicates the type of broadcasting Sonos 4 is being used for. 'digital_' is typically for internet streaming.'fm50_' is for FM broadcasting using 50us pre-emphasis. 'fm75_' is for FM broadcasting using 75us pre-emphasis. For FM broadcasting there are 'low latency' options for enabling off air monitoring while speaking.
The rest of the name gives an indication of how hard the processor is being driven. Mostly users will select 'loud'.
If you have not already got the sound coming through from the sound card input then you can select to use the sound card through the 'Factory Settings'. (Toggle through the top left window as explained above until the title bar shows 'Factory Settings').
The input level should be adjusted until the AGC indicates 0 with a typical input. This gives about 20dB of headroom on the sound card input.
If you are driving an FM transmitter from the discrete left and right outputs then you may have to add de-emphasis if your transmitter applies pre-emphasis. Also the transmitter may have a built in limiter. In this case the input level needs to be adjusted so that the level is just below the limiting threshold. It is best if any limiting and pre-emphasis in the transmitter is disabled. The de-emphasis control is found through the bottom left control window. Select Pre-Emph>De-Emph.The control will appear the the bottom right window. Select 50us or 75us. The value depends upon the pre-emphasis value applied in the transmitter.
If you are driving a transmitter with a stereo multiplex signal then it is only necessary to adjust the level to set the deviation. Use the left output to drive the MPX input of the transmitter.
Advanced Setup
This is run down of the full range of features available in MBL9. This guide details the features from input to output. Some controls are marked as an expert option. Expert is defined as somebody with acute hearing and an understanding of how the various controls affect the sound.
There are four stages of parametric equalization available. This is switched off by default to save CPU processing power.
A visual representation of the EQ sections frequency response is shown in the 'Meters' window. This made visible by clicking on the left button in the top right 'Meters' window.
Adjusting the EQ is an expert option.
Found under Controls>Input>Failsafe is a control for setting up a fail over source should the main feed fail. The left series of buttons select what source will be switched to during a failure. Typically this is the 'Player' running a repeating playlist. The central buttons enable or disable fail over with an option to test the failure source. The right hand buttons adjust how quickly the fail over switches over.
Controls>Input>LPF accesses the control for selecting the input and output low pass filter. It is marked by broadcasting type. FM has a 15kHz cut off. AMW is the wide band am filter. Cut off frequency is about 8kHz. AMN is the narrow band AM frequency. Cut off frequency is about 4kHz.
For SCA broadcasting the low pass filter should be set to AMW.
Controls>Input>HPF accesses the control for setting the input high pass filter. The usual option for FM broadcasting is 20Hz. AM broadcasters may use a higher value to reduce the bass to balance the lack of high frequencies. Use f the control in this way is an expert control.
Controls>Input>Mono should be set to mono for AM & SCA broadcasting.
Controls>Input>Phase Rotator is used to reduce asymmetry in speech waveforms. This increases the loudness of speech.
If the multiband filers are set to a non linear phase option the the filters will tent to break up asymmetry without the use of a phase rotator.
Controls>Input>Stereo Widener is a FFT based stereo image widener. It cannot be used if the processor is being used in low latency mode.
Controls>Input>Stereo Enhance is a clone of the Stereo Maxx stereo enhancer. Search online for Stereo Maxx manual that contains details of the adjustments available.
Adjustment other than switching in on or off is an expert control.
Controls>Input>Stereo Enhance Alt is a simple L-R enhancer. The L-R enhance signal is passed through a variable delay line.
Adjustment other than switching in on or off is an expert control.
Controls>Sp/Mu Detector Enable is used to enable the speech music detector. By itself this control does not affect the sound.
Under Controls>EQ>Sp/Mu is a control for controlling bypassing EQ when either speech or music is detected. The usual setting is 'On Speech' so that the EQ sections are bypassed when speech is detected.
Under Controls>AGC2>AGC2 Sp/Mu and Controls>AGC3>AGC3 Sp/Mu is a control that when speech is detected the bass and high frequency bands gain is set to the mid band value. This disables the EQ effect of the AGC when speech is present.
