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Barry Ober has more than 35 years research into the best methodology for the easiest and most comprehensive subwoofer integration and system alignment, including speaker imaging.
I've read most of his website and used his techniques to integrate my JL Audio F212v2 with my 2-channel system. Bass dynamics, imaging, and clarity are significantly better than any 2-channel system I've experienced at RMAF, Audio showrooms, or in my home. All but a very few ported speaker systems with separate bass towers should have subwoofers to experience evocative low frequency bass.
The following are excerpts from his extensive website: (The Sound Doctor)
A ported speaker is ALWAYS nothing more than a cheap way to attempt to get free bass out of an enclosure and /or driver that's too small. It's a holdover from the 1930's when because of driver inefficiencies (especially when compared to today's units) you had to do everything possible to increase the useable output over the desired range of low frequencies.
When the manufacturer of a speaker cabinet defines the frequency response (i.e., 37 Hz - 20kHz +/- 3dB) this is what is defined by the entire arrangement of the port and the air in the cabinet and the driver. At some low frequency the port air is exactly out of phase with the driver air pressure and since they cancel, there is NO output from the cabinet into the room. Therefore with a ported cabinet, the entire sloppy concept is this juggling game between the response of the drivers under air pressure, the passive crossover inside the box, the port size and placement.
Simply connecting a sub to existing mains speaker (or amp) terminals is the WORST POSSIBLE WAY to do this. EVERYTHING scientific and acoustic about this method is wrong, from the additive delay issues to the back EMF of the mains affecting the LF signal. However there are plenty of people who simply do not understand correctly integrated bass, and they will be reasonably happy simply sticking another box on to their system without regard to timing, phase and frequency issues, and they will think it sounds "ok" or "good" and for those people it doesn't really matter.
Some audiophiles don't want to introduce yet another active "thing" in their precious signal path, not realizing that adding the crossover is very much the lesser of two evils.
Actually adding a crossover is really a WIN-WIN situation:
WIN # 1) Since you are now NOT putting in 20 Hz - 80 Hz into the mains you are not using up the available LF cone movement with bass, so the LF cone in your mains is able to play its higher freqs (up to IT'S crossover point) much more cleanly. You get an apparent 6dB or more dynamic range. You can play your system LOUDER, and also with less compression distortion in the LF driver when you're having that Saturday night dance party and you're playing urban bass technopop at 110+ dB. Really.
WIN # 2) Since you are not putting bass into that same driver you are not Doppler modulating everything between 80 and 600, or whatever the next crossover point is. This means cleaner mids. By far.
WIN #3) You are not sucking current out of your main power amp at low frequencies, so there is more current reserve to play those highs louder...
WIN # 4) Since the cones aren't moving as far at the low freqs the driver itself is not generating as much back EMF therefore the damping factor and all of its issues are greatly negated. And you don't need to run silver plated cold water pipes to your mains as speaker wires because there is less current draw by the speakers.
WIN # 5) Freqs below 80 are now NOT causing transient intermodulation distortion with the higher freqs (and vice versa) in your power amp. Cleaner still.
If you have a 2-channel only system if you do not correctly use a crossover you are both wasting your time and you will be frustrated.
If your speakers are ported, you SHOULD close (seal) the ports. Towels will do for a test but you might consider purchasing a 3", 4", or 5" thick slab of "foam" at a notions / sewing store. What you are trying to accomplish is to NOT have multiple sources of differing phase relationships (the main driver, the port air, and the sub driver) at or near the crossover frequency.
Invert the polarity of the MAIN speaker the sub is CLOSEST TO. Disconnect all the other speakers in the room. Place your head equidistant between the sub and the speaker it is closest to. Play the 80 Hz tone. Adjust the phase control AND the level control and both settings of the polarity switch until you hear a distinct NULL. (IT MIGHT EVEN DISAPPEAR COMPLETELY) There should be some setting of the two controls on the JL sub which will provide a rather sharp null - this is a CRITICAL setting and you might find it to be very sharp. Now put the wiring back the correct way to that one speaker. Reconnect the other speaker and you're done.
