The subwoofer thing


#1

I only got my first subwoofer 18 months ago or so. I didn’t go looking for one, my dealer told me I needed one and brought it round. He told me I only needed one.

He was correct. First I had to connect a disc spinner, he had some test sounds (rather industrial) and 15 minutes later he was done.

The premise is that my speakers go to about 40Hz -3dB and it was to fill in below that. I knew there was a bit of an issue, stand-up bass was rather recessed and lovers of Hindemith will understand when I say his sonata for bass tuba was lacking a bit of zip.

The second thing I noticed about the sub, after the added pluck to the stand-up bass, was the complete lack of directionality. Ergo, the sub is in the left corner of the room, stand-up bass in just about everything comes pretty much exclusively out of the right channel, as the reinforcement was purely heard in the same spot. There was no blurring of the location of the bass, even though the lower part was coming from 12 feet away.

The third thing is the reinforcement concept, I’m not trying to blow the roof off the house, just reinforce sounds at moderate levels that have been trimmed below the knees. I notice the deeper sound, but equally the staging has improved.

So I ordered in a more powerful unit today (http://www.bkelec.com/hifi/sub_woofers/XXLS400-DF_WN.htm), preferable to the REL in S3 or S5 in several ways, and I was speaking to the manufacturer to place the order. Points that arose:

  • Anyone who claims that they can actually hear the location of the sub has better hearing than either of us, or is dishonest.
  • There really is nothing lost by not having two subs if one will do.
  • Downfiring is fine as long as it is firing onto something solid.
  • My setup of having the sub sit on an off-cut of Acetal, which in turn sits on a piece of acoustic foam, is really quite sensible. The sound has something to bounce off and the foam stops energy being transmitted into the suspended floor. It’s a set-up others have used to keep down noise transmitted through the floor. I did it because my floor is not exactly level and it cost about $25.

So the main thing seems to be first if your audio system can generate a mono sub pre-amplified output. Fortunately mine can, so I can get the missing/reinforcing sound for both channels from one sub. If it can only provide stereo outputs, you’re into two subs.

Finally, my system can set a high-pass filter for the main speakers, but the dealer suggested not to use that function and just blend the REL unit he brought round. Firstly that works, and secondly I can turn off the sub from the remote control, which I sometimes do if the music has no low frequency demands or I just want the main speakers to do their normal thing.

So that’s my tuppenyworth and thanks to Chris1948 for putting me on to BK.


#2

If one can hear the sub’s location it is not properly setup and is reproducing frequencies much higher than it should. Many, particularly home theater enthusiasts, set the high pass cut-off way too high so that they experience thudding slam.


#3

Funnily enough I too have a BK 12" DF sub. It is only 300w, but it is in light oak and thus much better :slight_smile: It lives tightly crammed into one corner of the room, the only place I could put it, and I think that at moderate volume the bass is slightly directional. It only cuts in below 40hz. If I had space I would place the sub centrally, or have a second unit in the opposite corner. Obviously I could be deceiving myself about this, and after a year I am not troubled by it.