Originally Posted by AustinJerry
Aren't we returning to the discussion of why we get (sometimes significantly) different results from our calibrations when we change the measurement positions? I don't think we have seen a satisfactory explanation for this, nor do I expect to ever hear one.
To avoid the frustration, I have adopted the practice of always using the same eight measuring positions (at least as close as possible), and have been rewarded by consistent results when I calibrate.
My situation with Audyssey was a little unique because I have two factors that make measurement techniques a little more sensitive.
1) a rather narrow room with an angled ceiling that is only about 3.5 feet high on the low side ( right wall). Plus I sit about 4 feet from the back wall.
2) My subwoofers have non defeatable DSP programs. Luckily they are not doing anything super funky to the signal, mostly effects to the overall output and in some cases the output at certain frequency bands. these are in place to compensate for the loading of the subs (where in the room they are placed and the ensuing effect that will have on the sub's performance). For example, a freestanding placement will need a boost since the sub benefits less from boundaries. A corner placement will usually need a reduction in output...etc.
The nice thing about a well designed dsp is that by selecting the right dsp BEFORE running Audyssey Pro, I was able to get a flatter response from the sub prior to Audyssey doing it's thing. Since Audyssey has rules and limits on cuts and boosts....this is a good thing IMHO. The before graphs with Audyssey Pro were invaluable to me in getting the flattest native response.
My experience with Audyssey has been incredible...and Pro plus Dynamic EQ has really made my speakers work wonderfully in MY ROOM. As Chris is always saying, speakers in a chamber act one way....speakers in your room act another. This is why EQ is so important, and Audyssey is the undisputed king as of now.
To the question of different results with different mic placements.....this is to be expected. Audyssey can only work with teh data you feed it. The more accurate data about what you will hear....the better. So how to capture that accurate data. The BEST method I have found is to use the guidelines in the first post of this thread as a starting point, and adjust ONLY the distance between measurements if it is required in your room.
For example...the 2-3 foot recommendation between placements is good general advice if you want to EQ for a couch as the important listening area and you room is wide enough so that the outermost measurements are not too close to the left and right side walls. I did 5 measurements across the MLP plane (one at the MLP and two to either side towards the right and left side walls), and if I did 2 feet between each measurement, that would give me a bubble width of 8-12 feet (depending on how far you chose between each measurement). I felt this was too wide, because that would put a mic placement almost touchng the left side wall and the rightmost placement would be farther from the wall (because my couch is left justified in my room...angled ceiling) BUT would have the ceiling coming IMO what is too close to the mic (again angled ceiling at work). So I chose 1.5 feet between the two measurements to the left side of the MLP, and about 2 feet between the two measurements to the right side of the MLP.
I have experimented with smaller bubbles, and never did like the results as compared to following the 12 point Audyssey recommendation with a slight reduction in my mic spacing due to my room AND beacuse I only care about EQ'ing my listening area....where my wife and I sit right next to each other on the couch.
Why do I think the smaller bubbles never sounded as good (notably the bass)?
Beacuse my room has room modes like all rooms, and at the MLP I have a decent bump at about 30 hz, a decent dip at 50-70 hz, and the output below 25 hz is less. That is if I were to put the mic at the MLP only. As I add in the data from the other 11 measurements, Audyssey correctly factors in what is going on on those locations....and since what we hear and experience is better defined by looking around the area you listen rather than measuring only at the MLP....my before graphs with Pro show a flatter response. It still is not flat...there is still a bump at 30 hz (but less so), it is still down from 50-70 hz (but less so), and I am still down below 25 hz (but less so).
If I were to compare a smaller bubble to a larger correct bubble this is what I theorize is going on with the subwoofer(actually not really a theory since this is straight from my before graphs using Pro):
-3db point looks to be about 26 hz and down 6db at 19hz, so Audyssey doesn't try and correct below 26 hz.
Up 5 db at 30 hz (so Audyssey cuts 5 db)
Down from 50-70 hz (down the most about 12 db at 60 hz)...so Audyssey raises it 9db.
Down about 2 db from 20-26 and then it increases above 26 hz(-3db point looks to be about 19 hz)...so Audyssey will boost 20-26 hz about 2db.
Up 3 db at 30 hz (so Audyssey cuts 3 db)
Down from 50-70 hz (down the most about 9 db at 60 hz)...so Audyssey raises it 9db.
The larger bubble sounded better in the sub region, and I beleive it was due to using the correct size bubble and for the reasons above.
As far as crossovers, using the recommendations of my favorite calibration they would be 70 hz for all except 100 hz for the center. I compared this to 80hz all around. 80hz was the 4th choice for the center speaker, and the second choice for the others. I listened to some scenes from movies (and while it wasn't SUPER extensive...it was getting late)...I only detected what I thought were a couple small instances where I thought I preferred 80 hz. But it was close overall...hard to tell a difinitive difference. So in this case both choices were great. I am using 80hz all around because of those two instances where I thought I heard a difference.