Subwoofers for Magnepan 20.1s?

My guess is that further extention may not be what you're really after -
unless you're a pipe organ guy. If you're down 6db below 33 hz, that's gonna
be inaudible on most recordings. There's a coupla keys on the piano that
MIGHT be slightly diminished, but they're not struck often.

However, that "little dip" in the 50-60hz range is right at the
point where the impact of a kick drum is established. You can certainly place
subs or EQ subs independently of your mains to get more energy in this range
- but you'd need to actively cross from your Maggies at a frequency north of
there, maybe 65-90 hz. A Velodyne SMS-1 sub-controller or SVS
"Audyssey box" (plus an active crossover like the NHT x-2) will
allow for EQing the problem.

The JLs (12" or higher) definitely show more beep bass extention than
the MJs or (almost any of)the RELs on tests. They are also show
"tight/fast" respone (group delay), but not quite as well as MJ or
REL and they are expensive. I chose Rythmik Audio 12" subs which look
like REL/MJ in terms of group delay, but offer better extention.

These observations are based on test results at AVTalk.com (seems to be dark
now) and HTShack.com - not on listening experience, so take that FWIW.

Good Luck,

Marty

One word of caution re: subs w/extra large large drivers.

Just be sure they can be crossed HIGH enough in frequency to suit your needs. I know that people generally like to cross as low as possible, but if you eventually decide that you want to EQ problems in 50hz to 60hz region, you'll be crossing at 75, 80, or 90hz. I don't know the 31.5" driver in question, but I'd imagine that it's not designed for optimal performance that high up, since some manufacturers of 15" drivers caution potential buyers about this issue.

Just food for thought.

Marty

John,

Rythmik Audio does not recommend crossing their 15" model above 80hz. Meniscus Audio, a custom builder (that often -but not always - uses the Rythmik drivers) told me the same thing and added that they prefer to cross most 12" drivers at or below 100hz (even for a stereo pair). I gather that they feel these drivers behave optimally below these frequencies - not that they're incapable of providing linear response above that point. Maybe it's just an abundance of caution.

Marty

John,

The crossover point deteremining "locatability" was NOT the issue. The reason I added the note in my original post about "even in stereo" was because I asked that very question. Rather, I'm sure that you hit it with your descrition of driver type and suitability for use only in the low bass region.

That's why I advised any buyer to determine the suitability of any sub with an extra large driver for use at higher frequency. I didn't recommend avoiding large drivers in subs, just double checking for enough flexibility to deploy as desired. I sure wasn't aware, however, that a 31+" driver had such flexibility. Thanks for the info.

As to suitabilty of such a "doughnut" driver for music, I'm working on that right now. It sounds different from my previous (Velodyne 8" x 2) subs - that much is clear. So far, I'd probably have to disagree with you, but my experience to date is too limited to take a really informed position. When I've had some more time with it, I'll post further.

Marty

John,

One further thought:

A lot of folks are going to be limited by cabinet size at SOME point - probably well before they could consider a box housing a 31.5" low excursion driver. The ability to accomodate a huge driver with minimal excursion is a luxury unavailable to many (probably most) music lovers.

Your preference for trading off driver size for excursion may be 100% correct, but I suspect that most people are weighing 8" vs 10" vs 12" (maybe vs 15" drivers). Depending on any buyer's particular need for deep bass performance, their choices may therefore be limited to driver designs you'd prefer to avoid. This being the case, I'd still advise anyone to double check the recommended high frequency limitations of the driver (particularly if they're thinking 15") in their prospective subwoofer purchase, since most of the commercial subs out there seem to use such drivers.

Marty