TC electronic DB8 User Manual

ALGORITHMS - CONTENTS

Introduction

Table of Contents . . . . . . . . . . . . . . . . . . . . . . . .1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Algorithms

ATX/DTX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Multiband 5.1 . . . . . . . . . . . . . . . . . . . . . . . . . . .9

MDX 5.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Downconvert 5.1 . . . . . . . . . . . . . . . . . . . . . . . .25

Upconvert 5.1 . . . . . . . . . . . . . . . . . . . . . . . . . .29

Upcon & Upcon+ . . . . . . . . . . . . . . . . . . . . . . .33

EQ/Delay 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Preset List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .a

TC Electronic, Sindalsvej 34, DK-8240 Risskov tcdk@tcelectronic.com

Algorithms DB8/DB4 Rev 1.60 English version

INTRODUCTION

Introduction

This chapter contains lists of available factory presets (defaults) for both Scene and Engine set-ups. Also comprehensive information about the specific processing configurations (algorithms) in DB8 and DB4 are available. If you are looking for detailed descriptions for the individual parameters in the processors, this chapter is the place to look.

Compatibility: Presets are fully compatible between DB4 and DB8 units. Scene, Routing and Engine presets may be shared between the units using Floppy Disc, PCMCIA Card or Banks via Network. However, Engine 3 and Engine 4 settings are disregarded by a DB4.

Channel Distribution In Surround Algorithms

To best comply with the channel allocation used by most digital AES-format equipment the Input/Output channels on surround algorithms are allocated as follows:

1 Left 2 Right 3 Center 4 LFE 5 Left Surround 6 Right Surround

These channel allocations comply with the following standards:

• ITU-Recommendation ITU-R BR.1384, Parameters for International Exchange of Multichannel Sound Recordings, 1998

• SMPTE 320M-1999, for Television - Channel Assignments and Levels on Multichannel Audio Media

• Surround Sound Forum Recommended Practice SSF- 02/1-E-2 (3-5-99), Multichannel Recording Format, Parameters for Programme Interchange and Archiving, Alignment of Reproduction Equipment

Grouping the Inputs/Outputs this way ensures optimal flexibility for further external processing and archiving, when working on setups following the above mentioned standards. It is, however, worth noticing that total routing-flexibility

of physical Inputs/Outputs to Engine Inputs/Outputs is available on DB8/DB4 via the Routing page.

Metering In the Engine Edit Pages

For logical channel metering in the various surround algorithms, the meters on the Engine Edit pages are displayed in the following order.

Left - Center - Right - Left Surr. - Right Surr. - LFE

We believe that by displaying the meters on the Engine Edit pages in the same order as your speakers are physically placed, the most intuitive metering of channellevels is achieved.

ATX/DTX

Introduction

This processor is a comprehensive, high quality Loudness control, Level optimizer and Peak Limiter. It can be configured as Stereo, Wide Stereo or Dual Mono. The processor uses 48 bit processing for extremely low distortion and wide dynamic range, and oversampled peak limiting on the Output.

The ATX/DTX algorithms can be operated in three distinctively different modes:

- Stereo. In this mode the Loudness, EQ and Multiband

sections operate in tandem: Whatever gain change is applied to one channel, is applied to the other. Also, many parameters have mutual left and right controls.

- Dual Mono. In this mode the Loudness, EQ and

Multiband sections treat the two Input signals completely independently.

- Stereo Wide. In this mode the apparent width and image

of stereo signal can be altered simultaneously with controlling loudness and peak level. The left and right signal is internally de-composed into an M(Mono) and S(Stereo) component, and reverted to left and right signals before peak limiting on the Output.

DTX/ATX

The algorithm previously known as Multiband-2 is now split into DTX for digital broadcast and ATX for analog broadcast. The ATX is high res, low latency loudness control algorithm with adaptive emphasis limiting for feeding analog transmission. The variations between ATX and DTX is found only on the Limiter page. All other pages are therefore described as the same in the manual section.

Reference Level

Reference Level defines the standard operating level, and scales the Threshold and Target Level parameters of the Loudness control and Multiband section. The Threshold of the Limiter is not influenced by this setting, but is always relative to 0dBFS. Typical Reference Level settings would be -20 dBFS in the America and some parts of Asia, and -18 dBFS in Europe, Japan and some parts of Asia. If you wish to relate all levels to 0 dBFS, leave the Reference Level setting at 0 dBFS.

