Originally Posted by SHadoWFoX
I finally got a free day and I did some measurement with the current ULS 15 placement. Please note that this is my first real subwoofers and also a beginner with REW for measurement.
The room size is 15.5' x 19.5' x 8'. The SWs are placed along the 15.5 wall. The right SW is 42" from the right wall and the left SW is 48" from the left wall (actually an opening to the dinning room). Their back edges of the SWs are 9" from the wall. The MLP is 13.5' from front wall.
Both SWs are connected by RCA cable and have crossover set to Out, volume at 11 o'clock, phase at 0, trim at 16. I took all measurements with Audyssey engaged.
The first group of measurements (orange-sh trace lines) are all from MLP with SW distance adjustments in my Pre-pro (Integra DHC80.1) of 0, 1, 2 and 3 feet (0 being the calibrated distance). Obviously the big dip at 40Hz is pretty bad. The adjustment with speaker distance seem to only affect frequencies above 60Hz and only with slight variations.
The second measurement (red trace line) is done by moving the mic 6" towards the front of the room just curious to see what the FR is at a slightly different location. I can see the dip moved to around 35Hz.
The third measurement (black trace lie) is with the mic moved up by 2'. The overall response seemed a lot better.
The last measurements (green trace lines) are with the mic moved up by 1' with speaker distances adjusted by 3' and no adjustment. The overall response is similar to the previous one.
I will need to use wireless (hope it works) to see how they perform at other locations. But before I do that (still need to buy the y-adaptors) I like to hear what are your comments? What else should I measure?
Your room dimensions produce modes as shown in the following chart:
While you don't say explicitly, I am assuming that the 15.5' wall is the width of the room, and the 19.5' wall is the length of the room, with the layout facing the 15.5' front wall. Is that correct? And the two subs are placed along the front wall, one 42" from the right side wall and the other 48" from the left side wall?
You don't mention where the left and right speakers are, and whether you have a television display. The traditional starting point in a room like this would be to have the left and right speakers arranged with the MLP in an equilateral triangle, with the front speakers away from the front wall by several feet. Is this anything close to your layout? A room diagram, even a rough sketch, would be helpful.
The Integra has Audyssey MultEQ XT, which has only one sub channel, IIUC. Since there is only one sub trim, your subs should ideally be placed equidistant from the MLP. However, that may not be possible for a number of reasons.
Post-Audyssey adjustments in the subwoofer distance setting will normally only affect the smoothness of the frequency response around the crossover point. What is the crossover between the subs and the mains?
The measurements you provided are really not adequate to make a good analysis. First of all, you should turn Audyssey off while moving the subs around to find the best placement. The Audyssey filters are calculated for a specific sub placement, and as soon as you move the mic or adjust the sub distance, the calibration filters are no longer valid.
Here is what I would do:
1. Turn Audyssey off.
2. Place one sub at the midpoint of the front wall. This places it in the 36Hz null associated with the room width, and will excite the null, possibly raising that dip you see in the graphs.
3. Place the second sub along the right wall either 58.5" from the front wall, or 58.5" from the back wall, which is the center of the 58Hz node associated with the room length.
4. Run three measurements, one for each sub by itself, and one for both subs combined, with Audyssey still off. And BTW, always present sub measurements with no smoothing.
5. Post the measurements here so we can look at them.
If the results are bad, you can try varying the mic position 6", 12", 18" forward and backward from the MLP, again with Audyssey off. Post these results as well (on a separate graph, because too many lines make the graphs harder to distinguish). If the MLP can be moved slightly, this may achieve the bass results you want.
The objective is to optimize the sub placement before running Audyssey. Audyssey can only do so much to correct bass issues. It can never fix a null, but it can bring down peaks quite effectively.
I'm sure we can figure out the best spot for two ULS-15's if you are willing to work a bit.
Edit: Are those measurements with the subs only, no satellite speakers? If yes, also take a measurement with both subs plus left and right front speaker (left and right set to "small", of course), and include that measurement in a separate graph. We want to see the flatness of the frequency response at the crossover point.
Edit 2: You might consider taking this discussion over to the REW thread. There are a number of participants in that thread who have a lot of experience with measurements, calibration, and speaker placements. The thread is here.
Edited by AustinJerry - 9/22/13 at 4:37pm