Hello Ken,
I have some quick questions for you before I give you some
tips.
First what frequency is the x-over set at on the Integra? If
you have it set at a low frequency like 40-60 Hz does the LFE level output
increase when you select THX processing?
Tip1:
Disable the subwoofer in the back of the room and play a continuous
low frequency test tone though the subwoofer located in the front of the room
at a loud level, THX reference would be a good choice. If you have a DVD with
subwoofer frequency test tone use that to generate the low frequency, If you don’t
have a DVD you can down load tones here.
http://www.stompaudio.com/index.php?main_page=index&cPath=6793
With the test tone now being produced from the primary
subwoofer walk to the front of the room and slowly walk back to the listening
position and beyond noting the differences in LFE output. Adjust your seat
forward or back to the first practical position that had the most LFE, sometimes
only a foot forward or backward will make a big difference.
Tip2:
Move the primary subwoofer from the front of the room and
position it at the listening position leaving the secondary subwoofer at the back of
the room disabled. With a low frequency tone playing in repeat through the
subwoofer located at the listening position start at the front left corner of
the room and crawl along all four walls slowly noting what positions reproduce
the most LFE. If you have an SPL meter you can use that but you should note
significant differences depending on where you are in the room. Once you have
completed this figure out what location are suitable for the subwoofer and
place it there.
Now that you have the primary subwoofer placed at the practical
location that produced the most LFE sit in the listening position and measure
the LFE output with your SPL meter, if you don’t have an SLP meter you will
just have to mentally note the amount of LFE. Once you get a good reading and
feel for the amount of LFE change the phase of the subwoofer and re measure the
amount of LFE at the listening position. If your subwoofer has a variable phase
start at 180 degrees and work back from there. Set the phase at the position
that produces the most LFE. You have now completed setting up the primary
subwoofer.
Setting up two subwoofer that have different specifications
in the same room can be a little tricky without an acoustical analyzer but it
can be done with a little patience and trial and error. Installing a second
subwoofer in the room should help to even out the frequency response in a large
room. To install the secondary subwoofer try installing it directly opposite of
your primary subwoofer on the opposite wall. Once this is completed calibrate
the secondary subwoofer to reference level, since you have two different subwoofers
you might want to calibrate the primary subwoofer to -5db below reference and
then calibrate the second subwoofer to reference level with both subwoofers reproducing the LFE tone. If
done correctly this will insure that your primary or better subwoofer located
in the primary position will be reproducing the majority of the LFE while the secondary
or lesser subwoofer will be used for fill in. This may or may not be a correct solution
depending on your room dynamics. Typically a +75 dB reading in most rooms using
an SPL meter will end up sounding dry and a little week because there is an
error reading low frequency’s using an SPL meter at the lower end of the
frequency range. Generally adding +3-+5 dB to the adjusted subwoofer
calibration will correct the calibration error. Relying on Automatic
calibration software regardless of manufacture is NOT and alternative for low
frequency calibration. Now that you have both of your subwoofers calibrated
switch the phase on the secondary subwoofer, if you heard or measured an increase
in SPL at the listening position this means the secondary subwoofer may be canceling
out the primary subwoofers LFE output at different frequencys or it could be
that the secondary subwoofers position interacts better with the room dynamic
out of phase. If this occurs you will need to set the secondary subwoofers
phase at the position that reproduced the most amount of LFE with the primary
subwoofer reproducing the LFE in conjunction with the secondary subwoofer and
recalibrate.
Although this is not an optimal solution for installing
subwoofers in a high end system it should get you in the ball park without
using an expensive audio analyzer and equalizer. I hope I dint miss anything but I may have considering I have only had one cup
of Java and it’s early.
Best regards,
Ray