Tight bass sub recommendations

The best yet, and that's saying something considering how high he's raised the bar-

Off and on over the course of a decade or so I tried building a sub that was "fast" enough to mate well with Maggies and Quads, on the theory that there might be a market for such. I built sealed boxes, low-tuned vented boxes, transmission lines (many different geometries), equalized dipoles, aperiodics, isobarics, and pretty much anything that seemed promising except for a full-sized horn. Some were better than others, but none passed the test.

The one day a really smart guy, Dr. Earl Geddes, taught me that the problem is room interaction, and regardless of how "tight" and "fast" a sub is, the room will impose large peaks and dips that will dominate its response. It is the peaks that are especially detrimental, in that they decay slower than the rest of the spectrum. His suggestion was to use four small subs asymmetrically distributed, such that each produces a different room-interaction peak-and-dip pattern, and the sum of the four dissimilar peak-and-dip patterns would be much smoother (and therefore much "faster") than any one alone.

This made sense to me. I was aware of an AES paper that showed a dipole has significantly smoother in-room bass than a monopole, and a dipole is two monopoles back-to-back with the polarity of one reversed, plus a path-length-induced time delay between them.

The general principle I learned from Earl is, the more intelligently-distributed bass sources within a room, the smoother the in-room bass. Two subs are potentially twice as smooth as one, and four subs are potentially twice as smooth as two. A dipolehas roughly twice as smooth in-room as a monopole in the bass region, so four intelligently-distributed monopole subs are theoretically comparable to two dipoles.

If you do a casual survey of relevant posts by Maggie and Quad owners, I think this is what you will find: Those who have tried a single sub usually go back to using no sub, and those who have tried two subs usually keep them in the system. I think this is because two subs exhibit less in-room smoothness discrepancy relative to a pair of dipole mains than does a single sub. So don’t fall into the trap of thinking "I’ll try one sub and if it’s an improvement then I’ll add another." One sub probably won’t be a worthwhile net improvement.

So to get back to your question, I believe two intelligently-positioned subs would be smoother (and therefore potentially "tighter") in-room than just one. Some EQ or other adjustability might be called for, because the amount of boundary reinforcement varies significantly from one room to another. If the two subs have continuously-variable phase controls, that might be sufficient adjustability: Set their phases 90 degrees apart to begin with, and adjust their relative phases from there (along with your adjustments of level and frequency).

I don’t mean to dismiss the qualitative differences between different subwoofer models, but I think the room-interaction advantage of two small subs intelligently distributed would probably outweigh the benefits that the single larger (more expensive) sub has to offer.

Duke

distributed multi-sub advocate

I tried a lot of these same things over the years, only instead of persevering l eventually just kind of threw up my hands in exasperation. Before that though I did build a transmission line, tried different subs, in all kinds of locations, and rooms, and it was a..... Total waste of time.

Well not quite. I did learn one thing. I learned you CANNOT achieve great bass with just one, or even two subs. Can. Not.

Sorry, Vandersteeners. Tough luck RELics. Its not you. Its physics.

But the one thing I did not do, the one thing I never saw or even heard of anyone doing until recently, was try a whole bunch (four) of small (10" is plenty) subs located around the room. Asymmetrically! And even sometimes out of phase!

This idea is so out of the box original and totally different than the reigning paradigm it deserves a Monty Python "and now for something completely different" introduction.

Although actually it feels more like something out of the Twilight Zone: At the signpost up ahead, people pretending nothing just happened.

When it did.

Puzzling strange. But, oh well. Thanks, Duke. I get it. UPS is on track to deliver four drivers, four cabinets, and two amps Monday. Got a few weeks of work ahead of me but then I should finally be able to get me some genuine audiophile quality bass in my room.

We now return you to your regularly scheduled comments.

That's the beauty of the Swarm approach. Because room reinforcement characteristics are so dominant, which sub matters much less than their number, location, and phase. And my understanding is, pretty much in that order. In other words four of just about anything beats one of just about anything. Especially if the four are optimally located, powered and phased. Might be a bit of an exaggeration or over generalization but this crowd being such a hard sell its warranted.

My set will use the same four 10" drivers, but in two different enclosures- two sealed and two ported. Plugging a port converts a cab into a sealed enclosure, making for three optional configurations. Together with placement and phase that is a huge amount of tuning flexibility and control!

The vast majority still do not appreciate what a game-changer this is. Which is good- I have a Talon Roc sub to sell! Depending on what that goes for this may turn out to be one of the most cost-effective upgrades ever!

@millercarbon, one thing to be aware of is that there may be more to the difference between a given company’s sealed and ported subs than the sealed or ported enclosure itself. Rythmik Audio offers subs with either a 15" or 18" woofer in both a sealed and ported enclosure, and using the provided foam plugs to block the ports in the ported model does NOT, according to Rythmik design engineer/owner Brian Ding, make them identical (for reasons explained by Ding in the technical pages of the company’s website). Interestingly, his subs using 8" or 12" woofers are offered as sealed designs only, not ported.

Highly technical details on all aspects of sub design are provided on the Rythmik Audio website. Well worth reading, even if you elect to get a sub or four from a different company. Speaking of four subs (a real good idea), as Duke said a swarm can be created from any group of subs, four identical ones perhaps easiest to optimize in a room (for reasons, again, explained by Ding). Another subject covered by Ding is that of mixing sealed and ported subs in a room. Though he recommends not doing it (again explaining why), for anyone insisting on doing so he provides the information necessary to do it correctly. The plate amps on the Rythmik subs include controls to aid in that endeavor, including continuously-variable phase and 3-position damping.

Right. I'm dealing with 4 identical drivers. Two will go in sealed cabs, two in ported. The two ported are larger, because porting calls for more volume.

The point of plugging a port is not to make the ported speaker identical to the sealed one, but merely to alter its output curve. Porting results in a curve that extends flat response a little lower than sealed, but at the cost of output that drops very steeply once it does begin to drop. Sealed begins to roll off quite a bit higher in frequency but at a much lower rate. 

Plugging a port won't make the ported speaker identical to the sealed one. It will however make it identical to a sealed enclosure of the same volume. That's the key. There's theory, and then there's practice. Or as a great philosopher once said, "Everybody has a plan until they get punched in the 

In practice what happens is plugging a port will cause that speakers output to begin to fall off at a higher frequency. So you got a little too much mid-bass, you plug one port. Still too much plug another.

Also keep in mind this is just one of several ways of getting beautiful flat low bass when using the multiple distributed or Swarm subwoofer system. 1. The location of each of the four subs. 2. Ported or Sealed or plugged port. 3. Phase (one or more can be wired out of phase). 4. Phase Quadrature (Continuously variable, per pair). 5. EQ.

The ground work has been laid. Now comes the work of getting it done.