The speech/music detector has a meter that discriminates between music and speech at its centre point.
Controls>AGC>AGC Type controls which of the three AGC sections to use. The default value is '2 Band'.
Controls>AGC>AGC Gate controls the gating threshold for all three AGC sections. If you are broadcasting high dynamic range material then the threshold may need reducing to a void quiet passages causing the AGC to gate and reduce the level as the AGC returns to its centre value of zero.
The remainder of this guide to the AGC will concentrate on the two band AGC.
Controls>AGC2 Drive is an attenuator to adjust the level entering the AGC section. When using the processor with the sound card as input then this control should be set to maximum. Level should then be adjusted externally. Either with the sound card mixer application or externally to the computer in the mixing desk.
Controls>AGC2 Bass Threshold controls the bass band threshold relative to the mid/high band. This is an expert control.
Controls>AGC2 Rate controls the speed at which the AGC responds to level changes in the audio signal.This should be slow with the multiband limiter handling step changes in amplitude of the audio signal. A value of 17 18 or 19 is the normal range of values that should be used.
Controls>AGC2 Max Boost are two controls the maximum boost that the AGC section can apply to the signal. The default value of 10 is recommended. For maximum AGC range set these controls to 20.
The next two controls affect the smoothing of the AGC side chain signal. The smoothing is a simple RC circuit that is only operative when the unsmoothed signal is within a window relative to the smoothed signal. When the unsmoothed value is outside the window the AGC side chain is driven directly by the unsmoothed value. The default values for these controls is normally adequate. These controls are for experts.
Controls>AGC Link is the control that sets how much boost that can be applied to the bass band relative to the mid/high band.
Controls>AGC2 Sp/Mu is a control that is only active when speech is detected by the speech music detector. When speech is detected the bass band gain is locked to the same value as the mid/high band.
Controls>AGC2 Bass XOver controls the bass crossover frequency in the two band AGC. The default value is 150Hz. This is an expert control.
Controls>Multiband>MB Filter has a selection of band splitting filters. The default value is 3rd Butter. The splitting filters are made up from third order butterworth low pass and high pass filters. The 5th Butter extends this to fifth order butterworth filters. The 1st BPF uses simple first order band pass filters. This option is not recommended because it can create audible distortion from the clipper. The Lin Phase option uses linear phase filters. This introduces too much delay for the processor to be used in low latency mode. Some people claim that linear phase filters sound better.
Controls>Multiband>MB Mono Bass puts the two bass bands into mono. This is to reduce L-R energy when using FM stereo multiplex encoding. Lower L-R energy reduces multipath distortion. The default value is off as the effect is marginal because the bass is often centred so that the L-R bass energy is low anyway.
Controls>Multiband Compressor>MB Comp Enable for enabling the multiband compressor.
Controls>Multiband Compressor>MB Comp Drive controls how much overall compression is applied to the audio signal. More tends to increase the loudness of the sound.
Controls>Multiband Compressor>MB Comp Attack controls the attack time of each band. This is an expert control.
Controls>Multiband Compressor>MB Comp Release controls the release time of each band. This is an expert control.
Controls>Multiband Compressor>MB Comp Rest controls the value of gain reduction applied when the AGC Gate is active.
Controls>Multiband Compressor>MB Comp Slope controls the slope of compression. This is an expert control.
Controls>Multiband Compressor>MB Comp Thresholds controls the compression threshold for each band. This along with any EQ applied controls the overall balance of the sound. This is an expert control.
Controls>Multiband Limiter>MB Lim Enable enables the limiting section of the multiband.
Controls>Multiband Limiter>MB Lim Drive controls how much overall limiting is applied to the audio signal. More tends to increase the loudness of the sound.
Controls>Multiband Limiter>MB Lim Attack controls the attack time of each band. This is an expert control.
Controls>Multiband Limiter>MB Lim Release controls the release time of each band. This is an expert control.
Controls>Multiband Limiter>MB Lim Plat Drive controls how much effect the platform affects the gain reduction is each band of the multiband limiter. The platform is an AGC that is applied along with the normal gain reduction. This an expert control.
