In Part 1 of this series, we discussed the Anthem ARC (Anthem Room Correction) firmware that is present in their SSPs as well as the AVRs which have a reduced filter bank size. By far, the most significant sonic issue for acoustic music when a subwoofer is deployed occurs around the crossover from the subwoofer to the main speaker. In Part 2 of this series, we take a look at Anthem's ARC (Anthem Room Correction) when adding a subwoofer to the system.
Introduction to Audio Calibration, Room Correction and Treatment Reviews
It is impossible to ignore the speaker – room interface if good sound is to be achieved. In multichannel the best solution is to pick a product that incorporates the required technology in its box instead of purchasing external products.
Products start with simple CD or Blu Ray and a sound level meter to verify connections, polarities and levels. The next step is a room measurement system with calibrated microphones. Some AVRs and Pre/Pros come with this inside the box. These tools will verify speaker and seat placement. Independent microphones and software require knowledge of acoustics to setup and use.
Digital Signal Processing (DSP) power has been increasing at the speed of Moore's law. This has made quality electronic room correction possible at a fraction of the cost 10 years ago. Todays DSP allow AVRs to have a room correction function to be internal. The performance of these systems can range from dreadful to excellent.
External, DSP based, room correction hardware is available for stereo and multichannel applications. In multichannel this adds significant complexity is setup and use. HDMI issues often require the signal to be processed by an extra stage of ADCs and DACs. Acquiring an AVR with a good room correction built in is the best approach.
In the world of Stereo internal room correction is extremely rare. Fortunately SPDIF and USB interfaces allow the signal path with an external room correction system to remain fully digital.
Some room correction systems allow the user to voice the room with target curves and other methods. No system can make a bad speaker sound good.
A room correction system should produce a smooth interface of the main channel speakers to the subwoofer however this is the downfall of most systems. Deployment of multiple subwoofers is an excellent way to improve bass performance over a number of seats. Specialized software and hardware is needed to achieve the best results.
Passive room treatment can solve issues that electronic room correction cannot address. Unfortunately these can be expensive especially for products that do not call attention to themselves. Selection and placement requires knowledge beyond the typical audiophile although it can be acquired.
Products designed to improve a loudspeaker’s anechoic performance, such as electronic crossovers and active driver equalizers, are best left to the DIY community. We continue to wait for consumer loudspeaker to evolve into active systems including these components custom designed, at the factory, for the specific design. In the professional community this electronics and the required multiple power amps are often inside the speaker box. To the user, the speaker is unchanged but the sound is significantly improved.