Springs under turntable


I picked up a set of springs for $35 on Amazon. I intended to use them under a preamp but one thing led to another and I tried them under the turntable. Now, this is no mean feat. It’s a Garrard 401 in a 60pound 50mm slate plinth. The spring device is interesting. It’s sold under the Nobsound brand and is made up of two 45mm wide solid billets of aluminum endcaps with recesses to fit up to seven small springs. It’s very well made. You can add or remove springs depending on the weight distribution. I had to do this with a level and it only took a few minutes. They look good. I did not fit them for floor isolation as I have concrete. I played a few tracks before fitting, and played the same tracks after fitting. Improvement in bass definition, speed, air, inner detail, more space around instruments, nicer timbre and color. Pleasant surprise for little money.
128x128noromance
UPDATE on my nobsound springs adjustment...

The adjustment by adding load is more delicate than i said at first ...

A difference of 2 pounds of load, not 4 pounds, on around 90 pounds of load in total, make a substantial difference in the high frequencies mostly but also all across the spectrum...

A little more than 1% variation in the load is critical....

Keeping off a number of springs from the 7 in the 4 boxes on each speakers would be a too much gross adjustement.... I prefer then with my speakers varying the damping slabs of concrete....For the last tweaking of the load i use 2 plaster book-end on each speakers because they weigh half the weight of a brick, around 2 pounds...

I think that would be very delicate for a turntable, because it is delicate and had take some listening time for my speakers....

One thing is sure, those that think mechanical embeddings makes a not so great difference, and are only an accidental secondary "tweak" would be surprized....

A "tweak" is only a minor addition, a minor refinement when it work; controlling the embeddings is not minor addition, it is a transformative major action on any audio system, be it mechanical, or electrical or acoustical....I am not interested by accidental "tweak" so much, i am interested by the method and the ways to embed the audio system and his parts.....
I forget to say that refining the load around 1 % affect the frequencies so much that it is audible on the instrument timbre expression... I was listening violins when i discover that i was with 2 pounds overweight.... Adjusting it was spectacular in the sense that suddenly all timbre expression become more natural....

:)

Then pay much attention to the load or the number of springs or the design of the springs itself especially for a turntable but anyway for any applications.... The taking off springs will be too gross ajustement for most turntables...

I think that other springs will be better for most turntable, depending of their weight in relation to the springs diameter, turns, mass etc....
These springs can be very good with one turntable because of their measures numbers and size and numbers possible adjustment, and not so much with another turntable.... People must be conscious of this...

Springs adjustment to the load to isolate in relation to frequencies is really something necessary to compute....

It is more easy with a varying load on speakers to compute with the ears, than with a turntable and only the 7 varying number of springs to play with....

:)

We will need rixthetrick.... :)

But i dont have a turntable....:)

Adding 6 Nob loose springs under the six tube phono amp brought improved clarity, musicality, vocal diction, speed and dimensional perception of instruments in the soundstage. BUT it reduced bass weight and enhanced upper mids to the point of coloration. I replaced the loose springs with 4 aluminum cones which brought things back. Bass returned but the improvements noted above faded. (The turntable is on springs.) Disappointed to lose the amazing clarity but frequency balance better. So it appears the phono prefers stability.
@lewm - yes.
RixTheTrick 09-05-2020 11:29am
Zero Stiffness is an ideal.
I have mentioned Minus K in Agon before, and I am on their email list.
They are very expensive. Their upright flexible pillars are an excellent means of controlling horizontal plane movement - a truly excellent product.

I also have reservations about seating speakers on close to zero stiffness systems. And I have many times stated that broadening the base to accommodate the instability created by spring isolation is essential on tall loudspeakers with a narrow base. I have springs under my subwoofer with absolutely no issues.

I have also suggested mass loading under turntables on top of springs as well.

I would also suggest that for loudspeakers anything over 10Hz should be isolated, and a plynth for a turntable I think if I recall correctly 4-5Hz on a mass loaded plinth.