Controls>Multiband Limiter>MB Lim Plat Attack is the rate at which the platform responds when increasing the platform gain reduction. This is an expert control.
Controls>Multiband Limiter>MB Lim Plat Release is the rate at which the platform responds when decreasing the platform gain reduction. This is an expert control.
Controls>Multiband Limiter>MB Lim Rest controls the gain reduction when the AGC gate is active.
Controls>Multiband Limiter>TC Mode. Smart reduces the release time when the density of the program material is higher. This is an expert control.
Controls>Multiband Limiter>MB Lim Thresholds controls the limiting threshold for each band. This along with any EQ applied controls the overall balance of the sound. This is an expert control.
Controls>Multiband Limiter>MB Look Ahead controls the look ahead delay line. The default value is Off as this increases delay in low latency operation. A typical value of 5ms will help when the audio signal suddenly increases in amplitude. This is an expert control.
The multiband clipper is not recommended and may well be removed in future releases.
Controls>Limiter>Lim Drive controls the overall limiting. The control should be set to only register a few dbs of gain reduction. The majority of gain reduction should be done in the multiband sections.
Controls>Limiter>Lim Rest controls the gain reduction applied when the AGC gate is active.
Controls>Limiter>Lim TC is the attack and release controls. This is an expert control.
Controls>Limiter>Lim Platform TC is the attack and release controls for the platform. This is an expert control.
Controls>Limiter>Lim Platform Drive is the drive control for the platform. This is an expert control.
Controls>Limiter>Lim TC Mode. Smart reduces the release time when the density of the program material is higher. This is an expert control.
Controls>Limiter>Lim Look Ahead controls the look ahead delay line. The default value is Off as this increases delay in low latency operation. A typical value of 10ms will help when the audio signal suddenly increases in amplitude. This is an expert control.
Controls>Limiter>Clip Drive is the final clipper drive control. It is the primary definer of how loud the processor is. The default value of plus two in combination with default values of attack/release in the limiter is about as loud as the processor will go without obvious distortion. This is an expert control.
Controls>Limiter>Clip Band Drives are individual clipper drives for altering the balance of the sound before final clipping. This is an expert control.
Controls>Limiter>Clip Mode. There are three modes. 'Purist' offers the lowest distortion while 'Loud' theoretically should be a bit louder. Hybrid is the old MBL4 way of clipping the high frequencies.
Controls>Pre-Emph>Pre-Emph is a switch for the various pre-emphasis options. Pre-emphasis is applied partially before the multiband section and after the final clipper.
Option '50' applies 50us zero with a pole at 25us.This creates a shelf before the multiband section with the remainder of the boost applied after the final clipper.
Option '50 Alt' is similar to the '50' option but the shelf pole is at 37us.
Option '75' applies a 75us zero followed by a 25us pole. This creates a shelf before the multiband section with the remainder of the boost applied after the final clipper.
Option '75 Alt' is like option '75' with the shelf pole at 37us.
These options apply exact pre-emphasis.
The following options '50+Bst' and '75+Bst' apply exact pre-emphasis before the multiband section with an arbitrary shelf boost after the final limiter. This scheme maximises high frequency boost. All the supplied presets use these options.
Options '150' and '225' are for use with the SCA generator found in the 'Sound Out' function. Setting the processor up for SCA operaton is for experts only.
Controls>Pre-Emph>Drive controls how much high frequency boost is applied when the pre-emphasis is set either to '50+Bst', '75+Bst', '150' and '225'.
Controls>Pre-Emph> HPF is for enabling a high pass filter on the boosted high frequency signal. When used it increases latency.
Controls>Pre-Emph> Clip Mode switches the clipping mode. A is theoretically lower distortion levels. B is the old MBL4 method of clipping.
Controls>Pre-Emph>De-Emph applies de-emphasis necessary for driving transmitters that have built in pre-emphasis.
The '50us LP' and '75us LP' are obsolete linear phase de-emphasis.