WEBVTT 00:00:00.000 --> 00:00:04.800 Why do speakers hiss? It doesn't seem like too much to ask that they just stay quiet if you're 00:00:04.800 --> 00:00:09.200 not trying to put any sound through them at the moment, but too often you hear unpleasant static 00:00:09.200 --> 00:00:14.160 if the volume is turned up with nothing playing. Is there a single cause of this? Like a malevolent 00:00:14.160 --> 00:00:19.200 spirit haunting your home theater? It turns out there are lots of reasons for the familiar hiss, 00:00:19.200 --> 00:00:23.760 so we're going to explain some of the more common ones. First off, let's talk about issues with 00:00:23.760 --> 00:00:30.080 the amplifier. The component that takes an incoming audio signal and, well, amplifies it up to the 00:00:30.080 --> 00:00:34.880 point it can drive your speakers. Without an amplifier, your speakers wouldn't generate noise, 00:00:34.880 --> 00:00:40.880 but unfortunately many amplifiers don't just amplify the sounds you want. Some cheap amplifiers 00:00:40.880 --> 00:00:45.360 produce hiss for two reasons. One, they're amplifying electrical noise at their input even 00:00:45.360 --> 00:00:50.560 if you're not playing anything at the moment, and they're adding their own noise. This can be 00:00:50.560 --> 00:00:55.440 easy to hear for yourself on inexpensive speakers with built-in amplifiers. These are the ones that 00:00:55.440 --> 00:01:00.320 might have volume control on the speaker itself, and although when something is playing, it can be 00:01:00.320 --> 00:01:05.840 too quiet to notice, but you often do hear it if you turn the volume up when nothing's playing. 00:01:05.840 --> 00:01:10.880 Typically, you can reduce or eliminate this kind of hissing by switching to a better quality, 00:01:10.880 --> 00:01:16.480 lower noise amplifier. Although a separate external amp and a pair of passive speakers can be a 00:01:16.480 --> 00:01:22.160 relatively safe bet, there are active speakers with built-in amps that are also very good at 00:01:22.160 --> 00:01:27.200 staying silent. You just have to make sure you're buying good quality equipment, so be sure to read 00:01:27.200 --> 00:01:32.720 reviews. Unfortunately, most manufacturers don't give a clear spec showing how much noise to expect 00:01:32.720 --> 00:01:37.840 at a certain distance, but a small handful do. Another common source of noise is called a ground 00:01:37.840 --> 00:01:43.120 loop, and this is not an organic cereal that tastes like cardboard. Now, this can happen 00:01:43.200 --> 00:01:47.680 when you have two pieces of equipment plugged into separate wall outlets. 00:01:47.680 --> 00:01:52.240 Then, you connect those two devices together with a single cable, think an audio source like a 00:01:52.240 --> 00:01:58.240 computer connected to an external set of speakers. That signal cable effectively closes a loop between 00:01:58.240 --> 00:02:03.920 the speakers and the audio source, as you can see in this diagram. Once a ground loop is formed, 00:02:03.920 --> 00:02:09.440 it's easy for electricity to start flowing through it in some undesirable ways due to the magnetic 00:02:09.440 --> 00:02:15.680 fields generated by the building's electrical wiring, and this can manifest as an undesirable hum 00:02:15.680 --> 00:02:20.400 in your speakers. I've had this, it sucks. Fortunately, there's a fairly easy way to 00:02:20.400 --> 00:02:25.360 make ground loops far smaller to the point you probably won't hear any noise. Try connecting 00:02:25.360 --> 00:02:30.480 everything to the same outlet with a power strip. Even though lots of consumer-grade audio products 00:02:30.480 --> 00:02:35.600 are shielded against radio frequency interference, this can still be a problem if the shielding 00:02:35.600 --> 00:02:41.360 isn't done quite correctly. The input and output connectors can be especially vulnerable to RF 00:02:41.360 --> 00:02:45.920 interference, which can be generated by everything from Bluetooth devices to dimmer switches, 00:02:45.920 --> 00:02:49.600 with the latter being a famous source of interference for home theater enthusiasts. 00:02:49.600 --> 00:02:52.960 That wasn't my problem, though. Solving this kind of problem is a little bit more difficult, 00:02:52.960 --> 00:02:56.640 as it might take some trial and error to find the problematic piece of equipment that's either 00:02:56.640 --> 00:03:01.280 creating interference or receiving too much of it. Sometimes, you can fix the problem simply by placing 00:03:01.360 --> 00:03:05.600 separate pieces of equipment farther away from each other, and there are also RF-filtering 00:03:05.600 --> 00:03:10.160 products you can buy if the problem is really bad, like you have an inconsiderate neighbor with 00:03:10.160 --> 00:03:14.400 a ham radio. But now, we're going to talk about a wonderful kind of hissing that can happen, 00:03:14.400 --> 00:03:20.160 even if there's nothing physically wrong with your setup. Although we're used to listening 00:03:20.160 --> 00:03:25.360 to music digitally these days, vinyl is making a comeback, and I know plenty of our older viewers 00:03:25.360 --> 00:03:30.000 still have a cassette tape collection. These media tend to be physically noisy formats, 00:03:30.000 --> 00:03:34.960 so you'll hear many of the small imperfections in the tape or the vinyl record itself. 00:03:34.960 --> 00:03:40.240 And though some listeners prefer the warmer sound of vinyl, many dislike how much crackling or 00:03:40.240 --> 00:03:44.640 hissing they can hear when listening to old-school audio. You can even hear this sometimes on old 00:03:44.640 --> 00:03:49.120 recordings that have been digitized. Because this extra noise is a natural consequence of 00:03:49.120 --> 00:03:53.680 playing back vinyl, it's very difficult to eliminate completely. But well-made equipment 00:03:53.680 --> 00:03:58.800 that isn't loose or wobbly and is kept clean is a great start, and if you're talking about 00:03:58.800 --> 00:04:05.280 turntables, using anti-vibration pads is also helpful. If you really want to try and cut down 00:04:05.280 --> 00:04:09.760 on additional noise, there are post-processing solutions out there that try and clean up the 00:04:09.760 --> 00:04:14.160 signal, though of course, these use digital algorithms. Don't want to throw the baby out 00:04:14.160 --> 00:04:18.480 with the bathwater. And speaking of out, we're out of time, but we know there are other things 00:04:18.480 --> 00:04:22.960 that can make for unwanted speaker hiss, such as electrical noise inside of an older PC. 00:04:22.960 --> 00:04:27.520 So go check out our other video on external DACs and amps, and leave a comment if you've ever had 00:04:27.520 --> 00:04:32.480 some kind of unexpected interference. Make your speakers sound like they were possessed by demons.