High Efficiency Speaker Asylum

Posted by Tom Dawson (A) on April 17, 2003 at 20:42:07

In Reply to: Re: Dinsdale & W.W. slotted port posted by freddyi on April 17, 2003 at 19:32:16:

Hi, Freddy -

You're probably right & the ports are a bit on the small side as it is (about 30 in sq total). I'm crossing over around 600hz or a bit higher to a 2445J on an aluminum near-2380 equivalent horn sitting right on top of the top 2226J, where the combination of baffle step & tuned eq boosts the on axis response above about 250 hz where the bottom two 2226J's kick in.

I'd say, so far, compared to the 4648 I have with two 2226J's in it, the extra woofer definitely adds a noticeable amount of maximum output below 100hz, but the narrower cabinet probably keeps the increase in efficiency between 2-400hz down to about, I'm guessing, 0-1db over the 4648 in that range depending on where I xover the two bottom 2226's. The basement blaster has three 'rib' type braces of 3" on edge plywood rings, so the cabinet itself has substantially less vibration than the 4648, particularly on the front panel. This seems to affect the way the bass comes across a little - it's a bit punchier but less 'full' sounding comparatively with the basement blaster. I'm still evaluating the floor port location on the basement blaster. I've noticed that right next to the speaker the greater distance to the ports gives a somewhat thinner sound, being that the ports are the farthest from the ears, rather than being betweeen the drivers on the 4648. But it's quite possible that that location gives an advantage farther away from the speaker in terms of output - still checking to see if that's actually true. Also, I was thinking that with the ports farther from at least two of the woofers, the ultimate effective rolloff below the port tuning would effectively start at a lower frequency. Both cabinets are retuned to 32 hz and have the LC bass boost. The third woofer in the basement blaster really makes a difference in available undistorted output below 50hz here when it's cranked.

Best of luck -

Tom Dawson