How Too Isolation Feet

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moray james

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How Too Isolation Feet
« on: 4 Feb 2003, 10:18 am »
Audio Isolation Feet – “The Nuts and Bolts of a Fine Audio System.

   There are very many  products on the market which promises to support your speakers and components and enhance their performance. Some are “Toes” that tip, some are “balls” that roll some are pods that “squish”. Some people swear by one brand or the other for one application or the other. Most do make changes but not always for the better. There are far more bad devices than good ones. The reason their performance varies so much has to do with numerous reasons. The esthetics of the finished product is one of the major reasons for this as is a sad lack of understanding of materials and the mechanics of the task at hand for the product.
   I present here a very simple “How Too” project for audio “Nuts” who want to improve their systems but have been “burnt” in the past with expensive toys that did not deliver or who just don’t have the money to experiment. The devices described here came into being as a direct result of Louis’s Omega speakers. The Omega’s are so revealing that many of the sonic traits people attribute to them are actually artifacts of their own system that the Omega’s reveal. It’s the old double edge sword because you get both the good with the bad. The good news is you can always clean up a lot of the bad. The even better news is that this project will cost you less than a Latte and cookie at Starbucks.
   Please do not let the seemingly very simple appearance of these devices fool you. While they are definitely low tech in their composition of parts they are far from simple in their actual functioning in how they do what they do. Much serious consideration has been given to enable the incredible performance of which they are capable. Do not “second guess” the design as it is carefully balanced, each and every material is crucial to how these devices work. Don’t decide to “improve” the parts for what ever reason. Build three sets and give them a good listen then if you wish to experiment. You can share you findings with the group. I won’t go into the why of the materials or how they function here. If you have burning questions about how and why please build a few sets first then ask. I do also plan to do a pictorial on the assembly procedure later.


Parts List for three sets       (two sets for your speakers and one set for your CD)

9pcs.     ½ inch flat washer
9 pcs.    5/16 inch flat washers
9 pcs.     5/16 inch nylon locking nut   (steel nut with an inset nylon locking ring)  
Quality PVC electrical tape recommend “Temflex #1700 by 3M electrical products
Slow cure epoxy glue suitable for steel (hard cure epoxy, no quick,5-min types)
Tooth picks for mixing and applying epoxy
Razor knife to trim electrical tape
Small can black Epoxy spray paint
Small package of “Mortite” or window glazing putty or “Dap 33 Glazing Putty”
Construction Details

Look at the washers carefully and you will notice that they are actually punched out of flat sheet stock. You can tell this by the fact that one side of the washer has smooth rounded over edges while the flip side has a sharp edged. You need to know which side is which as they will be used in a specific orientation.
   Take the larger ½ inch washers and place a piece of electrical tape over the center hole on the side with the smooth rounded edges. Place these washers tape side down on a smooth flat work surface.
   Next take the 5/16 inch locking nuts and insert one into each of the ½ inch washers so that the nylon locking ring points upward. You will need to give a good firm push to place these nuts. Should the nuts prove to be a bit snug just give them a light tap down with a hammer. The nuts must be inserted so that they are square in the washer’s hole and flush with the back side of the washer.
   Mix equal parts of the epoxy very well for one minute. With the tooth pick you will take the epoxy and fill in the small gaps left around the nut in the washer hole. You can be generous here and build up a small fillet of epoxy around the nut but don’t go overboard. Let the epoxy set for at least three hours then remove the black electrical tape off the back side of the washers.
   At this point in time the epoxy should be well enough set up that you can handle the nut/washer combo without any problems. You will now pack the inside of each nut tightly with one of the above mentioned compounds. I will say here that the denser (heavier) the material the more effective the damping will be. This means that if you use a very dense window glazing putty you will damp out more energy than you would using the “DAP 33”. That said, of all the materials mentioned the “DAP 33” is the best overall choice as it will stay in it’s “plastic” form almost indefinitely while the other compounds will eventually harden and shrink away from the inside of the nut and so loose effectiveness. The packing compound must next be trimmed flush on each side of the nut.
   You now have to leave the units for about 24 hours for the compound to skin over. Next you will use your epoxy spray paint and spray at least three good wet thick coats but you must allow each coat to dry before you spray the next coat. Next you will turn over all the pieces and repeat the above procedure. In the same way spray paint all of the 5/16 inch flat washers. The epoxy spray paint effectively damps surface traveling vibration on the metal. Let dry (cure) for a couple of days.
   Once the spray paint has fully dried after several days (full cure will actually take a couple of weeks) you can now apply the black electrical tape. You will apply a full layer to the back side of the large ½ inch washer/nut combination. You will also apply a full layer to both sides of the smaller 5/16 inch flat washer. I usually apply the tape so there is a seam exactly splitting the diameter of the washer. Then trim off all the excess tape with the razor knife.
   Now you can use the “ISO” feet. The bottom of the lock nut sits directly in the smooth sided hole of the 5/16 inch washer.
   For speakers place one “ISO” foot at each of the front corners of the speaker and one “ISO” foot at the middle of the back of the speaker. There is a significant difference in sonic performance of the speaker system with the feet placed this way verses two at the back and one at the front. You need two at the front of the cabinet to deal with the full impact of the driver in the cabinet and sink it into the speaker stand. For your CD player you will want one foot directly under the center of the transport mounting area, a second foot beneath the power transformer and the third foot beneath the analog output stage. You will need to balance the whole player so that as you lift each corner of the player the balanced weight of that corner up on the remaining two “ISO” feet is about the same as each of the other corners. In this way you will have approximately the same amount of weight on each “ISO” foot.
   What will you hear? Better dynamics with improved bass weight. Smoother mids and high frequency. Improved depth and width of image and pin point stage presentation. Space and ambiance will also be very much improved.
   How do they compare to commercial products? You will all choose to make your own conclusion with respect to comparisons you make to other products. Lets just say that there are on the market now some cones with white marbles in them that sell for $275.00 US a set. These little feet significantly out perform the commercial product by a wide margin IMHO.
   One last word. These feet will take some time playing in your system before they settle down and physically mate together. At that point they stop moving and every thing just locks into place. This will take several minutes to happen and you can actually hear the improvement in sound as they lock into place.
   Have fun, save money, experiment and share your findings with the rest of the forum. Regards Moray James.