Analog vs. Digital level

If you use analog interfacing, remember always to set the relationship between absolute analog and digital level before adjusting parameters in the Engines.

DB8/DB4 has analog scaling before the A to D converter and analog scaling after the D to A converter. These settings can be changed and stored from the user interface on the Slot A-C screens. Typical analog I/O level scaling would be +24dBu in the Americas and some parts of Asia, and +18dBu in Europe, Japan and some parts of Asia. The figure denotes the analog level required or produced for a 0dBFS signal.

Note 1:

Be careful when changing between configurations. Moving from Dual Mono to Stereo will result from parameter settings of the left (or “A”) channel being copied into the right (or “B”) channel. Going from Dual Mono to Stereo and back to Dual Mono will therefore overwrite original right (or “B”) channel settings.

Note 2:

In all configuration modes, linking of the Brickwall Limiter is set separately on the Limiter page. Some broadcasters like the sound of operating left and right limiting without stereo coupling because they feel that it maximizes loudness and widens the stereo image. On dual mono sources, of course you should always choose un-linked Limiter operation.

Main page

In Gain

Range: 0dB to Off Separate level controls for Left and Right Input (A and B).

Phase Inv

Range: Normal/Inverted Press to phase invert channels A, B or both.

Delay

Range: 0-1000ms Delay alignment of the Input channels. Depending on

Algorithm Inputs/Outputs are distributed as follows:

E1 - E4

L R

INPUT

OUTPUT

•

ATX/DTX

selected Configuration type, either one common Delay setting or individual delay settings are available.

Delay Unit

Range: ms, 24fps, 25fps, 30fps With this parameter it is possible to select which unit the Delay parameter should be shown in. Changing this parameter does not affect the actual delay value.

Lo Cut

Range: Off to 200Hz Second order LoCut filter on both Inputs.

Hi Cut

Range: Off to 3 kHz 8th order HiCut filter on both Inputs.

Look ahead Dly

Range: 0-15ms If the 5 band Compression sections is set to use a very short Attack times (up to approx 10-15ms) overshoots may occur. The Look Ahead function allows the DB8/DB4 to evaluate the material just before processing and artifacts can thereby be prevented. Be aware that the Look Ahead delay function actually Delays the Output signal.

Loudness page

Target Level

Range: +10dB to -10dB This is the level the Loudness controller will aim at on its Output. Target Level is relative to Reference Level on the Main Page.

Max Reduction

Range: -20dB to 0dB This is the maximum attenuation the Loudness Control is allowed to perform. If set to 0.0dB, the Loudness Control cannot attenuate the signal at all. The level diagram on this page is shown with Max Reduction set at 0.0dB.

Max Gain

Range: 0 to +20dB This is the maximum gain the Loudness Control is allowed to perform. If set to 0.0 dB, the Loudness Control cannot add gain to the signal at all.

Freeze Level

Range: -10dB to-40dB Sets the minimum level required before the Loudness Control will start adding more gain. It would typically be set to avoid boosting signals considered noise. The Freeze Level parameter is relative to the Reference Level setting on the Main page.

Freeze Hold

Range: 0 to 5 seconds When the Input signal drops below the Lo Level, the Gain Correction of the Loudness Section is frozen for the duration of the Hold time. When the Hold period expires, the Gain Correction falls back to 0dB gain.

Level Trim

Range: -18dB to + 18dB When using the Multinband algorithm, DB8/DB4 operates with 48 bit precision on all audio internally and it is possible to correct loudness manually without the risk of overloads. The Level Trim can be used for permanent off-sets or live loudness adjustments.

Ratio

Range: 1:1.25 to 1:6 Ratio is the steering factor used when the Loudness Control applies boost or attenuation to reach the Target Level. The higher ratio, the more rigid steering towards the Target Level.

Average Rate (Avg Rate)

Time constants in the Loudness Control are changed dynamically with the Input signal based on computations by multi-level detectors. When the Output level is close to the Target Level, gain changes are relatively slow.

The Average Rate offsets all time constants to be faster or slower. Values below 1dB/Sec produces a gain change gating effect when the Output level is already in the target zone, while values above 4dB/Sec will add density to sound.

ATX/DTX

Slow Window

Range: 0 to 20 dB The slow window is the area around the set Target Level. Within the slow window the Loudness is only gently controlled. When the signal exceeds the limits of the Slow Window the Loudness is treated more radically. Depending on the set Average Rate and Ratio. Please see illustration on the next page!

