1 00:00:04,400 --> 00:00:07,800 Speaker 1: Welcome to tech Stuff, a production from I Heart Radio. 2 00:00:12,000 --> 00:00:14,560 Speaker 1: Hey there, and welcome to tech Stuff. I'm your host 3 00:00:14,760 --> 00:00:17,160 Speaker 1: job in Strickland. I'm an executive producer with I Heart 4 00:00:17,239 --> 00:00:21,840 Speaker 1: Radio and How the Tech are You? I am working 5 00:00:22,120 --> 00:00:24,880 Speaker 1: right now on a couple of things. When I'm working 6 00:00:24,920 --> 00:00:28,920 Speaker 1: on getting over COVID, I'm almost there, not quite there, 7 00:00:29,240 --> 00:00:31,760 Speaker 1: but I'm getting there. And the other thing I'm working 8 00:00:31,800 --> 00:00:35,040 Speaker 1: on is an episode about a company called San Sui 9 00:00:35,520 --> 00:00:39,080 Speaker 1: that is a or was rather a company that made 10 00:00:39,600 --> 00:00:43,480 Speaker 1: audio equipment like amplifiers and receivers and stuff like that. 11 00:00:44,400 --> 00:00:46,040 Speaker 1: But as I was doing it, I felt like I 12 00:00:46,080 --> 00:00:50,240 Speaker 1: was retreading some ground on a on a previous episode 13 00:00:50,240 --> 00:00:54,880 Speaker 1: called how Speakers and Amplifiers Work? And I thought, why 14 00:00:54,960 --> 00:01:00,680 Speaker 1: not have that episode play out? And then next week's 15 00:01:00,720 --> 00:01:05,240 Speaker 1: Monday's episode will be about San Sui, and I won't 16 00:01:05,280 --> 00:01:07,600 Speaker 1: have to to cover quite as much of the same 17 00:01:07,720 --> 00:01:09,920 Speaker 1: territory again. I can focus more on the company in 18 00:01:09,959 --> 00:01:13,440 Speaker 1: its history because y'all know me. Y'all know that if 19 00:01:13,480 --> 00:01:16,800 Speaker 1: I start talking about a company that makes a certain 20 00:01:16,880 --> 00:01:19,080 Speaker 1: kind of tech or sort of a product that features 21 00:01:19,080 --> 00:01:22,600 Speaker 1: certain tech, I'll end up talking about how the tech 22 00:01:23,040 --> 00:01:25,240 Speaker 1: came about what it does all that kind of stuff, 23 00:01:25,720 --> 00:01:28,560 Speaker 1: but I've already done that. So we're gonna listen to 24 00:01:28,600 --> 00:01:32,759 Speaker 1: this episode how speakers and amplifiers work, and I'll be 25 00:01:32,800 --> 00:01:37,040 Speaker 1: back at the end to kind of tease next week's 26 00:01:37,200 --> 00:01:41,760 Speaker 1: episode on this topic. But sit back and enjoy this 27 00:01:41,800 --> 00:01:46,720 Speaker 1: classic episode. Today we are going to continue our episodes 28 00:01:46,760 --> 00:01:50,040 Speaker 1: about how speakers work and how they are able to 29 00:01:50,120 --> 00:01:54,000 Speaker 1: take electricity and make those sweet, sweet sounds for your 30 00:01:54,080 --> 00:01:57,520 Speaker 1: ear holes. So let us jump back with a quick 31 00:01:57,560 --> 00:02:01,919 Speaker 1: explanation of the electro magna at is um. So, electricity 32 00:02:01,920 --> 00:02:05,320 Speaker 1: and magnetism are very closely related, and you've likely done 33 00:02:05,320 --> 00:02:09,200 Speaker 1: the simple physics exercise of creating a basic electro magnet. 34 00:02:09,639 --> 00:02:12,440 Speaker 1: So you'll take something like an iron nail and you'll 35 00:02:12,480 --> 00:02:16,280 Speaker 1: wrap insulated copper wire in a coil around the nails 36 00:02:16,320 --> 00:02:20,480 Speaker 1: several times. The nail acts as a ferromagnetic core. The 37 00:02:20,520 --> 00:02:24,440 Speaker 1: copper wire coil is a conductor, so connecting the ends 38 00:02:24,440 --> 00:02:27,799 Speaker 1: of the copper wire to a battery will then allow 39 00:02:27,880 --> 00:02:31,720 Speaker 1: current to flow through the wire. Middle flow from one 40 00:02:31,800 --> 00:02:34,640 Speaker 1: end of the battery through the wire down into the 41 00:02:34,680 --> 00:02:37,560 Speaker 1: other end of the battery. As it goes around this coil, 42 00:02:37,840 --> 00:02:41,480 Speaker 1: the flow of electricity creates a magnetic field, the nail 43 00:02:41,639 --> 00:02:45,240 Speaker 1: and coil will behave like a permanent magnet. Would it's 44 00:02:45,240 --> 00:02:47,480 Speaker 1: an electro magnet, but it will behave like a permanent 45 00:02:47,520 --> 00:02:50,440 Speaker 1: magnet with a north pole and a south pole. And 46 00:02:50,440 --> 00:02:52,959 Speaker 1: if you brought it close to a permanent magnet, then 47 00:02:53,040 --> 00:02:56,720 Speaker 1: the opposite poles would attract each other and the similar 48 00:02:56,720 --> 00:02:58,920 Speaker 1: poles would repel each other. So if you brought the 49 00:02:58,919 --> 00:03:02,079 Speaker 1: electromagnets more poll next to a permanent magnets north pole, 50 00:03:02,120 --> 00:03:05,400 Speaker 1: it would push that other magnet away and the polls 51 00:03:05,440 --> 00:03:10,240 Speaker 1: will not change. Because the source of electricity is a battery, 52 00:03:10,520 --> 00:03:14,240 Speaker 1: and batteries provide direct current, which means the current is 53 00:03:14,280 --> 00:03:17,480 Speaker 1: always going to flow in the same direction. It's never 54 00:03:17,560 --> 00:03:21,480 Speaker 1: going to reverse. But if you hooked the same nail 55 00:03:21,600 --> 00:03:25,480 Speaker 1: and coil up to a source of alternating current, things 56 00:03:25,480 --> 00:03:29,640 Speaker 1: would be very different. With alternating current, the direction of 57 00:03:29,680 --> 00:03:34,400 Speaker 1: the flow of electricity changes rapidly every second, and as 58 00:03:34,440 --> 00:03:38,280 Speaker 1: the direction of electricity changes, it affects the magnetic field. 