|Meridian 861 Upgrade Adds Room Correction|
|Home Theater News EQ-Acoustics-Room Tuning News|
|Written by AVRev.com|
|Monday, 04 August 2003|
The new Version 4 software, coupled with the new EF20 DSP Card for the Meridian 861 includes a completely new feature: Meridian Room Correction. Conventional room equalization systems attempt to simply invert the room/speaker response – something which cannot be done accurately and produces undesirable effects such as listener position dependence, ringing, pre-echo and loss of headroom. Meridian’s Room Correction system, in contrast, relies on controlling room modes at low frequencies, where room problems are the most noticeable and effective results can be obtained for a wide range of listening positions. It should, of course, be remembered that room correction supports, rather than replaces, good room acoustics.
Meridian Room Correction uses Meridian’s on-board DSP (Digital Signal Processing) system to first measure the room and then automatically build a series of digital filters that reduce the reverberation time of significant room modes. As the filters generated are entirely digital in nature they can be created without any artifacts and easily incorporated into the all-digital Meridian signal path. The result is a noticeable improvement in the sound of a room, calming down resonances and smoothing out the acoustic.
The measurement of a room’s acoustic characteristics is normally difficult to carry out without expensive and complicated software and hardware. With Meridian Room Correction, however, both the measurement and the filter-creation are handled virtually automatically. You just set up a simple measurement microphone – such as a cheap sound-level meter obtained from a local electronics store – in the listening position and plug its output into an analog input on the processor, choose the Room Correction option in the Meridian setup program, and watch as the system performs measurements of each speaker in the room and builds the appropriate filters. Multiple sets of filters can be defined to be associated with different presets for different types of listening.
Along the way, the room correction program develops sophisticated “before and after” “waterfall” plots of the room’s frequency response, which can be used to analyze room acoustics and examine the performance of the filters.
In addition, filter information can be displayed, edited and even created numerically or graphically by an installer or advanced user.
In addition to Room Correction, Version 4 software adds a number of other enhancements: Smart Source, which automatically detects a wide range of digital signals and applies the correct decoding, and Meridian and THX post-processing, are now available on all inputs; all presets are now implemented with high-resolution processing and can handle input sampling rates up to 96 kHz; and a new bass protection system has been implemented, incorporating a revised calibration procedure.
Meridian System Software Version 4 has been available since early May for the 861 processor. To utilize the new room correction software, an EF20 DSP card and an analog input, such as is provided on the IA00 analog input card, are required. Both cards are standard in new 861 units. Existing Version 3 861 units can be upgraded by an authorized Meridian dealer, including the addition of an EF20 card and Version 4 software. Earlier units may require a factory upgrade.