Considering several questions and postings on choosing and integrating subwoofers to main speakers, I think a primer on certain basic facts regarding subwoofers may be helpful to some... (Emphasis here is on subwoofers for music, not just for LFE output in home theaters)
The best definition I have across for a subwoofer is that it is an "add-on" product that extends the bass response of a system so that it is flat or very close to flat all the way down to about 20 Hz. The other major point is that by integrating a subwoofer to main speakers, you don't stop the mains at, say 100 Hz, and start the sub at, say 99.999 Hz. The main speakers and subwoofer must overlap for at least one full octave. For example, if the crossover point is 80 Hz, the main speakers have to be flat to 40 Hz and the subwoofer should perform well up to 160 Hz.
The subwoofers which usually accompany small main speakers have normally little bass response below about 60 Hz and are never true subwoofers, we can call them add-on woofers with 8" or 10" drivers. The real and true subwoofer is capable of extending the bass to close to 20 Hz and usually comes with 10" or 12" single or multiple drivers. Then there are the infra subwoofers with huge 16" or 18" drivers extnding the bass to below 20 Hz but can never operate satisfactorily above 40 Hz or so.
The best way to get good deep bass in a stereo system is to have a pair of full-range main speakers and add a true subwoofer to extend the bass, or if possible, a pair in stereo (many believe all bass frequencies are not directional but this is not true). The best connection for musical subwoofers is at the output terminals of the main amplifier. Relative to the main speakers' 4-8 ohms impedance, the input impedance of the subwoofer amplifier will be several thousands of ohms and virtually no power will come from the main amplifier to subwoofer. Practically all the amplifier power goes to the low impedance main speakers. The subwoofer amplifier just "looks" at the main amplifier and boosts the lowest frequencies. The best type of subwoofer crossover is the one that rolls off bass into the main amplifier and relieves the main speakers and amplifier from having to produce as much bass. This gives the best performance from the main amplifier and speakers for mid-range and higher. To my knowledge, only Vandersteen makes such speaker systems (2WQ subwoofer) where a high pass filter is inserted before the main amplifier and the Vandy subs have a feed forward circuit which compensate the roll-off.
Finally, never believe that LFE subwoofers make good music subwoofers, whatever others might say. The best music subwoofer will be linear in response all the way down to about 20 Hz.
I had already mentioned in one of my postings that companies like Bag End, Rel, M&K, Vandersteen etc make excellent subwoofers for music, mostly with sealed enclosures and low-slope crossovers. May be there are others too I am not aware of.
So before spending your hard-earned money on subwoofers, please consider these facts and read and discuss more to decide. You can always buy a subwoofer and whether it is money wisely spent will depend...
Trust this helps someone.
Thanks for your patient reading and happy listening.
> murali
The best definition I have across for a subwoofer is that it is an "add-on" product that extends the bass response of a system so that it is flat or very close to flat all the way down to about 20 Hz. The other major point is that by integrating a subwoofer to main speakers, you don't stop the mains at, say 100 Hz, and start the sub at, say 99.999 Hz. The main speakers and subwoofer must overlap for at least one full octave. For example, if the crossover point is 80 Hz, the main speakers have to be flat to 40 Hz and the subwoofer should perform well up to 160 Hz.
The subwoofers which usually accompany small main speakers have normally little bass response below about 60 Hz and are never true subwoofers, we can call them add-on woofers with 8" or 10" drivers. The real and true subwoofer is capable of extending the bass to close to 20 Hz and usually comes with 10" or 12" single or multiple drivers. Then there are the infra subwoofers with huge 16" or 18" drivers extnding the bass to below 20 Hz but can never operate satisfactorily above 40 Hz or so.
The best way to get good deep bass in a stereo system is to have a pair of full-range main speakers and add a true subwoofer to extend the bass, or if possible, a pair in stereo (many believe all bass frequencies are not directional but this is not true). The best connection for musical subwoofers is at the output terminals of the main amplifier. Relative to the main speakers' 4-8 ohms impedance, the input impedance of the subwoofer amplifier will be several thousands of ohms and virtually no power will come from the main amplifier to subwoofer. Practically all the amplifier power goes to the low impedance main speakers. The subwoofer amplifier just "looks" at the main amplifier and boosts the lowest frequencies. The best type of subwoofer crossover is the one that rolls off bass into the main amplifier and relieves the main speakers and amplifier from having to produce as much bass. This gives the best performance from the main amplifier and speakers for mid-range and higher. To my knowledge, only Vandersteen makes such speaker systems (2WQ subwoofer) where a high pass filter is inserted before the main amplifier and the Vandy subs have a feed forward circuit which compensate the roll-off.
Finally, never believe that LFE subwoofers make good music subwoofers, whatever others might say. The best music subwoofer will be linear in response all the way down to about 20 Hz.
I had already mentioned in one of my postings that companies like Bag End, Rel, M&K, Vandersteen etc make excellent subwoofers for music, mostly with sealed enclosures and low-slope crossovers. May be there are others too I am not aware of.
So before spending your hard-earned money on subwoofers, please consider these facts and read and discuss more to decide. You can always buy a subwoofer and whether it is money wisely spent will depend...
Trust this helps someone.
Thanks for your patient reading and happy listening.
> murali