59 00:03:38,600 --> 00:03:41,080 Speaker 1: With electricity flowing in one direction, the head of the 60 00:03:41,160 --> 00:03:44,320 Speaker 1: nail might represent the north pole of the magnet, and 61 00:03:44,360 --> 00:03:47,280 Speaker 1: when the electricity switches to the other direction, the head 62 00:03:47,280 --> 00:03:49,960 Speaker 1: of the nail will become the south pole of the magnet, 63 00:03:50,160 --> 00:03:54,160 Speaker 1: and vice versa. You have created a fluctuating magnetic field 64 00:03:54,320 --> 00:03:58,160 Speaker 1: by running an alternating current through an electro magnet, and 65 00:03:58,200 --> 00:04:01,080 Speaker 1: you can do some pretty cool stuff with a fluctuating 66 00:04:01,120 --> 00:04:04,800 Speaker 1: magnetic field. For example, if you bring this apparatus close 67 00:04:04,840 --> 00:04:09,440 Speaker 1: to a conductive material, you'll induce a change of voltage 68 00:04:09,840 --> 00:04:14,080 Speaker 1: in that material, even without making physical contact between the two. 69 00:04:14,480 --> 00:04:17,240 Speaker 1: So if you do this with a stable magnetic field, 70 00:04:17,720 --> 00:04:20,479 Speaker 1: all you'll do is see a very short spike, but 71 00:04:20,520 --> 00:04:23,680 Speaker 1: then it stops because the magnetic field is not fluctuating. 72 00:04:24,080 --> 00:04:27,640 Speaker 1: To induce electricity to flow by changing voltage in this 73 00:04:27,720 --> 00:04:32,279 Speaker 1: other conductor, the magnetic field has to be fluctuating, or 74 00:04:32,360 --> 00:04:34,000 Speaker 1: the conductor has to be moving in and out of 75 00:04:34,040 --> 00:04:37,599 Speaker 1: the magnetic field constantly. If you get two coils of 76 00:04:37,680 --> 00:04:41,000 Speaker 1: copper wire and you make sure the second copper wire 77 00:04:41,160 --> 00:04:44,600 Speaker 1: has twice as many coils as the first one, you 78 00:04:44,640 --> 00:04:48,679 Speaker 1: can create a transformer. So imagine you've got your first 79 00:04:48,720 --> 00:04:51,880 Speaker 1: coil of wire. Let's say it's got ten coils ten 80 00:04:52,040 --> 00:04:55,960 Speaker 1: ten loops around its core, and you've got a second 81 00:04:56,200 --> 00:05:00,400 Speaker 1: core with copper wire, but there are twenty loops around 82 00:05:00,560 --> 00:05:03,800 Speaker 1: the second core if you run a current through the 83 00:05:03,839 --> 00:05:08,000 Speaker 1: first coil, it will induce current to flow through the 84 00:05:08,040 --> 00:05:12,479 Speaker 1: second coil. Moreover, the voltage in the second coil will 85 00:05:12,480 --> 00:05:16,000 Speaker 1: be higher than the voltage in the first coil because 86 00:05:16,160 --> 00:05:19,599 Speaker 1: the second coil has twice as many coils as the 87 00:05:19,640 --> 00:05:23,320 Speaker 1: first one. So the more times you loop a wire 88 00:05:23,440 --> 00:05:27,760 Speaker 1: around a core, the greater the change of voltage is 89 00:05:27,800 --> 00:05:32,160 Speaker 1: going to be between coil number one and coil number two. 90 00:05:32,560 --> 00:05:35,479 Speaker 1: This particular version of a transformer would be called a 91 00:05:35,560 --> 00:05:39,960 Speaker 1: step up transformer because the secondary coil has more turns 92 00:05:40,040 --> 00:05:43,400 Speaker 1: than the primary coil and steps up the voltage. If 93 00:05:43,440 --> 00:05:46,640 Speaker 1: the opposite were true, if coil number one had ten 94 00:05:46,720 --> 00:05:50,239 Speaker 1: coils or ten loops and coil number two had five loops, 95 00:05:50,680 --> 00:05:53,920 Speaker 1: then that would be a step down transformer. You would 96 00:05:54,000 --> 00:05:58,279 Speaker 1: lower the voltage from primary to secondary. Transformers are what 97 00:05:58,440 --> 00:06:03,000 Speaker 1: made alternating current the more viable solution to supplying electricity 98 00:06:03,040 --> 00:06:06,200 Speaker 1: to homes and businesses back in the early days. Because 99 00:06:06,839 --> 00:06:10,600 Speaker 1: transmitting electricity was all about efficiency. How could you efficiently 100 00:06:10,640 --> 00:06:14,039 Speaker 1: get electricity from a power plant to where it needed 101 00:06:14,080 --> 00:06:17,240 Speaker 1: to be well? If you used alternating current, you could 102 00:06:17,240 --> 00:06:20,360 Speaker 1: create transformers and you could step up the voltage to 103 00:06:20,760 --> 00:06:24,800 Speaker 1: very high levels, and that meant that you could transmit 104 00:06:24,920 --> 00:06:29,560 Speaker 1: power across power lines much more efficiently. If you didn't 105 00:06:29,600 --> 00:06:32,640 Speaker 1: do that, you had so much power loss that you 106 00:06:32,680 --> 00:06:37,080 Speaker 1: would have to have lots of different power generators throughout 107 00:06:37,080 --> 00:06:40,000 Speaker 1: the region in order to supply all the power needs 108 00:06:40,080 --> 00:06:42,200 Speaker 1: of your area, at least back in the old days 109 00:06:42,240 --> 00:06:44,520 Speaker 1: of direct current, because it wasn't easy to step up 110 00:06:44,560 --> 00:06:48,279 Speaker 1: the voltage. And again, high voltage makes it more efficient 111 00:06:48,320 --> 00:06:52,200 Speaker 1: to transmit power across long distances, so in the early days, 112 00:06:52,440 --> 00:06:55,159 Speaker 1: that's why a C went out over d C. These days, 113 00:06:55,360 --> 00:06:57,160 Speaker 1: you could actually do things a little differently if you 114 00:06:57,200 --> 00:07:00,640 Speaker 1: wanted to, and you could go with direct DC power 115 00:07:01,360 --> 00:07:03,360 Speaker 1: if you really wanted to, but it would require a 116 00:07:03,400 --> 00:07:06,800 Speaker 1: big overhaul of the infrastructure. But transformers made a C 117 00:07:07,080 --> 00:07:11,560 Speaker 1: much more practical anyway. Electromagnets are pretty awesome now. With speakers, 118 00:07:11,800 --> 00:07:15,040 Speaker 1: it's not so much about voltage and current as it 119 00:07:15,080 --> 00:07:17,720 Speaker 1: is about making the diaphragm of the speaker move in 120 00:07:17,800 --> 00:07:21,880 Speaker 1: precise ways. With speakers, the electrical current acts as both 121 00:07:21,920 --> 00:07:24,520 Speaker 1: the carrier of information and the means to make the 122 00:07:24,560 --> 00:07:28,640 Speaker 1: diaphragm move. So you start with a steady magnetic field 123 00:07:28,760 --> 00:07:33,040 Speaker 1: inside the basket You can create that steady magnetic field 124 00:07:33,480 --> 00:07:37,120 Speaker 1: either with permanent magnets like I mentioned before, or with 125 00:07:37,200 --> 00:07:40,240 Speaker 1: electro magnets, but it remains the same no matter what. 126 00:07:40,640 --> 00:07:42,400 Speaker 1: The north pole is always going to be the north pole. 127 00:07:42,440 --> 00:07:44,080 Speaker 1: The south pole is always going to be the south pole. 128 00:07:44,200 --> 00:07:48,000 Speaker 1: Inside the frame, that field does not change. The voice 129 00:07:48,000 --> 00:07:52,120 Speaker 1: coil on the cone ends up receiving the variable current 130 00:07:52,320 --> 00:07:56,520 Speaker 1: that came from the transmitter that represents the recorded sound. Now, 131 00:07:56,520 --> 00:07:59,840 Speaker 1: remember the way we record sound, as we typically will 132 00:08:00,120 --> 00:08:02,800 Speaker 1: something like a microphone, and a microphone is essentially a 133 00:08:02,840 --> 00:08:06,040 Speaker 1: speaker in reverse. A microphone has a diaphragm in it 134 00:08:06,360 --> 00:08:10,080 Speaker 1: that vibrates in the presence of sound waves. Those vibrations 135 00:08:10,320 --> 00:08:14,680 Speaker 1: cause fluctuations inside an electric current. You might vary the 136 00:08:14,760 --> 00:08:19,000 Speaker 1: resistance of the circuit, as we talked about with the 137 00:08:19,000 --> 00:08:24,200 Speaker 1: the old Johan Philip Rice approach, and by varying those 138 00:08:24,640 --> 00:08:27,880 Speaker 1: that electric resistance within the circuit, you can fluctuate the 139 00:08:27,920 --> 00:08:30,440 Speaker 1: electric current and then you can send that to a speaker, 140 00:08:30,880 --> 00:08:33,120 Speaker 1: though you would typically send it to an amplifier first, 141 00:08:33,120 --> 00:08:35,720 Speaker 1: but we'll talk about that in a minute. The speaker 142 00:08:35,800 --> 00:08:39,520 Speaker 1: then essentially reverses this process. It takes those fluctuations sends 143 00:08:39,559 --> 00:08:41,959 Speaker 1: them through an electro magnet, which will generate a variable 144 00:08:41,960 --> 00:08:45,679 Speaker 1: magnetic field in response, which then makes the cone vibrate 145 00:08:45,800 --> 00:08:48,520 Speaker 1: within the speaker and essentially do the opposite of what 146 00:08:48,559 --> 00:08:52,240 Speaker 1: the microphones diaphragm was doing and recreate the recorded sound. 147 00:08:52,720 --> 00:08:56,199 Speaker 1: It's pretty cool and pretty elegant, really. So the electrical 148 00:08:56,280 --> 00:09:00,280 Speaker 1: signal representing the recorded sound comes into the speaker, feeds 149 00:09:00,320 --> 00:09:03,360 Speaker 1: into the voice coil creates this fluctuating magnetic field. The 150 00:09:03,400 --> 00:09:06,560 Speaker 1: field interacts with the permanent magnetic field inside the basket, 151 00:09:06,840 --> 00:09:10,079 Speaker 1: either pulling the diaphragm forward in the basket and us 152 00:09:10,400 --> 00:09:14,800 Speaker 1: pushing air outward, or pulling the cone back towards the 153 00:09:14,840 --> 00:09:17,920 Speaker 1: back of the basket and allowing air to come further 154 00:09:18,040 --> 00:09:22,199 Speaker 1: in by creating that lower pressure. And these fluctuations happen 155 00:09:22,240 --> 00:09:25,880 Speaker 1: at high frequencies, so the diaphragm is moving very rapidly 156 00:09:25,920 --> 00:09:29,200 Speaker 1: inside the basket. It's not just pushing out then pulling in. 157 00:09:29,280 --> 00:09:32,400 Speaker 1: It's doing this hundreds or thousands of times per second, 158 00:09:32,760 --> 00:09:35,640 Speaker 1: and it increases or decreases the air pressure as the 159 00:09:35,640 --> 00:09:39,000 Speaker 1: cone pushes those air molecules or suddenly moves away, creating 160 00:09:39,000 --> 00:09:42,559 Speaker 1: more space for them. And because sound is vibration. Those 161 00:09:42,559 --> 00:09:45,640 Speaker 1: air molecules carry the sound up to our ears, and 162 00:09:45,679 --> 00:09:48,520 Speaker 1: then we rock out to a C d C or 163 00:09:48,520 --> 00:09:50,960 Speaker 1: whatever band you happen to like. That isn't nearly as 164 00:09:51,000 --> 00:09:54,439 Speaker 1: cool as a C d C. Now, keep in mind 165 00:09:54,840 --> 00:09:57,640 Speaker 1: what I have described is how a driver works. A 166 00:09:57,679 --> 00:10:00,760 Speaker 1: speaker can and often does have more than one driver, 167 00:10:01,160 --> 00:10:04,880 Speaker 1: and drivers come in different shapes, sizes, and purposes. So 168 00:10:05,240 --> 00:10:07,560 Speaker 1: let's talk a little bit about what those are and 169 00:10:07,600 --> 00:10:09,320 Speaker 1: what they do, and why you need to have different 170 