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Critic's Corner Discuss a review. Provide constructive feedback. Talk to the industry. |
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Critic's Corner Discuss a review. Provide constructive feedback. Talk to the industry. |
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In Reply to: Okay, a serious, non-obtuse, Stereophile (the clue) review thread posted by rebbi on December 14, 2014 at 06:18:15:
I got a chuckle out of the review because it reminded me of my very first DIY 2-way bookshelf speakers I built some 25 years ago. I used good Vifa drivers, built some really solid cabinets sized according to the distributor's spec for the woofers, and built 4th-order electrical "textbook" crossovers from the equations in Vance Dickason's "Cookbook."
But because I didn't understand (or even know about) baffle diffraction step (that early edition of Dickason didn't explain it at all!), I didn't account for it in the crossover, and for a long time wondered why the speakers sounded so thin and anemic in the LF when mounted on stands out in the room, but sounded OK shoved right back against the wall. Then I discovered they sounded even fuller in the low end on an actual bookshelf, with books on both sides of them, effectively extending the "baffle" much wider.
By this time, I was subscribing to Speaker Builder, and received (like all the subscribers) a project plan from North Creek Audio for their Borealis kit. This contained some of the best information I had learned yet, including a detailed explanation of baffle step and the transition from 4 pi to 2 pi space in a free-air mounted speaker. He detailed the way his particular design compensated for it (a third-order lowpass filter with an oversized L1). So I undertook some more research on the phenomenon, and learned of several strategies for coping with it: 2.5 way, LR shelving filter upstream from the lowpass filter, or a large-value L1 with a modified Zobel to let the impedance rise a bit, shallow out the initial rolloff, and push the crossover point up to a useful frequency to meet the tweeter. Most of my subsequent projects have incorporated one of these approaches, because I prefer my speakers out in the room with lots of air around them, but I did custom-build a couple more non-BSC pairs over the years for friends who intended them for on-wall mounting. Looking at the current North Creek offerings, I see that even their "near-wall specific" designs incorporate a very small amount of BSC, to compensate off-axis LF losses inevitable when the baffle stands out from the wall by the short distance necessitated by the depth of the cabinet.
The Clue speakers in the review are obviously "near-wall specific," with no BSC whatsoever, and additionally real fussy about listener distance and horizontal listening axis. The on-axis raggedness through (and beyond) the crossover region looks like it MIGHT flatten out to correct summation at certain critical angles off-axis, but still seems mighty sloppy. OF COURSE they measured the way they did in JA's usual nearfield-in-free-air FR tests, though I'm as puzzled as Mr. Reichert about why they wouldn't sound right when he set them up "more or less" according to the manufacturer's instructions. This seems like a troublesome design, which may not be worth the trouble to a lot of listeners.
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Follow Ups
- Total lack of baffle step compensation in crossover - Brian H P 11:26:45 12/15/14 (1)
- RE: Total lack of baffle step compensation in crossover - zendada@w-link.net 12:56:19 12/20/14 (0)
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