I’ll admit that last week’s column was pretty nerdy. There are some who couldn’t care less how technology around us works, and many who are adept at operating with high-precision tech say they don’t fully understand.
But some folks out there are like me and ask the question, “How does it work?” — partly from curiosity, but also because finding out how things work pays real dividends in life.
The concept of buy low and sell high is widely understood. But think about it — that’s saying that the price for something isn’t the cost, if you’re doing it right.
Salespeople know that everything around us has a cost and a price, and depending on what it is, the difference between those two can be large.
But finding out what actually goes into a commodity can reveal the cost-price difference and shed light on the origin of the cost. For a big purchase like an entertainment system or a serious audiophile multi-component setup, that’s an important revelation indeed.
If you find out, for example, that an expensive amplifier uses a $0.50 part in its driver stage when it could use a $20 one for better sound, while obviously spending extra money to construct the box out of pure titanium or whatever, you get a better picture of what you’re buying.
Knowledge is power. So I continue the amplifier discussion today to talk about power supplies, with apologies to the folks who stay out of the “how it works” realm.
Amplifiers turn wall power into loud music. They use the original music signal — your phone or TV or whatever — as a guide to modulate the wall power up and down to create loud music.
How the wall power reaches the amp is split into two methods: linear power supplies or switch-mode power supplies. Each has a sonic effect, and they’re easily differentiated by weight.
If you pick up an amp and it weighs a lot, it’s got a good old linear supply. That means it’s dealing with the wall power as it is — at 60 Hz (the “refresh rate” of alternating current or AC coming from the wall) — and at that speed, the current draw is considerable. It’s old fashioned, it sounds the best, but it’s also heavy, runs hot and isn’t very practical for anything remotely portable.
Newer power technology is called switch-mode, which is best recognized in the form of “wall warts,” which are those big black blocks you plug into the wall for things like TV antennas or phone chargers. Laptop power bricks are the same thing.
These increase the speed of the power wave to something really high, like 80,000 Hz. At this speed, the current needed for a supply like this is a lot less, so the big heavy iron-based transformers of the linear power supply are traded for tiny little featherweight transformers in the switch-mode.
The benefits are obvious: it’s small, light, cool. The downsides, however, are being understood better as time goes on, and good engineers are trying to fix what these little switchers screw up. More next week.