In yesterday's post I described what I consider to be the real problems of power–the ones that have the greatest sonic impact. Not the noise, but the dynamic reductions of voltage and the flat topped AC sine wave; the shape that robs our systems of needed power.
Armed with this information, the story of how I hoped to fix these problems now makes a bit more sense to tell.
In 1997 I furrowed my brow with a problem that really made no sense. Why was it that every power conditioner I tried made things both better and worse? Without exception, adding any kind of noise filter to the AC power gave me immediate benefits of cleaner sound, and blacker backgrounds. But, within minutes of listening, I also noticed that I had been robbed! Like a con artist who first succeeds by making you feel good - only to discover you're missing your watch. Dynamics, and in particular, upper harmonics that give the life and and openness to music were gone! Vanished. The sound was now sterile - overly cleansed if you will. As soon as I removed the power filter, the dynamics and life came back to the music - but it was dirtier too.
Intellectually I understood that removing power line noise was a good thing - and you could hear its benefits. So it seemed obvious to me that fixing one thing must be breaking something else. This happens often in electronic design. We add one element to the chain, perhaps a certain transistor that has a warmth to its sound, only to discover that added warmth came to us at a high price: loss of detail. And so, knowing something else was going on with power filters, I set out to discover what might be the problem. It didn't take me too long to figure it out. Doing something about what the problem was, well, that's another matter altogether.
The one thing common to all power filters is impedance. Impedance equals restriction. Using our water analogy, impedance is that which restricts flow, like a thinner pipe. Large diameter pipes have less "impedance" or, better put, "resistance". A resistor is an electronic component used in every circuit in your stereo system. Resistors do what their name implies.
Imagine a power amplifier with its massive power supply of high voltage and lots of potential energy just sitting there waiting for you to unleash it. But it's not valuable to dump all of it at the same time. We want to parse it out as needed, and this is where resistors are valuable. We use resistors throughout our circuits to dole out voltage from the supply to where it is needed and in exactly the right volume. But resistance is NOT what we want when it comes to the main artery feeding our systems - your home's AC power.
Tomorrow I'll try and explain the difference between resistance and impedance. Wish me luck.
