AVS Larry Chanin a écrit:
Originally Posted by parlyle a écrit:
There are 2 different microphone positions listed as the first placement when starting the Audyssey system.
1. ( 1. The first microphone position (#1) must always be where your head is located.) [ From the setup guide ]
2. What are the recommended measurement positions?
The first microphone position must always be in the center of the listening area. Then we recommend moving the mic about two feet to the left of that first position for measurement two and two to the right of the original spot for measurement three. ( From the Audyssey FAQ pages )
Which one is gospel? Has anybody else noticed this?
Maybe I have missed something, but, if anybody can refresh my memory, I would be very happy.
I believe there are two correct schools of thought on this issue, depending on whether you prefer to optimize more for a single "sweet spot" or a "sweet area".
First, let's consider setting the timing and levels on any system with or without Audyssey. It should be emphasized that there is only one single location in the room where it is possible to get the timing and the levels precisely correct.
If the primary listening location happens to be located in the center of the available listening locations then that's the ideal situation. However, if not then one has to decide whether or not to take the measurement in an actual seat or a location centrally located among the seating. If it is taken in a particular seat, that seat will have precise timing and levels, and other seating locations will have less precise timing and levels. If the measurement location is not centrally located the timing and levels for various seating locations about the measurement will vary based on how close it is to the measurement location. So selecting a central location that is not in an actual seat means that no seat has precise timing and levels, but on the average all seating will have about the same precision.
As you no doubt are aware, Audyssey uses the first microphone position to calculate its timing and levels, so everything I discussed above would apply to that position, but as I said earlier these considerations apply to any situation even if you are manually setting the timing and calibrating levels.
Aside from timing and level considerations there are issues regarding sampling the acoustic environment in support of Audyssey correction. Here it is important to be, in general, central to the listening area because you want to avoid sampling locations that are outliers, whose acoustic conditions greatly differ from most of the listening positions. For instance, it is not a good idea to place the first measurement location greatly off-axis simply because that is where you sit.
I think the thing to remember is that there is some latitude in setting the first microphone position. In general it should be centrally located to the listening area, but it certainly doesn't have to be in the precise geometric center. It can be in an actual seat, that is near the center of the listening area or in a location without seating, depending on personal preference.
Here's Chris' comments on the subject after a spirited back and forth discussion on the subject:
Originally Posted by audyssey a écrit:
On the issue of first measurement and mic spacing:
I have to admit that I lost track of the arguments going back and forth. I think some simple guidelines to follow would be:
The first measurement should be taken as close to the center of the audio system as possible. In most cases there is a seat there, but if there isn't I still think there is value in taking a measurement in that spot because that's where the delays are calculated from.
In situations where there is only one listener and they always sit off axis from the center speaker I can justify starting in that position and measuring in a tighter pattern around that seat.
But if other people ever come to listen and you have calibrated the distances from an off-axis position I think you will be skewing their soundstage too much.
As far as off-axis measurements are concerned: the guideline is to not take measurements outside the spacing of the two front speakers. That gives too much emphasis to the off-axis sound and can color the filters.
But as I have said before: I really think that this issue is being overly analyzed. The exact placement of the mic down to the cm is not that critical. What's critical is the data collected from moving the mic around the listening area. The 2' spacing that I referred to in past posts is approximate. Don't start pulling out the tape measures. The algorithm just doesn't pay attention to that. It just wants to be fed room info from different points around where people will be sitting.