I wouldn't use the picture in ARC to go by.
 
The proper way to do it is you take the impulse response of the before and after ARC profiles and analyze them to see what changed.

all i know is,
i'm glad it works for me.
 

bitflipper
It's based on a gross over-simplification of room acoustics that doesn't take the time element into account except as a simple aggregate average.

Dave, I'm sorry but you keep getting this wrong - the impulse response captures the time information completely for the spot in the room where it is taken. Time response in the time domain and frequency/phase response in the frequency domain are the same thing.
 
Look at the impulse response of a highly resonant filter with a spectrogram and you will see that the IR indeed captures the filter ringing over time. 
 
 
The problem with the IR only applying at one location is of course quite true, which is why ARC is only useful at only one listening position (at a time). 

Obviously the measurements are taken from the listening position and that is the "sweet spot," but I have found that ARC2 improves the sound of my monitors wherever I'm standing in the room. I wouldn't like to make EQ decisions from anywhere but my mixing chair, but everything sounds great nonetheless.
 
I have a completely untreated room which has a low ceiling, and not only that I have my monitors on a shelf about 6" from the wall. Although they're not in a corner, they're quite close to a corner. Additionally, they're positioned on the long side of the room. Basically I have every "bad setup" box ticked. I have a set of Equator Audio D5's, a very sweet sounding monitor with a great reputation. And they sound like crap without ARC2. The bass is flabby and boomy. The highs seem to get sucked into some mystery vortex. Not just in my mixes, but also with great mixes like The Nightfly. As soon as I flip ARC2 on, it's like putting contact lenses on the speakers. Everything is so focused and balanced. The bass sits perfectly on the soundstage and doesn't resonate. It's so clear I can almost "see" it. All the highs come back and I can hear the air in the track again. Every part is located clearly in space. I honestly think it sounds better than most "audiophile" hifi setups I've heard. I've had some pretty sweet hifi setups in the past but nothing beats ARC2 through my D5's. 
 
I don't care how it works....IT JUST DOES!

I think that the graph displayed by ARC2 shows you what it is doing in the frequency domain, not in the time domain.  The treatment you have applied to your room will affect its time domain response much more than its frequency response, which is why the frequency response graph displayed in ARC2 hasn't changed much.

Arc2 user here and indeed appreciate the difference the software makes in my untreated room. I still have hopes to treat the room.

My questioin to the OP: so, what's the difference "audibly" between Arc ON and Arc OFF post-treatment? Regardless of what the chart shows, perhaps this would speak more about the difference between actual treatment and software based correction.

Just a thought.

From a listening position using near field monitors at proper levels - the room does not play as big of a role as the monitors themselves (or the monitors positions) do. This is likely why ARC is not noticing a huge change... the sound and position of the monitors is still the primary source... and that has not changed.
 
Since ARC measures from the listening position, their slogan (Advanced Room Correction) seems very misleading. IMO, the slogan should be "Advanced Monitor Correction" or "Advanced EQ Correction", not "Room Correction". Arc adjusts EQ, it cannot absorb reflections.
 
You did the right thing by adding treatment ... Room treatment is about taming reflections through absorption and diffusion rather than trying to tame frequencies - which is what ARC corrects.
 
I'm not dissing ARC... it certainly has it's place. I'm just suggesting TREATMENT plus ARC is a better combination than ARC alone. IMHO... if I had to choose one, it would be treatment.

I appreciate everyone's feedback!  Sounds like there are some who've found ARC 2 to be very useful, and some are on the other side of the fence.
 
I should note that I took the largest amount of measurements possible (15, I believe), all of them within my primary listening positing.  Some additional info about my setup:
 
My mixing desk is about 1 foot away from the wall and centered between the side walls.  The desk is quite large and has a monitor shelf.  Due to space limitations, I can't put my monitors on stands so they're sitting on that monitor shelf on top of Primacoustic Recoil Stabilizers.  I've got Alesis M1 Active MKII monitors.  Yes, you may snicker.  They're all I could afford when building the studio, and without a proper room, I don't think it makes sense to dump a bunch of cash into better monitors. That's money better spent on treating the room.  :)
 
Others have talked about ignoring the graph/picture and instead looking at ARC 2's impulse response.  Where would I find such a thing?  Aside from the resulting before/after graph after taking measurements, I don't see any other options for detailed results/analysis.
 

fwrend
My questioin to the OP: so, what's the difference "audibly" between Arc ON and Arc OFF post-treatment? Regardless of what the chart shows, perhaps this would speak more about the difference between actual treatment and software based correction.

Just a thought.