@frogman
I’ve been stating for sometime now that what you put your isolation system on is equally as important as the design of the isolation system.
If you don’t mind, what was the VPI HW19 MK4 with springs supported by?
What was under it please?
So I had 12 springs removed from the ones under the turntable left over. And I had a bunch of 3/4" MDF disks that were cut out to make the Spring Things. So all I had to do was drill three 1/4" holes about 1/8" deep to make my own little Nobsound spring pods. 

Three springs per pod is stable and just about perfect for the Herron phono stage. There were 3 sets of BDR Cones and Round Things under it. Swapped them out and heard huge warmth, massive extreme low bass, somewhat rolled off top end. 

It was then I remembered mahgister saying how he tunes this by ear by varying the weight. Well adding springs would be equivalent and I had one more pod so in it went. Now with four pods the bass is still full but not exaggerated, the midrange still warm but more present and no longer the rolled off top end. It could probably be fine tuned even more but pretty impressive even as it is.

Good work, mahgister!


Adding 6 Nob loose springs under the six tube phono amp brought improved clarity, musicality, vocal diction, speed and dimensional perception of instruments in the soundstage. BUT it reduced bass weight and enhanced upper mids to the point of coloration.
They are not enough compressed.....

The rate of compression must be adjusted around 1%..... On any springs application if i go with my experience with mine....My speakers rightly adjusted gives me the better natural timbre i ever had but it takes me few days of listening....The first sign that all is rightly adjusted is NOT first the clarity, it is the naturalness of timbre, at first this new clarity induce me in error..... To decide we must listen to instrument like violin higher notes to hear their timbre, etchy or natural, lacking body or not.... :)

For turntable(i dont have one) mass loading the springs under the turntable, like recommended by rixthetrick, is the solution indeed....Then it is possible to adjust by varying the loading mass by ears around 1% ( + or -).


Using prings is NOT a tweak....

It is one of the essential way to embed the gear in the mechanical dimension of his working use....

"Tweak" are minor refinement or not, not always necessary..... Springs are indispensable tool to embed any gear in their vibration/resonance dimension (mechanical)....Tweak can modify or adding something that is not always wished for ( like my "sandwiches" that were a tweak wanting to be a control method but lacking the power of springs to be one)....Controls methods for the embedding DONT ADD something, rather they put the gear in the best of his conditions to reach his optimal level....Springs are essential and dont change the tone of my speakers at all if they are rightfully adjusted, rather they reveal the TRUE color of my speakers under the condition where vibrations/ resonance are controlled... Tweak are a fad + or - useful, or an attempt , a bid + or - successful, springs are necessary tool to any speakers.....

Just sayin for those who thinks lightly, or superficially ... :)

A bought bunch of tweaks will never be a method of listening experiments....
I may experiment with a couple springs under my phono or DAC but they will have their work cut out to beat the current porcelain ex ham radio 1" inverted cones under them right now.
These cost about 50 cents a pop from eBay and gave an astounding change in the level of detail and drop in noise floor.
This was documented in a thread by myself quite some time ago now.
I may experiment with a couple springs under my phono or DAC but they will have their work cut out to beat the current porcelain ex ham radio 1" inverted cones under them right now.
They are perhaps the tool to use for a dac better than springs..... Thanks for the information....




If you look at the third or fourth pic on my system you can see the type of cones I am using under the GoldNote phonostage.

https://systems.audiogon.com/systems/6466
**** If you don’t mind, what was the VPI HW19 MK4 with springs supported by?
What was under it please?****

rixthetrix, the table sat on either a maple shelf on a Target rack or a maple shelf on a Target wall rack/shelf. The table’s stock rubber feet had been replaced with BDR cones, same as those that replaced the stock spring suspension. A brief experiment with sorbothane pucks between table and shelf was...brief...no good. Both the stock spring suspension and the BDR cones were tried with the table on both the rack and the wall shelf. In both cases the BDR cones were much better and the differences between springs and cones were consistent with the table on either supporting surface.
Relating to fine tuning the load by weight, you may want to consider using a suitably  sized and shaped container appropriately  filled with sand or crushed rock.
For those who showed interest in the porcelain cones.
Ebay seller here.....

https://www.ebay.com/itm/INSULATOR-CONE-Porcelain-Ceramic-HAM-RADIO/264781306811?var=564605940024&hash=item3da6321bbb:g:jrQAAOSwzqtb8iCv

pretty sure all the 1" ones are gone as I think I bought all the stock they had left.......
Relating to fine tuning the load by weight, you may want to consider using a suitably sized and shaped container appropriately filled with sand or crushed rock.
Good idea...  :)
I won't be mounting my Transmission Line woofer cabinets on springs any time soon or ever, thanks.  I do go along with getting any speaker up off the floor by at least a few inches if it's a tall full-range type (to de-couple from the floor, you don't necessarily need a springy or spongy support) or by the typical stand if it's a 2-way monitor, but none of that applies to either of my two systems, since both are large planar types, one ESL and one Beveridge which is not quite a typical ESL.
My nobsound spring isolation feet arrived Sunday, late afternoon. I got them, hoping to alleviate some subwoofer influence on my turntable. I'd noticed some subtle muddyness in louder bass passages with vinyl that I did not detect when streaming the same tracks.
After reading several reviews and discussions, I assembled the feet with only 3 of the possible 7 springs in each foot to accommodate the 20lb weight of my Technics TT.
For starters, I chose Boz Scaggs' album "Dig" which has several bass-heavy tracks including:
"Payday", "Miss Riddle", "I Just Go" and "Thanks to You".
The tracks still had good dynamic range, but the low end was less muddy or boomy...revealing better detail.
Classical music was better too....
STRAVINSKY: THE FIREBIRD SUITE (1919 VERSION)ATLANTA SYMPHONY ORCHESTRA AND CHORUSROBERT SHAW, CONDUCTOR has passages where the bass and kettle drums come on strong. The accompanying woodwinds and echoes of the hall are more noticeable now.
Don't have any "cons" to report as of yet...still listening for any issues.

I copied the album info, so forgive the all caps! By the way, this Telarc version of the Firebird Suite is outstanding. Some of the best orchestral reproduction I've heard. At times, startling realism. 


mwinkc, I have that record. Lots of fun. I think they stuck the microphone in the kettle drum, makes my windows rattle. 
Isolating any turntable from the environment is essential for the best playback. The springs act as a mechanical filter. All frequencies above the resonance frequency of the system will not get through to the turntable. All frequencies below will get through. This is why the recommended resonance frequency is below 3 Hz. If you have ever played with an AR turntable or the LP12 that is pretty wobbly if not done right. Both these turntables use exactly the same suspension design. It was a good start but there was substantial room for improvement. Sota made the first stable suspended table in 1980 or so then came Basis and SME. All these tables have chassis that are hung from springs instead of sitting on them. The Solid Tech Feet of Silence are the best aftermarket springs I have seen if your table is not too heavy. The feet are hung from their springs. They offer two spring rates and two different kits of either three or four feet. Any turntable that is not already suspended should benefit. 
The next evolution is suspension design is MinusK's negative stiffness design. It isolates down to 1 Hz remaining reasonably stable. 
It was designed for delicate lab gear like Scanning electron microscopes.
I find it interesting that lab gear that is totally electronic does not require isolation.
I ended up using Symposium Rollerblock Jr’s in place of the springs. It was a revelation!

Use both, that’s what I’ve been using for awhile now with great results.

I had custom roller blocks made locally based on well known existing designs. The latest version from Ingress were not designed yet/available at the time I made mine but these are basically what I had made . These look to be of excellent quality and the mirror finish is a bit better than mine (which is important).

My sandwich is 4 springs on the shelf/platform > .75 mdf > 3 roller blocks (open face) > .5 marble (polished side down) > component. I have been wanted to try a symposium svelt shelf or equiv in place of the marble, but haven’t got around to that.

Its key that the total weight compresses the spring close to its max load.


@frogman When you say a Target shelf, do you mean the brand?

I have found that for the springs to correctly isolate the loaded mass, that substrate needs to be unyielding, well as much as possible.
In a situation where the structure under the springs is prone to vibrate due to materials, geometry, etc. I have no doubt at all that it could be accentuated by the springs the effect like cars and trucks creating corrugations in a road, where the specific frequency is made worse.

I have absolutely no doubt that what you claim happened.

Using springs for isolation requires planning and some knowledge.
mahgister, yeah tuning with mass, great idea - just like derekw_hawaii suggests. If you can't get the perfect springs, get the perfect load.

And I suggest, try to shore up the substrate under the springs?
Friend of mine says

Different is easy. Better? Not so much.

Might apply to many of the observations I read above. Engineering a comprehensive spring suspension is not as simple as balancing a turntable on some pods.
I keep indeed my springs isolated from the floor(in my case my desk) with my "sandwiches( quartz feet, 2 grannite plates with sorbothane duro 70 in betwween and cork plate and bamboo plate)..


Electron microscopes are electronic.At present there is no way to visualize biological molecules using only visible spectrum light microscopy, although there have lately been some tremendous advances in that science too.
Different is easy. Better? Not so much.
@neonknight Agreed. However, we're long enough in the game to know when something is an improvement and to also call out any negative considerations when they arise.
Yes Lewm, but they can not see Sh-t if the specimen is not held perfectly still, a mechanical issue.
Thanks for the amazon link. I've been looking at isolation options for my Micro Seiki BL-9. My 2nd floor listening room still has the original floors from 1929. I was also looking at trying the custom made feet from these guys,  https://www.mnpctech.com/collections/turntable-lsolation-feet
@mads1,

Looked at the link you provided. I'd stay away from rubber or sorbothane if I were you.
So much good information, what a great thread. I especially appreciate input from all those with experiences good and bad.

lewm, yeah you've already explained that yours are immune from the effects of vibration. Your objections are noted and I hear you.

@uberwaltz - I've looked at your system page before, impressive mate.
I gotta say, I just love that white translucent platter (I think it's called that?) and the Avid looks super cool. Which of the three is your favorite TT, and why if you don't mind?
I haven't been brave enough (and the opportunity hasn't presented itself) to hear a well sorted vinyl system yet - it might ruin me on digital.
Hey Rick
Thank you for the kind words.
Three TT is definitely overkill but you only live once...lol

The clear acrylic platter on the Rega is an aftermarket one by Deep Groove, metal sub platter and Zaphire bearing. The original Rega plinth was sandwiched between two  slabs of MDF and then Walnut veneer over the top. Different motor and an IEC receptacle in back to take any PC, tonearm rewired with Cardas and terminated with a din plug underneath.
Yep its been hot rodded. and now it is set up as a mono TT with 2M Mono cart.

The 401 is in a substantial plinth with curly maple top ala the best guitars, lol. I modded the platter to add extra weight with stick on car wheel weights underneath it, added 2lb total. Micro Seiki MA505LS arm in immaculate fully functioning form.

The Avid is a very nice belt drive deck with outboard speed controller but stock with Rega RB303 arm and I honestly think it deserves a better one.

Favourite?

Very close call between the 401 and the Avid which is more likely choice of carts than anything else.

The 401 being idler drive always gives me the impression of more drive and dynamics and feel of life to the music, certain less charitable members here just say thats the rumble from the drive.
Whatever, they may be right but I do not care.

The Avid does indeed have very detailed highs and mids but seems to lose that certain something in "soul" of the music. It is possible a better arm would change the pecking order, oh well its only money!
Thank you for the kind words.
I wasn't even being kind really, just calling it as I saw it. I thought just from the photos you'd put in some decent effort, now after reading just about the mods on just the turntables, there's an unseen iceberg of mods. And perhaps lead weights :-)

Almost don't want to know about vinyl, it's expensive to get into from where I am. But I am so curious, probably can't help myself, I'm going to have to make an opportunity to hear it.

Can you or have you ever swapped the arm off the 401 to the Avid?
My hifi knowledge is limited to a few things I've actually worked on, it was a fun way to make a living. I'm making better money now, and can buy better toys.

Thanks uber, this is an area where I know virtually nothing.
Rick
Not wishing to hijack this spring thread but I am a rank amateur on vinyl compared to some of our more long term esteemed members here.
I have picked up a lot of information from those guys on these hallowed pages!
One word of warning, it is a very deep dark rabbit hole.....lol.

