Originally Posted by Mahuzz13
If so here is a question to the pros on this form:
if you are just going with 2 18" subs in the stage does it make sense to have on at one height and a second at double the height, like what you see with guys that have 4 subs up front stacked but if would be just a platform holding one of the subs at the elevated level (hope that make sense)
By doing this would if give you a more even bass throughout multiple level seating or just having them at the same height do the same thing.
I can't speak to what Javeryh is doing, but I can say that generally most people don't stack their subs unless they are having more than 2 up front. Something that is somewhat common is to construct the second row riser such that it becomes a bass trap, which is designed to help alleviate the strong bass peaks that can happen in the corner, and I *think* it also helps deal with the concept of vertical-ness that the riser provides.
Generally though, as I understand it, the standing waves is more of a horizontal issue based on the room shape. So what most people do is what is known as the "subwoofer crawl". Which essentially has them putting their subwoofer in the chair of their room, and then crawling keeping their head where the possible sub locations would be. With a limited amount of space behind a false wall that normally gives people a few feet on each side of the center for each sub. I *think* you can have one sub in one seat, and the other in your secondary mlp, to help confirm how they work together. The idea with the crawling is to find a spot where the bass sounds good across a region of bass sound. When you find one, you put one sub there, and the other in the second spot where you had similar sounds. It allows you to not have to move the sub, go back to your seat, move the sub, go back to your seat, rinse, repeat 1000 times.
If you have some time, both of these videos are pretty good, and at least one of them talks about bass placement, and what is idea (and I think one might talk about sub crawl too, but it's been a while since I watched):
Originally Posted by javeryh
They are going on the left and right of my center speaker so it will be L SUB C SUB R behind the screen. I'm looking at the Denon 6300 or 6400 to power the 7.2.4 set up but it is still not clear to me if I need a separate amp to power the subwoofers...
Currently there isn't a 6400. If you get the 6300, you will not need an external amp, unless you feel you just aren't getting things loud enough, and then you can look at adding one or two to lessen the load on the internal amps. By default though, you will be able to run everything out the box. This is the *easy* solution, albeit a little more expensive.
The 4300, would require at least one external amp to power two channels. Sometimes you can get this for under 900, don't know what avs offers them for, and couldn't post it if I knew. Mike Garret could answer that for sure. So this is definitely a way to save a few hundred bucks, just a little more wiring involved.