Originally Posted by Nalleh
I started with JBL’s under the seat, didn’t like it that much, continued with a SI18" mk1 under the seat, liked i a bit better, then moved it to cantilever, LOVED IT, but the height was cumbersome, so changed to 4x JBL’s(pr
seat) cantilever and it is awsome! Both cases, JBL’s and SI18" worked better in cantilever.
I think it might be because cantilever excites both Y and Z-axis, more of a rocking motion, as opposed to a normal BOSS mounting, which is more concentrated on z-axis only.
Movement combining more axis tends to feel more violent than a bigger movement in just one axis.
Nalleh.....Thanks for the details on your different setups and experiences with each configuration (cantilevered and under-the-seat). Very helpful for those considering all their BOSS configuration options. Between you and
, I think both of you have tried almost all possible combinations
At least the ones thought of so far....
Also, great to see you and Shelby sharing your miniDSP settings to help with optimizing cross-overs and boosts for your particular BOSS/VNF/MA combinations. There's some golden nuggets there for others to experiment with to see if their BOSS experience can be improved, even without VNF and MA's.
Personally, I'm interested in exploring the negative delay effect when using negative HS's instead of LPFs to see if that enhances the BOSS experience with BOSS only. Will be fun to try some of these signal shaping tricks when things slow down at home....probably after the summer.
For the bold above, wanted to offer a bit of the science behind what's happening with BOSS technology. Remember, the back isolators of a typical mini-riser BOSS platform get most of the weight when seated or reclined due to the center of gravity of our bodies shown in the diagram below (the circles represent our body CG). That CG is mostly over the back isolators in either a reclined or un-reclined position.
This is important because our body weight becomes part of the dynamic BOSS system response. Imagine your body moving up and down a millimeter or so and how just that small amount of movement (say 200 lbs times 1 mm displacement) can start to have a rather large force effect on the back isolators when looking at the diagrams below.
Since the back isolators are doing most of the work, the mini-riser BOSS system always has rocking motion because our bodies are mostly over the back isolators and that’s where most of the force and energy is located in the BOSS system as a result.
That rocking motion can be maximized with setups shown on the left hand side of the diagram (both cantilevered and under-the-seat).
And, that rocking motion can also be minimized with setups shown on the right hand side of the diagram (both cantilevered and under-the-seat).
Basically, the more the CG of the body is in line with the driver and in line with the back isolator, the more up and down motion will result in the back isolator.
And, the more up and down motion of the back isolator will result in more rocking motion which will result in more efficient delivery of the BOSS system energy to the ULF TR experience.
This is also why the BOSS experience will be different for those that recline when compared to those that don't recline.
Once this basic BOSS principle is understood, one could really start to optimize their mini-riser BOSS system design based on seating preference (reclined or not reclined) and whether a cantilever design is best or under-the-seat is best based on seating preference and room layouts.
This is also, why VS measurements are good for determining directional changes from one setup to another but not so good about predicting the final BOSS system response. Because our bodies and the location of our bodies have the biggest impact on the overall BOSS system response. VS measurements with seating occupied are more accurate because of the overwhelming effect of our body weights on the overall BOSS system lever arms.
One caveat to all the above, these principles only apply to a mini-riser BOSS setup. For a full size riser BOSS, that platform could weigh much more than the occupants on top of the platform and is much more rigid. With these full size risers, the seating positions, isolator positions and driver positions on the platform become less important and the BOSS experience becomes more consistent anywhere on the platform.
Case in point, when I measure vibration on the floor of our 3rd row bar which is where people sitting back there rest their feet, its vibration is very similar to the vibration at the front of the platform where the second row guests feet are resting.
However, on our front row mini-riser, the vibration where the guests feet are sitting on the front of the platform is very small compared to the vibration measured at the back of the platform where most of the weight is located when the platform is fully loaded.
Maybe way too much information, but wanted to share as I’m seeing more discussion here about different BOSS configurations with mini-risers and what is the optimum layout.
Either cantilever or under-the-seat can deliver a similar experience. It really depends on your seating preference, location of your seats on top of the mini-riser and your room layout.
Also, bonus points for anyone who can see another lever (hint, hint) that could potentially be used to increase the BOSS system efficiency. Another hint….look at the configuration in the upper right hand corner of the diagram below and pay close attention to how the driver is cantilevered outside of the rear leg of the chair and the isolator directly below it.