Having the luxury of visiting many show rooms in Las Vegas, I learned that sound engineers utilize near-field subwoofer placement to solve a lot of bass problems. Specific show room pending, I’ve seen individual subwoofers serving no more than 12 seats per array. How they solve group delay and echo slab in a 2,000 seat room is another matter and them sound-techs weren’t to quick to divulge.
The advantages of using multiple subwoofers had been promoted to death. Off to the opposite extreme and for the normal one to two center seated listener, I’m an advocate of placing a subwoofer right behind the main seat. With main speakers capable of good 40-50hz extension, the sub can be crossed low enough to avoid any directional clue (provided with low distortion high quality sub and 4th or higher order lowpass)
Advantages:
1. Minimum sq.ft. displacement. (One sub and no clutter)
2. Minimize room node problems for one position.
3. At typical distance of main speaker of 12-15’, phase difference with sub is nominal at these frequencies and easily compensated.
4. Due to close proximity of sub, high power isn’t necessary.
5. Equalizing mainly to extend or smooth sub’s natural respond due to minimum room influence at listening chair.
To address time alignment, I’d learned a trick from videophiles by using digital delay they use to lip sync video/audio. Bit perfect not withstanding, one can delay digital signals going into either the main or subwoofers in 1ms or less increment. (1ms approximates 1.36inches) Yes I’d tried driving the main and sub with a pair identical DACs experimenting with various phase and time alignments. And believe me that it is nearly impossible to identify arrival peaks of the sub using impulse measurements. Main speaker will show distinct first arrival peaks/dips but subwoofers are nothing but a smooth gentle wave that looks almost like a straight line. Best compromise is to physically measure the distance and compensate arrival time.
No I don’t hear much of a difference with sub time alignment but phase i can. It is easier and more impactful to compensate for phase. Oh... sorry I got side track...
Best Regards
The advantages of using multiple subwoofers had been promoted to death. Off to the opposite extreme and for the normal one to two center seated listener, I’m an advocate of placing a subwoofer right behind the main seat. With main speakers capable of good 40-50hz extension, the sub can be crossed low enough to avoid any directional clue (provided with low distortion high quality sub and 4th or higher order lowpass)
Advantages:
1. Minimum sq.ft. displacement. (One sub and no clutter)
2. Minimize room node problems for one position.
3. At typical distance of main speaker of 12-15’, phase difference with sub is nominal at these frequencies and easily compensated.
4. Due to close proximity of sub, high power isn’t necessary.
5. Equalizing mainly to extend or smooth sub’s natural respond due to minimum room influence at listening chair.
To address time alignment, I’d learned a trick from videophiles by using digital delay they use to lip sync video/audio. Bit perfect not withstanding, one can delay digital signals going into either the main or subwoofers in 1ms or less increment. (1ms approximates 1.36inches) Yes I’d tried driving the main and sub with a pair identical DACs experimenting with various phase and time alignments. And believe me that it is nearly impossible to identify arrival peaks of the sub using impulse measurements. Main speaker will show distinct first arrival peaks/dips but subwoofers are nothing but a smooth gentle wave that looks almost like a straight line. Best compromise is to physically measure the distance and compensate arrival time.
No I don’t hear much of a difference with sub time alignment but phase i can. It is easier and more impactful to compensate for phase. Oh... sorry I got side track...
Best Regards