00:10:09,320 --> 00:10:12,160 Speaker 1: ones in the first place. Actually, that last question is 171 00:10:12,200 --> 00:10:16,360 Speaker 1: the easiest answer right away. Remember again, sound is vibration, 172 00:10:16,679 --> 00:10:20,760 Speaker 1: and low frequency sounds have longer wave forms. The points 173 00:10:20,800 --> 00:10:24,040 Speaker 1: of high and low pressure are further apart from each 174 00:10:24,080 --> 00:10:27,000 Speaker 1: other than with high frequency sounds. If you could actually 175 00:10:27,080 --> 00:10:29,400 Speaker 1: see the changes in air pressure due to sound, you 176 00:10:29,400 --> 00:10:32,040 Speaker 1: would see that the low frequency sounds have these larger 177 00:10:32,120 --> 00:10:34,720 Speaker 1: gaps between the high and low pressure points in the 178 00:10:34,760 --> 00:10:37,120 Speaker 1: waves as they move out from the source of sound. 179 00:10:37,440 --> 00:10:40,480 Speaker 1: So you need a cone diaphragm that can vibrate at 180 00:10:40,480 --> 00:10:44,800 Speaker 1: a slower frequency and push air effectively at that speed. 181 00:10:45,160 --> 00:10:48,080 Speaker 1: For that reason, you would typically go with a heavier, 182 00:10:48,640 --> 00:10:53,079 Speaker 1: larger diaphragm, both because the wavelengths of sound are longer 183 00:10:53,400 --> 00:10:56,320 Speaker 1: if you're looking at the lower frequencies, and because making 184 00:10:56,320 --> 00:10:59,319 Speaker 1: the material heavy gives it greater inertia, it takes more 185 00:10:59,360 --> 00:11:01,560 Speaker 1: force to move of the diaphragm, and it will move 186 00:11:01,559 --> 00:11:04,200 Speaker 1: at a pace that will reproduce as low frequency sounds 187 00:11:04,240 --> 00:11:07,280 Speaker 1: you want. This type of speaker falls into the whooffer 188 00:11:07,720 --> 00:11:11,439 Speaker 1: or sub whiffer categories. These are the speakers that create 189 00:11:11,760 --> 00:11:15,520 Speaker 1: the base sounds. A sub whiffer tends to handle frequencies 190 00:11:15,559 --> 00:11:18,880 Speaker 1: from around twenty hurts to two hurts. Think of a 191 00:11:19,000 --> 00:11:22,199 Speaker 1: hurts as how long it takes a wave to pass 192 00:11:22,240 --> 00:11:25,360 Speaker 1: through a given point in one second, or how many 193 00:11:25,400 --> 00:11:28,160 Speaker 1: waves can pass through a given point in one second. 194 00:11:28,320 --> 00:11:30,559 Speaker 1: Al Right, guys, we got some more to chat about 195 00:11:30,559 --> 00:11:33,040 Speaker 1: with speakers. Before I jump into that, Let's take a 196 00:11:33,080 --> 00:11:43,400 Speaker 1: quick break to thank our sponsor. Human hearing ranges from 197 00:11:43,480 --> 00:11:47,120 Speaker 1: twenty hurts, which is twenty waves passing a given point 198 00:11:47,240 --> 00:11:51,240 Speaker 1: in one second, to twenty killer hurts or twenty thousand 199 00:11:51,400 --> 00:11:55,080 Speaker 1: waves passing through a point in one second. This really 200 00:11:55,080 --> 00:11:57,880 Speaker 1: tells you more about the wavelength of the wave itself 201 00:11:57,960 --> 00:12:01,560 Speaker 1: and thus the frequency and then the pitch. Remember, the 202 00:12:01,720 --> 00:12:05,360 Speaker 1: lower frequencies are the lower pitches. The higher frequencies are 203 00:12:05,360 --> 00:12:08,720 Speaker 1: the higher pitches, and that's the frequency range for typical 204 00:12:08,800 --> 00:12:11,760 Speaker 1: human hearing twenty hurts to twenty thousand hurts. Now, I 205 00:12:11,800 --> 00:12:15,320 Speaker 1: can tell you from my experience using a frequency sweeper, 206 00:12:15,520 --> 00:12:19,920 Speaker 1: which will slowly go through a selection of frequencies that 207 00:12:20,160 --> 00:12:22,880 Speaker 1: is all set at the same volume, so you get 208 00:12:22,920 --> 00:12:25,560 Speaker 1: a standard volume across all of them, that while I 209 00:12:25,600 --> 00:12:28,520 Speaker 1: can technically hear stuff at twenty hurts, it's not until 210 00:12:28,520 --> 00:12:31,240 Speaker 1: you hit a frequency of about fifty hurts that it 211 00:12:31,320 --> 00:12:35,040 Speaker 1: quote unquote sounds loud to me, even though actual volume 212 00:12:35,120 --> 00:12:38,320 Speaker 1: of the two tones remains the same, so the amplitude 213 00:12:38,480 --> 00:12:41,599 Speaker 1: is exactly the same, But until you get to a 214 00:12:41,679 --> 00:12:44,679 Speaker 1: frequency of about fifty hurts, it just doesn't sound loud 215 00:12:44,720 --> 00:12:46,880 Speaker 1: to me because my ears are not great at picking 216 00:12:46,960 --> 00:12:51,080 Speaker 1: up those lower, super low frequencies. Also, I should mention 217 00:12:51,160 --> 00:12:54,599 Speaker 1: that while sound waves come in different frequencies, sound itself 218 00:12:54,800 --> 00:12:58,000 Speaker 1: travels at a speed that is dependent upon the medium 219 00:12:58,160 --> 00:13:01,240 Speaker 1: through which it travels. So, in other words, low frequency 220 00:13:01,280 --> 00:13:04,520 Speaker 1: sounds and high frequency sounds travel at the same speed 221 00:13:04,760 --> 00:13:07,559 Speaker 1: through the same medium. Otherwise you would have all the 222 00:13:07,640 --> 00:13:10,560 Speaker 1: high pitched sounds hitting your ears before the low pitched 223 00:13:10,559 --> 00:13:14,400 Speaker 1: ones and conducting an orchestra would drive you crazy. The 224 00:13:14,440 --> 00:13:17,760 Speaker 1: speed of sound is defined as the distance traveled by 225 00:13:17,760 --> 00:13:21,280 Speaker 1: a sound wave in a certain unit of time. But hey, Jonathan, 226 00:13:21,360 --> 00:13:23,000 Speaker 1: some of you might be saying you were just talking 227 00:13:23,000 --> 00:13:26,040 Speaker 1: about frequencies. If a high frequency sound has twenty sound 228 00:13:26,080 --> 00:13:28,440 Speaker 1: waves pass a certain point in the second, and a 229 00:13:28,480 --> 00:13:31,160 Speaker 1: low frequency sound has twenty waves passing that same point 230 00:13:31,160 --> 00:13:34,720 Speaker 1: in the second, are they traveling at different speeds? No, 231 00:13:34,880 --> 00:13:37,400 Speaker 1: they're not. This is easier to imagine if we take 232 00:13:37,440 --> 00:13:40,080 Speaker 1: an analogy. So let's say you're standing on the side 233 00:13:40,240 --> 00:13:44,200 Speaker 1: of the road. Every single vehicle going past you on 234 00:13:44,240 --> 00:13:47,600 Speaker 1: this one way road is traveling at a smooth twenty 235 00:13:47,600 --> 00:13:50,400 Speaker 1: miles per hour or about thirty two kilometers per hour 236 00:13:50,440 --> 00:13:53,079 Speaker 1: if you prefer. But they're all going that speed. Doesn't 237 00:13:53,120 --> 00:13:55,640 Speaker 1: matter what kind of card is, they're all going exactly 238 00:13:55,679 --> 00:13:59,760 Speaker 1: twenty miles or thirty two kilometers per hour. Some of 239 00:13:59,760 --> 00:14:03,080 Speaker 1: these vehicles are very tiny, little smart cars. Some of 240 00:14:03,120 --> 00:14:06,520 Speaker 1: them are super long extended buses, but they're all traveling 241 00:14:06,520 --> 00:14:09,319 Speaker 1: at that same speed. So even though they're going at 242 00:14:09,320 --> 00:14:12,560 Speaker 1: the same speed, the buses take more time to pass 243 00:14:12,640 --> 00:14:15,920 Speaker 1: you than the smart cars do because the buses are longer. 244 00:14:16,440 --> 00:14:18,880 Speaker 1: In the time it takes one super long bus to 245 00:14:18,920 --> 00:14:21,560 Speaker 1: go buy you, like the front passes you and you 246 00:14:21,640 --> 00:14:25,440 Speaker 1: time it out. Maybe for smart cars could go buy 247 00:14:25,480 --> 00:14:27,440 Speaker 1: you and that same amount of time, even though they're 248 00:14:27,440 --> 00:14:30,160 Speaker 1: all going at twenty miles. The same is true with 249 00:14:30,280 --> 00:14:33,520 Speaker 1: sound waves, so we're not just talking about speed but wavelength. 250 00:14:33,800 --> 00:14:37,920 Speaker 1: So low frequency sounds and high frequency sounds are traveling 251 00:14:37,960 --> 00:14:41,320 Speaker 1: at the same speed. It's just you can fit more 252 00:14:41,360 --> 00:14:45,200 Speaker 1: of the waves in at that time than others because 253 00:14:45,200 --> 00:14:49,440 Speaker 1: of the length. All right back to the speed of sound. Now, 254 00:14:49,480 --> 00:14:52,520 Speaker 1: I cannot give you a standard speed of sound for 255 00:14:52,560 --> 00:14:55,600 Speaker 1: all occasions because the speed of sound depends on a 256 00:14:55,600 --> 00:14:58,640 Speaker 1: lot of little things, For example, how much moisture is 257 00:14:58,680 --> 00:15:02,800 Speaker 1: in the air or how cold is the air. Sound 258 00:15:02,840 --> 00:15:05,400 Speaker 1: passes through the air, and air is made up of gases, 259 00:15:05,440 --> 00:15:08,000 Speaker 1: and gases are made up of molecules. So as you 260 00:15:08,040 --> 00:15:10,840 Speaker 1: heat up a gas, the molecules move apart from each 261 00:15:10,880 --> 00:15:14,680 Speaker 1: other and they bounce around more. They're more able to move. 262 00:15:15,120 --> 00:15:19,840 Speaker 1: As gas is cool, the molecules pack around together and 263 00:15:20,000 --> 00:15:22,560 Speaker 1: they move around less, so they get more tightly packed. 264 00:15:23,000 --> 00:15:26,280 Speaker 1: So a cold gas will transmit sound at a slightly 265 00:15:26,360 --> 00:15:29,960 Speaker 1: slower speed than a warm gas will. If the temperature 266 00:15:29,960 --> 00:15:33,280 Speaker 1: outside is sixty eight degrees fahrenheit or about twenties celsius 267 00:15:33,320 --> 00:15:35,800 Speaker 1: and the air is dry, sound will travel at one 268 00:15:35,840 --> 00:15:41,080 Speaker 1: thousand per second or three forty three per second. And 269 00:15:41,160 --> 00:15:44,560 Speaker 1: it doesn't matter what frequency sound waves you're working with, 270 00:15:44,720 --> 00:15:47,480 Speaker 1: that's the speed they're going to travel at. And again, 271 00:15:47,520 --> 00:15:50,080 Speaker 1: at different temperatures and there are different media, sound will 272 00:15:50,080 --> 00:15:52,160 Speaker 1: travel at a different speed. All right. Now, let's go 273 00:15:52,200 --> 00:15:55,480 Speaker 1: back to the different types of drivers. After you handled 274 00:15:55,520 --> 00:15:59,360 Speaker 1: the sub whoffers and the whoofers, well, the whoffers will 275 00:15:59,360 --> 00:16:03,480 Speaker 1: still handle lower frequencies, but subwhiffers are are specialized whoffers, 276 00:16:03,840 --> 00:16:07,440 Speaker 1: largely because they will frequently be paired with special circuits 277 00:16:07,480 --> 00:16:11,600 Speaker 1: and cabinets dedicated to creating those very very low frequencies 278 00:16:11,760 --> 00:16:14,080 Speaker 1: in an effort to produce a specific quality of sound, 279 00:16:14,320 --> 00:16:16,520 Speaker 1: such as let's say you're watching an action film and 280 00:16:16,600 --> 00:16:19,160 Speaker 1: something done blowed up real good. You want to have 281 00:16:19,240 --> 00:16:21,840 Speaker 1: that rumbly low base for those moments, you know, the 282 00:16:21,920 --> 00:16:25,400 Speaker 1: kind where you can actually