BK XXLS400 Subwoofer Performance Review


Standard Member
I am not affiliiated in any way with the products used!!!

A recent visit to my local Hi-Fi shop left me reviewing a second hand B&W ASW1000 subwoofer. I had always considered a sub for adding depth to my system and decided to give this a trial. I liked the additional depth but the speaker rattled audibly around 50Hz, so decided it was not worth the money and probably on it's last legs. Then I looked for an alternative and decided to buy a B&K XLSS400. Couldn't find any definive data, but the reviews were promising, so purchased anyway!
Here is the frequency data I obtained for the speaker set up installed in my lounge. Thought it might be of some benefit to others and give something back to the forum.
My lounge is 18.5x15.5x7.5 ft.
Used website data to determine the best position for room modes before I purchased, so I didn't have any suprises for odd placement. A crawlround listening test confirmed the calculated position.
Cranking up the volume - not that you need to - sucks the life out of the speaker. It appears the amp folds back for a couple of seconds and sub frequencies disappear momentarily; however, normal listening levels show the amp has more than enough power.
The settings I have decided upon actually seem to show a lower sub volume eg not a straight line, but in practice this provides a more listenable level with the sub blending in with my my main speakers and provides a more natural sounding image.
What is somewhat discouraging is the low level drop out below 31.5hz. It appears either the speaker or the amp cut out at this extreme lower point. B&K claim [email protected] in- room. As the B&W with 1000W only went down to 40Hz in the same room, I think this might be nitpicking.
Using the hi level input gives a more responsive bass that blends in better with my main speakers. The lo level was taken from the preamp tape output, so this may have introduced some phase/timing issues.
This speaker works extremely well, is musical, blends in with my B&W speakers admirably (sound and cherry wood finish), is well made, and well worth considering.


  • SubWoofer Frequency Response B&K Both.xls
    38 KB · Views: 281
  • SubWoofer Frequency Response B&K Lower Sweep.xls
    32.5 KB · Views: 148
  • SubWoofer Frequency Response B&K Separate.xls
    32 KB · Views: 141
Last edited:

PC Nut

Established Member
Looks like you have a flatter overall frequency response with both sub and speaker combination across the range. As for the drop out below 31.5 Hz, can this not be due to furniture and or room acoustics that cause this response. Great charts by the way.


Prominent Member
I think it must be where you have it placed, according to my audyssey pro calibration the pre corrected response on mine is below 20 IIRC


Prominent Member
I found the XXLS400 to start dipping at about 35hz in my room when measured.
Its also the same for my cousin in his room. This was setting up to a hard knee house curve but I am sure it would be similar anyway.

If you want that deeper bass then you will want to use a different product or work on your room / seating / sub location if possible

The latest video from AVForums

Spielberg, Shyamalan, Aronofsky, Chazelle, Eddie Murphy and Mel Gibson - all the latest movies
Subscribe to our YouTube channel
Support AVForums with Patreon

Top Bottom