ARC: Is it "Magic"?

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
 

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:
 

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.

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.

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

Hi Tom,
Be aware that a LDC as omni does not make a great test mic, as they are not very omni past 8kHz. The test mic that came with ARC is probably a better mic to use.
 
You can see a polar response of an example of the 414 family graphed here: http://www.akg.com/C414+XLS-1039.html?pid=1024
 

"Is the the top line in that Har Bal window a direct return or running through a speaker?"
The top line is the wave file (analyzed by HarBal) that I used for the test.
The bottom line is the "captured" (recorded) wave file, mic in the "sweet spot", ARC was not ON when that pass was made.
"For a fair comparison, you should increase the y-axis limits on your plots to match the +/- 15 dB limits used in the ARC"
Look in the upper left hand corner of the HarBal display. Magnitude x +10db.
So I believe we are looking at 10db per line, not 1 db.
Check the link I posted, the graphics are bigger.
 
T

This is by far one of the best investement i did ...and by far the Tools pretty all myststudents get (and i have 350 per year !!) , it's just a must have with good acoustic and great monitors
 
By the way for those that still don't know , you can use it in winamp via vst adapter  to listen to all your music ;)

I ran Mikes test tones (thanks for that Mike!).
Below are the results:

The results look pretty similar to the Pink Noise. The "brighter" line is the ARC corrected capture.
I think I had the 10k roll off engaged on ARC, I usually mix that way the A7's are pretty "bright".
I guess we need the "pretty waterfall" software!
 
T

DeeringAmps
I ran Mikes test tones (thanks for that Mike!).
Below are the results:

The results look pretty similar to the Pink Noise. The "brighter" line is the ARC corrected capture.
I think I had the 10k roll off engaged on ARC, I usually mix that way the A7's are pretty "bright".
I guess we need the "pretty waterfall" software!
 
T

my ears must be fried....   but I use Harbal also for various things and the difference I'm seeing here, would basically almost be inaudible to me.  Very minor.  What am I missing in this thread, that to me appears to be very minor adjustments -  to the point of not much difference?  Yes, the ear can hear 1dB change or so, but those graphs look almost identical.  Certainly MUCH less than what I might adjust using Harbal.   Interesting the drop off at 25Htz like that...and then back UP.  You're getting some pretty low freq response there too, on playback.  That's good.  Solid down to 30 Htz

Hi Tom,
 I think you have posted some interesting results. The use of the frequency sweep should negate any concern that the variety of levels found in an instantaneous sample of pink noise may have contributed to the wiggly response displayed by Har-Bal.
 
 Having said that, it's interesting to note how the results from a sweep are so similar to the results from the pink noise analysis. I guess that's why pink noise seems to work so well in practice. :-)
 
 The peaks and nulls you see when you use the sweep are a good representation of the room modes as, unlike pink noise each frequency is presented in sequence and at a predictable time and a predictable amplitude. There is no need to second guess how an "average" value for pink noise was established.
 
 It would be very interesting to see detailed waterfall graphs of the sweeps and to see if a characteristic such as RT60 would appear different with and without ARC. I am assuming that it would be much easier to see the differences with the sweep than with the pink noise as the pink noise analysis would include the seemingly random movement of the noise itself.
 
I suspect that my use of some terms is too generalized or perhaps even misplaced. I'm hoping drew, Bit, or Bill will stop by and fact check my comments! :-) :-)
 
 Thanks for making the tests!