[shajan]

I'm in the planning phases of my theater with a riser platform. I am thinking of converting the riser frame or part of it into a sealed box and putting in a Adire Tempest sub and plate amp.


Any drawbacks to this plan?


Thanks,

 

[I'mListening]

This gentleman did just that in his riser, as well as a sub array within the ceiling joists. Look here... http://www.wiseacres.com/theater8.htm


As for myself I seriously considered this option... http://www.partsexpress.com/webpage....ctGroup_ID=536 But decided that when I upgraded to the SVS subwoofers, that they would probably just overwhelm and cancel out the built-in riser subs.

 

[Dave Milne]

I did exactly what you're talking about. It worked out very well. To minimize cancellation effects, I routed LFE info to the riser sub and front sub info to the main sub.


The driver is a JBL 2245H 18". It's flat to 23Hz with 6dB boost from an active filter. Power is from a bridged Adcom 555 (600W). It really adds a nice tactile sensation to the movie experience. You should go for it.

 

[shajan]

Thanks guys.


David, good job. I think I'm gonna do it unless someone else has a reason not to. I'll route the LFE to this and mains lows to my dedicated sub.

 

[I'mListening]

Quote:

Originally posted by Dave Milne I did exactly what you're talking about. It worked out very well. To minimize cancellation effects, I routed LFE info to the riser sub and front sub info to the main sub. The driver is a JBL 2245H 18". It's flat to 23Hz with 6dB boost from an active filter. Power is from a bridged Adcom 555 (600W). It really adds a nice tactile sensation to the movie experience. You should go for it.

Hello, Dave? Dave's not here, man! NO,MAN! IT'S ME...DAVE!




Okay..so I thought that was funny. Seriously, what are the riser dimensions for your sub/riser? And, do have a protective grill over the speaker to prevent any unmentionable and unintentional damage? Looks great!

 

[jdb]

Above is the prime reason I changed my name to "Bob".


The platform sub does look nice: as do your other photos.

Thanks for posting them, jdb

 

[Dave Milne]

Thanks guys.


Darren, the riser is 61x49x9. The driver has a couch over it with short enough feet to prevent damage from little hands and small objects but I should think about a grille.


Shajan... The only thing I would do differently is to plan for wiring ahead of time. To do it right, this would have required slotting the concrete (they don't do basements in Arizona) but would have prevented the headache of snaking cable under carpet. I got the flattest stuff I could find and there's still a subtle lump.

 

[shajan]

Dave, I am thinking of putting the sub in a down firing configuration. The platfrom will have small rubber legs to elevate it from the concrete floor. I'm planning a sealed box but if ported, the port will come out of the front of the riser. . I'm hoping that the weight of the riser and couch and all will stop it from moving.

 

[usabrian]

Shajan, consider this, three points define a plane, so if you go with four rubber legs you can have some difficulty leveling it just right. But I agree that the weight of the structure, insulation, couches, people, etc., should keep it from going anywhere. (and will likely self level it) You could always attach a couple of angles as anchors if you needed them later.


Brian

 

[shajan]

Thanks Brian, the reason for the legs are to isolate the riser from the concrete floor, mainly for the tactile effect of low bass. I am thinking of using something called uboat (sp?). Thick U shaped rupper peices under the riser.

 

[Dave Milne]

Downfiring was not an option in my case because flipping the box over would have meant several more inches of height for the air gap to the floor. In upfiring mode, the feet and cavity of the couch provided natural "breathing room". I wanted to keep the total riser height at about 9" --which barely provided enough depth to maintain some space between the driver magnet and the back of the box.


More importantly, I believe downfiring (considering the large area of the box, distance to the edges, and only a few inches gap) would have significantly affected tuning. I don't know how to model this...

 

[shajan]

Dave, I didn't think of the tuning effects. I thought with a sealed box, I wouldn't have to worry about tuning. Well, I can put the woofer on the top, but I'd prefer to put it under the riser.

 

[Dave Milne]

For a sealed system, it's probably less critical (mine's vented), but the "front loading" of the driver will still affect Qtc. My intuition is that the more restrictive the front "space", the higher the Qtc will be. So you might get away with building the box a little larger than the standard model would call for...