Since subwoofers are nothing more than specialised loudspeakers, it stands to reason that designing a world-class subwoofer is in the same category as designing a world-class three-way loudspeaker. It’s all in the science.
Subwoofers have become a common component in a high-end system and although some debate how important a sub is in a two-channel system, it all comes down to each listener’s individual preference.
However, assuming you’ve decided to pair a subwoofer with one of our active music systems – LSX II, LS50 Wireless II, or the flagship LS60 Wireless – here are some helpful tips on how to set-up a subwoofer with your KEF LS Wireless speakers.
You can pair any subwoofer with one of our systems, but if you’re still deciding on which way to go, it’s helpful to keep in mind that our engineering team has taken the guesswork out of integrating a KEF subwoofer with a KEF active music system – their expertise and experience is available to you in the KEF Connect app.
Tips For Speaker Placement
Most people are aware of the equilateral triangle as a speaker set-up foundation and it’s a good place to start. KEF’s Uni-Q technology makes speaker placement far more flexible as the traditional ‘sweet spot’ is widened and more people in the room can enjoy the very best sound performance.
The simple rule of thumb is to position your loudspeakers as far apart as possible within your room. Too close together or too far apart and the soundstage begins to suffer. However, since every room is different, it’s not possible to give a definitive measurement – it’s all about a starting point and experimenting from there.
Next, conventional (old school) wisdom states the point of the triangle should converge about one foot behind the listener’s head. This is great advice if you’re the only person who is ever going to listen to your system, but if you have friends or family, you need something a little more forgiving – this is where our Uni-Q technology excels. Start with the point of the triangle at the main listening position. Uni-Q allows more flexibility beyond this – dispersion and exact timing between the highs and lows means that the ‘sweet spot’ is pretty much anywhere you sit.
In the past, toe-in – the angling of your front left and right speakers towards the listening area - was much more critical before the introduction of our Uni-Q technology. With traditional non-Uni-Q loudspeakers, toe-in is crucial for any chance of even a tight sweet spot at the main listening position. Uni-Q’s dispersion throughout the operating range is far broader – so toe-in is not necessary at the start.
Once you allow for factors like room dimensions, the sometimes-necessary differences in distance-to-wall for each loudspeaker, aesthetic requirements, and all the other things that make your space unique, a little toe-in may become necessary – but you must experiment.
Tips On How To Set Up Your Subwoofer
Once you are happy with the soundstage and placement of your loudspeakers, let’s integrate your subwoofer. If you have a KEF subwoofer, integration is as easy as answering a few questions. If you have a sub from another brand – no worries, we’ve got you covered.
After connecting your subwoofer, open the KEF Connect app and scroll through the menu to adjust the settings.
This menu option helps dial in the bass response of the loudspeaker when not using a subwoofer. When using a subwoofer, the KEF Connect app allows for greater control of the level and extension of the bass, beyond the simple “Bass Extension” control. We recommend leaving this on STANDARD – all of our subwoofer setting presets are designed this way.
If you are using more than one subwoofer, this option allows you to choose between mono and stereo subwoofer channels. There is no hard and fast rule for this, it’s all about personal preference, however setting it to MONO will result in more even bass throughout the room when using multiple subwoofers.
Normally, the main speaker will reproduce the entire signal, but when a subwoofer is used, the very lowest frequencies are filtered out, on the assumption that the subwoofer will fill the gap. This setting controls the frequency at which the filtering occurs.
If you are using a KEF subwoofer, just select the subwoofer model, and the high-pass and low-pass settings, determined by our engineering team specifically for your product pairing, are automatically applied. Feel free to use this as a starting point and experiment from there - you can always simply reset the setting on the app.
Because it can be complicated, crossover slope is often overlooked but this is where people run into the most trouble when integrating subs. If you have the option to use settings determined by the expert engineer who designed the product, you’re one step ahead of the game.
Sub Out Low-Pass Frequency
If you’re using a non-KEF subwoofer, it may be easier to disable the High-pass frequency option (that’s why we included it). You have the option here to set the crossover point from 40 Hz all the way to 250 Hz. This is where it can get tricky.
Sending bass information to a speaker that has been designed specifically for low frequencies allows the mid-range and high-frequency drivers to perform better throughout their operating ranges, but there is a point of diminishing returns. While it seems intuitive to send all the low frequency (LF) signals to the subwoofer, there’s a point where it becomes detrimental to the system’s overall performance.
Guitar, bass, violin, viola, cello, clarinet, alto sax, tenor sax, trumpet, French horn, snare drum, hand percussion, tympani, the male singing voice, and some female singing voices all perform under 250 Hz. Plus, every note on the piano below Middle C. Do you really want your subwoofer handling that much musical information without any help from the speakers that were designed to handle those frequencies with proper timbre and dispersion?
You’ll rarely need (even with KEF’s own subwoofers) to set the low pass filter as high as 250 Hz simply because you are taking away too much signal from speaker drivers that were easily designed to handle those frequencies. However, there are cases where that may be necessary – so, you guessed it – experiment!
For example, when pairing LS50 Wireless II with a KC62 subwoofer, our engineers set the high-pass crossover point to 70 Hz and the low-pass crossover setpoint to 45 Hz. This accounts for the slope and ensures that no frequency area becomes too prominent or too attenuated while simultaneously ensuring timbre is preserved.
The final key to great subwoofer integration is simple: You should sense the subwoofer but not necessarily hear it as a separate loudspeaker. If your eyes are continually drawn to the subwoofer, it’s too loud. Lower the volume a little at a time and you’ll soon find that magical spot of perfect subwoofer integration.
If you’re matching KEF products, subwoofer crossover integration is taken care of for you. If you’re matching your LS products to another manufacturer’s sub, then a little experimentation and common sense is all it takes to make your system come alive.
Musician, guitarist, and songwriter, Annie Wagstaff, recently told us how adding a KEF subwoofer to her LS50 Wireless II system has enhanced her listening experience – read her account here as she shares her thoughts.