I use the Nobsound springs under many of my components, but not the amps. The amps are considerably heavier than everything else- even my 86lb DAC. But I found the Nobsound springs are not as effective when placed directly under a component. I found they work better under a shelf and the component then sits on the shelf. One of the problems with the Nobsounds is that I cannot get the Fn below about 7-8 Hz regardless of the weight of the component. And that’s with as few springs as possible in the assemblies such that the two halves are almost touching. They can still be effective but the ideal range is 3 Hz. Maybe try the Nosounds under the component platforms and then damping materials between the component and the platform- or just use the factory feet on the components like I do.
The McMaster Carr coil springs worked out nearly perfect for my amps as well as my subwoofers in my HT system. The subs also sit on big butcher block platforms supported by the coil springs. Weighing over 120 lbs each they put the Fn at about 3.5 Hz. The subs sound amazing being isolated from the floor.
Sure thing. Metal springs are linear- F=kx. K being the spring rate which is constant for a metal, coil or leaf spring. That makes the spring/mass system frequency response easily predictable using Fn= sqrt(k/m), m being mass of the system. So with the 48 lb/in springs under our amps only frequencies around the resonance point, Fn= 3.8 Hz give or take, will pass through. That’s what makes springs great isolators.
Rubber can be a good isolator too and rubber also dampens, ie. It absorbs energy turning it into heat. The problem with using rubber as an isolator is that it is non-linear meaning the spring rate changes with load. Coupled with its damping properties rubber often adds coloration to the sound. It‘s non-linear properties make it harder to predict how it will affect the sound of a component. It‘s mostly going to be trial and error. I find metal springs with some dampening material is the best combination for isolation and minimize coloration. The hysterisis inherent in metal springs also provide some dampening on their own, but it doesn‘t hurt to stuff some dense foam inside the coil springs.
One more comment. I know your system rocks. I think you also seem to have the room set up well. It looks like you have the side absorbers set at the first reflection point which is same as me. I just wanted to mention that one way to find that first reflection point is to put a mirror on the side wall. When you can see the tweeter from your listening position in the mirror, that is the reflection point- same with the ceiling absorbers.
Very nice rig. I have the same amps. A couple of things I did was isolate my amps with springs and I put a large patch of constrained layer damping material on the inside of each of the top covers. The damping material eliminates that ting ting sound when you tap on the amp covers but also has a positive effect on the sound. I bought 48 lb/in springs from McMaster Carr and put them under the feet of my amp stands. That isolates them down to about 3.8 Hz or so. The result is more detail and better imaging. It’s worth a try.