Subwoofer in stereo

There was a big discussion on the topic of Subwoofer integration in stereo systems among my friends

Some say it changed their system for the best some says it is a heresy in a decent stereo setup ( me included)

Do we need a subwoofer to dig deep in bass? Where no speaker can reach….

I like to hear your experience and opinions

I was in the camp that associated subs with people that went to “boom town”

I had a room issue where bass was “being sucked out” - music sounding thin, lifeless and unbalanced.

I tried a rel sub and it pretty much resolved most of the issues - tempted to try stereo subs as that’s what Rel recommend.

I am now probably a convert to subs but I guess it may depend on your room. Many users talk about filling in the final octave as the main speaker bass rolls off.


Well, I believe it really depends on the interaction of your speakers with your room and your preferences.

To start with the latter: we mainly listen to pop, electronic and jazz music, where a sub does add to the experience. Not only by adding a fundament to the sound, but also by making the overall sound more 3 dimensional. Even at low volumes. We don’t want to do without the sub anymore.

To the first point: in our room we have had four types of speakers of which some interacted more with the room below roughly 100 Hz compared to others. The ones that interacted more with the room - activating the room modes, in our room mainly around 30, 50 and 100 Hz - only worked well with DSP, with the sub taking over below 100 Hz. The active speakers we have now, interact less with the room, probably due to the different bass reflex port design. Now I can use the sub to add up to 100 Hz without problems and since I reduced the bass on the speakers by 4 dB it sounds even better.

Note: measuring our room with REW has given me good insights in how certain speakers interact with our room and it helped me to optimise the integration between sub and main speakers.

So yes, a sub does add to the overall sound quality for sure, in our case. And yes, it does need tweaking to get it right which depends on your room, system and preferences.


I have been using a Velodyne DD10+ sub for years…it is amazing…when set sensibly it in no way effects stereo…if anything everything appears enhanced. For music I have found just do thee minimum to augment say from 45 hz down… A plug for the Velodyne … the speed and power DD+ range give is epic… these are sealed active subs…I believe SVS are also excellent… I use an output from my 552 to drive the sub via mogami cable…it is excellent. If I had the room I would definitely buy an additional sub…which would allow even better room integration.

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Anyone who has heard a poorly integrated sub will almost certainly think it’s heresy as they will often be hearing it out of phase, often set too high, and then everything falls apart.
Get it right and it can sound magical, but this can take time and patience.

Another happy Velodyne sub owner here (DD12). My N-Sats just can’t shift the air that my taste in music and preferred volume requires - absolutely transformational.
Of course dialling in is crucial. The great thing about the Velodyne is the way you can control this. It has a remote with (just counted) 32 buttons - the number of parameters you can set is way more than just volume and crossover. Using the remote I can sit in my listening position and view the adustments on my tv screen. It makes it easy to get an almost flat response to around 20hz and then tweak by ear to your final taste. I found phase control as useful as volume and crossover etc. which surprised me - it’s more than just in phase or out of phase.

There are speakers that do the whole frequency range including the bottom octave, undiminished - but they tend to be expensive because of the difficulty in design and build in doing that, and consequential size.

As for a using subs with smaller speakers missing the bottom octave or two, I have no experience (other than home cinema usage with a far cheaper surround sound system that is not so good with music). I always felt it would be a second best, but I have nothing on which to base that. For hifi positioning must be equally as critical as main speakers, probably more so than speakers missing the bottom end, which I suspect many people don’t appreciate. The required bass performance of the sub surely is every bit as critical as bass end of a main speaker (‘speed’, absence of overhang, flat response, etc), which marks it out as far more demanding than typically necessary for a home cinema sub. Integration (crossover frequency, level, speaker position, phase). The Wilson Benesch Torus on paper and from reviews strikes me as one I’d be seriously wanting to consider if I were to ‘convert’ to smaller speakers +sub, though I’m not sure if their peak output is adequate unless in a small room - but then I can’t see any reason why I’d want to go small unless faced with a seriously downsized room.

There is a question as to whether a single sub or a pair are needed. In theory if the crossover frequency is low enough a single one will do, but unless the room is huge or very well treated in respect of those very low frequencies it might be much easier to balance the sound using a pair.

I can assure you…when set correctly with small speakers like the PMC20.21 … a well integrated sub is totally un-distinguishable you would swear the bass was coming from small speakers…and I am being super critical. If you over egg the volume of the sub for fun…you start to here it… I am sure the Wilson is good…my experience is only with Velodyne DD+ series…

When you look at the way the driver is made…you realise that a hi fi bass speaker is severely compromised…and does not stand a chance…the driver alone is massive…with 50mm travel…and a 75mm voice coil…and an accelorometer…for precise control.

The main issue is that the best bass in your room is not necessarily where your speakers will image and sound the best. By making the setup more flexible, assuming you have optimised everything else, i am quite confident that a well integrated subwoofer setup will be much superior to a 2-channel stereo system. Unfortunatly integrating a sub properly is not easy, as you are now the designer of the crossover for the low octaves.

I can understand that if not done properly you may think it is an heresy, as probably many others, as the system will sound worse with a sub which has not been properly integrated.

It also depends of the music you listen to. Wether you like church organ music or electronic music which digs deep into the 20hz territory or acoustic jazz or folk music where everything is above 45hz anyway should also be considered.

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I’ve been grappling with this too. I’m using SBLs, and though I know there is a debate about their bass anyway, they are designed for a solid wall/solid floor location which I can no longer provide. So, while the sound is very good still, I’m not hearing what the engineers intended. I’m already compromised. The heresy (of sorts) has been done to me - how do I fix it?

Highly respected members of this community have recommended speakers that I expect will solve the issue, but I do love the SBLs, and want to keep them. Do I treat the room? That could be difficult, inconclusive and could get me throttled by the Missus.

So, I’m inching towards the recommendations of the sub users on this forum. I’m still somewhat reticent because it’s an unknown quantity but in my case we are really just talking about supporting the very bottom end to a limited degree, the outlay is not huge and if I don’t like it, or can’t get it to work I could always use it with the TV or flip it on.

Having heard a few Focal/REL combos, I am a believer in what a well integrated sub can do. However, I have always been puzzled by the fact that with most hifi subwoofer setups there is no high-pass crossover applied to the main speakers. I used to enjoy massive car stereo systems, back when you could install them without a $1000 computer interface and engineering degree. I always employed high- and low-pass crossovers on main and sub speakers, respectively, so that the sub actually relieved the main speakers of the low bass frequencies. I felt it made the main speakers more efficient in the higher frequencies and gave me greater control and I could really get things dialed in.

I am thinking of adding an REL S/10 to my Focal Kantas, and you just wire it up off the speaker terminals, I believe. That makes sense to me, but I don’t understand the lack of a high-pass crossover. Isn’t that just doubling up the bass? How does that relieve the Kantas of anything? People always say that adding a well-integrated sub improves the sound of the main speakers, but without a high-pass crossover does anyone have thoughts as to why that might be? Is it just one of those audio voodoo things that our ears hear whether we can explain it or not?

On the face of it I agree that it seems logical to relieve the main speakers of the burden of low frequencies that are handled by a sub. In practice there are different design approaches adopted by different manufacturers, and I don’t think you can say that any particular design is right or wrong.
Rel insist that splitting the signal in this way it not the right thing to do with their subs. A few other manufacturers such as Dynaudio produce subs that take the pre out signal, put it through an internet crossover, and send the higher frequencies on to your main active speakers or power amp.
There’s also the JL Audio CR-1, which is a separate, highly configurable crossover designed to split the sub bass from the main signal, but it’s not cheap.