Originally Posted by jrisles
Originally Posted by obie_fl
I have a fully treated room and I see the same roll off probably more then most graphs I see posted here. I don't think it is the room so much as a limitation of the mic and its positioning.
Yes beginning to think that the mic was more "the culprit" than anything else. So what we are seeing is a constraint of the mic itself. And as you say just about everyone is going to see a roll off around 5kHz because of this limitation. So do you set your Max Frequency above 5kHz?
Lots of things affect the ability to measure the high frequencies accurately, which is one reason Anthem sets the default upper limit for applying correction to 5KHz. First and foremost, the treble frequencies are far more directional than the bass frequencies. Most speakers will have a distinctly non-uniform output of treble, with the problem typically being more pronounced in the vertical direction than in the horizontal direction.
This means that when the mic is off the center axis of a given speaker, there is less treble heard simply because the speaker is not putting out as much treble in that direction. So the thing to do first is to check the pointing of your speakers. And in particular, if the speakers are not mounted at seated ear height, check their VERTICAL pointing. The Center and Surrounds should point at ARC mic position #1 (your center-most seating location). The Left Front and Right Front should NOT point at ARC mic position #1. The usual Rule of Thumb is to "toe those in" only about 1/3 of that angle. That is, if you consider how much you would have to rotate LF/RF to point at #1 (starting from pointing straight to the back of the room), only swing them 1/3 of that amount. The Subwoofer pointing is irrelevant for treble of course.
Next, make sure your tweeters are actually functioning. It is not uncommon to blow a tweeter in a speaker and simply not notice because the mid-range drivers also produce output up there (just not as much). By the way, this has happened often enough in this thread that we even have a name for it in here. We call it "Richard Syndrome", after the first poster to have this epiphany: The discovery -- via ARC -- that one or more of your speakers is actually BROKEN even though you have been happily enjoying it up to now!
To check this, play stereo content (e.g., a CD) with good treble components (bells and cymbals for example), set MONO ALL Audio Surround Mode in the Anthem -- which sends the same audio to every speaker -- and go put your ear right up close to the tweeter in each speaker in turn and make sure it is producing output. All the speakers should sound similar. If one or more speakers is not producing tweeter output, then fix that first before you do anything else with ARC. It could be wiring (separate input jacks -- or improperly wired bi-amp setup) or a fuse rather than a blown tweeter.
Next, consider the method of speaker installation. We've heard time and again here from folks who have in-wall or otherwise customized speaker installations who have discovered, for example, that the speaker grill cloth or grill mounting hardware was actually blocking output from the tweeters of one or more of their speakers. A grill bar across the center axis of the tweeter -- even several inches in front of it -- is enough to screw things up royally because the treble output of the tweeter is so directional.
Next, double check the way you are using the mic during your ARC Measurement passes. For proper Measurement of treble it is important that you follow several rules:
1) The mic must be pointed STRAIGHT UP at each mic position.
2) The tip of the mic should be set at seated ear height. If you recline your seats, then that's what you should do when judging seated ear height.
3) The tip of the mic must not be adjacent to blocking or reflective surfaces. Consider each mic position. Keep the mic at least 18 inches from walls/drapes. If you have high seat backs, raise the mic a few inches to clear the top of the seat, or move that mic location a foot closer to the screen to get it away from the seat back.
Keep in mind that you can use the Quick Measure tool (found in ARC's TOOLS Menu) to check, in real time, the raw (uncorrected) audio the mic is hearing at any given position from any given speaker. So you can see the affect any changes might be having.
The red Measured curves ARC displays in its charts are an "unweighted average" of what the mic is hearing from that speaker across all the mic positions. Each mic position will have a different direction angle to each speaker, so treble response will vary. The regular ARC chart averages that out. So what Quick Measure shows for any given mic position is unlikely to match that regular ARC chart curve in every detail. But if you move the mic around you can mentally average the Quick Measure result yourself to get a feel for what would happen with the real Measured curve. (ARC actually calculates its results using all the mic data -- not just the average shown in the charts -- but the averaged curve has proven to be an excellent surrogate for what's really going on.)
Do remember that Quick Measure reconfigures the Anthem so that it can hear uncorrected speaker output. That means that when you are done with Quick Measure, you need to open and re-Upload your current ARC solution, or do a whole new ARC setup pass if you've changed anything (e.g., moved speakers around).
A much less likely problem, but still worth checking, is that you are using the wrong mic calibration data file. These files are unique to each ARC mic. Your ARC mic has a serial number. Go to Windows > Program Files > Anthem > Anthem Room Correction (which is where the ARC application gets installed), and you will find in there two files with names made up of a pair of numbers -- the serial number of your Anthem and the serial number of your ARC mic. These are your ARC license and your ARC mic calibration data files. Check that the numbers match your mic. If not, then Anthem Tech Support can email the correct files to you.
While you are at it, check that you have the current version of the ARC application. Open ARC in the charts view and check About ARC in the Help menu. The version should be V3.0.2.
There are other things that affect the quality of treble measurement which are likely out of your control. These include things like room humidity. But when you have more treble roll-off showing in ARC than you think makes sense, take the steps above first to eliminate those causes that you CAN control.
Each room setup will be different, and each set of speakers will have more or less pronounced treble directionality. If it looks to you like ARC is picking up quality treble data for the speaker Measurements, then you can experiment with raising Targets > Max EQ Frequency to allow ARC to apply correction further up. If not, then leave Max EQ Frequency at 5KHz and trust that the high frequency roll-off you are seeing in the charts is "not real". But don't assume that until you have checked the basics as above.
--BobEdited by Bob Pariseau - 12/3/12 at 12:32am