Here is where I shared previously
On why we need to have the acoustic absorption panels right in the middle behind MLP. No matter where u place the LR speakers along the front row, the “ sound velocity “ is always higher at the back of MLP. Hence we need to use absorption right in the dead centre behind MLP. (Very important ) remember this
On the platform, it’s easy to build, you can use plywood, that works well as a “pressure membrane” . Just need it zig zag with air gap. Make sure it is able to support the weight of the RS2 JTR
Here is one DIY’ed by another member for his speakers to be elevated before going behind the AT screen… unfortunately he had to scrap the project
They followed the same method. This has more to do with vibration control and absorbing sound pressure.
Remember the diagram above? You see sound velocity is not at corners of the room ? That’s because sound pressure is concentrated at that area. This panel, now works at reducing sound pressure moving downwards.
The above is how I did it at my place, 26cm height. Below that DIY pressure plate, I used granite. Granite’s resonant frequency is 7khz range. So we are not concerned with “ringing” from the subwoofers because they don’t play that high up in the frequency. The granite 4cm thick , now works as a mass to absorb all the energy moving downwards . Beneath that granite place cork + sorbothane.
Next you just need to have 25kg of steel shots on the top cabinet of the JTR RS2. The steel shots now works to dissipate energy moving upwards towards ceiling . U can get it from pan abrasive
S460 will work
You are now done with subwoofers all 4 JTR isolated, with top cabinet having steel shots. It is now ready for integration. This integration part is where I will need to come into the picture. So u can first go ahead with the above and get it ready.
I’ll come down more on acoustics and why we shouldn’t go full range… they are all inter related…
Now that you can understand the difference between sound velocity and sound pressure, I’ll dive in to the room acoustics