Speaker isolation plinths.

[awkwardbydesign]

Having long been an admirer of the Townshend isolation stands, and making versions of the old inner tube designs, I decided to make a pair of isolation plinths using the current spring method. If I could afford to buy Max's pods I would, but at over £100 each they are way out of my reach!
So a bit of calculation was needed. My bass cabinets (the MF/HF cabs are cantilevered over the bass cabs; no contact) weigh 60kg each, so I needed 8 springs, each to support 15kg. They should resonate at about 2Hz, and be sized to be stable.
With a bit of on-line calculator action, I came up with 75mm long, 50mm dia, 3.25mm wire, 5 coils (3 active), closed and ground ends. This gave me a compressed length of 32mm @ 150N (15kg) and a resonance of 2.5Hz. Close enough. After a bit of searching I had them made for £60 cash, and they arrived within 4 days of posting off the cash!
I had just enough 18mm birch ply left over from making the speakers for 2 plinths, and some walnut veneer, so I bought some 50mm dia wooden toy wheels, 50mm MDF discs and bolts, nuts and washers. As I have a small lathe I was able to turn a step onto the wheels for the springs. They are height adjustable, but getting rubber tubing to cover them is proving difficult, so for now I will use some foam inside the springs to damp the resonance. it will probably take some experimenting to get it right.
I have stood on them, and at 70kg my weight compresses them as expected, so the 60kg of the speakers should be as calculated. Which is a relief!
The only parts visible will be the edges, the Mickey Mouse ears and the springs. I bought some plastic nut covers to hide the bolt heads, and used leather for the central pad.
They are finished now, just letting the lacquer dry, and then I'll have to get some help to get them under the speakers!
The floor in this house is solid oak stuck to concrete, less of a problem than a suspended floor, but the brick walls definitely transmit vibration upstairs, so hopefully there will be a cleaning up of the sound. Still, it keeps me off the streets doing it.
And the total cost has been about £80!
http://i1134.photobucket.com/albums/m604/awkwardbydesign/Speaker%20isolation%20plinths/P1000351_zpsugc6amxr.jpg (http://s1134.photobucket.com/user/awkwardbydesign/media/Speaker%20isolation%20plinths/P1000351_zpsugc6amxr.jpg.html)
http://i1134.photobucket.com/albums/m604/awkwardbydesign/Speaker%20isolation%20plinths/P1000365_zpsjk8orckf.jpg (http://s1134.photobucket.com/user/awkwardbydesign/media/Speaker%20isolation%20plinths/P1000365_zpsjk8orckf.jpg.html)

http://i1134.photobucket.com/albums/m604/awkwardbydesign/Speaker%20isolation%20plinths/P1000366_zpso7mcehp9.jpg (http://s1134.photobucket.com/user/awkwardbydesign/media/Speaker%20isolation%20plinths/P1000366_zpso7mcehp9.jpg.html)
http://i1134.photobucket.com/albums/m604/awkwardbydesign/Speaker%20isolation%20plinths/P1000368_zps1cdj0feb.jpg (http://s1134.photobucket.com/user/awkwardbydesign/media/Speaker%20isolation%20plinths/P1000368_zps1cdj0feb.jpg.html)
http://i1134.photobucket.com/albums/m604/awkwardbydesign/Speaker%20isolation%20plinths/P1000369_zpsd5v6l3bv.jpg (http://s1134.photobucket.com/user/awkwardbydesign/media/Speaker%20isolation%20plinths/P1000369_zpsd5v6l3bv.jpg.html)

I'll update when they are in use, so fingers crossed.

[Audio Al]

Bike inner tube ? for the outer cover ? or leather sleeve

[awkwardbydesign]

The original Townshend Seismic Sink platforms used inner tubes instead of springs, They then went to urethane elastomers (mountain bike fork springs) and then springs. IIRC. There is no space under my current speakers for the inner tube platforms, so it's springs in the corners.
Or did you mean for covering the springs?

[hifinutt]

superb , reminds me of my efforts years ago and great fun to experiment and keep us posted
after all this is how max started I am sure

[awkwardbydesign]

Well, they're in. I had to make a jig to compress the springs while I slid the speakers onto the platform, then I discovered they were too tall, and the rubber pads on the feet meant I couldn't slide them into place! So I took the springs out one by one, cut off the 3mm MDF and 2mm rubber, stuck felt on and put them back. All good now. I haven't got any damping in (or on) the springs, but I don't think it needs any. They only rock for a short while anyway, and can't tip over.
I have only played one CD so far, and the bass seems cleaner, but I may be imagining it! It will take a few different albums to really be sure, but at least I know that subsequent work on the bass cabs and crossovers won't be compromised by the floor.
I have put a piece of ply across the fronts for now, as the bare ends of the metal tubes for the upper cabs' stands were showing. Probably fill in with a black piece eventually.
And the final (hopefully!) crossover coils arrived today, so I can get on with altering the crossovers.
http://i1134.photobucket.com/albums/m604/awkwardbydesign/Speaker%20isolation%20plinths/P1000373_zps70rz8ud5.jpg (http://s1134.photobucket.com/user/awkwardbydesign/media/Speaker%20isolation%20plinths/P1000373_zps70rz8ud5.jpg.html)
http://i1134.photobucket.com/albums/m604/awkwardbydesign/Speaker%20isolation%20plinths/P1000371_zpsjyazwo6w.jpg (http://s1134.photobucket.com/user/awkwardbydesign/media/Speaker%20isolation%20plinths/P1000371_zpsjyazwo6w.jpg.html)