EQ page

Introduction

This digital EQ features a four-band parametric EQ with high- and low-pass filters switchable between Notch,

Parametric, Shelving and Cut filters. The needle sharp notch filter has a range down to 0.01 octave and the shelving filters has a variable slope, ranging from gentle 3 dB/oct over 6 and 9 to 12dB/oct. Cut filters are switchable between 12dB/oct maximum flat amplitude (Butterworth) or flat group delay (Bessel) types. The parametric equalizer features a natural and well defined bandwidth behavior at all gain and width settings:

Basic operation

• Press keys Lo, Mid and Hi to activate/deactivate the EQ

bands.

• Select Freq, Gain, Type or Lo/Hi to access all four

parameters on individual bands.

• Press Bypass EQ to bypass all four bands.

ype Selector

• Press Type and use faders 1-3 to select filter types.

For Lo and Hi filters select between filter types: Parametric, Notch, Shelve and Cut.

Multiband parameter illustration

ATX/DTX

For the Mid filter select between filter types: Parametric and Notch.

Parametric Filter - Broad type

Shelving Filter

Notch Filter - Narrow Type

Cut Filter - Bessel type

Cut Filter - Butterworth type

Freq

Press Freq and use Faders 1 to 3 to adjust frequence for each of the four bands.

Range - Lo band : 20Hz to 20kHz Range - Mid band : 20Hz to 20kHz Range - Hi band : 20Hz to 40kHz

Gain

Press Gain and use Faders 1 - 3 to adjust gain for each of the four EQ bands.

Range for the Parametric, Shelve and Cut type: Lo Gain : -12dB to +12dB Mid Gain : -12dB to +12dB Hi Gain : -12dB to +12dB

Range for the Notch filter: Lo Gain : -100dB to 0dB Mid Gain : -100dB to 0dB Hi Gain : -100dB to 0dB

Type

Press and use Faders 1-3 to set BW value for each of the 4 EQ bands.

Range for the Notch filter: Lo BW : 0.02oct to 1oct Mid BW : 0.02oct to 1oct Hi BW : 0.02oct to 1oct

Range for the Parametric filter: Lo BW : 0.1oct to 4oct Mid BW : 0.1oct to 4oct Hi BW : 0.1oct to 4oct

Range for the Shelve filter: Lo BW : 3dB/oct to 12dB/oct Hi BW : 3dB/oct to 12dB/oct

Range for the Cut filter: Lo BW : Bessel or Butterworth Hi BW : Bessel or Butterworth

Bandwid

th/Q - Key-Values:

BW Q

0.5 - 2.87

0.7 - 2.04

1.0 - 1.41

ATX/DTX

5 Band Page

Xovers

Press this button to access the four cross-over points between the five-bands. The parameters are Automatically assigned to faders 1-4. Parameter range: Xover 1: Off to 1,6kHz Xover 2: Off to 4kHz Xover 3: 100Hz to Of, Xover 4: 250Hz to Off

Defeat Thresh

Range: -3 to -30dB This is a unique control which holds the gain from the multiband compressor below a certain threshold. No matter the spectral shaping applied from multiband system, below the Defeat Threshold, the frequency response is flat and gain is unity. Defeat Threshold is relative to Compressor Threshold, which is relative to Reference Level.

Defeat Ratio

Range: Off to Infinity Controls how close to the Defeat Threshold the make-up gain of the compressor is counteracted. At high ratios, the signal only has to be slightly below the Defeat Threshold before the compressor gain is fully defeated.

Thresholds A & B

Parameter range: -25 to 20dB Thresholds and the overall All Threshold. Press this button to access the five individual band Threshold is relative to Reference Level set at the Main page.

Gain

Parameter range: 0 to 18dB Press this button to access the five individual band Gains and the overall All Gain.

DXP Mode - introduction

The 5-band section is either in normal compression mode, or DXP mode. Instead of attenuating signals above a

certain threshold, DXP mode (Detail Expansion) lifts up signals below the Threshold; thereby bringing out details rather than squashing the loud parts. DXP mode therefore is capable of adding intelligibility and air to speech, lifting harmonics, or emphasizing ambience without increasing overall peak level.

