Top notch speakers with their own sub

Can the MTS be surpassed, even today? Its technology is far from outdated, its form factor is supreme (it takes up less horizontal space than a monitor) it is relatively efficient (allowing wide latitude in choice of amps) and its high powered, RABOS system can eliminate the primary bass resonance and integrate into your room better than all but the most expensive subwoofers (and without digital eq!) Unless the rest of your system is beyond belief, you might be better served improving other components.

Thanks for the kind words, Jax2.

The distributed multisub concept is something I learned from Earl Geddes. Here's a brief synopsis in his words:

"The modal response of rooms at low frequencies causes large peaks and dips in the overall response of a system...

"By using multiple subs distributed around the room, low frequency response can be smoothed out. Placing multiple subs in multiple locations, each sub will excite the room’s modes in a different way. While the response of each would still have the anomalies suggested above, the total combined response is much smoother than any of the individual responses. In essence, they balance each other out, resulting in a much smoother overall response."

Todd Welti of Harmon International has published multiple technical papers on the subject, as well as a non-technical paper which is posted on Harmon's website. Welti did not investigate asymmetrical sub placement, but this paper is still excellent information for anyone interested in a high quality subwoofer system:

http://www.harman.com/wp/pdf/multsubs.pdf

There are of course other issues, but a configuration that is conducive to relatively smooth in-room response is a good starting point.

One primary requirement for a distributed multisub system is a steep-slope lowpass filter (at least for those subs which are positioned away from the main speakers) so that you don't have subs reproducing lower midrange energy loud enough to betray their locations.

Duke
dealer/manufacturer

Spatine,

In theory, one great advantage of subs is that they can be placed where they work best (against the walls) - which is almost always far from where main speakers work best (away from the walls). You lose this option when the subs and mains share a cabinet.

When bass is generated out away from the walls in a room, the omnidirectional, long wavelength signals (i.e. bass) will reflect back off the walls and cause cancellation (nulls, or dips in response) at some particular frequencies and reinforcement (peaks) at others. Near wall placement reduces this bass effect because the strongest reflected signal is virtually coincident with the original signal. There is nearly uniform reinforcement evenly across the sub's entire output, and you can adjust (lower, relative to free space placement) the output level of the sub accordingly. To (virtually) eliminate the remaining peaks and nulls, you can EQ, or try Duke's "distributed" system which provides flexibility in using one (or more) sub's peaks to offset the other subs' dips.

BTW, the other approach is to find mains that are designed to work up against (or inside) a wall. Shadorne's soffetted system is one approach, Roy Allison's designs have offered a variation on the theme for a long time.

The Deqx idea I mentioned in my previous post is simply a "brute force" EQ solution. It allows the peaks and nulls to develop and beats them into submission with EQ. Audyssey and Velodyne (among others) also make EQ products for this purpose.

BTW, I can't localize the (carefully integrated) subs in my EQ'd system, even though they're far from the main speakers. Of course, YMMV.

Good Luck

Marty

I don’t know any of the mentioned brands of speakers in this topic, except for Wilson Audio. Venturing beyond the big brands does have the typical advantages and disadvantages we all know about. To do proper homework I really should look at the reverse role and take on what Lloydc said, that is if anybody wants to join the discussion and throw a monkey wrench. Is Prelude MTS really that outdated? Frankly speaking, edging out the well respected Watt/Puppy 8, which sure is current in technological development, is no easy task. Yet in my opinion the Prelude MTS has more details, fuller body, and less harsh a presentation. Granted that in the grand scale, mine is closer to the Watt/Puppy than the Maxx. An upgrade for my speakers without venturing out into the unknown (brands and sub equalization technology) would be getting the Wilson Maxx, or say the Gershman Black Swan. These are wonderful speakers from high to the very low frequency; however they are out of my price range.

They don't exist apart from speakers with dipole bass where you won't get enough output to cover the last octave for things like home theater and organ music (symphonic works at subjectively realistic levels or 90dBC rock/techno are fine with Linkwitz Orions in reasonable sized rooms like 2500 cubic feet or 13x19x8 but open on most of one wall to the entire 600 square foot floor).

With monopole woofers placement for mid+high frequencies is never going to be good for low (below the Schroeder frequency where the resonances no longer overlap thus imposing significant peaks and nulls on the bass response) frequencies because good low frequency placements are not symmetric.

With dipoles there's little (-20dB from the on-axis sound in practical examples) output towards the ceiling and along the dipole nulls 90 degrees off-axis horizontally. The speakers put audibly and measurably less energy into the room's height and width modes. You also get multiple bass sources stimulating the room length-wise with different phase although integrated dipole bass isn't going to be in an ideal location for this.

Linkwitz Orions, some of the Emerald Physics speakers, and the Audio Artistry line which are still made to order have dipole bass.

The better solution is probably designed to integrate with separate bass systems that are placed separately. Audio Kinesis, Lyngdorf, and Gedlee do that. NHT's Xd system did (there may be 10 pairs left).

Earl Geddes is applying custom transfer functions to each of the multiple sub-woofers which should work better than sending them the same signal. Duke could comment on what he's doing.