Which box? FE207E in big room with 6 watts and Shadows

[OzMikeH]

I like to have a lot of volume sometimes, I also like quality, I have a big room. I have FE207E in Singulars at the moment with FT17H to fill out the top end. Running like this 6 watts isn't really enough for me (Trends TA10.1).

I want to active crossover (24dB) to a pair of Shadow SD12 to conserve the T-amp power for where it matters, above 150Hz and make life easier for the 207, hopefully it will sound cleaner. Shadow SD12 will have plate amps and appropriate Peerless XLS or XXLS drivers because it's too hard to get CSS drivers here.

Now if the FE207E isn't going to be producing the low bass it doesn't need a have a huge box. I have no idea what cabinet is better for 150Hz and up. In my case WAF of front loaded horns is not acceptable. I see three options.
1: Open baffle on top of the shadow.
2: Modify the shadow with more height and a 45 degree partition inside for a sealed chamber for the 207. Maybe a sloped upper front so it looks like the Dallas II on steroids.
3: As above bass reflex with a slot vent out the front? (angled down at the 45 degrees)

Is there a better way to do BIG sound and preserve the fullrange magic?
Is the Fe207E even suited to this sort of setup?
How critical is time alignment at 150Hz?

[planet10]

Originally posted by OzMikeH
1: Open baffle on top of the shadow.

This has the most potential. 150 Hz might be a bit low for the XO thou...

dave

[OzMikeH]

XO freq is flexible, being active I could get away with it being a lot higher. I'll go do some research on open baffles, thanks Dave.

[OzMikeH]

After the first bout of research and stealing ideas here is the first draft of the Cheapwitz Onion.

Width of about 20 inches with active crossover about 180Hz, 12dB high pass 24dB low pass. Size the baffle to fit with the crossover - really need to fully understand that part before cutting wood. 45 degree wings extending back and partway down the sides of the woofer box. May as well offset the driver from the centre and make one wing longer. (line the back with a sheepskin?)

Dipole tweeters - Two FT17H in series, one forward one backward with about 0.68 uF passive XO. Makes a very nice efficiency and impedance match to the FE207E. Might be a bit strange with no whizzer frequencies to the back.

Downside: needs to be at least 4 feet from the rear wall, I could only manage 2 and a half. Perhaps heavy drapes behind. Needs electric fence on the back to keep the cat out.

Unknown: I'd have to have the FE207 almost sitting on the woofer box. What happens with the front radiating into half space and the rear into quarter space? too much gain to the rear? This could easily end up a real mess.