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.

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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.

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.

Here's some more background.

The inventor of the underlying technology is an engineer named Chris Kyriakakis, a guy with lots of impressive paper on the wall. It's a familiar story: an academic, working on the public payroll and using free student labor for assistance, develops a concept that has commercial potential and cashes in. Can't blame him. An EE professor's wages aren't going to pay for a home in Malibu.

IK isn't about to give many technical details, but it is a patented process and therefore public information. Mr. Kyriakakis, along with his graduate student Sunil Bharitkar, holds two relevant patents:

Combined multirate-based and fir-based filtering technique for room acoustic equalization

Room acoustic response modeling and equalization with linear predictive coding and parametric filters

The first one is for a FIR filter that applies less equalization to low frequencies than to high frequencies. It doesn't really sound like a patentable innovation to me, but then most electronics and software patents don't. I probably couldn't be a patent examiner.

The second one is the other part of the ARC system: the measurement part. It's for an algorithm for automatically determining the amount of cut/boost and Q for each parametric filter. Here's the actual abstract:

A method for determining coefficients of a family of cascaded second order Infinite Impulse Response (IIR) parametric filters used for equalizing a room response. The method includes determining parameters of each IIR parametric filter from poles or roots of a reasonably high-order Linear Predictive Coding (LPC) model. The LPC model is able to accurately model the low-frequency room response modes providing better equalization of loudspeaker and room acoustics, particularly at the low frequencies. Advantages of the method include fast and efficient computation of the LPC model using a Levinson-Durbin recursion to solve the normal equations that arise from the least squares formulation. Due to possible band interactions between the cascaded IIR parametric filters, the method further includes optimizing the Q value of each filter to better equalize the room response.

So how does this differ from any other parametric equalizer? I haven't waded through the entire patent document yet, so I would encourage others to dive in. So far, I have not seen any magic fairy dust described. At the end of the process, it's a multi-band parametric equalizer that's been automatically configured for you based on weighted measurements.

As with any patent application, there is a lot of obfuscation designed to make simple principles sound unique -- uniqueness being necessary to obtain a patent. It will take a lot of wading through the mumbo-jumbo to separate the obfuscation from what's truly unique. Have fun!

Here's an interview with Chris K. I have not seen it, as I refuse to install the QuickTime virus on my computer. Let us know if it's any good.

Here's an IK salesman giving his take on ARC. He says it was developed by the "same team" that created THX. I haven't pursued that claim. He's conservative in his claims, saying if you have an acoustically-treated room, ARC provides the last "1 percent". His best statement: "when I take the CD out to my car it still sucks but it sucks less."

Here's a moderately positive review by Craig Anderton. Good screenshots and description of the measurement process.

Just came back to this post, and nice to find someone willfully misinterpreting my post in order to further there own views.

Yes Mike McCue, this ones foryou.

I'm just pointing out that one potential endorser isn't even using it correctly... (in fact he's now using it in the most regrettable way) and yet he thinks it's the "mutts nutts".

So I'm just wondering if that's really an endorsement.

Like they say... it's only money. :-)

You have made an assumption, I said that I have not had the time to re-calibrate it to the new layout of my room. You assume I still have it switched on when I mix, and that is where you have made an assumption and got it completely wrong.

I realize that for the ARC to work it must be re-calibrated everytime you move your speakers, and or set-up, since I moved them all to allow a relative to stay with me, I have turned ARC off and do not use it. I will not untill I have time to re-calibrate.

However when I intially set it up and took a lot of time about it, and marked out all my measurement points very carefully (please look up another thread where I actually go into my methods in quite some detail) then it was the mutts nutts and made a very real difference to my room.

Yes a better room and some acoustic treatment would probably make more of an improvement, but given my restrictions I have been very happy with it.

So please in future before jumping to conclusions about other forum uses abilities and competance, maybe think a second, becuase you came accross as an arrogant idiot with your post.

G

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Don't forget to take the plug in out before exporting.

I can't afford to even think about purchasing ARC at the moment but the one thing I don't like about it is that you need to do that! I would be one of those people who regularly forgets that particular process I think in someways this is where KRK's ERGO has an advantage in that it sits between the soundcard and the monitors.

Andy

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Mike: The issue with ARC and moving the mic around for several measurements etc is all about keeping it symmetrical. For example, in my bad screenshot, the mic was moved around the room symmetrically, but it was done by eye. Therefore, not perfect and not as symmetric as it *needs* to be. There were also less measurements so this adds to the mayhem with how ARC can be considered "crap and not a very good plugin". You also can get phasing like a few have mentioned. However, I guarantee you anyone making that claim, did not tape the room with measurements using a measuring tape nor did they position the mic height correctly and I'd be willing to bet they stopped at 13-15 measurements.

The more measurements you do (according to the manual as well as a few of the people I spoke with at IK) the more precise it becomes wherever you walk or sit in your room. I did an experiment just last week with just focusing in on my sweet spot. The results were nearly what I have now with the exception of moving out of my sweet spot zone. As soon as I moved myself around, the mix I was listening to did not sound very good....but sitting in my chair and moving around my sweet spot zone, it was exactly what I'd hope it would be. I posted this before, but I want you to take a look at it and allow me to explain what the additional mic placements can do.



