Springs under turntable

@derekw_hawaii - has anyone done any testing with dual-pitch compression springs?
It's a discussion I've had with another user of spring isolation, and it's another way to deal with the issue with broader frequency isolation.

I have seen the SoildAirAudio and some of their products appear to be very similar to Solid-tech out of Sweden.

+1 indranilsen

@lewm - I won't advocate for springs under the seat, with the speakers and electronics isolated correctly, there's absolutely no need. However nice padding to make it comfortable for hours of listening pleasure, ah yeah, I fully advocate for that!

Enjoy the tunes :-)

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.

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?

@mijostyn, is there any particular thing that I wrote that you question,
or the entirety of my post? I mean if it's only a couple of statements, I might take the time to find evidences, however, you're welcome to dispel and write it off with no further regard.

In most cases you are going to be better off fixing the speaker to the floor even if you are not on slab.

Okay, enjoy :-)

They make little blue pills to deal with zero stiffness

Well played!

@uberwaltz - I haven't had much success with the cheap Chinese knock-off of the Solid-tech Isoblack, perhaps the Nobosound knock-off is better?

Using the springs you tried earlier, and placed under your sub, you could add mass under your TT with a heavy shelf to try mass loading them?

Are you able to tell me more about the springs under your sub? Wire used, how many turns, spring rate etc?

@slaw

I've experimented with weights on top of speakers in the past, not on springs and found that it's easy to overdamp the cabinet. Not always a good thing.

Are you sure by adding the mass, you didn't actually overdamp, but perhaps moved the resonant frequencies into modes that sounded worse?

TMD dampers on top of a loudspeaker cabinet, the likes of the ETI AMG topper. http://www.audiopolitan.com/blog/eti-amg-toppers-review/

I was an employee of the inventor, almost all you need to know what I mean, is found in reading that review.

indranil, you are using the isolation in a room with a peer and beam substrate or joists? If so, please also consider the amplitude of which such a floor can itself move. Just like a car can only do so much to smooth out the hills of a road, it can smooth out the undulations of the road, but not the higher amplitudes.

Do you have an approximate weight of the TT and the preferred shelf you are using? Obviously I am guessing, it might be the amplitude of the floor movement that might need to be addressed also?

indranil,
another way you could try is to get the number of springs you have (hoping four?) under a heavy shelf, larger than the base of the TT you are using. Get the shelf completely horizontal, buy starting from the furthest edges of the shelf that will accommodate the leveling, moving the springs to suit under the shelf, creating the broadest sprung base. Now find where the TT with a record in it will sit on your shelf where that position will make the entire shelf and TT horizontal. Hopefully the center of gravity off the TT will align with the centre of gravity of the shelf in a vertical alignment.

millercarbon - now you can see why Townshend calls it seismic isolation!
I am glad you were willing to try it, to discover it for yourself.

And the springs on your wooden floors might be about the same as suspending the cables, have you shored up, or propped up under your floor where the springs are yet? Because if you have not, I wager money on it, there's more in store for you yet.

+1 indranilsen - Solid-tech & Townshend were pioneers, and are now being copied, probably cheap Chinese knock offs.

Next level is AMG toppers, or similar technology TMD dampers for the cabinets, in conjunction with isolation for speakers.

My next big thing is quasi-zero stiffness on my stand mounts.
There's no real shortcut here, it's going to require engineering and more math study to get this correct, and look pretty.

My previous employer has used isolation under turntables for over 30 years, and still manufactures mass loaded shelves with springs.
Happy experimenting, I am enjoying the sounds too!

@mijostyn - oh yes, you're absolutely correct. And you should totally ignore anything I say unless I can produce a peer reviewed paper on the subject.

You should also ignore isolation devices and stick to your guns.
Cheerio old chap.

If the speakers are correctly isolated, suspended, then the larger transients that produce energy storage in the cabinets, aught to deform the isolation device through a broad frequency range.

Correctly implemented the high frequencies aught to clean up as does lower frequencies, the cabinet swells and contracts as it will, but relative to the substrate, the goal is to have it’s center of gravity to remain as motionless as possible relative to the substrate.

When correct implementation of zero stiffness on loudspeakers is administered, there is no question of the superiority of this engineering practice on the voicing of the loudspeaker.

Please go ahead and try it, you may just realise a significant bump in performance for what is relatively one of the cheapest upgrades possible.

In correctly isolating using compression springs, (obviously not an issue if hanging from springs), the center of gravity can without a great deal of force, be moved across and outside the base. Short squat sub woofers are much less prone to being knocked over and damaged than speakers where the center of gravity is higher over a narrow base.

The springs themselves, under compression should also have a centralized load bearing low relative to it’s base, unless constrained as in the spring array mentioned above. I generalise that the diameter aught to be close to the final load height of a compression spring for the sake of stability, in this particular use.

The more rigid the substrate, the higher percentage of energies will deform the isolation device, such as a spring. I choose springs because of their broad range of isolation, relatively inexpensive, and easily acquired.
Correct spring rates and geometry are not hard to find, as springs are the most commonly used broad range isolation devices used worldwide.