As shown on the illustration, gain is positive below threshold, unity at Threshold, and the effect decreases above Threshold. In DXP mode, Ratio becomes Steer. Steer can be regarded as an adaptive Ratio that gradually approaches 1:1 above the threshold.

Multiband DXP DXP mode can be used with any number of bands up to 5. When used multiband it is particularly effective in bringing out air and clarity. The processor can act as an automatic Eq that removes a boost when it's not needed: At very low levels, where noise is dominant, and at loud levels where sibilance would become a problem. Besides from being effective on speech, DXP mode can be used in mastering to bring up low levels, e.g. when preparing film or concerts for domestic or noisy environment listening.

Try setting the Steer and/or Threshold parameters differently in the bands to hear the effect. High Steer values add more detail gain than low values, but remember that Threshold has to be negative to add detail gain at all. DXP Threshold relates to the Reference Level set on the Main page.

To disable DXP detail gain at very low levels, use the Defeat Threshold and Defeat Ratio controls. Defeat threshold relates to the DXP threshold, and allows for

a certain level-window, inside which detail gain is applied. Defeat Ratio determines the slope at which DXP detail gain is defeated.

ATX/DTX

Ratio - DXP mode OFF

Parameter range: Off to Infinity:1 Press this button to access the five individual band Ratios and the overall All Ratio. The parameters are Automatically assigned to fader 1-6.

Attack

Parameter range: 0.3 to 250ms Press this button to access the five individual band Attacks and the overall All Attack. The parameters are Automatically assigned to fader 1-6.

Release

Parameter range: 20ms to 7s Press this button to access the five individual band Release and the overall All Release. The parameters are Automatically assigned to fader 1-6.

DTX Limit page

Link Limiter

Range: -3, -2, -1, Normal +1, +2, +3 When Link is active, the same amount of peak limiting is always applied to both channels.

Some broadcasters like the sound of operating left and right limiting without stereo coupling because they feel that it maximizes loudness and widens the stereo image. On dual mono sources, of course you should always choose un-linked Limiter operation.

The Configuration control on the Main page does not affect the Link Limiter setting. This link is running individually from the selected configuration.

Softclip A/L and B/R

Parameter range: - 3dB to Off When active, Soft Clip applies a saturation effect on signals close to maximum Output level. The threshold is relative to the Threshold of the Brickwall Limiter. This controlled distortion of transients works well for adding loudness, but is not a desirable effect with some data compression codecs. While the Brickwall Limiter is extremely low distortion, Soft Clip is not. Use your own judgement if you want it or not.

Threshold A & Threshold B

Parameter range: -12 to 0.0dBFS Sets the Threshold of the Brickwall Limiter. The Threshold is relative to 0 dBFS, not to the Reference Level set on the Main page.

The Brickwall Limiter uses 48 bit processing with distortion figures surpassing the quality demands of DVD-Audio mastering. Oversampling is used to prevent intersample peaks from reaching the Output, and time-constants adapt to the Input signal.

Fader A & Fader B

Parameter range: Off to 0dB Fader function on the Output. When Dual Mono configuration is selected, individual Output faders are available.

ATX Limit page

Parameters that are not described under DTX Limit page:

Emphasis

Range: Off, 50µs, 75µs, J17 To pre-condition signal better for analog transmission, the limiter in ATX can take downstream emphasis into account. Note that the output signal of DB4 or DB8 does not contain pre-emphasis, but is linear, so STL data reduction isn't compromised. When the Emphasis parameter is set to Off, linear limiting (like in DTX) is available.

HF Offset

Range: -12dB to 0dB When set to 0 dB, emphasis limiting precisely follows the selected pre-emphasis curve. However, lack of peak conservation in the downstream signalpath (DA converters, sample rate converters, filters, data reduction etc.) may necessitate a more conservative HF Offset, targeting, for instance, 1 or 2 dB below the theoretical roll-off. When the Emphasis parameter is set to Off, HF Offset has no effect.

Output

Off, -100dB to 0dB Output level control

MULTIBAND-5.1

Introduction

The Multiband-5.1 algorithm is a multi-channel, multi-band optimizer, with Limiters and extensive possibilities to assign channels to multiple Sidechains. Four-band dynamics are available for 5.1-processing. With the Multiband-5.1 it is possible to integrate dynamics processing for 5.1 applications offering features, which are not possible if using multiple stereo dynamic processors.

