The Lawo AMBIT (AMBience IT) is a DSP module specifically designed for 5.1 surround channels providing upmix and spatialise processing. It can operate in one of two modes:

  • Upmix & Spatialise – a 2 in, 6 out upmixer which, using sophisticated algorithms, converts stereo signals into 5.1 surround.
  • Spatialise Only – a 6 in, 6 out spatialiser which processes the surround left and right channels only, ideal for treating incoming 5.1 signals.

Typical applications for the Upmix & Spatialise mode are:

  • On a 5.1 input, enable AMBIT to create a surround upmix from a stereo ambience microphone.
  • On a 5.1 sum, enable AMBIT to create a surround upmix from your stereo master.
  • On a 5.1 group, enable AMBIT to create a surround upmix group which is then assigned to a 5.1 sum. This allows you to upmix some stereo sources, but not others, by assigning a source either to the upmix group or directly to the sum.

    AMBIT Conditions
  • AMBIT can be applied to any 5.1 channel. If a different format is selected, the AMBIT module is not available.
  • AMBIT processing must be enabled in the System Settings display (using the Upmix/Spatialize Enable option).
  • AMBIT processing can be applied to input, group and sum channels, but not to auxes.
  • To enable AMBIT, you must have the Surround VCA master in access.
  • Once AMBIT is enabled, the 5.1 component channels lose their DELAY module. This is necessary to support the extra processing required for the AMBIT algorithm.
  • All AMBIT parameters are stored in productions, snapshots and presets.
  • AMBIT processing is fully compatible with any downmix.
  • The following functions are NOT supported by the AMBIT module - Link Groups; COUPLE; LISTEN; Snapshot crossfades; Timecode Automation.|

    How AMBIT Works

    The Upmix & Spatialise mode uses sophisticated algorithms to convert 2-channel stereo signals into 5.1 surround.
    Imagine that you are sitting in a virtual room, listening to the source from a pair of stereo loudspeakers. You are the target. Using AMBIT you can define:
  • The Virtual Room – the size of the room and how it handles reflections.
  • The Source position – the position and width of the source playback loudspeakers.
  • The Target position – your listening position.

Having defined how the source signal is "heard", you can then determine how the 5.1 output is processed:

  • Front Processing – these parameters define how much correlated signal (mono signal) feeds the discrete centre channel, as opposed to left and right (phantom centre). There are two modes in which you can work:
  • Auto-centre – in this mode the AMBIT module decides automatically how much correlated signal feeds the discrete centre channel versus left and right (phantom centre), based on the correlation threshold and time. The algorithm works dynamically, according to changes in the correlated signal level, producing a stable front image for any content.
  • Manual centre – with Auto-centre turned off, the correlated signal feeding the centre channel is set manually. You can adjust the left/right width (Basewidth) and discrete centre channel level (Centering). You can also choose to link Centering and Basewidth in order to maintain a consistent ratio.
  • Rear Processing – these parameters define the processing applied to the surround left and right channels. Parameters are available to control the left/right width (Basewidth), high pass filtering and the virtual room simulation:

In Spatialise mode, only the rear processing is applied to the incoming surround left and surround right channels.

Turning On AMBIT

AMBIT must be enabled and controlled from the Surround VCA master of the 5.1 channel.
1. Open the Main Display on the Central GUI.
2. Select the Surround VCA master by pressing its fader SEL button.
The UPX and SPZ buttons appear at the bottom of the MODULES list on the right of the display.

If you cannot see the Upmix (UPX) and Spatialise (SPZ) buttons, then check the following:

  • Is the surround VCA in access?
  • Is the channel format set to 5.1?
  • Is the Upmix/Spatialize Enable option turned off within the System Settings display?

    3. Turn on the Upmix & Spatialise mode (2 in: 6 out) by selecting the UPX touch-screen button.
    Both UPX and SPZ are enabled (green).
    4. Alternatively, turn on Spatialise mode (6 in: 6 out, rear processing only) by selecting SPZ only.


Once AMBIT is enabled, the 5.1 component channels lose their DELAY module. This is necessary to support the extra processing required for the AMBIT algorithm. This is reflected by the greyed-out Delay module on the Main Display.

5. To reinstate the suspended Delay modules, you must turn off the AMBIT processing - deselect UPX and SPZ.|

Changing the Signal Flow

The AMBIT module can be moved within the channel signal flow (using the Channel Config display).

Controlling AMBIT Processing

All AMBIT parameters are adjusted from the Main Display on the Central GUI.
1. Make sure that the Surround VCA is in access and assign AMBIT to one of the assignable views on the Main Display.

2. Make sure that AMBIT is turned on – either UPX and SPZ, or SPZ only.
3. Adjust the parameters from the on-screen buttons.
You have a choice of two modes: EASY or EXPERT.

AMBIT EASY Setup

Main Display

In most cases, the EASY tab provides enough parameters to configure a successful upmix.
1. First set the REF-SIZE for the VIRTUAL ROOM.
This defines the virtual room size in metres (m).
2. Then determine the FRONT PROCESSING parameters as follows:
Keep the AUTO CENTER option turned ON. In this mode AMBIT decides automatically how much correlated signal (mono source signal) feeds the discrete centre channel versus left and right (phantom centre) according to the Correlation Threshold and Time. The algorithm works dynamically, following changes in the correlated signal level, producing a stable front image for any type of content.
The correlated signal threshold and time determine the working point for the auto-centering algorithm:

  • CORR THRES – sets the correlated signal threshold (100% = +1, 0% = 0).

    Correlated signals above the threshold feed the centre channel and those below feed left and right equally (phantom centre).
  • CORR TIME – sets how quickly the auto-centering reacts to correlated signals falling above/below the threshold.

