Springs under turntable

Rix, a turntable suspension is just a simple mechanical filter. The trick is setting it up so it is stable. As for subwoofers the trick is to give the driver a perfectly solid enclosure with an infinite mass. Not so easy. Put your hand on your subwoofer enclosure while playing something bass heavy.
Any fibration you feel is distortion. That vibration is either from the enclosure walls moving or the entire subwoofer moving. In most cases it is both. Ideally you should feel nothing. You can not isolate a subwoofer from the house. Bass is insanely powerful. Put on a 30 Hz test tone and turn up the volume. Your entire house will sing at 30 Hz, glasses, plates, pictures, the walls, your teeth, everything. Fortunately for us our brains can only pay attention to the loudest noise. With music and the satellites running you can't hear it. If you don't want to hear your car rattle, turn up the radio. The medical term for this is "masking"
I had an older S5 V8 with a manual. It was hands down the prettiest car Audi ever made and a very satisfactory daily driver. 

Nobsound springs arrived today ( day late).
Set up with just three springs in each pod and used four pods under the 401.
Checking compression and height of plinth it looks to be very even all round despite the fact that it has a pretty weighty motor at rearcenter left.

Immediate impression with an album I am familiar with is somewhat increased bass although possible it is a bit more muffled/ muddied.
But very early days yet.
Not sure as I would say I am noticing much more detail level increase but it’s certainly no worse.
Mids also feel a little fuller but again maybe not quite as "tight".
No other changes at this time like mats etc, just spring pods installed.

May set the other set of pods up with just two springs each and try that out.
My 401 is not as heavy as noromance and maybe need to compress these spring pods a bit more.

Two springs does not work as it just wobbles like jelly...lol.
So went to one spring in center.
That compressed the pods too much so back to three.
Interesting experience.

The most dramatic difference was under my Herron phono stage. This is with the extra springs removed from the set under the turntable. I cut some MDF pucks out with a hole saw, drilled out 1/8" deep holes 1/4" in diameter and stick em together just like Nobsound. Only mine are for just 3 springs per. 

So I put three under the phono stage and the bass is off the charts deep and full, but the mods are too warm and the highs are gone. So I add one more and now the bass is just right, a little fuller than before but not exaggerated, the mids are nice and warm yet still detailed and the highs are almost as extended as they were before with BDR. 

The stage is still on BDR Cones, Round Things, and Shelf. The springs replaced the BDR Cones that were under the Shelf. Will probably eventually try swapping, springs directly under the stage on top of BDR. But for now this really is a pretty sweet setup!

If the resonance frequency of the sprung mass is higher than 20 hz the whole thing will vibrate at that frequency which will definitely do some interesting things to the bass. None of them good. The reason that you should set the springs below 3 hz is so you can't hear the suspension and anything that is happening in the room above 3 Hz. A good suspension should produce blacker backgrounds and isolate the turntable from foot falls and the kids hitting your equipment rack with a basketball. Otherwise it should do nothing to the sound.