@mijostyn
"When correct implementation of zero stiffness on loudspeakers is administered, there is no question of the superiority of this engineering practice on the voicing of the loudspeaker." (rixthetrick)

rixthetrick, What is zero stiffness? That is a term I have never heard before. How is superior when it comes to "voicing" a loudspeaker.

My father would have asked me if I'd bothered to look it up, before he'd answer such a complex question.

Zero stiffness:
http://www2.eng.cam.ac.uk/~sdg/preprint/OnZeroStiffness.pdf

As others have already mentioned, the effects of correctly implementing vibration isolation, is audibly heard. Correctly done, it's immediately recognized. And I don't need to prove it, you can do it for yourself, for really cheap. However, you need to know something about what you're doing.

For example the springs in your car/truck/motorcycle are rated specifically for that device. It smooths out the ride, it doesn't completely make it linear. Zero Stiffness is an ideal.

If you have electrostatic speakers (with their own limitations) or dipole speakers (with their own limitations) this is not likely (I would guess) to have nearly as much impact as an enclosure that is ported or sealed.

In most cases, I believe it's not the inertia of the small moving mass of the cone and voice coil that creates the most stored energy in a loudspeaker cabinet. I believe it is the sudden high and low pressure created by the drivers moving air within the cabinet (even a ported cabinet should see this pressure difference) that will deform the walls of the cabinet. It's not just pushing or pulling against the walls, it's doing both at a frequency that excites the cabinet.

Lewm mentioned transmission line woofers, I can see your logic,  and it makes sense. Have you tried isolation anyway?

millercarbon, please recall what I said about substrate, the more unyielding the substrate, the higher percentage of the energy will deform the springs.

Did you ever bolster the floor, specifically directly under the places where you have springs isolating your speakers?

One suggestion is to use the granite laminated to MDF, I haven't tried it, however I suspect laminating MDF (or some pretty hard wood?)  to it top and bottom, will change it's tone from ringing significantly. Use the granite under the TT, atop a shelf on your rack with appropriate springs to isolate? Sharing the kenetic energy between multiple absorbers, are you sure you want to do that?

For those of you supporting heavy speakers on springs, do you recommend stiffer or more moderate spring support? In other words, how does the supported combined speaker/stand weight compare to the total available spring loading capacity....something moderate like 50% or something less (i.e., stiffer springs)?

From experience, I would suggest somewhere in the 50% deflection of each spring would be a reasonably safe bet, I know that the tendency is to keep the tweeter (at least) on axis at listening position.

The term I use zero stiffness, stiffness or rigidity here couples the speaker to the support, by removing the stiffness (zeroing it) the speaker cabinet should find it's mechanical equilibrium (where it rests when not energised) and if you can gently move a big heavy speaker with just your pinky finger, you have a pretty good starting point for vibration control.

The spring rate is weight dependent. Weight / number of springs @ 50% compression.
Spring rate is critical, turns is also important, so far I have liked the most, are 3 to 3.5 turns + ground ends on each end of the spring.
I deliberately purchase with the diameter at least equal to or greater than the final load height.
I found that I like a taller spring, my guess is that small amplitude high frequencies are well sorted with more material to deflect them??

Any experts here?

I am not an expert, that was my employer, however I learnt all that I could from him before moving to USA. PM me again, we can go through it together and I'll see if I can get you similar results to MC.

Soild-tech are one of the pioneers (1995), I don't believe they copied anyone. Years ago when we were searching for isolation devices for loudspeakers, Solid-tech of Sweden and Townshend of UK (1987) were the main two to be found on the internet.

Solid-tech doesn't appear to use similar technology or use of springs in the same manner Townshend does?

I see many knock-offs now coming from newcomers though.

@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?

@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?

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.

@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. 

@indranilsen

I got the delivery of Solid Tech Feet Of Silence footers this AM

Indranil, you said that you thought the performance to investment wasn't as good as you'd hoped. Perhaps the price is higher than we experience from China, Sweden and Scandinavia in general is more expensive for everything (yes I've been). However if they actually have the engineering down to a fine art, and they work as well as you claim, how much would you have had to pay to upgrade to the same level with the device you are "floating" on them?

To restate my question, how much money have they saved you to get the same level of quality sound if you hadn't as mahgister calls it, "embedded" with the feet of silence?

They scream out, I'm sexy and I know it.. Well I don't know that, do you at least like the look of them?
Haha, congrats on your investment mate.

Millercarbon, glue an accelerometer to you garage floor and record its output while you start up your car, rev the engine and drive in and out. Please tell us what you get!

what you get is a vehicle suspended on... wait for it...springs! And tires, with rubberized engine mounts (some are even active), and you probably get almost no vibration?
Am I close?

Okay, I’ll admit I am being cheeky, please forgive me. I know, I know, smart alec post. Just shake your head an smile, I mean you no injury.

Perhaps try a block of wood (to protect the concrete) planted firmly on the concrete and give it a good tap with a hammer?

Congratulations uberwaltz, seems you're making promising advances mate. Keep us posted.

Indranil, have you tried the rubber bands thing we discussed?
If it works, then yeah I would seriously consider the uprated springs. I was also thinking, have you tried a little mass of something dense to level the whole suspended mass by moving it on the outer rim of the shelf?

mijostyn, seems like he's got it :-)