Does the use of a pair of subwoofers reduce the need for bass traps, due to wave excitement/ cancellation properties, or are the two complementary?
Yes to both questions if done right.
Unless the absorbers are very thick and/or there are very many of them they won't have much affect at subwoofer frequencies. Both subs and traps is best.
Which one? Room treatments? Multiple subs? Which room? Which seated position? Which frequencies? How many subs? Do you want to eliminate width modes, length modes, oblique etc. Is this a real question about a real room? Or are you just freestylin'?Dallas, so what is your definition of "done right"?
Which one? Room treatments? Multiple subs? Which room? Which seated position? Which frequencies? How many subs? Do you want to eliminate width modes, length modes, oblique etc. Is this a real question about a real room? Or are you just freestylin'?
If you are asking these questions in an effort to help you improve your room, I suggest you post the following to help others help you:
Room dimensions
Speaker position
Seated position
At least a 1/12 smoothed per octave SPL/phase plot
Will the expert bring a mic, ADC and a laptop with REW loaded over as well?Thanks. I am only interested in the seated position and it's an open floor plan. Speakers are 4-5 feet from the walls. I am just trying to get the general principles straight. As you know, there are many opinions about this stuff. I will have an expert put a couple of subs in, but I want to make sure I generally understand what's going on.
Will the expert bring a mic, ADC and a laptop with REW loaded over as well?
Gentlemen,
So when a sub is operating, does it affect the frequencies above the crossover point, say the range from about 150 to 300Hz, or is it exciting the room only below the cross over point?
Crossovers are not magic brick walls that stop all sound above and below. There is a roll-off set by the crossover's slope. I have seen that slope range from 12 dB to 24 dB per octave for sub crossovers. 12 dB/octave means that, for a crossover of 80 Hz, the sub is about 12 dB down at 160 Hz. That is about half as loud (little less, given sub frequency loudness contours are closer than in the midrange). That also means the main speakers are about half the loudness at 40 Hz, assuming they can still respond at that low a frequency (the roll-off of the speakers adds to the overall roll-off). With that same second-order 912 dB/octave) response the sub is down 24 dB at 320 Hz, again assuming the sub itself is flat that high (most are not). An 18 dB/octave slope is about 18 dB down an octave away, about 1/4 the volume. An octave is a factor of two in frequency (or one-half if you are going down instead of up).
At the crossover point, sub and mains contribute about equally (do't want to get into nit-picking details). That is why getting the phase right at the crossover point is so important, and since the crossovers and drivers impact phase helps explain why physical distance is often unreliable for setting the phase or delay of the sub relative to the mains. You want the signals from the mains and sub(s) at the crossover frequency to be in phase (add) at the listening position. As you move away from that frequency it becomes less important as one of the other rolls off and contributes less to the sound. Getting the phase wrong at the crossover is likely the reason folk say a sub didn't help or didn't sound right.
Room modes is a different though perhaps related question. If you want to position a sub to help with those, which are set by physical dimensions, then you want to place a sub in the room null to help overcome the room mode. You still have to align phase to everything else, but in general a sub placed in the wrong place will not help with a room mode no matter how you fiddle with its phase.
HTH - Don
Will the expert bring a mic, ADC and a laptop with REW loaded over as well?
Dallas,
So from a high level, what should the guy be measuring? What should he be looking for in the measurements?
I want to make sure I weed out the shysters
I'm not saying anyone is a shyster. You first need to describe your system. Do you own a DAC and a windows computer? If I were you, I would buy my own test gear. That way you don't limit yourself to the local-jokel. You can then shop in a much bigger pond to help you find the right person to dial-in the subs.
The way I integrate subs is, I think, ideal. However, you may not have the right gear to do what I do.
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