Just a quick follow-up note; I had made a few minor adjustments and the low end measured:
The woofers have an fs of 31Hz, and I’m generally finding woofers drop off fairly quickly starting around 5Hz above fs. I’m not a fan of sharp drop offs (seen starting around 36Hz), and I’ve gone in and set a high pass (1st order) at 20Hz to smooth this out somewhat (at least mid 30s area). Additionally I’ve added a broad notch at 60Hz down 1.2dB with a Q of 1.4 to manage the rise as seen in this measurement. Haven’t measured post these corrections- just using the old ears listening technique. Low end sounds (to me anyway) much more natural.
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I need to button-up the OB Wans
While I personally like walking by the OB speakers from the back (drivers, crossover parts, wires… what’s not to like?), the much better halve is reminded of (a speaker with) a hospital gown that’s a bit breezy from the rear – ha.
So, I’m thinking of using this ‘opportunity for a rebuild’ with a slight driver change. Possibly going with a slimmed down (depth wise) version of The Vandersteen’s Model 1C – 3A designs, but instead of going with a full sock (which would be the easiest way), I’m looking at wrapping grill cloth around the sides and back (keeping open with a back ~frame attached for support with the baffle) and keeping with removable grills for the front (I want to be able to see the drivers, at least the fronts, once in a while).
On the driver front, dual 12’s were a very tight fit (I was lucky with my latest build), so I’m thinking of replacing the top woofer with a 10in (keeping with all beyma drivers), which is supplemented 1.5way with the 12in drivers. Net Sd of the combined (10 + 12) will still be approx. +8% of a 15 inch woofer, and +40% over the dual 10s as used in the PureAudioProject Line15 and Line10. The beymas have similar fs (29 and 31Hz, 10s and 12s respectively), sight edge to power handling for the 12s, with the 10’s Xmax 6.5mm vs the 12’s at 8.0mm. I’m anticipating these to work out well as a combo in view of the 12s being a bit more sensitive than the 10s (93dB vs 92dB 1w/1m), with the .5 12s carrying more weight in the lowest octaves. I haven’t come close to pushing the dual 12s and expect the lower Sd of the combo not to be of any issue, but incorporating the 10s will give me a bit more build breathing room, and maybe a (ever so slightly) shorter speaker. Here is my current doodles:
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I just ordered the 10s from USSpeaker.com (where I’ve previously ordered all the beymas). Need to place an order through woodworkerssource.com for some baltic birch ply (great quality btw) and I’ve yet to decide on top cap and base / support wood selection- thinking natural hard maple, walnut, something with lots of grain / character.
Edit: wood ordered, in addition to ¾ and ½ baltic birch ply, I went with 5 ½ in width 3/4" Natural Hard Maple PRE-CUT Pack, 4 Boards (Choose Your Size) - Woodworkers Source
sawdust to follow…
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