Multiband-5.1 processor contains:

• 5 channels of three band expansion and compression

• Full-range brickwall limiter on all Outputs

• 1 channel of full range expansion, compression and limiting for the LFE (Sub) channel

• 3 Sidechains for the five main channels, that can be assigned in flexible ways

• 1 extra Input channel that can be used for external Side Chain Input.

Main

At the Main page you have access to the general set-up parameters for the Expander and Compressor sections. Meters are shown for all seven Inputs and six Outputs at the right of the display.

Band Xover Frequencies

Lo Xover

Range: Off to16kHz Sets the Cross-over frequency between the Lo- and the Mid- Expander and Compressor bands for the five main channels (LFr, RFr, Cnt, LSr, RSr).

The two Cross-over points are not allowed to cross each other. Therefore the parameter range can be less than 16kHz if the Hi Xover parameter is set below 16kHz.

Hi Xover

Range: Off to16kHz Sets the Cross-over frequency between the Mid- and the Hi- Expander and Compressor bands for the five main channels (LFr, RFr, Cnt, LSr, RSr).

The two cross-over points are not allowed to cross each other. Therefore the parameter range can be less than going down to Off, if the Lo Xover parameter is set above the Off position.

Performance Settings

Crest

Range: Peak, 6dB, 10dB, 12dB, 14dB, 16dB, 20dB, 24dB, RMS Select compression method between RMS and PEAK. The dB steps between RMS and Peak are the dBs needed for a peak-value to override RMS measurement.

Nominal Delay

Range: 0 to 15ms (<2ms in 0.1ms steps. >2ms in 0.5ms steps) Sets the nominal Delay of the signal compared to the Sidechain signal. This is also known as "Look ahead Delay", enabling the Compressor section to become more responsive to the incoming signal.

Automatic Make Up Gain

Range: Off/On Switches the Automatic Make-up gain On or Off. As using compression is a reduction of dynamic range in the signal a compensation for this loss of gain on the Output side is possible. Use the Auto Make Up gain to achieve this.

Reference Level

Range: -24dBFS to 0dBFS in 0.5dB steps This parameter sets the reference level in the algorithm. The reference level is the level at which the Threshold parameters will start operating when set to 0dB. E.g. if the Reference Level is set to -18dBFS (often referred to as 0dBu), a Threshold setting at -4dB, will cause the Compressor to start operating at -22dBFS.

Algorithm Inputs/Outputs are distributed as follows:

E1 - E4

L R C LFE SL SR Xt

L R C

LFE

INPUT

OUTPUT

•

MULTIBAND-5.1

Side Chain - Control page

The Sidechain assignment possibilities in the Multiband-5.1 are very comprehensive. Carefully selecting which channels should be controlled by which Sidechains, is just as essential as dialing in the correct Threshold and Ratio values.

It is possible to freely select any or none of three Sidechains to control each of the main-channels. This also gives you the option of grouping the channels. In addition to this, the LFE channel has its own Sidechain control. This enables e.g. setting up two Multiband-5.1 algorithms in serial setup, while having six individual Sidechains available, enabling fully individual Sidechain controls of all channels.

At the Feed page it is possible to make additional Sidechain link Inputs, for e.g. having the Center-channel contributing to the Sidechain Inputs of the two Front channels, to create a more coherent sound from the front-channels.

The illustration above reflects the Processing parameter set to Multiband-5.1 in Normal mode.

Basic operation

At the Setup/Control page it is possible to decide which Sidechains should control which channels. Select any of three Sidechains to be assigned to any of the five Mainchannels. You can also chose to pass the channels unprocessed through the algorithm. The LFE channel can be assigned to its own separate Sidechain, or left unprocessed.

Setting a channel to unprocessed will preserve the processing delay through the algorithm, keeping the channel time-aligned to the other (processed) channels.

Side Chain - Feed page

The Setup/SC Feed page holds parameters specifying which Input channels should feed the three Sidechains.

Normal

Range: Off, On When this parameter is set to “On” the Input channels selected to be controlled by the respective sidechain will also Input to the sidechain.

Add 1, Add 2 and Add 3

Range: Off, LFr Max, RFr Max, Cnt Max, LSr Max, RSr Max, Xt Max, LFr Sum, RFr Sum, Cnt Sum, LSr Sum, RSr Sum, Xt Sum. These parameters enable extra channels to be assigned to the respective Sidechain Input. The extra Sidechain Input channels will not be processed by the sidechain. The Sum settings will add the Input to the sidechain, whereas the Max settings only will contribute to the sidechain if the level exceeds the other Input channel levels.

