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DIY Footers Part II

I posted a DIY footer forum here recently, I'll cut and paste it for reference:

"I can't help myself, I'm a tweak. I love playing with different footers and such, trying to find cost-effective solutions to vibration control. A lot of us use Tip-Toe style products but the trouble is they ruin hardwood floors and audio racks, damned pointy those cones. I've tried various "cups" under the points but find they make the sound a bit harsh, they're hard to get centered/seated properly under the cone, and they are a bit unstable. I tried some footers from a dealer, 1.5" by 1.5" squares built of ridged rubber, cork, ridged rubber. Stopped my turntable from skipping when walking around the room and saved my hardwood floors. Made the bass a bit flabby and the infamous PRAT went missing though.

I made my own "footers" this week, based on some inputs by a well respected stand manufacturer. This turned out to be a lot of fun and has solved my problem at a reasonable price.
Based on the recommendations of the stand manufacturer, the footers should be 3" by 3". They do not recommend you build a base the size of the item itself, but use individual footers. After some experimentation here's what sounded best:

You essentially make a sandwich, four layers to complete the footer. The top layer (and the one that comes in contact with the point of the cone is 1/2" MDF, next layer is a special compound that is used to dampen car doors and the like (Made in Germany, used by high end car audio installers), the next layer is 1/2" MDF, and the final layer (that comes into contact with your floor or rack) is thin cork. Reasonable cost but the damping material a bit pricey.

I used a 2' by 4' MDF top, 5 sheets of damping material, another 2' by 4' MDF, and finally 2' by 4' of cork. The best adhesive for this project is contact cement, it stinks to high heavens but works very well. You roll on a layer of contact cement to all the surfaces (except the top piece of MDF that comes into contact with the cone and the underside of the cork that comes into contact with the floor/stand). Let the surfaces dry til they're tacky then carefully make your "sandwich". You then lay some heavy well-distributed weights on the assembly and let it dry for 24 hours. You now have a pretty substantial 2' by 4' sandwhich ready to cut.

You need a table saw with a fine carbide tipped blade to get a good clean cut. A 2' by 4' sandwich yields about 100 these of 3" by 3" footers (there's always a bit of waste). I spilt the cost and the yield with a fellow 'phile, we're pretty happy with the results. If anyone is interested in learning more or seeing some pics of the final product drop me a note and I'll be happy to respond."

Well folks, we're back at it again, this time we intend to use 1/2" plywood rather than MDF this time around. The constrained layer approach works well and we intend on seeing if multiple layers (plywood) will make an audible difference. Oh, and for those who asked about the damping material we use; it's definately made in Germany, here's the info:

Wurth Noise Suppression Pads

Heavy bitumen pads with aluminum coating, self adhesive.

Suppresses transmission of noise caused by vibration, moving parts of the drive shaft, all parts under the car floor, wings, doors, and other panels.

- Strong adhesion
- Non pealing
- Suitable for painting
- Resistant to water, weak acids, alkalines, etc
- High temperature resistance

Sold six pads to a package, each pad is 550 x 250 x 2 mm

Wurth part no: 890 100 060

I'm curious what the plywood vs. MDF material change will make on the overall sound. Stay tuned folks! Jeff
jeffloistarca
2 responses Add your response
jeffloistarca OP
1,004 posts
 
Stehno,

If I didn't have hardwood floors and a very nice custom oak rack I'd agree with you... For those of us that have this dilemma there needs to be a reasonable solution that satisfies both our need to maximize our system and protect the fine surroundings. The layer of cork is VERY thin and does a fine job of protecting the surface under the footer without becoming a major part of the footer. All in all a sensible solution I think; so far I like the results.
stehno
1,453 posts
 
Jeff, by suppressing the transmission of 'noise', you are also suppressing the transfer of vibration and resonance. Therefore, any air-borne vibration or resonance inside your components, rack, and/or speakers have no exit path.

I'm relatively new to this, but even though you may still be using cones, you appear to still be applying damping and isolation techniques to the sharp part of the cone.

In essense, it appears that you are trying to combine the two major philosophies of handling vibration and resonance when in fact these two philosophies are almost diametrically opposed and one should be considered an oxymoron to the other. Like mixing light with darkness.

In essence you are still putting a cork in the vibration's only exit path and thus trapping those vibrations inside the unit. That component quickly reaches the point where the vibrations become congested like the 405 freeway in Los Angeles during rush hour traffice (at a standstill and getting worse).

But I believe a more accurate analogy would be the 405 freeway at rush hour completely congested with traffic at a standstill with every car having 4 passengers per car. And with every car at a standstill, every passenger of every car is running around the car doing the (foreign) fire drill. And in your application, if it can't exit from the cone, the resonance stays in cone and in the component resting on the cone.

The passengers are the microscopic vibrations running around like crazy but with nowhere to go. And that is what reaks havoc on the sonics at the micro- and even macro-dynamic levels.

To the best of my knowledge, one cannot suppress or dampen vibrations of this kind. One can only alter them or transfer them.

Have you ever been at a stop at a traffic light and some guy about 4 cars has his subwoofer blasting? You feel it in your chest and your inside rearview mirror is vibrating like crazy. You roll up the windows and it helps but just a little.

Yet your car is resting on what should be some fantastic suppressors or dampeners known as radial tires and air. So is the jerk's car blasting the subwoofer.

If only we could drive our cars around on Star Sound's Audio Points(TM). :)

I'm no expert, but this is what I've come to believe through my research and experience.

-IMO
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