1 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 2 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 3 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 4 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, 5 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 6 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 7 00:00:30,080 --> 00:00:34,880 point it can drive your speakers. Without an amplifier, your speakers wouldn't generate noise, 8 00:00:34,880 --> 00:00:40,880 but unfortunately many amplifiers don't just amplify the sounds you want. Some cheap amplifiers 9 00:00:40,880 --> 00:00:45,360 produce hiss for two reasons. One, they're amplifying electrical noise at their input even 10 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 11 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 12 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 13 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. 14 00:01:05,840 --> 00:01:10,880 Typically, you can reduce or eliminate this kind of hissing by switching to a better quality, 15 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 16 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 17 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 18 00:01:27,200 --> 00:01:32,720 reviews. Unfortunately, most manufacturers don't give a clear spec showing how much noise to expect 19 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 20 00:01:37,840 --> 00:01:43,120 loop, and this is not an organic cereal that tastes like cardboard. Now, this can happen 21 00:01:43,200 --> 00:01:47,680 when you have two pieces of equipment plugged into separate wall outlets. 22 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 23 00:01:52,240 --> 00:01:58,240 computer connected to an external set of speakers. That signal cable effectively closes a loop between 24 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, 25 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 26 00:02:09,440 --> 00:02:15,680 fields generated by the building's electrical wiring, and this can manifest as an undesirable hum 27 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 28 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 29 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 30 00:02:30,480 --> 00:02:35,600 are shielded against radio frequency interference, this can still be a problem if the shielding 31 00:02:35,600 --> 00:02:41,360 isn't done quite correctly. The input and output connectors can be especially vulnerable to RF 32 00:02:41,360 --> 00:02:45,920 interference, which can be generated by everything from Bluetooth devices to dimmer switches, 33 00:02:45,920 --> 00:02:49,600 with the latter being a famous source of interference for home theater enthusiasts. 34 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, 35 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 36 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 37 00:03:01,360 --> 00:03:05,600 separate pieces of equipment farther away from each other, and there are also RF-filtering 38 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 39 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, 40 00:03:14,400 --> 00:03:20,160 even if there's nothing physically wrong with your setup. Although we're used to listening 41 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 42 00:03:25,360 --> 00:03:30,000 still have a cassette tape collection. These media tend to be physically noisy formats, 43 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. 44 00:03:34,960 --> 00:03:40,240 And though some listeners prefer the warmer sound of vinyl, many dislike how much crackling or 45 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 46 00:03:44,640 --> 00:03:49,120 recordings that have been digitized. Because this extra noise is a natural consequence of 47 00:03:49,120 --> 00:03:53,680 playing back vinyl, it's very difficult to eliminate completely. But well-made equipment 48 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 49 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 50 00:04:05,280 --> 00:04:09,760 on additional noise, there are post-processing solutions out there that try and clean up the 51 00:04:09,760 --> 00:04:14,160 signal, though of course, these use digital algorithms. Don't want to throw the baby out 52 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 53 00:04:18,480 --> 00:04:22,960 that can make for unwanted speaker hiss, such as electrical noise inside of an older PC. 54 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 55 00:04:27,520 --> 00:04:32,480 some kind of unexpected interference. Make your speakers sound like they were possessed by demons.