Again thank youThe square is bracing for the hatch. However, it should be installed vertically like so:
Yes, you need to use gasket material for the hatch to prevent leaks. Here is an install example:
I use threaded inserts and machine screws for the driver, but coarse-thread screws will work. If you’re building with mdf, backer blocks are a good idea.
The 100Hz HPF would cut out most of the signal going to the Devastator. I would order the DSP soon and for testing just skip Demo low type stuff like EOT. Keep the volume down...I now have two amps both are QSC GX7. I haven't ordered a mini DSP yet. So, am I safe to test the speakers if I move the Crossover switch to the up position and us CH1 is this consider the high pass filter? Also the front knobs say LF and HF, lol looks Greek to me. Just trying not to pull a Back to the Future moment. This is to test JBL duel Devastators.
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That is a large space at 5700 cubic feet. You have a lot info for narrowing it down. The stepped resonators would be an absolute pain for constructing a windowed front. Something like Alpha II would be good for dealing with that large of a space, so there is a choice there. The Alpha I would be easier to install a Windowed front, but the response cuts off hard around 80Hz. However, the 1099s should not have much of a problem reaching down to 60 or 70Hz. The HT-8s could be a more tricky proposition crossing lower. The depth requirement culls the herd further, Finalizers unless it is the FV4 are out. That leaves cabs like the Devastator 21 V4. If you are on a slab of concrete I would keep the tunes higher at 19Hz or 20Hz. Ideal situation is seeing if the new stepped fronts work according to the model. The Alpha II would be the most flexible, either giving you very high amounts of 20Hz + output or adjusting it with a port plug for 16Hz tuning. The NSW would keep composure for longer vs the SAN when driving power into the woofers. If you can save longer it is a worthy investment.I've had plans to build a couple Dev's since the spring, but am just now getting back to it after I ended up moving this summer. The new room is now a little bigger , but I'm still planning to start with 2 Dev's to go along with my 3 1099's and 4 HT-8's I'm finishing up. The room is ~17' wide x 37' long x 9' tall. My AT screen wall will be 3' out and I'm planning to have the Dev's visible under the screen flush with the front of the screen wall. That way they'll be "part" of the wall. I may even do windowed versions like what @a77cj7 has done in a couple builds. I thought that would look great with the windows and the ports creating some features as part the screen wall. Anyway, I'm not quite sure which version to build now. I know I probably can't go too deep if I want to keep the front flush at 3' out and still want some clearance behind the subs as I've read somewhere in here it's best to have some space between the sub and the wall. That eliminate the deeper versions but any 30" and down are probably fine. Also, I had thought to use the reducer concept and start with an 18" driver and build a Mini Dev 18" V5 / Mini Dev 21" V4, but I've since decided to just go with the SAN214.50 drivers to start instead.
So, to summarize: I'd like to get some help deciding which 21" version to build that works well with the SAN 214.50, is <= 30" deep, and will crossover well with the DIYSG 1099's in a fairly large room with a carpeted concrete floor. With the Dev's, mini's, BMD's, LFE's, Finalizers, etc....I'm not sure what the best route is. I'll take any other advice you're willing dole out to me too.
The sticks look right. Most if not all the rear chamber bracing will have the 1.5" dimension in the horizontal plane. The .75"/material thickness is in the vertical plane. The exception being the hatch where 1.5" is in the vertical plane.