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Subwoofers and LS3/5As

Discussion in 'audio' started by foxwelljsly, Feb 14, 2022.

  1. foxwelljsly

    foxwelljsly Hawkwind and Fire

    Am now thoroughly enjoying my 11 ohm LS3/5As.

    Has anyone had any joy with integrating a sub with them?

    Mine are 2m apart in free space and I was thinking of using a single small sub in between them to add a little bottom.
    Tarzan likes this.
  2. Yivez

    Yivez Active Member

    foxwelljsly and narabdela like this.
  3. john-boy

    john-boy Active Member

    Rel would be a good starting place. Maybe a local dealer could let you demo at home.
    KevinCorr likes this.
  4. IGGI

    IGGI Member

    I like to use a sub to help out the bottom end of a smaller stand mount monitor. Currently use Chartwell ls3/5 with a B&K sub. I cannot recommend highly enough this company from Essex. They previously supplied subs to REL but now sell direct. I go for sealed box, set the crossover to between 80 to 110 on the crossover and then dial in on the volume the amount of assistance you want. Always trying not to upset the character of sound of the speaker itself. Downward firing or direct doesn't seem to make a whole lot of difference. Hope this helps.
    foxwelljsly likes this.
  5. S-Man

    S-Man Kinkless Tetrode Admirer

    I would also recommend trying the KEF KC62. KEF don't seem to emphasise its main advantage; low group delay. This means that it doesn't mess up the time coherence that small sealed boxes like the LS3/5A provide. Done right, the bass should be more extended, tighter and more tuneful. However the other big win is to be found by rolling off the bass to the LS3/5A, which gives a significant increase in ease and midrange clarity and dynamics by reducing excursion and hence distortion in the bass/mid unit.

    I actually prefer JR149s in this situation, but haven't heard the Falcon LS3/5As.

    I have been using the analog prototype/precursor to the KC62 for about 10 years. I use stereo subs but I have heard a solo KC62 with JR149s and it was excellent.
  6. Tony L

    Tony L Administrator

    A sub, no matter how good, would just wreck what I like about the LS3/5A. They are an astonishingly good and coherent little nearfield speaker. No sub is ever going to integrate in the nearfield. Just not possible. For mid/far-field listening I’d buy a larger speaker of similar heritage (e.g. any of the Spendor, Graham, Stirling etc BC1 equivalents). I’ve certainly never liked the AB1s at all, and whenever I’ve heard mono subs in nearfield systems it has taken me less than a couple of seconds to spot their detrimental effect to soundstage, imaging, coherence etc. LS3/5As are special things, but only at being LS3/5As. Try to get them to do anything else and they won’t IME.
    Rockmeister, Frizzy, PeteVid and 7 others like this.
  7. mark121211

    mark121211 pfm Member

    Totally agree with Tony's post.
    For some time I ran my LS35As as a nearfiled monitor with a REL Strata 3 Sub. I spent countless hours tweeking the sub position, tried stereo subs (Strata + REL Storm whcih was not ideal), changing the settings only to relaise that in my room they were better without. I never managed to get the subs to seamlessly integrate on all recordings.
    ArtK, EPear, Jodet and 1 other person like this.
  8. Darren L

    Darren L pfm Member

    I haven't been using a sub for that long, just the past couple of years, no detrimental effect to the soundstage, imaging, coherence, etc, in fact I would say all the the above has been improved, that's the bit I don't really understand, so understandably the bass goes deeper, you can actually feel it in your chest but the midrange and treble from the main speakers is actually better, it's easy to A/B as you can just switch the sub on/off. My speakers are ported standmounts, maybe this makes a difference? The sub is not positioned in between the speakers it's actually slightly behind me to my left, you can't hear where the bass is coming from, I did have the sub positioned in the right hand corner in a previous room and then centrally placed in between the speakers, this was just to accommodate short wiring as I'm using monoblocks and short speaker cables.
    Now I'd like to hear two subs in my system.
    I think to get the most from a sub it takes careful set up but more so the "low pass" and gain than positioning.
    clownfish and Cato like this.
  9. Alastair

    Alastair pfm Member

    Might be worth trying to borrow one? Only potential issue is having enough time to assess / integrate. The latter being hard to do.

    Or you could go for an Arendal model, buy it but can return within 60 days for a full refund (you'll have to cover shipping back) if you don't like it.
  10. foxwelljsly

    foxwelljsly Hawkwind and Fire

    This is my suspicion and exactly what happened when I tried to integrate a sub with some P3 ESRs a while back - although in a far more challenging room. I am also aware that having abandoned the wife for 4 hours last night just to have a few beers in front of my LS3/5as as they played away, I am wary that any more tweaking may sour that simple pleasure - one I have not observed for a very long time.

    This intrigues me though. Am I right in understanding that the KC 62 can sit between the pre-amp and power amp and you can set the low rolloff frequency for the onward signal to the power amp? I can see how that would work.

