Passive sub for Magnepan 3.6r?

Duke,

Thanks for the reply.
My comment re: a dipole = 2 monopoles was intended to illustrate my actual
experience measuring such designs in my room. I assume (as you allude to
in your post) that the problem with the analogy is that it's frequency
dependent. The bass region, where we're lurking, finds monopole speakers
delivering omnipolar response, so perhaps the analogy is least applicable
here.

As to dipoles being "easily matched" in the x-over region, I've had
the opposite experience. I get pretty smooth reponse from my Maggies down
to app 80hz (I use bass busters which help in the octave or so above this
frequency), but it gets pretty ragged below there. IME, the smoothest
"handoff" occurs when the subs and mains are precisely level
matched through a region that is both free of "humps/divots" and
appropriate in level for good overall octave to octave balance - no mean feat.
The Maggies have proved tougher than either omnis or monopoles for me. I
eventually got good results - with a fair bit of EQ - but it was WORK.

The point about local vs global EQ is simply that - if you look at the virtual
systems links - almost all of these set-ups limit the listening area sufficiently
to allow effective EQ while ignoring any "global" room issues.

BTW, I use 2 subs and this helps reduce the need for EQ. However, fine
tuning with EQ, particularly right around the x-over point, is still - IME -
extremely beneficial, particularly for dipoles.

These points are only based on my own (reasonably extensive) in-room
experience and measurements. It's always possible that my specific
experience is idiosynchratic.

Marty

Hi Marty,

Well I can't discount your experience, especially since you were taking actual measurements, nor can I explain it.

In an AES paper entitled "Dipole Loudspeaker Response in Listening Rooms", researcher James M. Kates compares the response of monopole and a dipole at various listening positions and toe-in angles, and he finds the dipole to be usually (but not always) smoother in the bass region.

In an unprinted supplement to his review of the dipole-bass Gradient Revolution, Robert E. Greene records its in-room frequency response, which he finds to be remarkably smooth in the bass region. You can see this supplement at his website:

http://www.regonaudio.com/Gradient%20Revolution%20Loudspeaker.html

Again, I cannot explain your experience. Perhaps the Maggies do not start out "flat" in the bass region; I recall seeing a Stereophile measurement that did not look flat, but it may have been their measurement technique.

Best wishes,

Duke

Duke,

I checked that link. If you can get that kind of in-room response (app +/- 4db down to 25hz!) without EQ, my hat's off to you. I've never gotten close in any of my rooms with monopoles, omnis, di-poles, or even bi-poles (Sunfire CRM) until I added EQ. Pretty impressive.

Marty

ML Depth with my 3.6 maggies has worked well for me.

http://www.integracoustics.com/MUG/MUG/pix/HTFer/

Well Marty, the resolution of Greene's posted measurement is pretty low, showing 1/3 octave bands in one dB averaged increments. So I doubt that the actual curve stayed within +/- 4 dB... but that's still impressive in-room performance (which isn't recognizable as such unless you're all-too-familiar with how truly horrible most in-room bass response really is!).