In this screen shot, you see the numbers showing how you should symmetrically move the mic around and how you should take your measurements. When you do this to the numbers and measure it all out, it's been fool-proof for me in all my tests. I even was able to fix my NS-10's that I had originally thought failed with this thing. What failed...was me. Anyway, you see all those mic placements in this diagram, right? If you branch out and do more in all the empty spaces, this (in my opinion as well as my experience) gives you even more of a proper sound anywhere you go in your room. If we took the 15 measurements they give us here and focus those 15 around the main sweet spot just like a pro room EQ would do, you're left with the exact same results but...as soon as you get out of that sweet spot zone, like pro room EQ, the sound changes drastically. If you do the 15 as they are and add-lib, there's not a bad spot in your room. It's just something you have to mess with and if you've never tried it and have room issues, the only thing I can suggest is to try it and compare mixes done without ARC and then mixes done with it. The only "remix" stuff I have to do these days is leveling when I need to fix one of my mixes. The eq's within my mix rarely change from the first mix I create. To me, that's 95% of the battle really. Levels are pretty subjective in the mixing field....but improper eq's can be the death of us. My old mixes without ARC had sub low rumbles and quite a bit of 200, 500-800hz that I just could not hear. The reason for this was because my room and monitors were not putting out the bass I needed to hear and this 500hz to 800hz deal was not present either which gave me a bit of mid-range congestion. My highs were always pretty good here...it was the bass and low mids that were absolutely killing me and mudding up my mixes. Hope this answers your question.

Bit: In your comment that read:

"The first question has to do with resonance, the primary reason small rooms have so many spectral problems. If you have a resonant null, that's something that is physically impossible to counter with equalization. And I don't use the absolute term "impossible" lightly."

There's no doubt in my mind you know what you're talking about. How it did what it did, I really can't answer that. The only differences in those 2 screen shots I showed was more mic placements and precise, accurate, symmetrical movements on the mic. I also adjusted the height using a mirror so it was about nose/ear level as close as possible. I swear to you none of those screen shots were photo shopped or edited in any way. My Adam screen shots look almost the same. I'll show ya measurements taken with the sub and without. I didn't save any of the bad Adam corrections so these are freshly done. The bad Adam corrections weren't bad "looking" I just got a phased type issue like what was mentioned on here a few times. Re-correction with the right measurements symmetrically, fixed that too. Here's a shot of them with and without sub using the latest software to correct with on the one that says 1,1 and the oldest version of my room corrected Adam's using the old software. The 1.1 you see means the room was corrected with the latest software which also is the software that added in that "full bass response" check box. That was not there in earlier versions and any correction made using a previous version of the software that was saved, will leave that check mark box greyed out and un-useable.



I can't tell you what it does or how it does it. Like I mentioned to Mike M, all I can say is it has made such a drastic difference, I can't even begin to tell you. Whether what it's doing is a scam that made me blow $499 or it's completely impossible, I leave that to people with more intelligence and experience in that part of the field. All I know is it made me realize I wasn't such a bad engineer after all because all my mixes prior to installing ARC made me look as well as sound, like a dude that would have no business ever sharing a song in an open forum let alone all the work I have done for clients while using this thing. I know how deep you and Mike M get into the logistics of this stuff and chances are, between the 2 of you, you'll find out how this thing works, what it's pros and cons are as well as if the wool had been pulled over my eyes and many others. But like I say man, whatever the case is or the final outcome, I'd be completely lost without this thing and my old mixes compared to what I've done post ARC are like night and day.

As far as corroborated ARC measurements by any other means.....the only thing I did was test it in a 2 million dollar studio that had proper traps and pro room correction. We did an A/B test to where the room EQ's that were permanently set could be disabled and we ran ARC in place of them. When the ARC corrections were done, all room eq's were disabled. When the engineer compared ARC to his room eq's, he smiled and immediately said "I can't believe it....this actually sounds better to me" and he went on to mention his problem areas as well as having to just know what to fix based on knowing his room and his monitors. He mentioned that he could hear what he had been compensating for while using ARC. He went out and bought it a week later and has been using it ever since. I've never done any waterfall plots or additional testing in my room, so God knows what story that would tell. LOL!!! But I do know that it really does make an incredible difference for me. Everything I mix sounds good on everything I play it through. My toughest sell is my Xbox 360 running and old Audiovox 5.1 rig. If something sounds good through that, it sounds good everywhere. It even sounds good on boom boxes as well as pricey car stereos and lame car stereos. So I don't know man....whatever it does, it does it well enough for me to get what I'm looking for at all times. A weird thing I noticed just last night (not that this will tell any stories or anything, but I found it strange) is when ARC is turned on, it sounds nearly identical to my AKG K 240 DF headphones with a bit more bass. The mids and highs sound like a mirror of those headphones and I had never noticed that before. Of course when I listen through those cans, ARC is disabled....and I know it's hard to tell what you get through cans as opposed to real monitors...but you know how it is man...you just learn your gear and you can tell when something just doesn't sound right. Like my Sennheiser HD 280 Pro's are completely different. They seem to accentuate lows and mids a bit more. But when I listen through the AKG's, I hear ARC in them even though it's disabled and there is a bit less bass at around 60hz. I wish it was something to where I could say "buy it Bit, if it sucks, I promise ya I'll buy it off ya" but it's one of those things that you only need one of. :(

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ORIGINAL: Danny Danzi
I gotta ask ya...in your screen shots, what the heck is that little tool bar at the top of your ARC plug with the +, Param, 2in 2 out, UI, 100% wet stuff all about?! LOL!! I don't have that and I want it just because...well it looks cooler and makes mine look incomplete! LMAO!!! What's that all about and what does it do if you alter that stuff up there?

Oops.....sorry about that I should have captured a couple of SONAR screenshots. For expediency I just uploaded a couple of existing screen captures which I had used previously in a similar themed ARC thread on a R****R forum. LOL