Here is an idea of what the Amplifier Cabinet will look like:
MDF painted off-white (Old English White?) gloss,
toughened glass front panel flush to the edge beading,
backed by either black or white plastic sheet (shiny edge visible)
The cabinet will be made from MDF for acoustic reasons, not for cheapness. I am in agreement with Denis Morecroft‘s ideas that there should be as little metalwork around the signals as possible. Electrical signals give off magnetic waves which travel out and induce electric currents through any metalwork they pass through. These currents create their own magnetic fields and reflect voltages back into the original signal. It is called ‘Back EMF’ and is well known. Most amplifier manufacturers use metal boxes to stop the amplifier picking up Radio Frequency Interference (or Electromagnetic Interference). It is also cheap and very easy to manufacture. Plus it is thin so doesn’t take up much storage space plus it is easy to store and handle.
My solution to reducing interference (you cannot get rid of it completely) is to keep the components as close together as possible (given certain constraints) and symetry. So no long wires to act as aerials and everything gets an equal dose of whatever interfering signal there is.
No relays will be used as I will be d.c. coupling amplification stages (I hate capacitors) and I am concerned the magnetic field given off by the coil will induce d.c. into the signal. That means all controls will be mounted directly to the p.c.b. and actuated by an extension rod to the knob on the front of the cabinet.
While I am in the mood for telling my likes and dis-likes; I don’t like the idea of co-axial cable either at least not for audio hifi signal paths. Mostly for the reasons just given above. I do like the idea of signals using single cores spaced about an inch apart as being ideal. I can’t tell you why, I just do.
I manipulated an image off the web to create this mock-up using Gimp (a freeware image manipulation app much like Photoshop only totally free to use!). Here is the page I took that image from, my gratitude to the owner (I didn’t ask permission): Source of Image.