Once you get a good HDMI connection, our tests indicate, you can expect flawless performance from any 4-meter cable, regardless of price. "That is what I would expect from the HDMI cables," says Maxim's Nelson. "It is not too difficult to make them work perfectly at 4 meters."
Digital cables are inherently more dependable than analog ones. Both transmit data by controlling the voltage levels in an electrical signal. With analog, slight shifts in voltage correspond to precise values in the final picture. Thus, if the signal carrying blue color information loses voltage as it travels down the cable, the blue objects on screen will appear weaker than intended. (Think faded skies.)
For its part, digital carries just ones and zeros. In HDMI, if the signal voltage is high, it encodes a one; if low, a zero. The voltage encoded as a one can drop a fair amount and still be distinguishable from voltage encoded as a zero. After a certain point, however, the signal voltage drops so low that ones and zeros look alike, and the TV's receiver chip attempts to guess their value. So rather than gradually diminishing in accuracy, the way an analog signal does, a digital signal may remain perfect up to a critical level and then fail catastrophically. According to the experts, such problems are likelier to occur with an 8- to 12-meter copper cable (which is significantly longer than most users need) than with a 4-meter cable of the same type.