Side Chain Control

Range - for the five main channels:

• Unprocessed

• Side Chain 1

• Side Chain 2

• Side Chain 3

Range - for the LFE channel:

• Unprocessed

• LFE

MULTIBAND-5.1

Expander

Exp. page

Pressing Threshold, Range, Ratio, Attack and Release keys will immediately assign Lo, Mid, Hi, All and LFE values for these parameters to Faders 1-4. Be aware that the range of the All parameter is relative to the settings of the same parameters in the Compressor section.

Threshold

Range: -50dB to 0dB (in 0.5dB steps) When the signal drops below the set Threshold point the Expander starts to generate downward expansion.

Range

Range: -40dB to 0dB in 0.5dB steps Sets the maximum range of the expansion.

Ratio

Range: Off to Infinity Sets the Expansion Ratio below the Threshold point.

Release

Range: 20ms to 7sec. Sets the time it takes for the Expander to release its attenuation of the signal when the signal exceeds the Threshold again.

Attack

Range: 0.3 to 100ms Sets the time it takes for the Expander to reach the attenuation specified by the Ratio parameter when the signal drops below the Threshold point.

Meter Zoom

Press Zoom to decrease meter range and have a more accurate metering.

Bypass Exp.

Press to bypass the Expander section of the MD 5.1 algorithm.

All LFE page

Pressing any parameter will assign this to Fader 6.

All - parameters

These parameters are equivalent to the “All” - Threshold, Range, Ratio, Attack and Release parameters.

LFE - parameters

These parameters are equivalent to the “LFE” - Threshold, Range, Ratio, Attack and Release parameters.

All L M H page

Pressing any parameter will assign this to Fader 6.

This page holds all Expander Threshold, Range, Ratio, Attack and Release parameters for the Lo, Mid and Hi bands.

MULTIBAND-5.1

Compressor

Comp. page

Threshold

Range: -25dB to 20dB (in 0.5dB steps) Sets the Threshold level at which the Compressor starts to operate. The Threshold parameter relates to the Reference Level setting. Example:

If the Reference Level is set to -18dBFS, a Threshold setting of -4dB, will cause the compressor to start operating at -22dBFS.

Gain

Range: Off, -18dB to 12dB in 0.5dB steps. Adjusts the gain after the Compressor.

If the Auto Make-up gain parameter is set to On in the Main page, these gains will already have been adjusted according to the Threshold and Ratio parameters.

Ratio

Range: Off to Infinity Sets the Compression Ratio that must be performed above the Threshold point.

Attack parameters

Range: 0.3 to 100ms Sets the time the Compressor takes to reach the attenuation specified by the Ratio parameter when the level exceeds the Threshold point.

Release parameters

Range: 20ms to 7sec. Sets the time the Compressor takes to release the attenuation of the signal when the signal level drops below the Threshold point.

Meter Zoom

Press Meter Zoom to decrease meter range and have a more accurate metering.

All LFE

Pressing any parameter will assign this to Fader 6.

All - parameters

These parameters are equivalent to the “All” - Threshold, Range, Ratio, Attack and Release parameters.

LFE - parameters

These parameters are equivalent to the “LFE” - Threshold, Range, Ratio, Attack and Release parameters.

All L M H page

Pressing any parameter will assign this to Fader 6.

This page holds all Compressor Threshold, Range, Ratio, Attack and Release parameters for the Lo, Mid and Hi bands.

MULTIBAND-5.1

Limiter

The Limiter page is divided into three Sub-pages. One covering the Softclip section, one for the Full Range Limiter and one for the LFE Limiter.

Generic p

arameters in this algorithm:

Meter Zoom

Press Meter Zoom to decrease meter range and have a more accurate metering.

Bypass Limiter

Press to Bypass the Limiter section of the 5.1 algorithm.

Soft Clip page

Softclip

Full Range Softclip

Range: -6dB to Off Softclipper Threshold setting after the Compressor for the five multiband channels. Threshold is always relative to 0dBFS (Not the Reference Level.

LFE Softclip

Range: -6dB to Off Softclipper Threshold setting for the LFE channel only.

