Help please choosing Subwoofer


Active Member
Hi everyone,

Looking for recommendations regarding a new sub for my set-up. I have recently changed my fronts, centre and rear speakers all of which I am very happy with. I am currently using a KEF 20b (specifications below) purchased new way back in 1996 so pretty old and dated!!!

Thinking this may now be the weakest link I am wondering if an upgrade would achieve a 'big step up' performance wise? Please find below my current set-up along with my 'man cave' layout, also included are pictures of my seating area and existing sub for reference. I currently only use the sub for movie's and listen at moderate volume levels. My QA 3050i's are sufficient in the bass department for music but I may experiment with the new sub if there are gains to be made.

Having done some research my current choice would be a BK Double Gem? Not too big and would fit in either of the positions as seen on my floor plan. However open to suggestions.

AV Amp: Denon AVR X3300W
Amplifier: Audiolab 8000A Used direct for front speakers (both music & movies)
Front's: Q Acoustics 3050i
Rear's: Q Acoustics 3010i
Centre: KEF Q650c
Amos Heights (front): CA Minx 21's

Specification: KEF 20B
System type: Active subwoofer
Enclosure type: Closed box
Dimensions (H x W x D): 326 x 302 x 335mm (13 x 12 x 13.2 inches)
Weight: 9.3kg (20.5 lbs)
Drive Unit: 250mm (10”) long throw
Amplifier: 70W
Frequency response: 45Hz to 150Hz +/-3.0dB (-6dB at 36Hz)
Maximum output: 107dB
Finish: Video Grey
System: SP3259
Drive Units: B250 bass unit (SP1420)
Amplifier: SP2262(230V)

A special Thank you to all respondents!


  • thumbnail.jpg
    49.7 KB · Views: 68
  • 3.jpg
    115.7 KB · Views: 64
  • 4.jpg
    98 KB · Views: 64
  • 2.jpg
    102.2 KB · Views: 57
  • 1.jpg
    82.9 KB · Views: 72
Last edited:


Active Member
Hi sorry £3-400 preferably. Maybe slightly more if worth spending a touch more.



Active Member
I think you'd notice a huge difference if you looked at something like an SVS PB/SB 1000. They go significantly lower than your current subwoofer and suspect you'd be delighted. Its a fine balance between upgrading, and not upgrading far enough meaning you need to then buy again in the future


Distinguished Member
AVForums Sponsor
You could look at one of the SVS SB1000 or SVS PB1000 we have on offer, the woofers were hugely popular and has recently been surpassed by the latest pro editions. Having said that, these model as no slouch and should easily offer you an upgrade without having to push your budget much further


Distinguished Member
AVForums Sponsor
SVS SB1000 dimensions (H x W x D): 330mm x 330mm x 330mm

Kef 20b dimensions (H x W x D): 326mm x 302mm x 335mm

So yes the width is approximately 30mm wider, but in reality, they're almost identical in subwoofer terms of size
Last edited:


Active Member
Hi sorry £3-400 preferably. Maybe slightly more if worth spending a touch more.

The left side of the left chair on your diagram looks like there's plenty of room to fit a reasonably sized subwoofer in the room. If you got the WAF you could buy a Monoprice Monolith 10 THX sub.

For a bargain £390 from Monoprice UK with the HAPPY22 22% off new years discount code. That would be a significant step up from your current sub.

And better overall performance than the BK Double Gem subwoofer you were considering. Monoprice Monolith 10 THX is Actually smaller in height than the BK Double Gem, not much longer depth.


Active Member
Thank you all for the replies and suggestions. Although not critical to my final decision making I would prefer a white finish to blend in with my new speaker set-up if possible (hence the Double Gem).

Having said that if any of the other suggestions put forward are a 'significant' step up performance wise then I would have to seriously consider them. I will probably stick with this new sub for a long time (I will be 63 this year) and more than likely it will see me out haha.

Thank you for the reassurance that my money will be well spent on the upgrade. Not quite sure what to expect if i'm honest, I have had the other one for so long and it sounded Ok to my ears but remembered listening to a huge REL before I bought the KEF and mine never quite sounded like that so hoping the new one will sound similar to the REL of old if possible at this price point.

Apologies I checked the measurements for the PB1000 and not the SB hence my incorrect comment doh. Agree the SB would be perfect size wise. Size apart which in your opinion would perform better the SB or the ported PB?

Performance wise what would be your reasoning behind choosing either SVS models over the BK Double Gem or alternatively the Monoprice Monolith suggested by Kingchin above?

Finally I see that SVS do a SB1000 in white BUT it's £179 dearer for the privilege, bit steep if you ask me?

Thank you for the suggestion of the Monoprice Monolith, The price is bang on not sure i'm keen on the design however. However still a contender but why would you rate this sub above either of the SVS sub's or indeed the BK Double Gem?

Again thank you so much for your advice and I welcome anymore comments you may have.



Active Member
However still a contender but why would you rate this sub above either of the SVS sub's or indeed the BK Double Gem?
For movies the ported Monoprice Monolith 10 THX delivers much higher output impact in the lower frequencies. Than both the sealed SVS SB-1000 and BK Double Gem.

I agree a gloss white BK Double Gem will look much better with your white speakers. I do like the design of the Monoprice Monolith 10 THX, it's just the vinyl wrap finish I don't like. I prefer a painted gloss or nice wood veneer finish.

Good luck with your sub hunt!


Active Member
Thank you all for your recommendations. I eventually spoke to Tom at BK Electronics and he recommended the Double Gem over the P12 with it's Passive Radiator because my set up is in a bedroom upstairs.

Ordered one via BK's ebay store 'B' grade for £352 inc delivery. Arrived Saturday and so far am quite impressed although trying to find the 'sweet spot' sound wise is proving somewhat elusive at present!

Thanks again to everyone's participation.

The latest video from AVForums

Panasonic LZ2000, LZ1500 & LZ980 Hands-on Launch Event | No QD-OLED for 2022, new 77-inch for LZ2000
Subscribe to our YouTube channel

Full fat HDMI teeshirts

Support AVForums with Patreon

Top Bottom