Springs under massy plinth?

[Non-Smoking Man]

In conversation with Diceman the idea of sprung suspension for a massloaded plinth came up.

Any Wammers been down that path?

Any experiences to relate?

Ive had tennis balls under a marbled 401 and toyed with mini valve springs under same.

Im thinking of a slate plinth sitting on (captured?) car valve springs. The slate and 401 must amount to 20kilos I suppose - what sort of compression, bounciness and resonant frequency might that be?

 

[awkwardbydesign]

Funnily enough, I looked here http://www.hifiwigwam.com/showthread.php?94420-RJC-Audio-and-Townshend-Seismic-Isolation-Pods just a moment ago.

 

[i_should_coco]

I used springs on my SP10 as does Guy, I think. I felt the ones I had were too stiff so the resonant frequency was too high. The springs have cosmetic plastic tubes round them.

The two layers have stillpoints between them.

 

[TheMooN]

I had quite forgotten how fine your SP10 mit tombstone rig looked Pete , still in situ at the CoCo ECT Sanitarium ?

 

[i_should_coco]

I had quite forgotten how fine your SP10 mit tombstone rig looked Pete , still in situ at CoCo Sanitarium ?

Sadly not, I sold it and the Tannoys to buy the Voyd Reference. I do miss the old beast, though!

Here's a gratuitous copper mat shot.

 

[TheMooN]

Zshhhhwinnnggg Had me mulling upon dusting off the o'll SL1000 MKII , for all of 3 seconds flat !

 

[i_should_coco]

Lol. :^

 

[f1eng]

I think a heavy plinth isolated from its support is a very good solution to minimise pickup of structure borne vibration.

A static deflection of around 25-30mm gives good isolation over the audio range.

The Townshend products are amongst the few IME based on sound engineering rather than BS.

Polymer type "isolators" are either too stiff, too non-linear or take a set.

 

[Non-Smoking Man]

Your SP10 went to Speedysteve, Pete?

If so Ive heard it many times; very impressive.

Jack

 

[pure sound]

I have something very similar weighing in at around 65 kg but with larger diameter more compliant springs. It bounces very slowly (2Hz) & is pretty much earthquake proof. I have a suspended wooden floor but can jump up & down next to the table carrying the deck without disturbing it at all. The springs did need a coating of plasti-cote to prevent higher frequency resonance. I think most of the valve springs I've seen are too long, too narrow & too stiff for this purpose.

Sent from my GT-P3110 using Tapatalk 2

 

[AmDismal]

Beetle valve springs work OK under speakers, giving the right kind of frequency, but I think you will need lighter springs for something lower mass. I found some a while back, but can't remember where from. Will check later...

 

[pure sound]

I found a spring supplier, worked out what each spring would be loaded by & how much I wanted it to be compressed by ie from about 5" down to 2.5". Chose some suitable items from their online catalogue, ordered 4 & they did as expected. Not very expensive either.

 

[diceman]

http://www.leespring.co.uk/uk_index.asp?CountryCode=011

I am happy to stick up some info and equations later when I get more time to give basic guidance on resonant frequency and isolation efficiency.

 

[Non-Smoking Man]

Good stuff so far everyone, thanks.

Jack.

 

[AmDismal]

http://www.leespring.co.uk/uk_index.asp?CountryCode=011I am happy to stick up some info and equations later when I get more time to give basic guidance on resonant frequency and isolation efficiency.

That's it, Hooke them in so you can reel them in later...

 

[Vinyl Art]

That's it, Hooke them in so you can reel them in later...

Nooooooooooooooooo:shock:

 

[pure sound]

That's it, Hooke them in so you can reel them in later...

My elastic limit has just been exceeded.

 

[pmac]

That's it, Hooke them in so you can reel them in later...

Law de be :doh:

 

[themadlatvian]

My elastic limit has just been exceeded.

That happened to me once whilst singing on stage.

Most uncomfortable.