Originally Posted by Aaron Gilbert
Previously, Audyssey/Onkyo had reported that my front and surround speakers are full range and my center speaker should be crossed over at 60Hz. I can't really compare surround back, because they are completely different speakers, placed in very different positions.
Now, my front speakers have a recommended 150Hz crossover, surrounds at 60Hz, center still at 60Hz, and surround back also at 60Hz. This is very odd for several reasons:
It's not that odd.
1. The front and surround speakers are identical, same drivers, cabinets, and crossovers.
But they are in completely different locations in the room. That greatly affects the bass region of the speaker.
2. The position of the front speakers has not changed. Surrounds have moved forward about 2', but this shouldn't affect the front speakers?
The -3 dB point is calculated from all the measurements. So, now that you took more the value is expected to be different (and more accurate assuming you take the measurements as indicated in the guide).
3. The center speaker is a chopped version (literally) of the front L/R and surround speakers. Moreover, it's a sealed cabinet about 1/3 the volume of the others, which are vented. So, there's no way it has better low end extension than the front L/R, and is in no way the equal of the surround back, either - even were it placed at the junction of two walls, as are the surround back.
The wall boosts the bass significantly so this can certainly happen even for a smaller speaker.
4. All speakers except the center have considerable output into the low 30's, and still quite present at 20Hz, which is why I wasn't surprised when it previously chose to set them to full range.
Actually, the Onkyo you have uses 80 Hz as the criterion for Full Band so this is a non-issue.
Using the latest Audyssey EQ, a huge amount of bass has been removed from the front L/R speakers, even if I reset the crossovers to 40Hz or bypass them completely by selecting full range.
This usually happens if you have taken measurements too close to the walls. There is huge bass buildup there due to standing waves and taking measurements there tells MultEQ there is "too much bass".
Regarding measurements, I do have one question. Our couch is offset to the right side of center by about 2'. Thus, the left seat on the couch is actually the center of the room, in front of the center speaker. The speakers are arranged symmetrically around this point, other than the subwoofer in the front right corner. Should I use the left seat on the couch as the center position, and perform the other measurements 2' on either side and three positions 2' in front of those, therefore omitting the right seat on the couch completely? All the guides I've ready don't don't seem to specify whether the six-eight positions need to be centered within the speaker array, although the pictures do show this. Audyssey did get all the distances correct using the center of the couch as position #1, both today and back in October.
You should always take the first measurement in the center of the system (in line with the center speaker) even if your main seat is off-center. That way there will not be dramatic delay settings for the other seats. Then, follow the 2' approximate spacing described in the guide. Don't worry about measuring in every seat. You will get better results by measuring 8 positions in an area around the center location. Going off axis (e.g. outside the front left and right speakers) will not give you good results.