Originally Posted by trhought
carp....I think you'll find no DSP will be needed once you get your isolators. I'm running both my BOSS platforms from a single sub out feed from my Onkyo AVR directly to my BOSS amp. Just select 80Hz LPF for LFE in the AVR and you should be golden! Of course, DSP can be added to taste, but I think you'll be very impressed with the single digit ULF and TR with the prescribed isos.
Regarding you iso placement, that makes a lot of sense and I was going to recommend experimenting with iso placements once you get them since your drivers are cantilevered behind your seating positions. That cantilever is going to cause your platform to bend more than it would if the drivers were spanned in the middle of the platform like a traditional BOSS riser. Moving the isos outward will help keep the platform from bending. That energy can now be used for more up and down movement which is what you want.
Below is a graphic to help illustrate. The top pic shows the isolator right below the chair leg, the triangle labeled B. This will cause the platform to bend. Moving that isolator out towards the edge of the platform as shown in the bottom pic will help keep the platform from bending as the JBL's are moving up and down. That energy can now provide more up and down motion from the JBL's which are shown in blue.
Hope this helps for anyone else considering a cantilever JBL mounting location behind or to the side of your seats.
Changing isolator location with JBL's behind the platform will increase up and down (z-axis) BOSS movement (the bottom picture is what you want to minimize BOSS platform bending):
I will definitely experiment more with placement. When I first tried it out yesterday before I tried stacking the isolators I put them on the carpet because I wanted to make sure that the driver had enough room to not hit the carpet. However, when you suggested that I try stacking them I then put the stacks in the places where I cut small squares out of my carpet a couple years ago for where I had isolators for the Crowsons. These holes in the carpet happened to be closer to the edge of the plywood than where I initially tried the single isolators.
So... my future experimenting will include trying out the bare concrete cut outs (the rear holes in the carpet/pad are still in front - and to the sides obviously - of the driver) vs. moving the rear isolators back to where you have them in your diagram above. It will be no carpet vs. more optimal placement. I could of course cut more holes in the carpet.....
My wife happened to come in the room while I had the chair up yesterday and she saw the holes... and I panicked and yelled, "this is not for your eyes, you weren't meant to be here right now - look away!!!!!" or something to that effect.
She wasn't mad, she lets me do whatever I want since she thinks of it as "my" room, however, at the same time I don't want her to think that I'm completely insane. I think I'm too late on that one.
So far there are things I like better about the Crowsons (dig a lot deeper with more power way down low below 15hz) and the NF sub (chest punch) BUT the BOSS has way more headroom above around 20hz than the Crowsons and feels more realistic and it also is more realistic than the NF sub.
The BOSS still doesn't feel as natural as the wave of bass coming from the 8 18's up front. The BOSS can move me more but doesn't feel quite as real and freaky (in a good way) if that makes sense. I'm sure it will never move my hair/clothes/etc. of give that wave of pressure. However, it is the closest thing I've found so far in fooling my brain into thinking I don't have any "tricks" connected to my seating. My Crowons will be in the classifieds if I get even a little bit of improvement with the other isolators.
One other nice side effect that I have found in my experimenting is that I get more seat movement from the front subs than I did before now that I'm on a double decker of isolators.