Power supply madness

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The story behind PS Audio introducing the high-end world to the oversized external power supply is a good one that I cover in this video.

But that was more than 40 years ago. Is power supply “overkill” still a factor after four decades? Indeed it is. And for good reason.

In the early days of audio design, the power supply was considered secondary to the amplifier itself: a necessary hassle designed to meet the minimum requirements and not much else. The magic of sound was thought to be in the amplifier itself, not the lonely power supply converting the wall voltage to something useful.

Over the years it became apparent that changes to the power supply had unexpected benefits to the quality of music’s reproduction. The first I ever heard about power supplies affecting sound quality was in early 1974 when it was suggested that placing a small 1/10th of a microfarad capacitor in parallel with a large electrolytic capacitor made an immediate improvement to sound quality. Transients were quicker, the music more open and alive—as if a veil had been removed from the speakers.

This first technique, known as bypassing, is still in use today. Look at any one of our circuit boards and you’ll note that every single electrolytic on the board has been bypassed with a small capacitor—the type and size chosen for the specific circuit application. Bypass capacitors improve the high-frequency performance of their more sluggish electrolytic mates. Bypassing is but the tip of the power supply iceberg.

Today we understand the power supply is as important to the circuit’s performance as the circuit itself. In fact, some designers (including myself) often place a greater level of importance to the power supply than the amplification circuit it feeds.

After all, an amplifier’s only job is to modulate the power supply in cadence with the music. Get the power supply perfected and everything else has a better chance at getting the music right.