UPMAX® Upmixing

The LA-5300 uses the same new upmixing algorithm found in the Linear Acoustic UPMAX® ISC. If the channel count and format of the incoming content matches the desired output format, the LA-5300 will pass it through as-is. Or, it can upmix stereo and legacy 5.1-channel content to one of several supported immersive formats.

The UPMAX menu is separated into Basic and Advanced sections. The Basic menu is displayed by default. The Advanced menu can be expanded with a dropdown menu as needed.

The controls in the Basic menu can be divided into four basic groups: Preset and Format controls (1A), LFE Channel controls (1B), Center Width controls (1C), and Auto-Detect controls (1D).

Preset and Format Controls

UPMAX processing is largely based on presets. Several factory presets are included which can be used as-is or serve as starting points for a custom user preset.

Use the Preset dropdown menu (2C) to choose a preset. To save any changes as a user preset, click on the Save As button (2D) and name the new preset. You must refresh the browser window to see the new preset in the Preset list.

The Input Format menu (2B) is used to specify the channel format of the source audio. If the input format matches the selected output format (as selected with the Output Format control) the unit will pass the signal through as-is without additional processing. Input options include:

Auto Detect: In this mode, the unit continuously monitors the input signal to determine its format and will automatically switch to one of the processing modes below (Stereo, Stereo + Dialog, or 5.1)
Stereo: Stereo content will be upmixed to the desired output format
Stereo + Dialog: Stereo content will be upmixed to the desired output format, while a dedicated dialog input on Channel 3 will be passed through to the Center output
5.1: 5-1-channel content will be upmixed to the desired output format
Pass-through: Pass-through will pass the input signal directly through to the output with no additional processing; this can be used as a “soft bypass” function as the signal still runs through the upmixer and therefore incurs the same amount of latency as it would if it was actually upmixing a signal, thereby preserving A/V sync and avoiding lip sync issues

The Output Format menu (2A) determines the output channel configuration. Output options include:

5.1: Provides a constant 5.1-channel output from Stereo, Stereo + Dialog, and 5.1-channel input sources
5.1 Legacy: Like the standard 5.1 output, it provides a constant 5.1-channel output from Stereo, Stereo + Dialog, and 5.1-channel input sources but with upmixing that is sonically closer to the previous UPMAX algorithm used in the Linear Acoustic UPMAX v4 upmixer and the algorithm employed in the various Linear Acoustic AERO®-series processors
7.1: Provides a constant 7.1-channel output from Stereo, Stereo + Dialog, 5.1-channel, and 7.1-channel input sources
7.1+2: Provides a constant 7.1.2-channel output from Stereo, Stereo + Dialog, 5.1-channel, 7.1-channel, or 7.1.2-channel input sources
5.1+4: Provides a constant 5.1.4-channel output from Stereo, Stereo + Dialog, 5.1-channel, or 7.1.4-channel input sources

LFE Channel Controls

The LFE Channel controls are used to tune the crossover frequencies, gain, and signal routing of the low frequency effects audio.

LFE Crossover

The LFE Crossover control (3B) defines the crossover frequency at which to extract the low frequency signal routed to the LFE Channel and is typically set between 60 and 100Hz. It works in combination with the LFE Routing and LFE Gain controls to create the LFE Channel.

Mid-Bass Crossover

When a mid-component signal is created for the Center Channel, it is split into two bands, LF and HF. The Mid-Bass Crossover control (3A) defines the crossover frequency of the split.

Splitting the mid-component into two bands allows the user to freely control the two signal widths and independently distribute them across the Center, Left and Right Channels.

This can be very useful in keeping the main phase-correlated signal (HF band) in the Center Channel for dialog while spreading the remaining part of the mid-component (LF band) – which could still have some low-frequency dialog along with music and effects – across all front channels.

LFE Routing

The LFE Channel is not typically used in creating a stereo downmix on end-user devices such as set-top boxes (STB) or television tuners. As a result, information in the LFE channel can get lost.

To prevent this, UPMAX uses an internal process that routes some of the extracted low frequency audio to the Center Channel. The amount of low frequency content routed to the Center Channel is set by the LFE Routing control (3C). Though values are expressed in a decimal format, they easily correlate to a percentage value (0.00 = 0%, 0.05 = 50%, 1.00 = 100%, etc.).

