Why do speakers hiss? It doesn't seem like too much to ask that they just stay quiet if you're
not trying to put any sound through them at the moment, but too often you hear unpleasant static
if the volume is turned up with nothing playing. Is there a single cause of this? Like a malevolent
spirit haunting your home theater? It turns out there are lots of reasons for the familiar hiss,
so we're going to explain some of the more common ones. First off, let's talk about issues with
the amplifier. The component that takes an incoming audio signal and, well, amplifies it up to the
point it can drive your speakers. Without an amplifier, your speakers wouldn't generate noise,
but unfortunately many amplifiers don't just amplify the sounds you want. Some cheap amplifiers
produce hiss for two reasons. One, they're amplifying electrical noise at their input even
if you're not playing anything at the moment, and they're adding their own noise. This can be
easy to hear for yourself on inexpensive speakers with built-in amplifiers. These are the ones that
might have volume control on the speaker itself, and although when something is playing, it can be
too quiet to notice, but you often do hear it if you turn the volume up when nothing's playing.
Typically, you can reduce or eliminate this kind of hissing by switching to a better quality,
lower noise amplifier. Although a separate external amp and a pair of passive speakers can be a
relatively safe bet, there are active speakers with built-in amps that are also very good at
staying silent. You just have to make sure you're buying good quality equipment, so be sure to read
reviews. Unfortunately, most manufacturers don't give a clear spec showing how much noise to expect
at a certain distance, but a small handful do. Another common source of noise is called a ground
loop, and this is not an organic cereal that tastes like cardboard. Now, this can happen
when you have two pieces of equipment plugged into separate wall outlets.
Then, you connect those two devices together with a single cable, think an audio source like a
computer connected to an external set of speakers. That signal cable effectively closes a loop between
the speakers and the audio source, as you can see in this diagram. Once a ground loop is formed,
it's easy for electricity to start flowing through it in some undesirable ways due to the magnetic
fields generated by the building's electrical wiring, and this can manifest as an undesirable hum
in your speakers. I've had this, it sucks. Fortunately, there's a fairly easy way to
make ground loops far smaller to the point you probably won't hear any noise. Try connecting
everything to the same outlet with a power strip. Even though lots of consumer-grade audio products
are shielded against radio frequency interference, this can still be a problem if the shielding
isn't done quite correctly. The input and output connectors can be especially vulnerable to RF
interference, which can be generated by everything from Bluetooth devices to dimmer switches,
with the latter being a famous source of interference for home theater enthusiasts.
That wasn't my problem, though. Solving this kind of problem is a little bit more difficult,
as it might take some trial and error to find the problematic piece of equipment that's either
creating interference or receiving too much of it. Sometimes, you can fix the problem simply by placing
separate pieces of equipment farther away from each other, and there are also RF-filtering
products you can buy if the problem is really bad, like you have an inconsiderate neighbor with
a ham radio. But now, we're going to talk about a wonderful kind of hissing that can happen,
even if there's nothing physically wrong with your setup. Although we're used to listening
to music digitally these days, vinyl is making a comeback, and I know plenty of our older viewers
still have a cassette tape collection. These media tend to be physically noisy formats,
so you'll hear many of the small imperfections in the tape or the vinyl record itself.
And though some listeners prefer the warmer sound of vinyl, many dislike how much crackling or
hissing they can hear when listening to old-school audio. You can even hear this sometimes on old
recordings that have been digitized. Because this extra noise is a natural consequence of
playing back vinyl, it's very difficult to eliminate completely. But well-made equipment
that isn't loose or wobbly and is kept clean is a great start, and if you're talking about
turntables, using anti-vibration pads is also helpful. If you really want to try and cut down
on additional noise, there are post-processing solutions out there that try and clean up the
signal, though of course, these use digital algorithms. Don't want to throw the baby out
with the bathwater. And speaking of out, we're out of time, but we know there are other things
that can make for unwanted speaker hiss, such as electrical noise inside of an older PC.
So go check out our other video on external DACs and amps, and leave a comment if you've ever had
some kind of unexpected interference. Make your speakers sound like they were possessed by demons.