LFE Management¶

Overview¶

Bass management selection tab in miniDSP Flex HT

The LFE Mgmt tab is used to configure the bass management filters:

LFE management with default settings for the miniDSP Flex HT

Each speaker channel is optionally high-pass filtered. In addition, its low-frequency content can be summed with the LFE channel to send to the subwoofer (or subwoofers).

Parameters¶

Frequency¶

Set the frequency of the high pass and low pass filters. The HPF slider sets the high pass filter corner frequency on the speaker channel: signal above this frequency is passed through to the speaker channel. The LPF setting sets the low pass filter corner frequency: signal below this frequency is summed to the LFE Mgmt channel.

Note that these filters do not create an abrupt change: there is a more or less gradual transition as determined by the filter type and slope.

Filter Type¶

Selects the type and slope of the filter. There are three types of subwoofer crossover filter with several slopes:

Butterworth (BW): Available in 6, 12, 18, 24, 30, 36, 42, and 48 dB/octave, Butterworth crossover filters are 3 dB down at the cutoff frequency.
Linkwitz-Riley (LR): Available in 12, 24 and 48 dB/octave, Linkwitz-Riley crossover filters are 6 dB down at the cutoff frequency.
Bessel: Available in 12 dB/octave only, a Bessel filter gives a more gradual roll-off through the crossover region.

Bypass¶

Bypass the respective filter. When "lit", the filter is bypassed. To enable the filter, turn this switch off.

Reduce 10 dB¶

Toggles the LFE compensation gain on and off.

When this is on, the bass frequencies from the speaker channels are reduced in level by 10dB before being mixed with the LFE channel. This is needed because movie soundtracks have the level of the LFE (low-frequency effects) channel reduced by 10dB during mixing in order to accomodate the high signal levels needed on this channel.

This will usually be set On. It is typically only set Off in the case where upstream equipment has already applied this gain adjustment on the LFE channel. This usually occurs only in upstream equipment with analog outputs (and is therefore not usually relevant for the Flex HT).

Examples¶

Below are some examples of how to set the bass management for each channel.

Bypassed¶

This is the default setting. Both filters are bypassed, and there is no processing on this channel.

Bass management active¶

This is a typical setting for a speaker channel with bass management active:

Typical bass management filter settings for speaker channels

Both filters are enabled and set to 80 Hz Butterworth 24 dB/octave.
The 10 dB gain adjustment for mixing to the LFE channel is enabled.

Setting the LFE channel¶

This is a typical setting for the LFE channel when using bass management:

Typical bass management filter settings for LFE channel

The high pass filter is left disabled.
The low pass filter is enabled with a 120 Hz Butterworth low pass filter. (It is often recommended that the LFE channel be low pass filtered at 120 Hz in case there is any extraneous high frequency content on the soundtrack.) The 10 dB gain adjustment is not enabled.

A complete example¶

For reference, here is the complete screen with bass management set up for 7.1 processing. In this example, we have filtered the rear surrounds at 120 Hz:

LFE management with typical settings for 7.1

Note also that the LFE Mgmt signal will need to be routed to the subwoofer output channel on the LFE Routing tab:

Routing for bass management in miniDSP Flex HT