Sub to complement KEF LS50s: SVS vs. Rythmik

Paradigm X12.   I’d bet you can get a dealer down to around $1,1050 if you’re nice.   It’s an incredibly musical sub and has probably the best room correction available on any sub.

See if you can borrow one from a local dealer.  I guarantee you will be blown away.

Thanks. I'll definitely have a look!

jdtalv,

     Through experience, I've discovered that one sub is able to provide good bass performance at a single designated listening seat if located properly utilizing the 'crawl' method but you may find it difficult, depending on the main speakers utilized, to configure it so that the bass seamlessly blends with the sound performance of your main speakers' reproducing the mid-bass or midrange on up to the treble. The bass may sound as if it's lagging behind and/or disconnected from your main speakers, especially on fast, smooth and detailed speakers such as electrostatic and planar-magnetic panels.  I know the KEF LS50s are very good bookshelf speakers but I'm not certain if they're fast, smooth and detailed enough to cause integrating seamlessly with a single sub an issue.
     I understand you'd prefer to buy a single top-notch sub and be done with it but, unfortunately, the truth is that attaining good in-room bass response is not that simple no matter the price or quality of the single sub.  The reason this is true really has more to do with the quantity of subs in a given room and how they're positioned, than the quality of the subs utilized. Better quality of subs never degrades from good bass performance, it's just not as important as most would assume.  I'll try to explain why.
      Two properly positioned and configured subs in a given room typically provides bass response at a designated listening seat that's approximately twice the quality level of utilizing a single sub. Two subs provide increased bass output capacity and impact as well as increased bass dynamics due to the sharing of total bass requirements between two subs operating well within their limits and stress free with ample power reserves for sudden bass output dynamic demands.
    Psychoacoustic principles also begin to be applied beginning with the use of two subs in any given room that results in the bass being perceived as smoother, more detailed and better integrated with the main speakers.  
    To understand how this psychoacoustic process works, it's important to understand how bass soundwaves behave in a room with a single sub. Soundwaves increase in length as the frequency decreases and deep bass tone soundwaves are very long. A full cycle soundwave of a 20 Hz deep bass tone is 56' long, a 30 Hz is 36', a 40 Hz is 28' and a 50 Hz is 23'.  For reference, a full cycle soundwave of a 20,000 Hz high treble tone is a fraction of an inch long.  This mainly explains why humans are easily able to determine the originating source location (localization) of the shorter soundwave and higher frequency tones above 100 Hz and are unable to do so on the longer soundwave and lower frequency tones below about 100 Hz.
     It's also important to know three facts:
1. Our brains can't even process the presence of a deep bass tone until the full cycle soundwave exists in the room and our ears have inputted this information into the brain.
2. Our brains require the input of at least three full cycle bass tone soundwaves before we're able to recognize a change in bass volume and pitch.
3. Our brains cannot localize deep bass tones (detect where the sounds are coming from) with frequencies below 100 Hz.
    With the deep bass soundwaves being longer than any room dimension in many individuals' rooms, this means the soundwave will leave the single sub and need to travel as far as it can in the room and then reflect off the first room boundary (floor, ceiling or wall) it meets then keep traveling in the reflected direction until it meets the next room boundary. This process continues until the soundwave runs out of energy and with each subsequent bass tone launched into the room by the single sub.
    These numerous bass soundwaves of various frequencies launched into the room by the single sub, and reflecting off room boundaries, inevitably run into each other at various angles causing what are called a Bass Room Mode at each specific room location at which they meet or collide. Depending on the specific angle at which the soundwaves meet, we perceive these bass room modes at specific spots in the room as either a bass overemphasis (bass peak), a bass attenuation (bass dip) or even a bass cancelation (bass null). The result is an overall perception of the bass from a single sub as uneven or 'lumpy'.
    However, when a second sub is properly deployed and positioned in the room, the very interesting and useful principles of psychoacoustics (how our brains process sound and our perceptions of it) begin to come into play, which results in a perception that the bass is smoother, more detailed, better integrated with the main speakers and more natural or realistic.
      Unexpectedly, this is accomplished through the second sub actually significantly increasing the number of bass room modes (bass peaks, dips and nulls) in the room. Our brains naturally and fortunately process the presence of multiple bass soundwaves below 100 Hz, by adding them together by frequency and averaging them out. This results in fewer bass modes being perceived in the room and a perception overall that the bass is smoother, more detailed, better blended with the main speakers and more natural.  
    Acoustical experts, such as Dr. Earl Geddes, Dr. Floyd Toole and others, have proven scientifically that in-room bass performance perception improves as more subs are added to virtually any given room, beginning with two subs and with improvements continuing up to the theoretical limits. Of course, there's a practical limit to the acceptable number of subs in a domestic room.
    I'm fairly certain the exact number of subs considered acceptable in a domestic room is higher for most men than most women but, interestingly, the scientists found significant bass performance perception gains were attained with each additional sub up to four but smaller more marginal gains were attained with each additional sub beyond four.