feel it because it's vibrating 283 00:16:25,600 --> 00:16:28,280 Speaker 1: the chair and the air around you, and so it's 284 00:16:28,320 --> 00:16:30,720 Speaker 1: it's that kind of rumble you can feel in your chest. Well, 285 00:16:30,760 --> 00:16:33,560 Speaker 1: that frequently means you need a dedicated subwhoffer unit that 286 00:16:33,600 --> 00:16:37,240 Speaker 1: has its own power supply to generate the vibrations with 287 00:16:37,440 --> 00:16:40,520 Speaker 1: enough force necessary to create that effect. So it's not 288 00:16:40,560 --> 00:16:44,560 Speaker 1: just the speed but how hard it's pushing. After subwhiffers 289 00:16:44,600 --> 00:16:48,840 Speaker 1: and whoffers, you've got mid range drivers or mid range speakers, 290 00:16:48,840 --> 00:16:51,760 Speaker 1: and as the name suggests, these drivers are responsible for 291 00:16:51,800 --> 00:16:54,880 Speaker 1: producing sounds in the middle range frequencies of human hearing. 292 00:16:55,120 --> 00:16:57,920 Speaker 1: A typical range might include two fifty hurts to two 293 00:16:57,960 --> 00:17:01,840 Speaker 1: thousand hurts. You may have also the term squawker when 294 00:17:01,920 --> 00:17:05,600 Speaker 1: referencing mid range speakers. They're made of lighter materials and 295 00:17:05,640 --> 00:17:09,160 Speaker 1: they can vibrate at higher frequencies than whiffers and subwhiffers, 296 00:17:09,280 --> 00:17:12,359 Speaker 1: which is necessary to create those mid range tones. And 297 00:17:12,400 --> 00:17:15,639 Speaker 1: then you have tweeter speakers. These are made of the 298 00:17:15,720 --> 00:17:18,480 Speaker 1: lightest weight material and they vibrate the fastest in an 299 00:17:18,480 --> 00:17:21,960 Speaker 1: effort to reproduce frequencies on the upper levels of human hearing, 300 00:17:22,320 --> 00:17:24,959 Speaker 1: which tends to be between two thousand and twenty thousand 301 00:17:25,000 --> 00:17:28,159 Speaker 1: hurts at least for consumer speakers. There are tweeters that 302 00:17:28,160 --> 00:17:30,960 Speaker 1: can be made for special purposes that can generate sound 303 00:17:31,000 --> 00:17:33,919 Speaker 1: frequencies well above the range of human hearing, some of 304 00:17:33,920 --> 00:17:36,040 Speaker 1: them as high up as a hundred kill hurts or 305 00:17:36,160 --> 00:17:39,600 Speaker 1: one hundred thousand hurts. That's five times higher than the 306 00:17:39,680 --> 00:17:43,119 Speaker 1: highest frequency the average human is capable of perceiving. So 307 00:17:43,160 --> 00:17:46,160 Speaker 1: why would you want a tweeter that could go beyond 308 00:17:46,480 --> 00:17:48,919 Speaker 1: the range of human hearing. Well, you might use it 309 00:17:48,960 --> 00:17:53,040 Speaker 1: for scientific research purposes, like finding out what high high 310 00:17:53,080 --> 00:17:58,040 Speaker 1: high pitches the ultrasonic pitches might due to affect animal behavior. 311 00:17:58,280 --> 00:18:00,320 Speaker 1: So you might be able to do that to learn 312 00:18:00,520 --> 00:18:03,560 Speaker 1: how high a pitch a dog might be able to hear, 313 00:18:03,600 --> 00:18:06,200 Speaker 1: for example, because dogs can hear at a different range 314 00:18:06,200 --> 00:18:09,040 Speaker 1: than humans can. Or you might want to do experiments 315 00:18:09,359 --> 00:18:13,679 Speaker 1: to see if those imperceptible frequencies have an effect on 316 00:18:13,760 --> 00:18:17,600 Speaker 1: the sounds we can here. So there are audio files 317 00:18:17,800 --> 00:18:21,760 Speaker 1: who insist that frequencies beyond the human range of hearing 318 00:18:22,080 --> 00:18:25,320 Speaker 1: can change the quality of the sounds that we do here, 319 00:18:25,720 --> 00:18:28,600 Speaker 1: and thus it's imperative to get a sound system and 320 00:18:28,680 --> 00:18:31,960 Speaker 1: a type of media capable of reproducing sound frequencies at 321 00:18:31,960 --> 00:18:34,639 Speaker 1: every level if you want a true reproduction of an 322 00:18:34,680 --> 00:18:39,440 Speaker 1: original sounds quality. This falls into the realm of psychoacoustics 323 00:18:39,480 --> 00:18:43,800 Speaker 1: the study of sound perception. Because hearing involves processes in 324 00:18:43,800 --> 00:18:47,320 Speaker 1: the brain, there is a subjective component to it that 325 00:18:47,400 --> 00:18:50,640 Speaker 1: cannot be easily described through physics. We can talk all 326 00:18:50,680 --> 00:18:54,400 Speaker 1: about the physics of sound waves and sound propagation, but ultimately, 327 00:18:54,400 --> 00:18:57,320 Speaker 1: when it comes to the way we experience sound, we 328 00:18:57,400 --> 00:19:00,480 Speaker 1: have to take gray matter into account, and that gets 329 00:19:00,520 --> 00:19:03,760 Speaker 1: tricky since our experience of perceiving sound can depend upon 330 00:19:03,880 --> 00:19:07,320 Speaker 1: other things unrelated to the actual physics of the sound itself. 331 00:19:07,600 --> 00:19:10,359 Speaker 1: For example, if I were to tell you that I 332 00:19:10,440 --> 00:19:12,600 Speaker 1: have a sound system, and I've set it up and 333 00:19:12,640 --> 00:19:17,680 Speaker 1: it consists of the most expensive and most technologically advanced components, 334 00:19:18,040 --> 00:19:20,600 Speaker 1: and the media that was going to play represented the 335 00:19:20,600 --> 00:19:23,960 Speaker 1: most true reproduction of an actual sound, that might be 336 00:19:24,080 --> 00:19:27,120 Speaker 1: enough to influence your perception of the sound. Even if 337 00:19:27,200 --> 00:19:30,719 Speaker 1: what I was really using was just good equipment, not 338 00:19:30,800 --> 00:19:33,960 Speaker 1: the best, but just good stuff. Even if all all 339 00:19:33,960 --> 00:19:35,840 Speaker 1: that stuff I told you wasn't true, your perception of 340 00:19:35,840 --> 00:19:38,240 Speaker 1: sound might make it seem like you're listening to the 341 00:19:38,280 --> 00:19:41,840 Speaker 1: most perfect reproduction of the original performance as could be attained. 