The storage debate

I wrote in yesterday's post about the difference in sound quality when switching to battery power; a difference that was not complimentary to the music. I didn't realize the level of passion for batteries that would stir so many comments in emails to me; everything from "batteries suck" to "there is nothing better". After thinking about this for a bit I am convinced a blanket statement about battery power is inappropriate. For, like any technology, it really depends on the implementation. At their heart all audio equipment run on battery power. By that I mean DC which is what a battery puts out. Every DAC, computer, power amp, preamp etc. runs on (essentially) battery power. Typically we convert the AC in the wall to this needed DC for our equipment, but that process happens not because it's better but because it's more convenient. Had Nikola Tesla failed and Thomas Edison succeeded, we might have DC coming out of our home's wall sockets in the first place. But I digress. Because all equipment runs on DC and that is what both a battery as well as a power supply provides to our equipment, why do they sound different? In a power supply we do our best to make it clean, to remove any vestige of the original AC. In other words, we work hard to make it look like the output of a battery. But there's more going on than just keeping it clean and this difference is impedance. And I think impedance gets to the core of these differences. Impedance is the ability of a device to deliver power without changing its level. If a power supply or battery is providing 12 volts DC to your circuit and that circuit demands more power, the ability of either supply to maintain that 12 volt level is what determines its impedance. In the same way your bathroom lights dim a little when the hair dryer switches on, if the impedance of the supply is high, the level will drop when the demand for power goes up and vice versa. Where it gets tricky for sound quality is two fold: dynamic power demands and minute impedance differences. Both are important to the sound quality and both are lumped into the low or high impedance category. Here's the bottom line: a big battery supply, one that uses many batteries in parallel to achieve low output impedance and improve power demand, will sound significantly better than a single battery; like the one found in your laptop. Power supplies are critical to sound quality. It's why a Power Plant, which lowers the output impedance of your AC wall socket by several magnitudes, works such wonders on sound quality. And it's why some battery supplies sound better than some AC supplies and others sound worse.