Squeaky Floorboard

There’s occasional talk about an audio system’s noise floor. You may hear someone claim a new component, or set of wires, or whatever, has lowered their noise floor to provide a “darker background,” or an “inky blackness.”

rhetoric

No doubt, noise is distortion. No doubt, I’m a freak about distortion. No doubt, a lower noise floor is better. No doubt, the noise floor on my system is not so low. No doubt, as high as it is, no one who has listened to my system, and listened critically, has ever mentioned the noise level, or even noticed it. And yet, I can lower the noise floor easily.

Let’s back up. There are two noise floors to consider. First is the electrical noise floor that makes its way through to the speakers. In most cases, what you’ll hear through a speaker is nada. However, my system, and plenty of others, are noisy enough to hear. If you get close to the tweeter, you’ll hear a little hiss. As you back away from the speaker the slight hiss quickly disappears. At the listening position it’s meaningless simply because of the other noise floor. So, reducing the electrical noise to “inky blackness” is nice, but inconsequential, and as we shall see, inaudible at your listening position.

astronomy

The second noise floor is your room. Generally it’s much higher than you might suspect. Most rooms have a noise floor that’s easily 35-40 dB. My dedicated listening room is about 31.5 dB (29 dB A weighted). That low number is because it’s in the basement and insulated with rock wool. But that number could be reduced by 1.5 dB. That may not sound like much until you realize all the reduction is above 200 Hz, and clearly audible throughout the room. The extra noise is from the amps’ fans. They could be disconnected to effectively and audibly lower the room’s noise floor. Does it bother me? Sometimes. When there’s a soft-soft passage, at the end of a fade-out, between cuts, I hear it. It doesn’t belong there, and I’d rather not hear it. Why haven’t I disconnected the fans? The amps also have a number of lights, bright flashing lights. The room is used also for movies, and the amps are up front. Those lights are distracting, so the amps have been covered. The cover, though, partially restricts airflow for cooling. Natural convection would be okay if it weren’t for the cover, so the fans are left running. The cover is 6mm industrial felt, which is heavy enough to absorb some of the fan noise. Without the felt, noise reaches 33 dB (another 1.5 dB), and the peak frequency is close to 1 kHz. That frequency is very audible. Fortunately, the peak is well absorbed by the felt.

arithmetic

Still, this raises a question. If the room’s noise floor, under really good conditions, is around 30 dB, what’s the point of reducing the system’s electrical noise floor when it isn’t even audible more than a few centimeters from the speakers?

Let’s get real. The “inky blackness,” that “darker background,” is so far below your ambient noise level, you couldn’t hear the difference if it went up or down by an order of magnitude. No power cord, no interconnect, no speaker wire, no power conditioner is going to have any meaningful effect, no matter how much you pay, or how much the manufacturer promises. The benefit is nada. Fix the squeaky floorboard. That you’ll hear.