342 00:19:42,400 --> 00:19:44,720 Speaker 1: Or if I did play a sound back on what 343 00:19:44,840 --> 00:19:48,760 Speaker 1: really was an amazing sound system, but Before I did it, 344 00:19:48,800 --> 00:19:51,199 Speaker 1: I made a whole bunch of apologies for how the 345 00:19:51,240 --> 00:19:54,600 Speaker 1: system I was using could not faithfully represent high tones, 346 00:19:54,840 --> 00:19:57,400 Speaker 1: or had a very weak base output, or something like that. 347 00:19:57,760 --> 00:20:01,560 Speaker 1: You might perceive the playback as fall lewing these trends 348 00:20:01,600 --> 00:20:04,960 Speaker 1: that I had mentioned, even if scientific recording instruments were 349 00:20:05,000 --> 00:20:07,399 Speaker 1: to show that the playback didn't suffer from those problems 350 00:20:07,440 --> 00:20:10,720 Speaker 1: at all. All that being said, the psychological aspect of 351 00:20:10,720 --> 00:20:13,679 Speaker 1: how we perceive sound does have limitations. No amount of 352 00:20:13,680 --> 00:20:16,800 Speaker 1: snake oil salesmanship is going to convince you that a 353 00:20:16,880 --> 00:20:20,520 Speaker 1: truly subpar stereo system is capable of reproducing the glory 354 00:20:20,600 --> 00:20:24,280 Speaker 1: of the Philharmonic Orchestra, for example. But because there is 355 00:20:24,359 --> 00:20:27,560 Speaker 1: the subjective element and how we perceive sound, there's the 356 00:20:27,560 --> 00:20:30,439 Speaker 1: opportunity to exploit that element and make a lot of 357 00:20:30,440 --> 00:20:32,879 Speaker 1: money in the process. I've talked before about how certain 358 00:20:32,920 --> 00:20:36,080 Speaker 1: manufacturers have used this to market high end audio equipment, 359 00:20:36,480 --> 00:20:39,240 Speaker 1: and some of that has little to no scientific evidence 360 00:20:39,240 --> 00:20:41,960 Speaker 1: to back up the claims that they make about those gadgets, 361 00:20:43,119 --> 00:20:45,879 Speaker 1: and yet they're able to set exorbitant prices for components 362 00:20:45,880 --> 00:20:48,399 Speaker 1: that audio files will cover it because they're always in 363 00:20:48,400 --> 00:20:52,600 Speaker 1: a quest to get that perfect representation of a sound. Uh, 364 00:20:52,720 --> 00:20:56,160 Speaker 1: so this stuff does happen. I also covered this when 365 00:20:56,160 --> 00:20:59,200 Speaker 1: I talked about MP three compression, because if you remember 366 00:20:59,400 --> 00:21:02,919 Speaker 1: an MP threes, part of the compression strategy is to 367 00:21:02,960 --> 00:21:05,639 Speaker 1: take all the different parts of a sound that we 368 00:21:05,800 --> 00:21:09,399 Speaker 1: humans typically don't notice, and you just cut them. You 369 00:21:09,440 --> 00:21:11,400 Speaker 1: get rid of them, because that way you cut down 370 00:21:11,440 --> 00:21:15,080 Speaker 1: on the size of the sound file. The strategy is, 371 00:21:15,400 --> 00:21:18,639 Speaker 1: if you can't perceive it, then we don't need it 372 00:21:18,800 --> 00:21:21,520 Speaker 1: in the information. We can just cut it that. Audio 373 00:21:21,560 --> 00:21:23,919 Speaker 1: files say no, if you do that, it affects the 374 00:21:23,960 --> 00:21:27,280 Speaker 1: stuff that we can here, and thus you are changing 375 00:21:27,320 --> 00:21:31,440 Speaker 1: the nature of the audio recording. Just because you couldn't 376 00:21:31,480 --> 00:21:35,000 Speaker 1: hear the thing doesn't mean the thing wasn't doing something else. 377 00:21:37,160 --> 00:21:39,080 Speaker 1: I think the jury is still out on that in 378 00:21:39,119 --> 00:21:42,639 Speaker 1: a large part. I mean, there are some legitimate arguments 379 00:21:42,680 --> 00:21:45,520 Speaker 1: to make about harmonics and things that do come into play, 380 00:21:46,240 --> 00:21:48,040 Speaker 1: but I'm not sure it gets to the level of 381 00:21:48,080 --> 00:21:51,080 Speaker 1: subtlety that a lot of audio files argue. At least 382 00:21:51,119 --> 00:21:53,879 Speaker 1: I don't see the scientific evidence supporting it. That doesn't 383 00:21:53,880 --> 00:21:55,840 Speaker 1: mean it's wrong, It just means I haven't seen the 384 00:21:55,880 --> 00:21:59,880 Speaker 1: evidence supporting it. Anyway, As soon as we come back. 385 00:22:00,000 --> 00:22:03,920 Speaker 1: I'm gonna go into talking about amplification and why that's important, 386 00:22:03,920 --> 00:22:07,000 Speaker 1: but first let's take another quick break to thank our sponsor. 