Originally Posted by TRecord
Hello, got a few questions about a little project I'm working on. I'm basically making a small pair of full range, open baffle speakers. Their not intended to be a serious pair of speakers, just a bit of fun and to practice my woodworking. However I'd still like them to sound reasonable if possible.
That's not physically possible. Good sounding open baffle speakers take at least a couple drivers and baffle widths, equalization, and ample displacement (which you don't get from full-range drivers, especially small ones. 22cm and 5mm Xmax is a good start to reach a conventional sub-woofer).
I say that having heard a variety of open baffle setups (and built Linkwitz Orions) including a $40,000 pair of Feastrex field-coil drivers with and without woofers on Nelson Pass's big baffles (Nelson is a super cool guy and analog whiz but that's not enough to crutch a flawed concept into acceptable sound).
Your problem is that dipoles roll off at 6dB/octave with output matching a monopole at .17 * v / D with v the speed of sound (1130 feet/second) and D the path length difference between both sides of the driver to listener which is baffle width on a flat baffle. At .5 v/ D the reverse polarity rear wave (from the acoustically small drivers) is delayed a full 180 degrees producing a 6dB peak and beyond that you end up with a multi-lobed polar mess approaching the null at .75 v / D and beyond until driver directivity precludes an acoustic dipole response.
Baffle widths need to be small to avoid the polar response problem and you need multiple widths with multiple drivers and/or equalization to get the bass.
|So I've been looking at drivers (been looking at some peerless 3" models) but am unsure what would be a good choice. I'm after something small, they're only going to be small speakers and I can always use a sub with them if need be. So I'm looking for a reasonably cheap full range driver, around 3" would be ideal, which you could use with an open baffle setup.
That's not possible.
If you want to play with full-range drivers, the small Fostex drivers work great in tall thin back-loaded horn enclosures. Output levels are severely limited from the low displacement but they sound natural and have some bass.
If you want open baffles accept that it will take equalization and 2-3 drivers until you can use a sub-woofer for the bass.