I've read most of his website and used his techniques to integrate my JL Audio F212v2 with my 2-channel system. Bass dynamics, imaging, and clarity are significantly better than any 2-channel system I've experienced at RMAF, Audio showrooms, or in my home. All but a very few ported speaker systems with separate bass towers should have subwoofers to experience evocative low frequency bass.
The following are excerpts from his extensive website: (The Sound Doctor)
A ported speaker is ALWAYS nothing more than a cheap way to attempt to get free bass out of an enclosure and /or driver that's too small. It's a holdover from the 1930's when because of driver inefficiencies (especially when compared to today's units) you had to do everything possible to increase the useable output over the desired range of low frequencies.
When the manufacturer of a speaker cabinet defines the frequency response (i.e., 37 Hz - 20kHz +/- 3dB) this is what is defined by the entire arrangement of the port and the air in the cabinet and the driver. At some low frequency the port air is exactly out of phase with the driver air pressure and since they cancel, there is NO output from the cabinet into the room. Therefore with a ported cabinet, the entire sloppy concept is this juggling game between the response of the drivers under air pressure, the passive crossover inside the box, the port size and placement.
Simply connecting a sub to existing mains speaker (or amp) terminals is the WORST POSSIBLE WAY to do this. EVERYTHING scientific and acoustic about this method is wrong, from the additive delay issues to the back EMF of the mains affecting the LF signal. However there are plenty of people who simply do not understand correctly integrated bass, and they will be reasonably happy simply sticking another box on to their system without regard to timing, phase and frequency issues, and they will think it sounds "ok" or "good" and for those people it doesn't really matter.
Some audiophiles don't want to introduce yet another active "thing" in their precious signal path, not realizing that adding the crossover is very much the lesser of two evils.
Actually adding a crossover is really a WIN-WIN situation:
WIN # 1) Since you are now NOT putting in 20 Hz - 80 Hz into the mains you are not using up the available LF cone movement with bass, so the LF cone in your mains is able to play its higher freqs (up to IT'S crossover point) much more cleanly. You get an apparent 6dB or more dynamic range. You can play your system LOUDER, and also with less compression distortion in the LF driver when you're having that Saturday night dance party and you're playing urban bass technopop at 110+ dB. Really.
WIN # 2) Since you are not putting bass into that same driver you are not Doppler modulating everything between 80 and 600, or whatever the next crossover point is. This means cleaner mids. By far.
WIN #3) You are not sucking current out of your main power amp at low frequencies, so there is more current reserve to play those highs louder...
WIN # 4) Since the cones aren't moving as far at the low freqs the driver itself is not generating as much back EMF therefore the damping factor and all of its issues are greatly negated. And you don't need to run silver plated cold water pipes to your mains as speaker wires because there is less current draw by the speakers.
WIN # 5) Freqs below 80 are now NOT causing transient intermodulation distortion with the higher freqs (and vice versa) in your power amp. Cleaner still.
If you have a 2-channel only system if you do not correctly use a crossover you are both wasting your time and you will be frustrated.
If your speakers are ported, you SHOULD close (seal) the ports. Towels will do for a test but you might consider purchasing a 3", 4", or 5" thick slab of "foam" at a notions / sewing store. What you are trying to accomplish is to NOT have multiple sources of differing phase relationships (the main driver, the port air, and the sub driver) at or near the crossover frequency.
Invert the polarity of the MAIN speaker the sub is CLOSEST TO. Disconnect all the other speakers in the room. Place your head equidistant between the sub and the speaker it is closest to. Play the 80 Hz tone. Adjust the phase control AND the level control and both settings of the polarity switch until you hear a distinct NULL. (IT MIGHT EVEN DISAPPEAR COMPLETELY) There should be some setting of the two controls on the JL sub which will provide a rather sharp null - this is a CRITICAL setting and you might find it to be very sharp. Now put the wiring back the correct way to that one speaker. Reconnect the other speaker and you're done.
opcorn:
