Excuse my ignorance / scepticism.. How can oak feet improve the sound ??
Quoted from Russ Andrews
The Importance of Feet
Chapter 3
The feet on the equipment have a pivotal part to play in the fight against
feedback energy storage. The use of Oak Cone Feet achieves optimal results
technically, aesthetically and inexpensively.
Stability is also very important. One of the biggest problems with most
loudspeakers is the way in which they wobble about on their floor stands or
wheels. As the speaker cone moves it rocks the cabinet resulting in a loss of
information and energy. Discover our simple cure for this problem.
The materials and construction used to make equipment furniture is by no
means the end of the story. Each piece of equipment needs feet and those feet
play an important part in the energy coupling process. Fitted with the usual
rubber feet (felt and cork are also used) the equipment acts as a reservoir
storing the feedback energy - and stored energy is just what we dont want!
We need to dump the energy into the floor.
Luckily, energy - like water running downhill - will flow into a higher mass if
it can. Rubber feet or High Tech squidgy feet prevent this happening. They
are decouplers that form a higher resistance to the flow energy, trapping it in
the equipment and the feet themselves.
It is often claimed that these decoupling rubbers turn the energy into heat.
This is a fallacy. It is extremely difficult to turn energy from one form into
another and the process is very inefficient. Just how difficult it is and how
little of the input energy is turned into heat is quite surprising. A few years
ago I asked one of the biggest manufacturers of decoupling rubbers if they
could tell me exactly how much energy was turned into heat in their products.
After a short silence they admitted that it was so low that they hadnt been
able to measure it! That is just what I expected to hear.
Consider this for a moment: the kind of rubber we are talking about is used in
squash balls. These balls are designed to bounce very little (and there are
different grades or bounce rates) and to be hit very hard into a hard surface. If
they convert energy into heat at any appreciable efficiency at all the heat
generated by hitting the court wall would cause them to melt and run down
rather than bounce off!
So what happens to all the energy you put into the ball with the racket? In
simple terms the energy has just changed down in frequency to the resonant
frequency of the rubber. Every material has a resonant frequency the level
of which is determined by its mass. Every object or substance converts
energy into its resonant frequency and so stores vast amounts of energy.
The low bounce rate of the squash ball is an expression of the low resonant
frequency of the rubber- you can hear the thud. A tennis ball, on the other
hand, bounces better and you can hear the higher frequency in the dong ring
sound.
If you use this sort of material as equipment feet (and some people use squash
balls cut in half) the feedback energy is converted down to the resonant
frequency of the rubber and it just sits there and wobbles. I have to tell you
that I think this is a very bad idea! The destructive effect on sound quality is
enormous. It increases the time smear and changes the balance of the sound
to a slow, boomy bass heaviness.
The Solution for Equipment
A hard material with a highish resonant frequency will perform better at
coupling equipment, so that energy flows quickly and easily from one thing
into another and finds its way to the floor (the highest mass around) as fast as
possible. The floor, of course, couples the energy directly to the speaker (see
Chapter 1, Diagram 1, page 7).
A number of obvious hard materials could be (and are) used for this purpose -
steel, aluminium, titanium, stainless steel, brass, ceramics, carbon fibre - even
wood. All of these materials sound different because the sonic signature of the
material has changed the feedback frequency response. I have tested all of
these materials and found that wood (hardwood) distorted the sound the
least and its sonic character was the most natural.
From my research, I have found that the cone shape is the most effective
for dumping energy out of the equipment, and that the larger the
diameter of the cone the better it works. I have chosen to make
our equipment feet from oak, a suitably hard wood and one
which is commonly grown locally and in North America,
rather than a harder but scarcer wood like Greenheart or Ebony,
the use of which encourages destruction of rain forests.
Thanks Bob. I think thats the winner
