THX Loudness Plus™ is a new volume control technology featured in THX Ultra2 Plus™ and THX Select2 Plus™ Certified Receivers, pre-amps and amplifiers. With THX Loudness Plus, home theater audiences can now experience the rich details of surround sound at any volume level.

What is THX Loudness Plus?

All movies, music and games are mixed at Reference Level in the studio, to be played back at the same Reference Level in the cinema or home theater (0 db on the volume dial for THX Certified Receivers is equal to the studio Reference Level). However, many of us find Reference Level is too loud for our homes. But, turning the volume down often means that elements of movie, music and other soundtracks are lost or perceived differently from the original sound mix.

THX Loudness Plus maintains the integrity of soundtracks when listening below Reference Level. The technology compensates for the tonal and spatial shifts that occur when the volume level is reduced. By automatically raising the levels of the ambient sound, you experience the true impact of movies, music and games regardless of the volume setting.

How Does THX Loudness Plus work?

THX Loudness Plus incorporates two new THX Technologies. As the user changes the volume, THX Multi-channel Spectral Balancing™ and THX Dynamic Ambience Preservation™ automatically and seamlessly apply the appropriate compensation. This delivers a more accurate listening experience at any volume level.

THX Multi-channel Spectral Balancing™

adjusts frequency response to counter the perceptual loss of low and high frequency sound in all channels. Begins with a flat response at Reference Level, and continually adjusts the response as the user selects lower listening levels. The equalization is applied to all channels in a multi-channel listening environment.

THX Dynamic Ambience Preservation™

Surround channel processing preserves the spatial detail that is lost when listening below Reference Level. It automatically shapes the output on surround channels to maintain the perceived balance in the original mix.


THX Loudness Plus automatically adjusts the front-to-back speaker level relationship as you turn the volume level down.