    Three properly positioned and configured subs in a given room typically provides bass response at a designated listening seat that's approaching the optimum quality level attainable at a single listening position. Three subs provide even further increased bass output capacity and impact as well as further increased bass dynamics due to the sharing of total bass requirements between three subs operating well within their limits and stress free with very large power reserves for sudden bass output dynamic demands.
     Psychoacoustic principles are more strongly applied with the use of three subs, as opposed to two subs, in any given room that results in the bass being perceived as even smoother, more detailed and better integrated with the main speakers.  
     My opinion is that the SVS SB-1000 (a small sealed sub with bass extension down to 24 Hz) and the PB-1000 (a slightly larger ported sub with bass extension down to 19 Hz) subs are ideal for utilizing in two and three sub bass systems because they're both very good quality, are relatively small, have all the necessary features/controls and are currently great bargains at about $500/each (slightly more for gloss black or white finishes). Here's a link to the SVS subs:

https://www.svsound.com/pages/compare-page

    The Salk Rhythmik, SVS SB--4000, a larger JL Audio or a Martin Logan sub all may be better subs with more features but, remember, the critical factor for in-room bass performance is the quantity of subs used in the room and the quality and features of each is much less important.  Besides, the reality is they're all high quality subs and room correction is not required for optimum performance on bass systems utilizing two or more subs.  
      However, if you prefer the best in-room bass performance,  the Audio Kinesis 4-sub Swarm distributed bass array (DBA) system is definitely the ultimate bass system that I'm aware of. This is a complete $2,800 kit that includes four 4 ohm unamplified subs that are each 1' x 1' x 28", weigh 44lbs and have a 10" aluminum long-throw driver and a 1,000 watt class AB amplifier/controller that powers all four subs and controls the volume, crossover frequency and phase of all as a group.  
      The use of a 4-sub DBA system will provide near state of the art bass performance not only at a single listening position but throughout the entire room. This is very useful if you have multiple seating positions in your room and prefer having very good audio at each position for both music and HT.
    Of course, only the designated listening position will be optimized for bass, midrange and treble response along with stereo imaging but very good full-range audio will still be provided at each seating position.
    They're also other benefits of the 4-sub Swarm DBA system.  Absolutely no bass room treatments are necessary. You'd just need to incorporate room treatments for the midrange and treble response on your main speakers (first reflection points on each side wall and possibly some treatment on the front and rear walls).  And these subs look very stylish in the room, kind of like hi-end wooden art gallery pedestals, since the 10" drivers face towards the nearest wall and have connections hidden on the bottom so all that's visible is three wood sides and the top in the wood of your choice.  My wife usually has a small vase with fresh flowers sitting on one of the two that are visible in my room.  They also make good end tables since they're an ideal height of 28 inches.  
    You also have the option of creating your own custom 4-sub DBA system, rather than using the complete Swarm system, by utilizing four SVS SB or PB-1000 subs for about $1,900 ( $950 discounted price for a each pair of SVS subs) or any four subs you'd like.  The only down side is that you'd need to configure the volume, crossover frequency and phase settings individually for each of any self-amplified subs used rather than once for all four subs as a group on the Swarm system. Here's a link to an Absolute Sound review of the A K Swarm system that is very accurate (I use this system in a 23'x16'x8' room with Magnepan main speakers and it works like a charm):

www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/

Best wishes,
     Tim

nice post Tim !