Springs under turntable

I am new to decoupling and springs in the past two weeks and have been very pleased with the results compared to spikes on a concrete floor.  I have noticed similar sonic improvements as those you have listed.
I considered the spring device you are using and opted for single springs under the corners of my amps and speakers.  I will also be using them under my subs soon.  For me, the single springs work great with the key being to determine the right combination of diameter for stability, total load capacity per spring, rate of compression for the desired stiffness, and finally the compressed height that is appropriate for the equipment or speaker being supported.
I had good luck finding what I needed from Century Spring Company, that has an interactive specification tool to help you find the appropriate springs.  One other thing you can try if using single springs is to encase them in heat shrink overlapped at the top, which not only hides the springs but also provides a bit of protection against scratches for both the gear being supported and whatever you are supporting it on.  If you believe air needs to escape from inside the spring, simply poke a hole in the heat shrink.

Thanks for the replies. I did some more critical listening. Some notes below.

• Lots more detail - I can hear more of the acoustic, inner detail, deeper stage.
• Tiny details more obvious - like listening to records all over again
• Speakers are totally GONE
• Cleaner but lighter bass - reduced bass?
• Volume needs to be set higher - not as loud - this is weird.
• Brighter - maybe a little too bright - not unpleasant - makes the 401 idler sound more like a suspended - I also have an LP12.

More later when I can get away from desk.

@mijostyn It is bouncy - I have to use the arm lift. But it settles in about 1.5 seconds. The plinth/401 is heavy. I can't use the same type of spring as the weight distribution is not equal.
I am only going by "does it sound better or worse?"

I've always been a cones and rigidity man.

Me too! Everything on BDR. Everything! https://systems.audiogon.com/systems/8367
Even so I always was aware of the drawbacks, just never thought this could possibly be the solution. Did not help AT ALL that the least credible biggest joker in all of audio was pushing springs. Oh well. Under the bridge. 

Put springs under the subs last night. Not all the subs just the 3 closest to the turntable. Replaced BDR Cones with springs. At first was like, well this is underwhelming. Bass was maybe a bit better, but also maybe a bit less. Probably because eliminating bass being transmitted through the floor leaves only bass in the air. So it feels different. Which makes sense. But then, wait a minute, what the.... midrange presence, top end extension, holy crap the springs under the subs just massively cleaned up everything else and the detail is so much more natural and amazing! Al Stewart isn't just singing he is RIGHT THERE in freaking person!  

My cones and rigidity thinking had me convinced that my 750 lb rack of solid concrete, granite and sand was impervious to acoustic and even mechanical energy. Evidently not! Not even close! The subs are putting out the same acoustic energy. More. I turned em up!

The only logical explanation is mechanical vibrations from the subs had been transmitted through the floor to the rack and right through its 750lbs all the way to the turntable. Crazy!

Why this works has to be what Max Townshend says in his video. Look at a record, the light pattern tells you there's sub-micron scale squiggles. These unbelievably small details are where the sense of 3D placement and room size acoustics are. They're easily blurred over by even the slightest vibration. That's what I'm hearing. That's what noromance is hearing:

• Lots more detail - I can hear more of the acoustic, inner detail, deeper stage.
• Tiny details more obvious - like listening to records all over again
• Speakers are totally GONE

My Nobsound springs are coming Friday. It sounds so good already, can hardly wait to hear with springs under the table.

This is insane. Sound is getting better as they bed in OR as I acclimate to the new presentation. It's the delicacy thats amazing. Like going from an okay MM to a superb MC. It's also showing me that I was wrong about the limits of the Garrard/Decca as being a touch shy and rough and ready in the upper range. Nope. This is see-through detail. Best part is that the music isn't sharp and seering - it's warm and beautiful and very detailed.