In yesterday's post, we discussed how balanced vs. single ended signals work. But what we are going to touch on today is where size matters.
Balanced is important to small signals, but not so much for big signals.
We engineers like to throw around terms like “small signal” and “big signal,” but what do they actually mean?
A small signal is exactly what it sounds like—tiny. The output of a phono cartridge, for example, might be just a few millivolts. Even a DAC or preamp output is only around 1 or 2 volts. These are the whisper-level signals in our systems, and they’re fragile. Like trying to whisper across a noisy room and hoping someone hears you clearly.
Big signals are what come out of a power amplifier. By then, the signal’s been bulked up—voltages jump to 30, 40, even 60 volts, and current can surge into the tens of amps. Big signals are what drive loudspeakers and move air. They’re robust, powerful, and much harder to mess with.
Here’s why the distinction matters.
Small signals are vulnerable. Because their amplitude is low, they’re easily corrupted by noise—RF from a smartphone, hum from a nearby transformer, or EMI from a switching power supply. That’s why we work so hard to keep small signal paths clean, short, and—when possible—balanced.
Balanced interconnects with good CMR (common mode rejection) make a night-and-day difference at this stage. They reject the garbage and let the music through.
But once the signal gets big, that vulnerability fades. A 100-watt signal driving a speaker doesn’t care if there’s a few millivolts of noise hitching a ride—it’s like trying to steer a freight train with a feather.
So, while balanced connections can still exist in the big signal world, they’re no longer the heroes they were in the small signal domain.
Next time, I’ll explain exactly why balanced stops mattering when we get to power amps and speakers.