LFE Gain

The overall gain level of the LFE Channel is set by the LFE Gain control (3D) and is typically set at a value of 0dB.

Center Width Controls

These controls define the routing of the LF and HF bands across the Left, Center and Right Channels. Used in combination with the Mid-Bass Crossover frequency control, the provide the ability to craft the image of the Front Channels in a way that maintains a direct sonic-visual association of dialog while providing a pleasant and wide image of the phase-correlated elements. Though values are expressed in a decimal format, they easily correlate to a percentage value (0.00 = 0%, 0.05 = 50%, 1.00 = 100%, etc.).

The LF Center Width control (4B) determines the amount of LF audio routed to the Center versus the Left and Right Channels. The HF Center Width control (4A) does the same for audio in the HF band.

A setting of 0% sends all audio in the respective band to the Center Channel, while a setting of 100% sends it to the Left and Right Channels only. Intermediate values provide a blend to create any desired mix.

Auto-Detect Controls

When the Input Format is set to Auto-Detect, the LA-5300 continuously monitors the input signal to determine its format and will automatically switch to Stereo, Stereo + Dialog, or 5.1-channel processing modes.

The level at which the detector circuit determines that the incoming signal is program audio (and not noise or silence) is set by the Auto-Detect Threshold control (5B). The proper setting depends largely on the quietness (or noisiness) of channels that are not muted but also contain no audio. Set too low, it may cause a false trigger to upmix; set too high, it may cause a late transition to upmixing. The default value of -70dB should work well for most situations.

The amount of time in milliseconds a signal must stay above the Auto-Detect threshold before the unit begins upmixing - or below the threshold to cease upmixing - is determined the Input Switch Transition control (5A). A value of 10ms is a good starting point for most material.

The Advanced parameters are included for audio experts who wish to dig deep and tweak settings for very specific applications or demanding tastes. They are not required for most users and are accordingly not displayed by default.

Cycles per Octave

The Cycles per Octave control (6A) defines the number of teeth there are in one octave of frequency change of the comb filter. The comb filter is used to separate different frequency components of the input signal to aid in steering sounds in the surround field.

Minimum Comb Filter Frequency

The lowest frequency of the comb filter is set by the Minimum Comb Filter Frequency control (6B). For most applications, this should be set at or near the same frequency as the Mid-Bass Crossover frequency.

Comb Filter Level

The Comb Filter Level control (6C) sets the overall level of the comb filter. This control can have a significant impact on the movement of audio between the front and rear channels, with higher values rendering a greater sense of depth. In nearly all cases, leaving this control at its default value will result in the most pleasing soundfield.

Front-Rear Balance Factor

The Front-Rear Balance Factor control (6D) determines the amount of upmixed sound pushed to the surround channels (analogous to the Surround Depth control in previous UPMAX versions).

Center Channel Gain

The Center Channel Gain control (6E) sets the gain of signals determined by the upmixer to belong in the Center Channel, typically dialog.

Rear Channel Downmix Level

In order for a stereo downmix to render at the same level as the original stereo source that was upmixed, the gain applied to the rear channels must be the inverse of the Dolby Rear Channel Downmix Level. Put another way, if you want a 3dB boost in the rear channels, the Rear Channel Downmix Level control (6F) should be set to -3.

Front-High Crossover

The Front-High Crossover control (6G) adjusts the crossover point between the Front Left and Right channels and the Front Height channels.

Side-Rear Filter Crossover

The Side-Rear Filter Crossover control (6H) adjusts the crossover point between the Left and Right Surround channels and the Left and Right Back channels when upmixing to 7.1.

Side-to-Rear Gain LF

The Side-to-Rear Gain LF control (6I) adjusts the gain of the low frequency content in the Surround and Rear channels when upmixing to 7.1.

Side-to-Rear Gain HF

The Side-to-Rear Gain HF control (6J) adjusts the gain of the high frequency content in the Surround and Rear channels when upmixing to 7.1.

Rear Channel Boost

The gain of the Left and Right Back channels when upmixing to 7.1 is set by the Rear Channel Boost control (6K).

Highs in Laterals

The Highs in Laterals control (6L) determines to what degree higher frequencies from the ear-level to height speaker crossover circuit are mixed back into the ear-level speakers.

Lows in Heights

The Lows in Heights control (6M) determines to what degree lower frequencies from the ear-level to height speaker crossover circuit are mixed back into the height speakers.