Let me start off by saying that ARC "works" for me!
Recent discussion lead me to run some "tests" yesterday.
I've always assumed (there's that proverbial A$$ out of u and me)
that ARC was doing some fancy phasing to "fix" the room.

Pretty impressive, that AFTER line!

Well this is the before/after real results in my room.
You can see all the results in far more detail here: http://deeringamps.com/arc/arc.htm
 
Tom
 

... oh behave.
 
 
 
 
 
 
 
 
For the record I've been suggesting that true believers do this for years and years.
 
Mainly because I am fascinated by the power of suggestion and how it effects our impression of sound.
 
Also because I knew what people would find as it had been related to me by people who had already made such tests.
 
Having said that, I think it has always been obvious that if someone were to come in to your room and adjust the EQ so the playback sounded better to you, that it would indeed sound better to you.
 
Well done.
 
As a further comment, I suggest that the pink noise, if routed directly round trip, without the speakers, into your inputs will average out as a nearly straight line. In other words a pink noise source file will appear as an "ideal" straight line. If someone is going to suggest that they can make the speakers perform as "flat" then, it seems to me, the results should approach the ideal that can be achieved with a direct electronic signal.
 
Thanks for making the tests.
 
 
 

Here's what Pink Noise looks like, after an averaged frequency analysis, of the electronic signal measured without the *distortion* from the speaker or room:
 

Pink noise falls off by 1/f, thus the approximate 10db per decade for 3db per octave fall off. White noise would look flat. See http://hyperphysics.phy-a...base/audio/equal.html,

Yes, if the speakers have been successfully adjusted to be "flat" then the pink noise emanating from them will be analyzed and displayed as a "straight" line sloping at 3dB per octave.

mike_mccue
Yes, if the speakers have been successfully adjusted to be "flat" then the pink noise emanating from them will be analyzed and displayed as a "straight" line sloping at 3dB per octave.

When's that gonna happen? I live in the "real" world (well except when I'm drinking kool-aid).
Here's what HarBal "thinks" the pink noise (top line) I used looks like.
Close enough to your "straight" line?

What I think is "relevant" here is what the mic picks up at the sweet spot.
ARC's "pretty" picture "predicts" that the recorded file should be virtually identical.
I "drank" the kool-aid; but really, do you think I accepted their "straight" line as "real"?
And maybe "kool-aid" is harsh, I DO think the low end is "better", in MY room, with ARC on.
I'm going to run this again with my 414 (omni?) and see what I get.
How should I orient the mic? Diaphragm left/right or front/back?
 
T

For a fair comparison, you should increase the y-axis limits on your plots to match the +/- 15 dB limits used in the ARC plots. Part of the reason the ARC plots look so much better is because they're showing a range of 30 dB compared to about 7-8 dB in your plots.
 
On the other hand, ARC claims that it's correcting the spectrum by as much as 6 dB in some places, but your before/after comparison plots show changes of less than about 1 dB. So something doesn't add up.

Is the the top line in that Har Bal window a direct return or running through a speaker?
 
 
 
The thing an averaged frequency analysis does not show is how ARC may be using the Impulse Response to clean up the bass in an appreciable way by filtering with very short term results.
 
IMO, it is reasonable to expect that the system can and does actually make the bass response cleaner and clearer.
 
Of course the pretty white line that they show in ARC doesn't show anything about the quality of the bass character either.
 
The part I keep bringing up is that if one watches the frequency analysis of a room in "real time" one will see things like the dip at 500Hz shown on Tom's graph fluttering vigorously both up and down and side to side in a dancing cycle. 
 
That is exactly what the water fall graph has a chance of showing.
 
I think the static line displays serve as a suggestion that a complete solution may be achieved with a filter whose characteristics have been averaged. I've been thinking that a solution will have to be dynamic and adroit.
 
 
 
http://www.roomeqwizard.com/ has a free waterfall plot.
 
Blue Cat and Izotope have some that seem fancier.
 
If someone wants to see the nature of the movement make sure you use a FFT window size that results in detailed graphing.
 
 

So...... did I make a good investment in ARC/ARC 2?
 
I need someone to tell me in layman's terms.

Y.
E.
S.