What are the best subwoofers to use with Magnepan 20.1s?


Hello all.  Which subwoofers would give the smoothest response/integration with Magnepan 20.1 speakers?  The rest of the system is Audio research Ref 3 preamp, Pass labs 600.5 amps, VPI ref scoutmaster turntable, Pass Labs XP 25 phonostage, UHA Tape Deck.  Thank you in advance for the help.
powerdoctor
Subwoofers DO make a positive difference with Maggies!  I know, I use two Rel G2's with my 20.7's.  The primary purpose for using subs with Maggies is not for the reason you might be thinking; more, deeper bass.  My Maggies go down to approx 27 hz in my 17.5 x 26 room which is Plenty Low for most music.  

What I have found is that adding the Rels makes the entire soundfield bigger, more dense, more full, adding to the PRAT, and actually Improving the level of Detail that I hear in all my music.  Yeah I know, you've heard that last one before, but it's True! Once the Rel's settled-in I began to hear intricate details and subtle cues in the music that I had not previously noticed.  

I don't know or understand the physics, but adding the two Rel's took my rig to the next level!  I seldom run the Rels above 28hz or 30hz and always at a very low volume level (typically less than 10).  It WORKS!

I prefer the Rels over Magnepans own supplemental woofers beacuse they do not add an additional Load to your amps; the Rels have a very high impedance so they dont add a burden to your main amps (which are already working overtime to drive the Maggies).  

The Rels make an Excellent speaker, the Maggie, an even better one!




Great description, Stickman. I believe REL invented subwoofer integration by hooking up at the speaker output.  

James Kates published a paper in the Journal of the Audio Engineering Society years ago that showed dipoles to have smoother in-room bass than monopoles.   Since getting smooth in-room bass at low frequencies is difficult at best, getting in-room bass from a subwoofer system that can subjectively keep up with dipole mains is even more of a challenge. 

Note that smooth bass = fast bass, because the in-room peaks correspond with longer decay times.  The good news is that when we have smoothed the frequency response we have fixed the time domain response because they are the same problem.

Dipole subwoofers seem like the obvious solution, but dipoles have a subjective lack of impact down low.  They don't give you that chest-compression WHACK! that a good monopole sub does.

One way to have both smooth bass and impact at the same time is to use a distributed multi-sub system.  Four subwoofers intelligently distributed around the room will be inherently far smoother than a single unequalized sub, and that smoothness will hold up pretty much throughout the room, which is not the case with a single or even a pair of equalized subs.  Remember smooth bass = fast bass.  And those four subs can be fairly small because, well, there's four of them. 

The Absolute Sound awarded a 2015 Product of the Year award to a four-piece multisub subwoofer system, so apparently the concept works well.   You can of course cook up your own version with Rhythmics or Vandersteens or RELs or JLs or whatever.  

Duke

dealer/manufacturer/multisub advocate


Two points:

- The Rythmik sub plate amp allows for high-level hook-up to binding posts (on the main speaker’s power amp), like Rel’s.

- OB/Dipole subs (such as the GR Research/Rythmik), their figure-of-8 radiation pattern creating a null to each side of the sub, do not excite the sidewall-to-sidewall resonance mode that Monopoles do, therefore creating less of the "room boom" often associated with and attributed to subs.

There is, unfortunately, a price to be paid for those otherwise-advantageous nulls: a corresponding bass cancellation that increases with descending frequency---a 6dB/octave, 1st order acoustic roll-off. Rythmik designer Brian Ding compensates for that roll-off by installing a complimentary 6dB/octave bass boosting "shelf" into the plate amp which comes with the OB/Dipole Sub kit, which counter-acts the roll-off, resulting in bass response claimed to be flat into the teens. Clever fellow.

When using a Magneplanar Tympani as bass augmentation, the panel can be butted right up against a side wall, with a significant resultant benefit: A prevention of the normal dipole cancellation, as the front and back opposite-polarity waves can’t meet and cancel each other, the path obstructed by the wall. That results in the absence of the 1st order, 6dB/octave roll-off inherent in a dipole speaker. Hence, no dipole bass roll-off (at least not from that end of the panel). Free extra output to a lower frequency, with no extra cost, or penalty!

20.1's would get better amps not subs.  I would probably be happy with the pass labs, but you might want to check into something like a boulder.