[quote author=JohnF link=1132164275/0#6 date=1132969404]Regarding tunable HWKs- I've often thought of trying it, but with moveable driver baffles not changeable ports. I'd be very interested in the effect of changing the size of the center chamber that way. [/quote]
John,
About 2 months ago I built an 8" HWK and built a DB style moveable center chamber. I know I talked about it in another thread, but, I actually made the overall size 6" longer so I could tune (GOOF around with) it.
I ended up making the low chamber (top) only about 1 inch longer, since it tuned about right, but the tuning on the high chamber was way too high for my taste on my first attempt and 4 more inches was a welcome benefit. They were still tuned different enough to forget about the phase difference.
It would be fun to make the center chamber in 2 pieces that were both moveable and the box a bit larger to tune the whole thing lower and play around with the damping chamber also. All I need to do is remove the chamber and saw it in 2, but the baby HWK has been evicted from the bedroom system in favor of a very unusual WO, using 8 - 4" drivers that fits under the bed. There's just no way to stop this insanity.