To be honest, audibly ARC 2 sounds bad when the correction is on.  Some have stated that turning ARC 2 makes their speakers sound great, I've found the opposite to be true.  The speakers sound quite peaky and glassy, but I understand that ARC 2 isn't necessarily going to make the monitors sound better; it's designed to make the mix sound better by accentuating/attenuating frequencies that are problematic in the room.  I haven't done a full mix with/without ARC 2, but I have done some quick tests by throwing an EQ on the master bus to tweak the sound of the mix in accordance with what I'm hearing through ARC 2.  (Yes, I disable ARC 2 when I bounce.)  I've actually found that the mixes sound better without monitoring through ARC 2, then again, I haven't done a start-to-finish mix using it, and throwing an EQ on the master fader isn't the same as tweaking individual instruments as the mix is built up.  (Plus, the mix was a work in progress anyway, so it was far from perfect to begin with.)
 
I definitely need to do some more experimenting with ARC 2 and eventually I'll figure out if it helps my mixes or not.  If not, at least I got an extra mic out of it. :)

sharke
 
 
I have a completely untreated room which has a low ceiling, and not only that I have my monitors on a shelf about 6" from the wall. Although they're not in a corner, they're quite close to a corner. Additionally, they're positioned on the long side of the room. Basically I have every "bad setup" box ticked. I have a set of Equator Audio D5's, a very sweet sounding monitor with a great reputation. And they sound like crap without ARC2. The bass is flabby and boomy. The highs seem to get sucked into some mystery vortex. Not just in my mixes, but also with great mixes like The Nightfly. As soon as I flip ARC2 on, it's like putting contact lenses on the speakers. Everything is so focused and balanced. The bass sits perfectly on the soundstage and doesn't resonate. It's so clear I can almost "see" it. All the highs come back and I can hear the air in the track again. Every part is located clearly in space. I honestly think it sounds better than most "audiophile" hifi setups I've heard. I've had some pretty sweet hifi setups in the past but nothing beats ARC2 through my D5's. 
 
I don't care how it works....IT JUST DOES!

This is me too.  The result of ARC in an untreated room is remarkable.  I have the D5s also, and ARC makes them sound the way I imagined they would when first read about them. The "contact lenses" analogy is perfect.  Everything becomes focused and sharp.  Its quite amazing. I'm sure room treatment would do even more wonderful things, and I understand the limits of the software, but I can only say great things about ARC and how it has improved the sound in my crappy untreated room.

streckfus
I appreciate everyone's feedback!  Sounds like there are some who've found ARC 2 to be very useful, and some are on the other side of the fence.
 
I should note that I took the largest amount of measurements possible (15, I believe), all of them within my primary listening positing.  Some additional info about my setup:
 
My mixing desk is about 1 foot away from the wall and centered between the side walls.  The desk is quite large and has a monitor shelf.  Due to space limitations, I can't put my monitors on stands so they're sitting on that monitor shelf on top of Primacoustic Recoil Stabilizers.  I've got Alesis M1 Active MKII monitors.  Yes, you may snicker.  They're all I could afford when building the studio, and without a proper room, I don't think it makes sense to dump a bunch of cash into better monitors. That's money better spent on treating the room.  :)
 
Others have talked about ignoring the graph/picture and instead looking at ARC 2's impulse response.  Where would I find such a thing?  Aside from the resulting before/after graph after taking measurements, I don't see any other options for detailed results/analysis.
 

fwrend
My questioin to the OP: so, what's the difference "audibly" between Arc ON and Arc OFF post-treatment? Regardless of what the chart shows, perhaps this would speak more about the difference between actual treatment and software based correction.

Just a thought.

To be honest, audibly ARC 2 sounds bad when the correction is on.  Some have stated that turning ARC 2 makes their speakers sound great, I've found the opposite to be true.  The speakers sound quite peaky and glassy, but I understand that ARC 2 isn't necessarily going to make the monitors sound better; it's designed to make the mix sound better by accentuating/attenuating frequencies that are problematic in the room.  I haven't done a full mix with/without ARC 2, but I have done some quick tests by throwing an EQ on the master bus to tweak the sound of the mix in accordance with what I'm hearing through ARC 2.  (Yes, I disable ARC 2 when I bounce.)  I've actually found that the mixes sound better without monitoring through ARC 2, then again, I haven't done a start-to-finish mix using it, and throwing an EQ on the master fader isn't the same as tweaking individual instruments as the mix is built up.  (Plus, the mix was a work in progress anyway, so it was far from perfect to begin with.)
 
I definitely need to do some more experimenting with ARC 2 and eventually I'll figure out if it helps my mixes or not.  If not, at least I got an extra mic out of it. :)

Actually it's designed to make the mix sound accurate not better or worse. I don't doubt ARC can make a mix sound worse. How does reference material sound through ARC? Is there a chance you have your old measurements loaded?
 
Rocky