FYI: REW measurements of dipole vs monopoles

[paulspencer]

I've recently started some experiments with REW and a multisub arrangement. I'm aiming to achieve a flat response in 4 listening positions. Out of curiosity I measured some dipoles to see how they compare. The common notion is that they are flatter in room than monopoles.

Chart 1
Magenta and blue show subs in the corners, black shows a dipole next to the right main speaker and orange shows the dipole moved back. As you can see, without EQ the dipole (H frame) clearly looks the best. It uses an AE AV12 with one VC driven and no filtering except the 30 Hz low cut filter on the amp. It doesn't look fantastic, but many of us aren't used to seeing in room bass response. It's probably a fair amount flatter than most are used to hearing. Most likely the dips aren't as bad as they look.

Chart 2
Orange shows a left corner sub (Rythmik) with a TL on the left side. Blue shows the H frame again on the right side next to the right main speaker. Green shows all of the above combined. The phase on the sub is wrong for this arrangement, hence the reduced output, but this is fixed in the black trace, which now shows the best result.

Don't trust the absolute levels as I had to turn the gain down on some of the combined measurements to avoid clipping.

It seems to me that the challenging area to get right is actually 60 - 200 Hz. If you look at the 2 corners in the first chart, it's possible to combine them and with a little eq of the midbass peak, get it flat within the subwoofer range (20 - 80 Hz). The dip of the blue trace (57 and 70) will be removed by the magenta trace (dips don't tend to subtract when below the level of the other sub).







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