In Reply to: Ideal Parameters for OB Woofer posted by Joseph Cohen on February 3, 2007 at 12:28:05:
The above is the 3rd version of the bass portion of my OB, LA, DIY speakers.The 1st used 4 of the 6-1/2" drivers while the 2nd used one of the Sonic Craft SCC300 bass drivers.
All of these were/are driven by a channel of an Outlaw 770 (200-Watts-into-8-times-7) poweramp driven by a Dahlquist DQLP-1 active-low-pass filter. Its bottom-octave-boost control was always flat with all 3 of these systems. (Raising that boost simply made the room nodes MUCH more audible.) I was advised that the quartet of 6-1/2-ers wouldn't reproduce good bottom-octave bass, but I had to try it myself. Jeff Glowacki of Sonic Craft was correct--the bottom 2 octaves of bass sounded OK but not great. Version 2 sounded MUCH more authoritative in the bottom octave than the quartet, but the sensitivity was low enough that I had to run the LP-1s level controls full up to try to match the output of the 97dB-sensitive main system. That sensitivity problem was solved by adding the 2nd bass driver in parallel, and the bass system's output increased exactly the 6dB it theoretically should have.
I was VERY pleased with the sound of this system including the bass--it was tuneful, extended, dynamic, tight, etc..
You may have noticed my use of the past tense. I still have this LA system, but it's now driven thru a dbx DriveRack PA digital Speaker-Management System, is triamped, and has NO passive parts in the speaker system. It now sounds even better, even with the tweeters driven temporarily by a 20-year-old Hafler 60WPC sand amp.
The wings are 30" (outside) and 25" (inside) deep at their bottoms, and when I build the next version of this dipole system, the wings will be shallower, maybe 24 and 20 inches deep. The front plate will have fairly narrow...maybe 8"...curving-back wings on it, and I'll use more of the the SMS's equalization capability to recover ('overpower'?) the lower-midrange and bass energy lost to wrap-around cancellation.
Open-baffle bass? I love it.
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Tin-eared audiofool and obsessed landscape fotografer.
http://community.webshots.com/user/jeffreybehr
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Follow Ups
- Joseph, I didn't read all these notes, but I thought I'd offer my experiences with OB bass. - jeffreybehr 21:53:27 02/04/07 (2)
- Re: Joseph, I didn't read all these notes, but I thought I'd offer my experiences with OB bass. - Joseph Cohen 23:40:55 02/04/07 (1)
- Actually the ONE 12 was superior to the four 6-1/2s; it just didn't have the sensitivity I needed. - jeffreybehr 10:01:46 02/05/07 (0)