In addition to surround sound decoding, AV-amplifiers have a variety of additional audio features. This section of the guide covers the most common features. p>
Some home theater amplifiers have bass and treble controls for use when listening in stereo. These controllers works as you know it from regular stereo amplifiers by increasing / decreasing the treble and bass depending how to set controller.
Loudness Loudness is a function that increases the bass at low volume. This is to counteract the human ear's low sensitivity to bass at low volume. Some AV-amplifiers have this feature. p>
When current amplifiers are packed with functionality that affects the sound using either room correction or that other circuits interfere into often have many home theater amplifiers a mode that enables all room correction is switched off and all picture circuits switched off. This for the most pristine stereo reproduction. p>
Many of the projectors and especially TV-sets are equipped with advanced imaging processing. This processing is often so demanding that it requires some time to perform. This causes the image to be slightly delayed on the screen relative to the output from sources like a DVD or Blu-Ray player. This again leads to the sound comes before the picture and you find that audio and video is out of sync .
This is especially noticeable in speech where the sound and lip movements do not match the. Therefore, many amplifiers have lipsync adjustment so you can manually delay the audio to audio and picture matches the. Typically, one can adjust this delay in stages from 0 ms to 100-200 ms. Some AV-amplifiers supports automatic adjustment through HDMI if your TV supports this feature.
Most home theater setups does not have speakers to reproduce bass completely for all channels and need subwoofers. To redirect the low frequencies to the subwoofer the AV-amplifiers is equiped with low pass filters. This filter sends bass sound below a set frequency to the subwoofer or front speakers. Many amplifiers have common crossover frequency for all speakers, while the most advanced have the opportunity to share different frequency for the different speaker groups.