Anthem Room Correction (ARC) for the Anthem D1 and D2 SSP




ARC is the most recent addition to Anthem's famed D2 Audio/Video Processor Preamp, or Surround Sound Processor , i.e., SSP (existing D1 or D2 owners can purchase it as an add-on kit).

The system consists of three elements:  A calibrated USB microphone (complete with robust mic stand), the ARC computer software application, and supporting firmware for the D2 itself.  Unlike most such systems on the market, ARC requires a personal computer to set it all up due to the complexity of the system.  Just how sophisticated it is will be apparent in a minute.

The software comes with a license file which will only work with a single D2 and microphone serial number combination.

Installation of the Windows application is straightforward (and works just fine under Windows Vista by the way).  The supplied microphone connects to the PC via its long USB cable, while the PC connects to the D2 via an RS-232 serial cable (if your PC does not have a serial port, you will need your own USB-to-RS232 converter).  On launch, the software presents you with a  choice of Standard or Advanced operation.

The Standard option is like a setup wizard.  You start by telling the system which channels you have (i.e., what your speaker configuration is).  You can if you wish have completely different setups for Movies and Music.  I am personally diametrically opposed to the notion that the two source materials need different settings.  The performance metrics of Hi-Fi audio reproduction do not change with media.  Hi-Fi is Hi-Fi, period.  The feature does have a couple very good inadvertent uses through: you can define a much narrower listening area for one mode compared to the other such that you can have one mode optimized for a theater full of people, and the other optimized for when you are the sole critical listener.  In addition, having two different setups makes comparing different ARC settings a breeze.  By setting different “targets” (which we'll explain in moment) for Movie and Music, one can very easily A/B the different settings later by flipping between the Movie/Music presets in the D2.

You must also tell the system how many seats you have (or really how many locations in the room to measure).  ARC requires you give it a minimum of five positions to measure.   Even if you have just, say, two chairs, you must take measurements at at least five positions, and they must be at least 12 inches from each other (preferably 20).  Although at first it may seem pointless to measure what the sound is like in places no listener will be, this minimum is imposed so that the system doesn’t misinterpret what it is hearing in the actual seats in terms of identifying what is a room mode and what isn’t (in other words, one or two measurement positions just don't tell you the whole story of the room).

If you chose the Standard option, that's the end of your input.  The system will ask you to get the mic ready in the first central, or prime, seat, the PC will then take control of the D2, ordering it to cycle power, and start the first set of test noise bursts through each speaker.  You’ll be prompted to move the mic to the second position, it will repeat the test noise bursts, prompt you to move the mic to the third seat, and so on.  The software then crunches the numbers, figures out basic setup parameters such as speaker level and distance, sets crossover points, and ultimately figures out what filter it is going to apply to each speaker.  Its last step is to send all these data to the D2, and you are done.  You can go into source setup and make sure it indicates that EQ is on.

The Advanced mode is much more interesting.

You start the same way, but on completion of the measurements, the application shows you a frequency response graph for each speaker.  These graphs are a simplification in that they represent an average of all the measurements taken for each speaker, yet the system is using the separate measurements from all positions to calculate the requisite target curves and filters.