Full Limit. p

age

Threshold

Range: -12dB to Off

-6 to OdB in 0.1dB increments

-12 to -6 in 0.5dB increments Brickwall limiter for the five multiband channels. Threshold is always relative to 0dBFS. LED on each Output meter indicates when Limiter is active.

Release

Range: 0.01 to 1.00 seconds Release time for the Limiter.

Ceiling

Range: -0.10dB to 0dB Fine-tuning parameter setting the Ceiling for the Limiter.

The Ceiling parameter prevents the Output signal from exceeding the adjusted Limiter Threshold. It can be used to "hide" overloads to downstream equipment, but it does not remove the distortion associated with an over.

LFE Limiter page

LFE Limiter

Threshold

Range: -12 to +3dB

-6 to + 3 in 0.1dB increments

-12 to -6 in 0.5dB increments Brickwall limiter for the LFE channel. Threshold is always relative to 0dBFS. LED on each Output meter indicates when limiter is active.

Release

Range: 0.01 to 1.00 seconds Release time for the Limiter.

Ceiling

Range: 0 to -0.10dB in 0.01dB steps. Fine-tuning parameter setting the Ceiling for the Limiter.

MULTIBAND-5.1

Output

Trim Levels

Output trims

Range: 0dB to -12dB in 0.1dB steps Level trim of the Output channels. Only the fader is placed after these trims. These parameters can be used to trim the levels of the monitoring system, but please note that it also affects the recorded material.

Mute

Allows muting of each Output-channel.

Output Fader

Range: Off to 0dB (<-40dB: in 3dB steps, >-40 in 0.5dB steps) Output fader for all 6 Outputs. Can be controlled with the optional TC Master Fader connected to the GPI Input.

Compare

Easy switchable On/Off compare function for the entire MD

5.1 algorithm. This is not a bypass function as you are able to set a Compare Level (see below).

Compare Level

Range: -20 to 0dB This function allows you to set a Compare level of the processed signal to match the unprocessed signal for better A/B listening.

MDX 5.1

Fig 1. DRT map for consumers under different listening situations.

Dynamic Range of Broadcast Material

Today, program material for TV broadcast is generally aimed at a listener in the Living Room or Kitchen region, see Fig 1. This kind of material should be thought of as having a normal broadcast dynamic range signature. Commercials, promos and consumer CDs typically have a more restricted dynamic range, and therefore appear loud on TV, where normalization is based only on peak content. This kind of material should be thought of as having a hot dynamic range signature. On the opposite side we have film production, aimed at a completely different listening scenario, where much softer and much louder level than the average can be reproduced and heard. Production for wide dynamic range listening can also include classical or acoustic music. All material of such nature should be thought of as having a soft dynamic range signature. Music and entertainment radio is typically aimed at Car listening, so the dynamic range signature is generally hot. The only type of radio with a wider dynamic range typically carries classical music, drama and low key, talk based programming. To summarize, broadcast material is produced in a way that fits the listening conditions of a wide majority of consumers in the best possible way. The most dramatic difference between program material and consumer requirements concerns feature film. To have a feature film align with domestic listening conditions without loosing too much detail, or distorting the loud parts, low level may need to be brought up by 12-20 dB, and the headroom restricted by 12-16 dB.

Introduction

MDX5.1 is a high resolution dynamic range processor for multichannel signals. It may also be used to process for mono or stereo, thereby making changes or adjustments unnecessary. Its combination of low level lift, multi-band structure, output limiting and extensive controls offers the most sophisticated dynamic range translation capabilities in the professional audio industry today. Not surprisingly, MDX5.1 has become the standard for dynamic range control in film and music mastering.

Dynamic Range Tolerance, DRT, at the consumer

The Dynamic Range Tolerance map, Fig 1, illustrates the dynamic range targets for various listening environments. It is therefore a practical tool for optimizing listener pleasure in digital broadcast. According to recent studies, listeners typically object against too wide dynamic range much more than when the range is too restricted. Lack of speech intelligibility is the second worst offender, and often the cause for requesting more dynamic range limitation. Against the hopes of audio aficionados, as more people are listening through headphones (iPods and other personal entertainment systems), the DRT trend is therefore currently moving towards more dynamic range restriction in broadcast.

