Home Theater Hacks

Hack #27. Use Dynamic Range Compression to Regulate Volume

Dynamic Range Compression can lessen volume of Dolby Digital playback material.

All Dolby Digital–compatible receivers offer a feature called Dynamic Range Control (DRC). The DRC setting on your receiver, usually found in one of the speaker setup menus, offers three options: Off, Mid, and Max. This DRC control will reduce the dynamic range of Dolby Digital material. Dynamics are reduced significantly if you select the Max setting, reduced moderately if you select Mid, and left unchanged if you select Off. The overall effect is the squashing detailed in "Use Gain Offset to Regulate Volume" [Hack #26] .

Some receivers also offer an additional Midnight mode that incorporates elements of DRC, bass reduction, and delaying the center and rear channels for better ambiance effects at lower volume. This is another, albeit similar, means of reducing the playback volume of playback material.

The most important caveat with DRC is that it operates by reading digital compression flags in the Dolby Digital bitstream; as a result, DRC usually works only with Dolby Digital signals. It is unable to affect DTS signals, or audio signals coming in via analog inputs. In addition, a Dolby Digital soundtrack must be encoded with these compression flags, and some lower-budget productions have no flags; these won't work with DRC.

Thankfully, many modern receivers have expanded the Dolby-specific DRC to apply basic dynamic reduction to analog soundtracks ...