Anthem Room Correction (ARC Genesis) Anthem Room Correction, third generation (ARC Genesis)

What ARC Genesis is

Anthem Room Correction, or ARC, is software that measures how a loudspeaker and a room interact and then builds digital equalization filters to compensate for the room. The first software appeared in 2010, and ARC Genesis is the third generation, announced on May 17, 2019. Anthem says its development was influenced by a three-year study at Canada's National Research Council, the Athena Project, with Dr. Floyd Toole among the contributors. The software runs on a computer, takes measurements through a calibrated ARC or PBK microphone, and uploads the resulting filters to the device, where the DSP applies them in real time.

Genesis is not compatible with older products that rely only on RS-232 for data transmission. For those, Anthem points users to ARC-1. Supported platforms are Windows 7, 8, 8.1 and 10 and macOS 10.12 or later, with the interface available in English, Chinese, French, German and Spanish.

How ARC measures a room

ARC plays short, loud tone sweeps through each speaker and records the impulse response at the microphone. It converts that response to the frequency domain with a Fast Fourier Transform, smooths and averages the results, and calculates filters. Anthem's guidance on the measurement positions is specific. Use five positions for most rooms. Put the first at the primary listening spot with the microphone at ear height pointing at the ceiling, because the first position sets the level of the overall system. Place positions 2 through 5 two feet (60 cm) from the first, and no farther than three feet (90 cm), in an X pattern. Vary the height so that two are 6 to 12 inches below the first position and two are 6 to 12 inches above. Keep the first position two to three feet (60 to 90 cm) from walls where possible.

The mistakes Anthem lists are equally specific: never take all five positions at one location, and never place positions 2 through 5 at the room corners. Shorter spacing of about one foot (30 cm) is acceptable only for systems where ARC is used for low-frequency correction alone. Measurement sets can be saved, resumed and re-measured speaker by speaker, and Quick Measure shows the response in real time while you move a subwoofer.

Minimum-phase filters and why Anthem avoids mixed-phase

ARC builds minimum-phase filters, which respond quickly and decay briefly, like a drumstick on a drum. Anthem argues against mixed-phase correction because equalizing the all-pass part of a response needs a time delay that must be limited, and the limited correction produces pre-ringing, a backward echo that blurs transients, especially at low frequencies where the delays are longest. Anthem also notes that finding frequencies with matching phase across several microphone positions below the Schroeder frequency is hard, which restricts mixed-phase systems to a few correction points. The company's claim is that its frequency-domain approach picks exact correction frequencies without those artifacts. This is Anthem's design argument, and it has not been independently tested in a published comparison.

ARC is also built around the point that an ideal flat measurement does not always sound right. Anthem says its algorithms keep the room's natural acoustic signature while smoothing peaks and dips, and it evaluates thousands of possible crossover points, slopes and target responses when it recommends bass management settings. On the digital side, Anthem notes that analog filters depend on resistors with tolerances as high as 1% and capacitors as high as 5%, while digital filters at 16, 24 or 32 bits can sit at exact frequencies.

ARC Genesis vs ARC-1 and other room correction

Compared with the earlier ARC generation, Genesis adds adjustable target curves with deep bass and high-frequency options, saved and resumed measurement, per-speaker remeasure, a new user interface, an improved algorithm, and a separate maximum correction frequency for each speaker group. On Anthem STR products it adds automatic speaker and subwoofer phase alignment. Loudness compensation of the Audyssey Dynamic EQ kind is a separate function, and none of the Anthem pages cited here describe an equivalent inside ARC. For a comparison with another room correction family, see Audyssey MultEQ XT32 and Dirac Live Bass Control.

What you can adjust and what it runs on

Professional Mode exposes the target curve of the whole system through room gain, deep bass boost and tilt controls. Each speaker group gets its own high-frequency roll-off and crossover frequency and slope, and subwoofers get high-frequency extension, low-frequency extension and low-frequency extension slope controls. The default maximum correction is 5,000 Hz for small speakers such as in-ceiling heights, and Anthem's own example sets 400 Hz for dipole electrostatic fronts. The full range runs from 20 Hz to 20,000 Hz.

Some microphones carry a six-digit serial number that lets ARC download that unit's individual response curve. On supported products, up to four measurement sets and up to four profiles can be stored. A typical use is one set with a drop-down screen deployed and another with it hidden, or a profile for multichannel home theater with a subwoofer and another for two-channel music without one. For sub EQ, Anthem advises running the sub's own correction first only if it is ARC or PBK based, and otherwise disabling the sub's EQ before running ARC.

Which products support it

Anthem lists these as compatible: the AVM 60 and AVM 70/90 processors, the MRX Generation 2 (710, 510, 310), Generation 3 (1120, 720, 520) and Generation 4 (1140, 740, 540) receivers, the MDX amplifiers and the STR preamplifier and integrated amplifier. Paradigm products include the Defiance V12/V10 and X15/X12/X10 subwoofers, Founder 120H, Persona 9H, Prestige 2000SW and 1000SW, and the PW 800 and 600 line. MartinLogan products include the BalancedForce 212 and 210, Dynamo subwoofers and the Expression ESL 13A, Impression ESL 11A and Renaissance ESL 15A. Anthem's own reason for requiring several positions is that correction based on one point can improve that point and make the rest of the room worse, so ARC's gains are an average over the measured area. Room modes and bass management settings still decide what is physically possible, and ARC does not replace good speaker and subwoofer placement.