A Guide to Amplitude Panning

Amplitude Panning Optimization#

This section offers several ways to deal with the usual optimizations needed for amplitude panning algorithms. These advices applies to VBAP, VBIP, LBAP and Angular 2D, as they all rely on amplitude panning.

Choosing an amplitude panning algorithm over another is mainly driven by the speaker layout.

Apparent Source Width#

Amplitude algorithms always use the smallest number of loudspeakers, the source signal can be fed from one, to up to two (2D) or three / four loudspeakers (in 3D), depending on the algorithm.

Therefore, when moving a source accross the setup, its apparent width will vary, going from one speaker to multiple speakers.

On inhomogeneous layouts (i.e. that feature ereas with more space between speakers than others), the source width can also vary from a denser area to a sparser one.

Both of these issues can be solved by using the spread parameter to obtain a constant apparent source width across the setup. However, spreading the source over too many speakers can cause a critical signal coloration.

For very inhomogeneous setups, an other solution is to tend towards a more regular repartition by using fewer speakers in the denser area. This avoids having to spread the source signal over too many speakers.

Try finding the right balance between speakers density, the spread and the delay correction.

Gain and Delay Compensation#

Those algorithms were designed to only takes into account the azimuth and elevation of the speakers. Whatever a speaker's distance to the center is, it will be fed with the same source signal level, at a given direction.

In most setups, the loudspeakers distances to the center are not constant, thus altering the setup homogeneity and signal coherence at the center of the venue. Using the ‘GAIN COMPENSATION’ and ‘DELAY COMPENSATION’ can be useful to balance this effect.

When using the spread parameter, adding delay correction can also help deal with the comb filtering coloration (due to sending the same signal to multiple speakers), especially when applying a high spread value.

Clément Vallon

Training and User Support @ HOLOPHONIX
Sound Engineer | M.Eng from ENS Louis-Lumière, Paris