2 way subwoofer ????

[muddasirwaheedmalik]

yes. after weeks of listening to (mostly sealed) subwoofers diy with the following drivers, wilson audio watch dog, pradigm servo, focal 13 W7 and B&W asw 855 i found that subwoofers cannot sound equally good for full 2 octaves from 20 to 80 HZ. yes, instead of equalizing tweaks, room compensation driver placement its much easier (but more expensive) to go multiple size subwoofers.

For instance i used 15 inches ASW855 and paraddigm with Fb of 28 Hz low passed at 40 Hz , there is lowest rol off in sealed design so two subs did a pretty good job in provivding the air to the bass.

Now the main speakers are run at full and the 12 inch wilson audio and 13W7 were crossed over at 80-100 Hz with a HPF of 50 HZ, the 50-100z regions can be easily adjusted in gain to match the punch between the 15 inch subwoofer and the mains.

I tried in many different configurations running each subwoofer full range from 20-100 but believe me the split subwoofer combintation works wonderful particulary i used the D class 1000 watt amp to drive the 15 inch below 40 hz and class A krell fpb 600 to drive the punch section from 100-40 hz , even a vintage 200 watt sony monoblock class A/B worked very good, i think i increased both the power requirement efficiency and the driver output efficiency.

The large woofer 15 inch or higher when asked to provided 20hz with 80 hz would give intermodulation distortion which i have experienced to be more noticeable than harmonic distortion at lower levels at higher levels even Harmonic distortion was greatly reduced by segmenting the frequency spectrum in which the subwoofer was required to operate. similaly the tighter bass in 50-100hz region was better controlled by filtering the lower frequencies limiting the excusion and driving the woofer ( i would like to call mid-bass driver) much much cleaner with lesser power requirement , better amplifier control and greater linearlity.

Most importantly the bass adjustment of each section with amplifier gain was much easier rather than banging your head with a single subwoofer.

However i found that very steep cross overs over 12db/octave makes life more tricky, filters with 12 db/octave mix very easily as a result the mid-bass driver still produced some output at 20 hz although crossed over at 50 hz that helped it to integrate with the sub-woofer.

I intend to go 18 inch with one 12 inch ?????? I saw it with velodyne 1812 and i think its practical..... views/comments are highly welcome.

[qguy]

Interesting...have you tried experimenting with identical subwoofers but with different frequency ranges ?

[Radugazon]

The 2 ways sub can seem overkill, but it's also my solution.
4 x 15" in IB, 2 x 15" in slighty cardioid. The IB drivers are representative of the "sub" school : heavy mms, long Xmax, low efficiency. The IB load allows them to go very low. Their partners are just the opposite.

When wired in parallel with a stepped low pass, and some EQ, their differences of bandwidth and efficiency result in an acceptable 2 ways combination, without passive correction.
Time alignment is not a problem and the little woofers can be moved in the room for founding the best match.