fid writes:
Hello everyone,
After I installed a single Rel subwoofer into my system I realized
that it would be in phase with one speaker and not with the other.
I explain: My room is just a bit more then 4000 cubic-feet, L shaped.
I set the subwoofer into the left corner behind the left speaker
(Unfortunately this is the only option I have). So, I measured the
frequency response of each front speakers with an real-time analyzer
and I found out that when the phase of the subwoofer is set to 0 the
right speaker's mid-bass frequencies decrease the output considerably.
When I switch the sub's phase to 180 the left speaker's mid bass
portion is sucked in. I checked the wiring, all matches red-to red,
black to black. I thought... maybe I should reverse the polarity of
one of the mains to even up with the sub, but that would screw up the
phase between the two mains. Is there any solution?
Is the distance between sub and mains the cause of this phase
'disparity"?
Any input would be greatly appreciated.
Thank you.
You didn't mention what the cutoff frequency is of the subwoofer's
crossover. Is it 80 Hz? 120 Hz? 200 Hz?
The wavelength of a frequency f is about 1100 / f [ft]. So if the
highest frequency in your subwoofer's output is 100 Hz the wavelength
is about 10 feet. At that frequency, a distance difference of 5 feet
will correspond to 180 degrees out of phase. Of course it's not
black-and-white either - a distance difference of 4 feet will attenuate
the signal somewhat but not completely (theoretically).
So, if you're getting unwanted cancellations in the "mid-frequencies"
I'd say the best thing you could do is lower the crossover frequency of
the sub, down to maybe 60 to 80 Hz.
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