[walpurgis]

Industrial isolation mounts have potential as speaker supports.

http://www.ebay.co.uk/itm/Set-of-4-Vibrachoc-Paulstra-Anti-vibration-mounts-E1N-2296-23-40-90-/331507729576?pt=LH_DefaultDomain_3&hash=item4d2f6684a8

[awkwardbydesign]

Industrial isolation mounts have potential as speaker supports.

http://www.ebay.co.uk/itm/Set-of-4-Vibrachoc-Paulstra-Anti-vibration-mounts-E1N-2296-23-40-90-/331507729576?pt=LH_DefaultDomain_3&hash=item4d2f6684a8

I have considered such mounts, but at £100 for 8 as against £60 for the springs it would be a bit pricey. And with mine I know what the resonant frequency is. Anyway, where's the fun in buying something off the shelf? Especially something as ugly as those! :D

[awkwardbydesign]

Changed the fascia to black. The camera flash shows up the wood behind, but it's not visible normally. My wife says it looks OK, and that the exposed springs match the speaker bars, so that's how it will stay! I fancy some silly LED lights underneath, but she says NO! So I'll have to sneak them in. :D Multi-coloured remotely controlled like these - http://www.ebay.co.uk/itm/201126190863?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT What's not to like? Chavtastic! :lol:
Anyway, the bass is definitely cleaner, drums sound more natural, and low frequencies rumble across the floor. Hopefully it will also reduce transmitted sound; then I won't keep the neighbours' kids awake! :doh:
It looks as though the top and bottom cabinets are touching, but there is a gap of 2-3mm, so not contact at all, as the top cabs are suspended from steel pillars at the rear.
http://i1134.photobucket.com/albums/m604/awkwardbydesign/P1000378_zps0dpjpvz7.jpg (http://s1134.photobucket.com/user/awkwardbydesign/media/P1000378_zps0dpjpvz7.jpg.html)
http://i1134.photobucket.com/albums/m604/awkwardbydesign/P1000380_zpsz3njrn8y.jpg (http://s1134.photobucket.com/user/awkwardbydesign/media/P1000380_zpsz3njrn8y.jpg.html)
(The cardboard box on the floor is the cat's.)

[archiesdad]

Looking good.
Lava lamps too.:respect:

[awkwardbydesign]

Looking good.
Lava lamps too.:respect:

I also have a lime green one, and a glitter lamp. Going for these next, to create a "tasteful" glow under the speakers. http://www.ebay.co.uk/itm/201126190863?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
:D

[SLS]

I've been looking today for a suitable urethane elastomer to dissipate vibration from my amplifiers and the best thing I've found so far are skateboard bushings, which will cost £5 per unit. I am currently using some marine pine blocks, which are an improvement on the stock rubber feet.

Another solution I may try is constrained layer dampened shelves for my hifi unit out of a sandwich of 12mm MDF with Regupol 3912 in the middle. This is rather more expensive as a roll of Regupol 3912 costs £120. Other options are Neoprene (also quite expensive), possibly just 3mm ribbed rubber.

[Gazjam]

Sound damped steel isofeet are extremely good.
Have a set under my turntable and my Transporter.

Award winning accredited Industrial application, used in a hifi context.
(Handy the MD's a hifi nut!)

Cool demo video
https://www.youtube.com/watch?v=Rtmnr62wDsw

[awkwardbydesign]

I've been looking today for a suitable urethane elastomer to dissipate vibration from my amplifiers and the best thing I've found so far are skateboard bushings, which will cost £5 per unit. I am currently using some marine pine blocks, which are an improvement on the stock rubber feet.

Another solution I may try is constrained layer dampened shelves for my hifi unit out of a sandwich of 12mm MDF with Regupol 3912 in the middle. This is rather more expensive as a roll of Regupol 3912 costs £120. Other options are Neoprene (also quite expensive), possibly just 3mm ribbed rubber.

Which durometer rating do you use? I have the very soft Holey smoke bushings (72A) on my longboard, they might be good for you.
http://www.longboardshop.de/shop/buy%20longboards%20skateboards%20@%20longboard%20s hop%20de/HOLEY_bushings_2011.jpg

[awkwardbydesign]

Sound damped steel isofeet are extremely good.
Have a set under my turntable and my Transporter.

Award winning accredited Industrial application, used in a hifi context.
(Handy the MD's a hifi nut!)

Cool demo video
https://www.youtube.com/watch?v=Rtmnr62wDsw

I saw his demo at Scalford last year, and downloaded the accelorometer app that he was using. Rather cool to play with.