But quite simply the MA505LS( long series) is an 11" arm whereas the RB303 is a 9" arm so would need a different armboard to even think of trying that on the Avid.
But I probably never would as the 401 and MA505LS are both nice vintage pieces and belong together.

Now back to springs, mine are out for delivery today!
Mijo, No argument here on the necessity for stabilizing an EM, but you previously intimated that this was necessary because of optical requirements.  Anyway, this is off topic, and I just wanted to be clear.  I used to have an EM, and a person to run it, as part of my lab. She wouldn't let anyone get even close to "her" machine.
Then I did not present it correctly, my fault. If I had an EM I would not let anybody near it either:)

Uberwaltz, you REALLY need a Schroder CB on your Avid. Your other turntables will become conversation pieces. It would be very expensive to make a better record playing device. With the different weight cartridge mounting plates you can put just about any cartridge on it. It is the most perfectly designed pivoted tonearm in existence. "Rank Amateur"? Surely you jest. 

rixthetrick, Whether or not vinyl sounds better than digital depends almost entirely on the way the music was mastered. An album mastered for digital is very hard to beat. But there are masters that sound better in their vinyl versions. I can only guess but I would say off hand it is about 50/50. Vinyl requires more effort, space and mechanical aptitude. If you like old sports cars you will love Vinyl. If you only drive Audi's stick with digital. 
If you have wood floors this is a very important thread. There are many audiophiles who have to walk around on tip toe while playing a record. Because of anti skate if the stylus loses contact with the groove the arm will skip backwards. In some houses this can happen with every step.
A turntable that is suspended correctly will not skip at all. Examples of properly suspended tables would be the Sota, SME, Basis, Dohmann and I believe the Avid Acutus. Sorry if I missed any. The Sota's certainly represent the best value. I can hit a Sota with a hammer and you will not hear it through the system. 
You can not believe the amount of noise and vibration that travels through a house. The term used was house rumble. The washing machine, various transformers, fans, plumbing, the truck traveling down your street.
A turntable is a very sensitive vibration measuring device. With a suspension tuned to 2 Hz the only vibration that will get through to the cartridge is you picking up the turntable and dropping it on the floor. 
This is only one aspect of turntable performance. As uberwaltz related, this is one very deep rabbit hole. Try starting a thread on Direct vs Belt drive and see what happens:)
Mijo
I have looked at the Schroeder CB arm before.
However...$5k....
A wee bit more than I was thinking of spending.
@mads
I was also looking at trying the custom made feet from these guys,
Stick with springs. Sorbothane has a bad rap for sound quality!
mijostyn
Uberwaltz, you REALLY need a Schroder CB on your Avid ... It is the most perfectly designed pivoted tonearm in existence
It is? Do you own one? Have your heard one? Tell us more.

@mijostyn - 
If you like old sports cars you will love Vinyl. If you only drive Audi's stick with digital.
I want to buy an S5. For real.

Isolating a TT with a wood peer and beam construction would be a daunting task for me. Most of my experience with isolation was from work and at a loudspeaker factory in Australia. Where my former employer sells speakers with spring isolation built in as standard feature. I have since done quite a bit with various subs and speakers etc.

I am fully out of my depth with TT isolation I am afraid. I did mention isolating the loudspeakers which I do have experience in, because I would assume a non isolated TT would certainly receive energy from a full range loudspeaker through the floor.

The hardcore mad scientists like noromance and mahgister for example who just dang well give it a red hot go, inspire me too. 