    Is this precursor/prototype something I may find secondhand?

    edit: from reviewing the KC62 manual it appears that this is exactly how it works. I had a Linn Pre amp that used to do the same, but not really needed with Katans.
  11. Rug Doc

    Rug Doc pfm Member

    I disagree, having been through competition to integrate subwoofers in an even trickier situation and still being able to make them disappear - in car SQ competitions.. I don't know who else here has sat in a competition winning SQ car, but they sound incredible and the car simply disappears with the soundstage appearing on the bonnet.

    Subs add to the air and 'ambience' of the upper registers.. It's uncanny once you have heard it.. but being in a position where it can be switched in and out, and adding the subwoofer 'in' improves the soundstage focus and width is quite amazing.. To let you know the lengths we go to to get the sub to integrate well, I used a 10" Velodyne active subwoofer, Nelson Pass designed Class A amplification, a DAC using Burr Brown PCM63K's and analogue active x overs with 32 bands of EQ per channel.. so not mucking about!
    AndyCC72 likes this.
  12. foxwelljsly

    foxwelljsly Hawkwind and Fire

    I'm thinking some monoblocks and one of these fancy pants Kef subs might be a setup worth trying.
  13. S-Man

    S-Man Kinkless Tetrode Admirer

    No. There are only two pairs in existence. Mine and the ones belonging to the guy who invented the principle behind the KC62 driver control/correction. They also need an active crossover and a special bass ampifier with the correction circuit. The KC62 is the DSP version with everything nicely integrated and with the rather clever force cancelling drive unit.

    I have to admit that I was surprised how good the KC62 was with a pair of JR149s. I had previously thought that two subs with accurate time-alignment were critical to achieving excellent sound. That said, I do prefer the 2 X originals to 1 KC62, they seem to have a more extended and more natural bass.

    FWIW, things like AB1 are crap. Just don't bother.
  14. Gervais Cote

    Gervais Cote Predator

    I came to the same conclusion after many speakers swaps.
  15. RJohan

    RJohan pfm Member

    I spent a year integrating a sub (or two) with my Kef R100's. It's not easy and one need to measure, move speakers around, measure again, change settings in the EQ and crossover, listen, measure, etc, etc... I finally got the result I wanted and now can sit down and just enjoy the music. But it was hard and I wouldn't want to do it again. So, as TonyL wrote, you are probably better of with speakers that can do proper bass in the first place.

    I have a set of LS3/5a's in the collection, knew them well and can say that the procedure would have been the same as above!
  16. Tigerjones

    Tigerjones Bagpuss

    A year? That deserves a medal.
    RJohan likes this.
  17. RJohan

    RJohan pfm Member

    I'm a pensioner and didn't have that much else to do :);)
    Johnjo, lordmortlock, Rug Doc and 2 others like this.
  18. rag987

    rag987 pfm Member

    I don't have experience with LS3/5As, so not directly answering the question, however I am in the "separate subs add a lot" camp. I have also messed with separate stereo subs adjacent to the main speakers and (my current setup) pair of mono subs optimally placed for the room.

    In a small(ish) room, it is not just the ability to produce the low frequencies at a sensible volume, but also about the interaction of the low frequencies with the room and management of the room modes. I can get much better control of these factors if I position the subs independantly of the main speakers. But there is no free lunch, the complexity of getting this to work well is very high and you do need some measuring equipment to get it right. The subs need to have sufficient control over delay/phase and volume, and you need some way to set the cross-over point between mains and subs.
    RJohan likes this.
  19. ampedup

    ampedup Lost in audio

    The Kef KC-62 seems to carry a premium price for what it does. SVS, for example, has a similar model for half what the Kef goes for, and other makers do too. At the listening chair, I wonder if 'twice the price' will be audible.
    The ls3/5a is difficult to pair with a sub in the first place. I've tried passive and active subs and preferred the solo boxes myself. However, I do use a Loki equalizer to augment the lowest frequency band and it works very well. It increases bass palpability. Cheap too.
    RJohan likes this.
  20. Brian Ellis

    Brian Ellis pfm Member

    I would 100% try a subwoofer and invest a little time to get it set up appropriately. My new listening room is very small (7ft by 10ft), I replaced my large floor standers with a pair of PMC twentyfive.26 and wasn’t happy with the sound until I integrated a BK XXLS400. I never would have imagined this combo would work so well in such a small room but after some playing around with the set up it sounds great.

    My son popped around for a quick listen and was blown away and he spent years hearing my last system in a big room and loved it.

    My sub is connected via a pair of phono’s from a Chord TT2 and sits up close to the right hand wall as I face the main speakers. You can’t locate the sub when playing and if you close your eyes you would be certain there were just 2 speakers.

    Good luck and have fun.
    KevinCorr likes this.

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