MDX 5.1

Processing for Digital Broadcast

Digital broadcast has the potential to carry more formats at a wider dynamic range than analog. For example, feature films can be presented more like they were mixed and edited, with fewer compromises on the picture as well as on the audio side. However, even for HDTV, audio still needs optimization for a presentation environment different than a cinema, like the picture still needs color space, rate and resolution corrections. The jumping level problem from analog TV will become bigger if stations transmit feature films with a less suitable dynamic range than today, because film fall way outside the Dynamic Range Tolerance of the average consumer under her domestic listening conditions. Consequently, dynamic range restriction must take place either at the station, or inside the consumer's receiving device. Dynamic range translation should deal with both overly soft and overly loud parts. Ideally, the perfect re-mapping should happen at the receiving end to accommodate a wide range of listening conditions. Metadata in conjunction with, for instance, Dolby AC3, provides some of these capabilities. However, even if the consumer knows how to adjust the dynamic range of a film to her current listening conditions, the optimum dynamics treatment unfortunately far exceeds the capabilities of an AC3 decoder. The dynamic range control in the codec is acceptable for cut and boost ranges of 4-6 dB, but preparing a feature film for broadcast needs considerably more than this. If such a large correction is left only to the AC3 decoder, the wide-band gain changes can be quite audible. Film and music dynamic range correction requires a multiband structure so listeners don't sacrifice speech intelligibility, or get subjected to the spectral intermodulation of a crude, wideband range controller.

MDX5.1

The MDX5.1 processor available in DB4 and DB8 is capable of bringing up low level detail, rather than boosting everything, and then having to limit the transients afterwards, see Fig 2. Low level lift can even be applied to specific channels selectively in one, two or three frequency bands.

Fig 2. DXP processing vs. traditional Compression and Limiting. Note how already loud signals are unnecessarily affected when relying on limiting and clipping.

MDX 5.1

Applications

MDX5.1 is well suited for dynamic range control of any kind of broadcast material. Film, sports, music or game shows. It may be applied during ingest, transmission - or both places. With suitable parameter settings, high resolution audio can pass through more than one hundred MDX5.1 processors without perceivable degradation of quality The ingenious topology of DB4 and DB8 allows for the processing to be performed instantly (the latency is below 0.5 ms, equivalent to moving a microphone approximately 16 cm or 6 inches), making re-alignment of audio and picture a non-issue.

Processing strategies

The major part of dynamic range translation should be done at the station, leaving only smaller corrections to be performed at the consumer. This ensures competitive audio with regards to consistency, quality and speech intelligibility, and prevents asking more from the AC3 decoder than it can deliver in a civilized manner.

Fig 3. Example of dynamic range re-mapping: From Home Theatre/DVD to Living Room listening conditions (Fig 1). Fig 3 and Fig 4 show rational transfer characteristics complying with the DRT of the consumer, without affecting levels when they are already on target.

Fig 4. Example of dynamic range re-mapping: From Home Theatre/DVD to Living Room listening conditions (Fig 1).

MDX 5.1

Basic Operation

On the Main page, MDX5.1 offer Input Gain controls for the Main Channels and for the LFE Channel. This enables positive and negative gain normalization to be performed in the 48 bit domain prior to low level processing and output limiting. These gain controls therefore operate in a safe location, well protected from generating output overloads.

Tip: Use the Input Gains as overload protected level trims in a critical realtime system, such as broadcast, OB or live music.

On the Link pages, the 5 Main channels (L, C, R, SL and SR) can be linked in numerous ways. The concept is to assign a channel to a Sidechain. If all channels are assigned to the same Sidechain, processing is identical on all of them. If a channel is assigned to a different Sidechain, processing on that channel may be different from processing on the other channels.

The DXP pages reveal separate controls for Sidechain 1-3 plus LFE. This enables, for instance, different settings for the Center or Surround channels, where speech intelligibility or low level ambience tend to get lost. Like when a feature film is re-purposed for broadcast or DVD under domestic listening conditions. If it is required to process more audio channels than 5.1, Engines can be run in parallel to cater for 6.1, 7.1, 10.2, 12.2 or even higher number formats. Parallel Engines attain perfect phase conservation and resolution, and do not compromise audio in any way.

MDX5.1 features 48 bit fixed point processing throughout. Split and reconstruction filters are phase linear when the algorithm is used in multiband modes.

Fig 5. MDX5.1 Level Diagram for different Steer and Threshold settings.. Defeat Threshold relates to DXP Threshold which relates to Ref Level. Limit Threshold only relates to Digital Full Scale output level.

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