    You can monitor the affect of the auto-centering algorithm using the on-screen graphics.
    If you wish to control the front processing parameters manually, then use the EXPERT tab.
    3. Next adjust the REAR PROCESSING parameters:
  • DE-CORR – sets the amount of de-correlated signal applied to the rear. In other words, the impact of mono source content on the rear channels.

    100% is the default value. You can increase it to 200% (only de-correlated signal) or reduce it to 0% (only correlated signal).
  • PRE-DELAY – sets the amount of pre-delay in milliseconds (ms) applied to the rear channels.

    The bigger the pre-delay, the more reflective the virtual room will appear.
  • HP FREQ – sets the roll-off frequency for the high pass filter in Hz (see below).
  • HIGH-PASS – turns the high pass filter on or off.

    The rear processing high pass filter is a 2nd order (12dB/octave) filter which can be applied to the rear channels.
    4. Finally adjust the LFE low pass filter parameters:
  • LFE FREQ – sets the roll-off frequency of the LFE filter in Hz.
  • LFE FILTER – turns the LFE filter on or off.
    The LFE filter is a 4th order (24dB/octave) filter which can be applied to the Low Frequency Effect (subwoofer) channel.

AMBIT EXPERT Setup

The EXPERT tab provides access to more advanced parameters.
These are arranged in four pages: ROOM, POSITION, PROCESSING and FILTER.

ROOM

Main Display

1. Select ROOM to define the virtual room.
2. Use the ROOM-SIZE parameters to define the shape and size of the virtual room:

  • REF-SIZE - Room size in metres (m). Also available in Easy setup.
  • LENGTH - Length as a % of the room size.
  • WIDTH - Width as a % of the room size.
  • HEIGHT – Height as a % of the room size.

    Any changes are represented by the on-screen graphics.
    3. Use the WALL REFLECTIVITY parameters to define the reflectivity of the surfaces within the virtual room.
    100% = very reflective; 0% = not reflective:
  • SIDE - Reflectivity of the side walls (left/right).
  • REAR - Reflectivity of the rear wall.
  • CEILING - Reflectivity of the ceiling.

POSITION

Main Display

1. Select POSITION to define the source and target positions.
2. Use the SOURCE parameters to define the position and spacing of the stereo source loudspeakers:

  • FRONTAL - front/rear speaker position: 100% = front; 0% = middle of the room; -100% = rear.
  • LATERAL - left/right speaker position: 100% = right; 0% = centre; -100% = left.
  • HEIGHT - height of speaker position: 100% = top; 0% = middle; -100% = bottom.
  • SPACING – left/right spaving: 100% = full width; 0% = mono.

    3. Use the TARGET parameters to define the position of the listening target:
  • FRONTAL - front/rear target position: 100% = front; 0% = middle of the room; -100% = rear.
  • LATERAL - left/right target position: 100% = default.
  • HEIGHT - height of target position: 100% = default.

    The on-screen graphic provides a visualization of the resulting reflection pattern.
    4. If not already visible, select the ROOM tab and you will see that the source and target positions are represented by the yellow (left channel), red (right channel) and turquoise (target) dots.

PROCESSING

Main Display

1. Select PROCESSING to define the front and rear processing parameters.
2. When dealing with the FRONT processing parameters, it is best to work with AUTO CENTER either on or off:

  • AUTO CENTER ON - use the correlated signal threshold and time as described for Easy Setup.
  • AUTO CENTER OFF – control the front upmix processing manually:
  • BASEWIDTH – sets the left/right width: 100% = default; 200% = overwidth; 0% = mono.
  • CENTERING – sets the amount of correlated signal feeding the discrete centre channel: 100% = discrete centre only; 0% = phantom centre, no discrete.
  • LINK - turn on this option to link BASEWIDTH and CENTERING. This ensures that the correlated signal level remains constant and that there is an equal distribution of power between the three front channels.

    The results are best represented by the on-screen graphic within the Easy tab.
    3. The REAR processing parameters are identical to those in Easy setup.

FILTER

Main Display

1. Select FILTER to define the remaining parameters.
2. Use the REAR DIRECT REFL. and REAR CROSS REFL. parameters to adjust the virtual room reflections applied by the Spatialiser to surround left and right.


Note that these parameters affect the room simulation, and are completely separate from the rear processing high pass filter (controlled from the PROCESSING page).

Direct reflections describe reflections from the closest wall; cross reflections come from an opposing wall. So, if a signal eminates from the left source loudspeaker, then direct reflections come from the left and cross reflections from the right.
For each pattern, you can apply a shelving filter with parameters for:

  • FREQ - the roll-off frequency of the shelving EQ.
  • GAIN – the gain of the shelving EQ.
  • ABS GAIN – offsets the resultant shelving pattern.|

    AMBIT Settings

    • Saving and Loading AMBIT Parameters

      All AMBIT parameters are stored in productions and snapshots. This makes it easy to store and recall upmix processing as part of your mix.
      AMBIT parameters can also be stored as DSP presets in order to save and load favourite settings. Right-click on either the UPX or SPZ button, on the right of the Main Display, to open the 'Load/Save Preset' pop-up.
  • Selecting the AMBIT Module

    Some operations, such as copy channel, require you to select the AMBIT module. This is achieved by using the on-screen Sel button (at the top right of the AMBIT area in the Main Display).
    Main Display

    The Sel button turns green when selected.
    Note that the AMBIT module is automatically selected by pressing SEL ALL on the Central Control Section.
  • Copy and Reset for AMBIT

    AMBIT parameters can be copied between Surround VCAs. You cannot copy AMBIT parameters to other channel types.
    AMBIT parameters can be reset.
    See Copy & Reset for details.|