Anatomy of the Decoder

Don't try this at home

Remember how great Dolby Digital was a few years ago? Early support in blockbuster films such as Batman, and Jurassic Park and Schindler's List made it very popular. Now, similar technology can be found on our desktops. It's rather impressive, especially when you consider the size of the VideoLogic DigiTheatre decoder. We couldn't help but open this baby up for a little peek.

A Look Inside

A Closer Look

Ohhh.. shiny!

Wait! Is that a copper shielded chassis, like the ones that are found in all the high end audio components? Copper shielding helps to reject stray photons (remember electromagnetic energy is both a wave and particle) that could interfere with the electronics on the device and add noise to the signal. The theory behind this is that electric fields can only travel on the surface of perfect conductors. By making the case of an object a conductor, in theory, no external fields should be inside the box. These "boxes" are called Faraday cages.

We determined that the outside of the decoder case is definitely not metallic; it was plastic. No additional layer of material could be separated from the inside of the case, and upon closer inspection we discovered that the "copper" was actually copper colored paint.

Blasphemy?

This was pretty tricky -using copper colored paint to feign copper shielding, or so we thought. Why would a company waste money with paint on something that is probably never seen by the consumer? My instincts told me that the British were much more resourceful than this -- have you seen the old James Bond movies? We still don't have that kind of technology today.

Going back to the theory about shielding, if the outer surface is a perfect conductor… Nothing really is a perfect conductor, but what if the paint was conductive? I whipped out my trusty hand digital multi-tester, and proceeded to measure the electrical resistance between two points on the copper surface. To my surprise the paint was conductive! When the multi-meter probes were placed on non-painted surfaces, there was no current flow.

Amazing. Could this be the answer to all our radio frequency interference problems? Should I run down to the hardware store and paint the inside of all my electronics with conductive paint? Maybe. All this is still theory, and how much effect shielding from RF radiation will do to improving audio quality will have much to do with the environment in which the system is being used. If there are few photons jetting through your room, then shielding won't have as much of an impact. With the VideoLogic system, shielding is a good idea as the system will be used next to your computer. If your computer is like any of ours, overclocked, running with the case off and tons of fans blowing, chances are you wouldn't come close to passing FCC B (residential) or FCC A (commercial) standards. Bravo to the engineer who thought this one up.