40 Hz -10 dB (45 Hz -3 dB on axis). This is enough to reproduce most bass program material. However, it may not be adequate for those listeners who prefer strong bass content, or listen to some modern music with low bass content like most electronica, or listen to classical piano or organ music.

For me, I prefer the bass support a good subwoofer provides. For music I also prefer a sealed subwoofer, with a low Q, and preferably servo controlled. The Rythmik F12 comes to mind as an ultimate choice. The SVS SB12-NSD is somewhat less expensive and would do a good job. The Epik Legend is less money yet and is also good.

The problem is that the NAD C316BEE does not have a subwoofer output and the tape out does not work as it has fixed output. It would also be problematic to use speaker level connection as the NAD C316BEE only has speaker outputs for one pair of speakers.

The NAD C326BEE does have a subwoofer output.

So, I guess with the NAD C316BEE a sub isn't going to work very well anyways.

The solution is to buy a subwoofer with speaker-level inputs and outputs.  Connect its inputs to the amp and the PSBs to the outputs.

usually have high impedance, around 200 Ohms. So connecting both the PSB Image B6 loudspeakers AND a subwoofer with speaker level inputs to the speaker terminals of the NAD C316BEE would work. The Rythmik F12 and Epik Legend subwoofers have high (speaker) level inputs. The SVS does not.

A subwoofer with both inputs AND outputs could do the job simply, and well.

I haven't researched current products, but my own subwoofers have a high pass filter on the outputs to the speakers, so it filters out frequencies below 80 Hz before sending the signal on to the speakers, thus relieving the speakers of low bass load. I'm pretty sure there are comparable Subwoofer units available.

I'm not using the speaker level option these days, though it did work well. The only potential downfall to that hookup is that the signal driving the subwoofer was amplified twice. First by your the main system amplifier or receiver, then the signal was reduced by the sub, only to be amplified again by the subwoofer's amplifier. If it wasn't for the double amplification, I'd still be using that method today, but I figure I'm getting cleaner low bass by running a line level signal from my pre-amp into the subwoofer's RCA's.

I wish I could figure an easy way to filter the signal before sending the low bass to the sub, and the higher frequencies to the main amp. I don't really want to get into an active crossover though. So for now I have the subs crossed in at 40 Hz and the speakers have output above that. If I could reasonably limit the bass frequencies to the main speakers, I'd use a higher split, like 80 Hz.

Beware, many speaker level connections on powered sub woofers have a non defeatable non variable 120Hz high pass fillter for the main speakers. If the sub woofer you purchase is of this type, connect the sub woofer and the main speakers to the amplifiers speaker connections. The sub woofers 200 Ohm or higher input impedence will have little effect on the amplifier. This way you will not be forced to have a 120Hz high pass filter before your main speakers.

While two subwoofers increases output substantially they also can work to reduce or eliminate room peaks and nulls in frequency response. However, proper placement, phase and EQ can do the same with one. Unless your room is large, one should do.

I always recommend Rythmik as they are excellent at faithfully reproducing low frequency program material.

JoeE SP9 wrote:

Beware, many speaker level connections on powered sub woofers have a non defeatable non variable 120Hz high pass fillter for the main speakers. If the sub woofer you purchase is of this type, connect the sub woofer and the main speakers to the amplifiers speaker connections.

My advise is to do the proper research and avoid purchasing such a sub.  There are many with more useful crossover options.

Kal

As long as we're on the subject of subwoofers...

My father-in-law recently moved from Colorado to the LA area.  We're trying to put together a 5.1 system for him, and I need a little help with the sub.  The speakers will most likely be Noble Fidelity L-65LCRS at all five points, or L55s across the front, and the 65s in the back. He's got a 20-year-old Velodyne sub that no doubt has a rotted out surround - it puts out about 60 watts. 

Needs to be musical, but also pull double-duty in an HT system.  Prefer sealed box, probably minimum 300 watts. Any recommendations?

It's been a long time since I thought about subs - I owned a REL Stadium III over ten years ago, then moved to Genesis V and finally NHT Xd with dual subs, so I haven't had to deal with this issue in a while. 

Thanks in advance for any suggestions.  We're trying to keep it under $1000 if possible.

J