Hello,
I got the delivery of Solid Tech Feet Of Silence footers this AM. The delivery was lickety spilt, all the way from Sweeden and I didn't have to pay any Customs duty for this purchase. The footer design was excellent ad it does move in all directions as advertised. I have just installed three footers underneath my Clearaudio turnable and listened to it. The sound was ok without much adjustment. I have to do the load adjustment tomorrow, which is really the key and see if it addresses the footfall issue. If it does then I have found a commercially made spring isolator which isolates above 2-3 hz at least in the vertical direction. I would keep you all in the loop,
Thanks.
@indranilsen Hopefully they'll sound better tomorrow. Thing is, they are a lot more expensive compared to the Nobsound at $35. How do they compare to them?
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. 
Hello,
I spent last night adjusting the load on Feet of Silence footers and got it to work. I am excited to report that the footfall issue with my turntable is now gone which I couldn't accomplish using the Nobsound discs. The soundstage has opened up quite a lot as expected with better imaging, depth and clarity. The speaker disappeared much better than it did before. So I am happy with its performance but not completely satisfied with the price to performance ratio. I will continue listening to this set-up to see if there is any change in the performance over time.

I am not able to compare it with Nobsound discs because I was not able to get Nobsound springs work/eliminate footfall when placed under the turntable. However I have previously used Nobsound discs under heavier electronics and coming from that experience I can say that the Solid Tech feet of Silence footers do offer a much better performance. Better in terms of overall clarity, imaging and the speaker disappearing factor. As I mentioned before Solid Tech design being able to isolate in more than one dimension allowing smooth spring movement is expected to perform better but its price to performance ratio didn't impress me...

In my experience, the spring based isolator performance regardless of its design/price depends on the load sitting on top of it. Utmost care should be taken to ensure that every spring is compressed to 97/98% of its max load. Without that sound could appear to be bloated, bass heavy and veiled besides surfacing footfall issue for few turntables. For Nobsound discs, I measured a set of 3 discs each having one spring can cary a max of 18.5 lbs (approx). So this configuration needs to be loaded with almost 18 lbs to be able to get to the desired isolation point. Each spring/disc should need just a slight finger touch (not press) to get to the bottom and you should hear two discs touching each other. Any further load, you are not going to get the real isolation benefit. What I have stated here is purely my experience and I am not trying prove any theory or point...

@uberwaltz- What you are describing sounds like a less than optimal load situation with Nobsound springs. These springs are stiff and can take a lot of load. These discs can be used with one spring and hence your two spring per disc layout should work. You can refer to the following manual to see how a two spring layout could be implemented.
https://www.audioadvisor.com/pdf/SolidTech_Isoclear_Application_Instructions.pdf
It is a Solid Tech manual but it works for Nobsound discs... Hope that helps.

Thanks.

@uberwaltz Try 3 Nobsound springs under the 401. 2 at front -the way I have them. Then 2 at back. Interesting upset in your result. Mine is the opposite with the mids projecting free of the speakers and the highs sparkling. Frankly, I thought my ESLs were tired in the treble. Until now. Lit up!
@mijostyn- I couldn't agree more on that 3hz isolation level. That is our target. However getting to that 3 hz natural frequency with compression springs needs a special focus on the load interms of weight & material that to me is the most difficult factor....That is where you are playing with balance, precision and the level of damping of the surface.
Thanks.
The big problem with just two springs is that it's now like a bike, only support on two 180 degree opposed points.
You really need three or four to be stable.
Try supporting your amp with two points.
You get the picture.
Now four pods means yes you can do it but it is very wobbly as I said even with them being compressed.
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.
I have a pair of dual voice coil drivers firing opposed in a sealed cabinet (32mm or 1.26" thick MDF), with substantial bracing. The cabinet is not totally inert, however it is pretty decent. Though certainly no contest for my stand mounts with the steel plate lining it, also with cast iron braces, silicone filled hard drawn copper tubes and birch differential bracing. I have exposed the internals in my system page (the stand mounts, not the sub).

Both lifting the sub an inch, and isolating it at approx >4-5Hz makes for significantly less energy to be injected into the floor, the walls, and everything else.
It is an experiment worthy of the almost puny investment.
You may very well be surprised if you were to experience it for yourself?
My two Martin Logan Depth i subs are made '6 sided' with 3 equally opposing 8" drivers, This, as stated above, eliminates almost all internal vibrations. Several months back I put Stillpoints SS feet under each sub directly to my sprung wooden floor and they made a substantial positive difference. I already had these on hand. I plan on trying springs there at some point, in no hurry though.