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Bass reinforcement for very large room

My main system resides in the great room of our open-concept house - essentially a 30x30 open area (entryway, family room, dining room, kitchen) with 15' ceilings.

My second system resides in the 11x15 master bedroom.

Recently I have become especially aware at how much better the much more modest system in the BR sounds - it is weighty and more authoritative. Why? Because no matter what sort of main speakers I use in the large room, it seems they cannot produce enough space for that very large space. In contrast, the BR speakers, with smaller drivers and lesser bass extension, pressurize the room and fill it with sound so easily.

The speakers (now) are Hyperion 938s. They are a quite-capable full-range speaker, solid to the low 30s or so. (The 'lack of weight' that plagues the great room is something that surely extents all the way up to the upper-bass, probably 125-150 Hz, so the speakers' extension is really not too vital. IOW, if they were flat to 20 Hz it wouldn't be much different.)

I am thinking subs are the only/best way to cure this. I could use some kind of EQ - but that would undoubtedly result in great driver excursion and an extreme load on my (modestly-powered) amplifiers. I think I need a lot more driver *area*. In other words, in this case there's no replacement for displacement. (And, by the way, I am no 'bass fiend'.)

I've had subs before. I don't like them because it seems they just never integrate *perfectly*. Especially if they must be relied on all the way up to 100 Hz or higher (which is something I've never even tried).

I don't really have any questions per se and am really just ruminating out loud, but if anyone has any thoughts to share, be my guest. (Moving might be my best bet.)
paulfolbrecht

Showing 2 responses by drew_eckhardt

drew_eckhardt
394 posts
 
>My main system resides in the great room of our open-concept house - essentially a 30x30 open area (entryway, family room, dining room, kitchen) with 15' ceilings.

Modal issues dominate the bass region for nearly all systems and with identical length+width which are an even multiple of height yours are going to be worse than most.

I doubt you'll be able to solve your bass problems without multiple sub-woofers (where placement will fill in some of the nulls and average out the peaks) and/or bass traps (which will reduce the size of peaks and nulls).

The Earl Geddes/Duke LeJune multi-sub reference given by Jdombrow is a fine starting point.
drew_eckhardt
394 posts
 
12-22-09: Kijanki writes
> Bipolar speakers don't make nodes in the room.

Bipolar speakers most definitely stimulate room modes - I measured over 10dB peak around 70Hz in one room with a pair of Definitive BP8s.

In the modal region conventional speakers are omnidirectional (a 100Hz wave is 11' long and wraps around any speaker you can fit in your living room like it wasn't there). Apart from the force cancellation you get which reduces structure borne vibrations having the drivers on opposite sides instead of one surface doesn't make a difference you can't get by moving a box with drivers on one side.

Dipoles with the front and back waves 180 degrees out of phase do interact differently, producing measurably weaker height and width modes although you need to equalize at 6dB/octave and use multiples to get sufficient head room (with 15" separating the drivers, at 40Hz it takes 4 drivers to play as loud as a single driver in a closed box).
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