Focal Sopra no. 2 - adding Subwoofer

In the first place.. How are you sure the frequencies you are looking to hear in the music are there in your source  ?

The trick to adding a sub woofer is for it to integrate into the soundstage such that you don’t really hear the sub woofer itself. Depending upon the amount of bass you want to add, you may be better off with two tHan one.   I think it essential to get one where you can control its level, frequency cut off and phasing, as adjusting all three of these variables are essential to good soundstage integration. 

 I have had a sub woofer in my system for a number of years now, but I am tired of having to adjust it and I am now auditioning true full range speakers that will eliminate  it’s need. 

Try a supercap first, you’ll be surprised what it will do to the bass.

Those are not the specifications of the nSub, including power, size and frequency response, which goes down to 20Hz. The Sopras are very large speakers that go very low. Maybe the bass isn’t actually in the mix, or the amplification is insufficient. If adding a sub it would make sense to get a Focal one, as it will be similarly voiced and should be easier to integrate. 

Yes, as HH says , I think there's an error with the n-Sub specs - I don't think it extends up to 20kHz, or anywhere near that figure.  It looks like you have copied the specs for a different speaker.

The n-Sub manual quotes specs as follows

I'd be wary of the benefits of a sub with those speakers.  I used to run a Rel Strata II sub when I had a pair of Focal 816SWE in my main system. When I upgraded those speakers to Focal Electra 1028be it was very obvious that the sub was redundant.  The Sopra 2s are even more capable at the bottom than the 1028s.  

One sure way of increasing the bass is to upgrade your 250DR to 300DR. I heard a 250.2 v 250DR v 300DR comparison on Sopra2s at my dealers.  The jump in scale in going from 250DR to 300DR was very, very noticeable. The already large Sopra 2s seemed to grow significantly, especially in the bass department.   

The Sopra No 2 have quite an extended bass response already (34Hz @ -3dB), so unless you have a very large room with a minimum length or width of at least 27m, you should first look at repositioning your speakers and dealing with the fundamental room resonances before trying to integrate a sub.

One tool that can be of considerable help with this is the room simulation dialogue of REW (Room Equalisation Wizard).

Also note that to correctly integrate a sub it should not be placed in the corner of the room and it should also be closer to the listening position than the main speakers (to account for the sub's group delay, so it should not be placed close to the main speakers).

I'd start with the free and fun repositioning of the loudspeakers. In my humble experience, even half a centimetre can make a significant difference on the bass response.

Walk thru the room while the music is playing, you'll notice differences on the bass response.

I would guess that the Focals put out plenty of bass, and it’s the room acoustics that are the issue rather than the electronics. No harm in trying a sub, but it can be difficult to integrate one well into the system. Speaker positioning, room layout and furnishings would be the first thing I’d look at, with or without a sub. 

[@mention:4804681822138532] can help maybe. I know he has 2 REL subs running with his new Dynaudio C2 and I believe his music taste are very similar to the OP. Matching sub to speaker brand is not needed. I would suggest REL and then the help of a dealer or knowledgeable friend to help integrate. 

Your needs may be very different to mine but I have Sopra 2s and have never found anything lacking in the bass department which is nicely balanced and isn’t overblown. I used to have  one of the bigger B&W subs with a previous system stem but could never get the balance right. I sold this and a previous REL and now have more floor space to boot.

MDS posted.

One sure way of increasing the bass is to upgrade your 250DR to 300DR.

Very much agreed changed my 250dr to a 300dr and the increase in bass plus the added  grip and control was excellent it was if you had bigger speakers.

spurrier sucks posted:

[@mention:4804681822138532] can help maybe. I know he has 2 REL subs running with his new Dynaudio C2 and I believe his music taste are very similar to the OP. Matching sub to speaker brand is not needed. I would suggest REL and then the help of a dealer or knowledgeable friend to help integrate. 

Right, like the OP, I listen to jazz and classical, and same system (282/HCDR/250DR). I am running two REL R-328 subs. Initially with Dynaudio Contour S3.4, and as of early this week with a pair of Dynaudio Confidfence C2 Platinum. Even though the C2 are -3db at 28Hz (Contours were -3db at 35Hz), the subs take it further, and it makes a difference. When I first brought a sub home to demo I played the Bach Solo Sonatas and Partitas for Violin for my wife. Once she settled into enjoying the music I turned the sub off. It surprised her: she didn't even think the sub was on for one, and asked what happened. She said the presence (imaging/staging) dropped away and the violin lost some of its woody timbre. That's how I got permission to buy the sub.

I have since added a second sub, which makes it even betetr. It really helps contribute to soundstage and midrange texture. It's not just about bass extension per say. RELs work especially well since they are designed to integrate with two-channel audio and have high-level inputs (no need for a LFE output from preamp), and provide for separate xover, level and phase adjustment. Once setup properly, one can forget them.

Setup, especially with two subs has to be done right. This is critical and benefits from expert help (i.e. dealer). If it's wrong it will sound boomy and draw attention to itself. When setup correctly, they disppaear into the room and you won't notice they are there. Well, put on some Strauss at concert volume and watch the bass driver excursion. LOL

I'm serious about the supercap but looking at your system it seems a little undernourished in the source department with a bare NDX and a Magik LP12. Is Kuala Lumpur somewhere demos can be arranged? In shop would do to start with, with similar kit to yours, try a 555ps (or even an XPS if the 555 is too rich) on the NDX or a higher spec LP12 if that's your prime source and a supercap on the 282 against adding a sub. If the dealer knows what he's doing I think you'll be surprised.

I had a demo a few years ago of a CDX2 with XPSDR, 555ps and a 282 with HC,HCDR,SCDR all into 250-2 and Kudos C2s in a dealership. Each step resolved more bass but it was muddy sounding, until we put the supercap on the 282 when it did things I thought would need a power amp and possibly speaker upgrade to achieve. If I'd had C2s at home I'd have done the SC first but I had Thiels that had no trouble with bass clarity so I bought the 555ps first as it got so much out of the CDX2 and the supercap DR a  year or so later (I did get to check them at home too before buying).

I had smaller stand mounted speakers and a sub for quite a few years and it is extremely hard to get them playing in unison and when I eventually did if was by accident and using the same brand as the speakers. 

It was not until I eventually got big deep floor standing speakers that I got the sound I wanted. They do stand out and they do dominate the room a bit but they sound so good that we are prepared to put up with the physical size.