Well, get crackin' then, mudgel. Inquiring minds want to know!

ORIGINAL: mike_mccue

Dude,

It seems that one has to assume that ARCs EQ is markedly different from any other well regarded EQ?

Which I don't.

best regards,
mike

Apparently it is "markedly different from any other well regarded EQ". It uses audussey's MultEQ technology. This is form Electronic Musician:

A company named Audyssey Laboratories (audyssey.com) has come up with a different approach to room correction that goes much further than conventional solutions. The system, dubbed MultEQ, began as an academic research project at the University of Southern California under the direction of professor Chris Kyriakakis and one of his PhD students, Sunil Bharitkar. In 2002 they went on to found Audyssey with USC Audio Lab researcher Phil Hilmes and USC professor Tomlinson Holman (of THX fame).

The basic idea is to play test tones through the sound system in a room and measure the room's acoustic response at multiple listening positions. MultEQ then creates a precisely tuned inverse filter that counteracts most room-based distortions (see Fig. 1b). The technology, rather than using a few EQ bands, uses finite impulse response (FIR) filters with hundreds of control points, allowing a much more accurate and comprehensive correction in the time and frequency domains. A majority of the system's correction power is dedicated to the low end of the frequency spectrum, because that's where the worst acoustic anomalies arise.

Instead of simple averaging, the MultEQ algorithm accounts for the differences at each listening position using a technique called fuzzy clustering, which assigns locations with similar responses to a group or cluster. The process also calculates weighting factors that reflect the relative importance of each location to the other clusters. This allows the system to devise one filter that corrects the anomalies at various locations over a large listening area. The number of measurable locations is limited only by the amount of memory and DSP horsepower available.

MultEQ has been implemented in many modern A/V receivers to automatically calibrate the sound for up to eight locations in a consumer's listening room, and it has enjoyed accolades from many reviewers. Now Audyssey hopes to make similar inroads with recording studios. Two products are currently available: a hardware processor from Audyssey called the Sound Equalizer (which requires a Windows PC to provide the user interface) and a software plug-in from IK Multimedia called Advanced Room Correction (ARC).

I've heard the result of MultEQ in consumer systems, and it's very impressive. The sound is clean and clear, and the difference between turning it off and on is like night and day. This system could be a real boon for recording musicians who want to hear their music exactly as they intend it, without the unwanted contributions from their rooms.

I've heard the result of MultEQ in consumer systems, and it's very impressive. The sound is clean and clear, and the difference between turning it off and on is like night and day. This system could be a real boon for recording musicians who want to hear their music exactly as they intend it, without the unwanted contributions from their rooms.

+1
FWIW I've used the MultiEQ system in the world's worst listening room - my old Alfa - it's part of an Alpine car stereo. I have no idea how accurate it is but the listening "experience" is markedly improved. Measurement for 1 listening position (driver's seat ) took about 20 minutes.

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Come on Mike. Just give it a try or find someone who has it installed and give it the "ear test".

You asked if you're missing something here, and you are: ARC also corrects for the time domain as well as EQ. Your graphic EQ can't do that. Even slight time misalignment can create audible "smearing" in your listening environment.

Do I have ARC? Yes. Am I wild about it? Not really. Is my room properly treated? Yes. (I have a 9 sided, symmetrical room with no parallel surfaces with full acoustic treatment done using RTA.) Does it help me to create mixes that translate better? ABSOLUTELY!

That's all from me...

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This system could be a real boon for recording musicians who want to hear their music exactly as they intend it, without the unwanted contributions from their rooms.

This is the kind of statement I take issue with*. I read a similar description in a Recording Magazine review.

It's misleading because the room will always make its contribution to what you hear, no matter what steps you take. One would have to be completely ignorant of acoustical principles to accept such a claim at face value.

This is not to say that ARC doesn't have value. But such exaggerated claims are what nudge it toward the snake oil category.

Mike, the equalizer is probably very similar to the one used in Har-Bal, which is the equivalent of an 8,192-band parametric. But while a conventional parametric EQ with that many bands would be a CPU-killer, these FIR filters are remarkably efficient considering the degree of control they offer.

*Edit: to be fair, IK is careful not to make such statements in their own marketing. These claims originate exclusively from magazine reviewers.

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I've never used the ARC system but if it works as advertised, it's probably due in no small part to the following:

Instead of simple averaging, the MultEQ algorithm accounts for the differences at each listening position using a technique called fuzzy clustering, which assigns locations with similar responses to a group or cluster. The process also calculates weighting factors that reflect the relative importance of each location to the other clusters. This allows the system to devise one filter that corrects the anomalies at various locations over a large listening area. The number of measurable locations is limited only by the amount of memory and DSP horsepower available.

If I understand this so called "fuzzy clustering" approach (and I may not), it sounds like ARC creates a relational sonic map of the room which helps it expand the sweet spot (mixing wise). And, as we all know, a large sweet spot makes it easier to get a decent mix that translates well.

Mapping and weighting these "clusters" is, in my opinion, a significant departure from traditional RTA. I think it's an interesting approach that warrants a closer look.