Cone Feet - Isolation or Draining?

What is the Purpose of Component Feet?

When I first looked at component feet, most of them were made from a rubberized material, which would suggest that their prime function was to prevent vibrations from being transferred to the component.

I quickly learned that those rubber feet were less than ideal at satisfying that particular goal, so I looked into Cone feet.

Having considerably less surface area in contact with the shelf of the component rack seemed like a logical step, but I was not sure of the effectiveness of the various cones and spikes and thought they might actually anchor” the component to the shelf.

After applying some thought to the problem I came up with a DIY “ball bearing” and “marble” feet (see below), which seemed to work very well and did not require the little spike protectors to prevent the foot from digging into the shelf.

I also applied a small piece of sorbothane between the component and the DIY foot to further isolate the component from rack-born vibrations.


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More recently, I decided to investigate cone feet in more depth after an interesting exchange with the fellow DIY audio enthusiast,

For more information take a look at:
http://www.symposiumusa.com/tech1.html

Turns out, my thoughts about isolating the component from the rack were only partially correct.

A much more interesting aspect of applying cone feet to a component, is their ability to drain vibrations from he component case/chassis, which improves clarity and imaging.

So I decided to try some beech wood cones just to see what effect they might have, and was quite surprised at the improvement in sound quality


The DIY enthusiast informed me that Brass cones provided the best sound, so I decided to try some different materials in order to assess, which material would provide the best improvements.

I decided I would limit this exercise to the materials in the above picture, wood, brass, steel ball-bearing on steel washer and glass-marble on steel washer, which were placed under the Phono stage, since in previous auditions the phono stage appeared to be quite sensitive to the style of foot..

The first audition was the Ball-bearing on steel washer - without the layer of sorbothane
  • this combination sounded very clear, but unfortunately the image had been moved very far back behind the speakers.
  • imaging was very focussed but overall the image was very narrow
  • it also resulted in a loss of volume
  • it sounded similar to being at a hockey game in the seats furthest away from the ice
  • however, the dynamics were very fast, to the point of sounding quite brittle

The second audition was the Glass Marble on Steel Washer
  • This was much better than the Ball-Bearing in that it brought the image back to a more disirable location behind the speakers
  • Clarity sounded a little less harsh than the ball-bearing
  • image size was larger and very well focussed
  • Dynamics were crisp, without appearing brittle

The third audition was with 1.25” Beech wood cones
  • This was the warmest of all the materials with mid tones being a touch more prominent
  • The image was larger than either of the DIY feet but a little less focussed.
  • The dynamics were not quite as crisp as they were with the DIY feet, but just by a very small margin

The final audition utilized brass feet that I had made for me.
  • The brass feet performed very close to the Beech Wood feet
  • They provided the widest image and improved on musician placement and focus
  • Dynamics improved to match the DIY feet
  • They were not quite as warm as the Beech Wood feet, but sounded very full

Other factors that will effect the sound quality ...

The size of the foot used for a given component
  • On my Bluesound Node 2 there is very little space within which to place the feet, so I use 3/4” diameter cones.
  • The Phono stage was a little larger, so I am using 1.25” diameter cones and larger cones made no difference
  • My amp seemed to sound the best with 2” diameter cones
  • The Turntable has 2.5” diameter cones, but that is more for overall styling than effectiveness

Foot placement
  • This is unique for each component
  • For my amp the two main feet are placed each side of the mains transformer and the third foot positioned for optimal stability
  • For my phono stage the best results were obtained be placing one under the transformer one under the circuit board and the third for optimal stability
  • For the Bluesound Node 2 there was not much room, so I placed 2 at the rear and one at the front
  • The turntable was perhaps the most complex (see diagram below)


The Node 2

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The Phono Stage

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The Turntable

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Foot Location is as follows...
  • As close to the edge of the turntable as possible
  • Equal distance from the three centre lines created by the
  • FOOT 1 to spindle to arm bearing
  • spindle to FOOT 2
  • spindle to fFOOT 3

TT Feet

PLEASE NOTE: This is far from a definitive analysis of Cone performance and placement, but it did yield a substantial improvement in clarity, imaging and focus.

I would recommend you try both wood feet and brass feet to see which works best for your individual components and try different foot positions - it will surprise you.

I hope this inspires you to try them for yourself.

DIY BRASS CONE DIMENSIONS
  • The angle of the cone section was 10 degrees from the horizontal plane
  • the height of the shoulder on the cones were
  • 3/4” diameter cone had a 3/16” shoulder
  • 1 1/4” diameter cone had a 1/2” shoulder
  • 2” diameter cone had a 3/4” shoulder
  • 3/4” diameter cone had a 1”” shoulder

The cost of making 5 sets of three feet was $300 CDN

The cones were made at a small local fabrication company and the brass was purchased from Metal Supermarkets

My Rack is made from steel, from a company called Lovan and is there entry level product
http://www.lovanaudiogroup.com/basic-line.html

Each shelf is MDF and has a granite tile on top with a layer of drawer liner between them

The cones sit directly on the granite - I do not use the little brass protector feet often sold for speakers


page6_blog_entry61-page6_blog_entry60-page6_blog_entry52-page6_blog_entry40-two-thumbs-up-2 A highly recommended project!