387 00:22:14,160 --> 00:22:15,800 Speaker 1: All right. Now, Back when I was talking about the 388 00:22:15,800 --> 00:22:18,240 Speaker 1: development of the loud speaker, I mentioned that Rice and 389 00:22:18,320 --> 00:22:22,280 Speaker 1: Kellogg observed there needed to be advancements in amplification, and 390 00:22:22,359 --> 00:22:24,200 Speaker 1: by that they meant there needed to be a way 391 00:22:24,240 --> 00:22:28,560 Speaker 1: to boost the electrical signal from the risk the transmitter 392 00:22:28,720 --> 00:22:32,320 Speaker 1: the microphone in order to give a speaker enough umph 393 00:22:32,480 --> 00:22:35,160 Speaker 1: to vibrate at a force strong enough to play back 394 00:22:35,200 --> 00:22:39,399 Speaker 1: the sounds at a suitable volume. Without amplifiers, the signal 395 00:22:39,520 --> 00:22:41,879 Speaker 1: strength might only allow a speaker to play back a 396 00:22:41,960 --> 00:22:45,080 Speaker 1: sound at a low volume, or if the signal is 397 00:22:45,200 --> 00:22:48,480 Speaker 1: very weak, it might not even move the speaker significantly 398 00:22:48,640 --> 00:22:52,080 Speaker 1: enough at all to create any real sound. The reason 399 00:22:52,119 --> 00:22:54,560 Speaker 1: the signal tends to be weak goes back to the 400 00:22:54,640 --> 00:22:57,600 Speaker 1: limitations we face when we record sound in the first place. 401 00:22:57,960 --> 00:23:02,200 Speaker 1: So using the microphone effect, we transform sound into electrical 402 00:23:02,200 --> 00:23:06,800 Speaker 1: signals by making the microphones diaphragm vibrate, mimicking the way 403 00:23:06,840 --> 00:23:09,320 Speaker 1: our ear drums work. Right, So it's like we're speaking 404 00:23:09,359 --> 00:23:13,680 Speaker 1: into someone's ear. When we talk into a microphone. Then 405 00:23:13,760 --> 00:23:18,680 Speaker 1: we transform sound into electrical signals by making that microphone 406 00:23:18,960 --> 00:23:23,120 Speaker 1: diaphragm vibrate, and those small vibrations introduce fluctuations into an 407 00:23:23,119 --> 00:23:26,800 Speaker 1: electrical signal in some way. But for sound to affect 408 00:23:26,800 --> 00:23:29,879 Speaker 1: the diaphragm at all, the diaphragm has to be very lightweight, 409 00:23:30,440 --> 00:23:34,000 Speaker 1: very sensitive, and it has to make very small movements. 410 00:23:34,160 --> 00:23:36,800 Speaker 1: Otherwise we'd have to make sound an enormous amplitudes or 411 00:23:36,880 --> 00:23:39,920 Speaker 1: volume in order to generate the force necessary to vibrate 412 00:23:39,960 --> 00:23:43,000 Speaker 1: the diaphragm. So it has to be very lightweight, very 413 00:23:43,119 --> 00:23:46,880 Speaker 1: very sensitive, and it's moving in a very small distance, 414 00:23:47,040 --> 00:23:50,679 Speaker 1: so it can only make tiny changes in electrical current 415 00:23:50,920 --> 00:23:53,960 Speaker 1: or generate a very tiny electrical current. Now that's good 416 00:23:54,080 --> 00:23:56,800 Speaker 1: enough for the purposes of recording the sound. You can 417 00:23:56,840 --> 00:23:58,800 Speaker 1: do that. You can use that to record sound. It's 418 00:23:58,840 --> 00:24:02,639 Speaker 1: fine because it can record at those tiny details. But 419 00:24:02,720 --> 00:24:05,080 Speaker 1: if you want to play the sound back on a speaker, 420 00:24:05,359 --> 00:24:08,240 Speaker 1: you have to boost that signal in order to drive 421 00:24:08,400 --> 00:24:11,120 Speaker 1: the speakers to physically move them. You want to make 422 00:24:11,119 --> 00:24:13,520 Speaker 1: the signal more powerful, but you also want to keep 423 00:24:13,560 --> 00:24:17,719 Speaker 1: all the fluctuations of the signal, all the dynamics of 424 00:24:17,760 --> 00:24:21,600 Speaker 1: the signal, So that way, you can represent when a 425 00:24:21,680 --> 00:24:25,320 Speaker 1: song gets louder or more quiet, or when one element 426 00:24:25,560 --> 00:24:28,480 Speaker 1: is taking over over another element. All of these things 427 00:24:28,480 --> 00:24:31,520 Speaker 1: are very subtle, and you have to preserve that. So 428 00:24:31,600 --> 00:24:34,160 Speaker 1: you want the signal not just to be boosted, but 429 00:24:34,359 --> 00:24:36,760 Speaker 1: for all the different fluctuations of that signal to be 430 00:24:36,840 --> 00:24:39,360 Speaker 1: represented in that boost. You want it all to be 431 00:24:39,440 --> 00:24:42,439 Speaker 1: at the same relative strength as they were in the 432 00:24:42,480 --> 00:24:45,880 Speaker 1: weaker signal. Now, an amplifier does this through the use 433 00:24:45,960 --> 00:24:50,199 Speaker 1: of two separate circuits. The first circuit is the input circuit. 434 00:24:50,440 --> 00:24:52,600 Speaker 1: That's the weaker of the two signals, that's the one 435 00:24:52,640 --> 00:24:56,520 Speaker 1: that's coming from the microphone. The second circuit is your 436 00:24:56,520 --> 00:25:00,760 Speaker 1: output circuit, which sends a stronger signal out to this speakers, 437 00:25:00,800 --> 00:25:04,479 Speaker 1: and it draws upon the amplifier's power supply to boost 438 00:25:04,520 --> 00:25:07,280 Speaker 1: the signal. So you have an amplifier, it has its 439 00:25:07,320 --> 00:25:11,600 Speaker 1: own power supply. It's generating the signal that's going through 440 00:25:11,600 --> 00:25:14,840 Speaker 1: this output circuit. The power going through the output circuit 441 00:25:15,000 --> 00:25:17,720 Speaker 1: is a direct current, so it's flowing in a set direction. 442 00:25:17,800 --> 00:25:21,159 Speaker 1: It does not change. If you have an amplifier and 443 00:25:21,160 --> 00:25:24,440 Speaker 1: you've hooked it directly up to your house, is alternating 444 00:25:24,440 --> 00:25:27,960 Speaker 1: current there's a power supply element inside the amplifier that 445 00:25:28,000 --> 00:25:31,440 Speaker 1: converts it from alternating current to direct current. Now, think 446 00:25:31,480 --> 00:25:35,200 Speaker 1: of the output circuit as always pushing a strong signal 447 00:25:35,359 --> 00:25:38,320 Speaker 1: out towards the speakers. It's just most of the time 448 00:25:38,600 --> 00:25:42,200 Speaker 1: this signal is not carrying any information. But when the 449 00:25:42,280 --> 00:25:46,000 Speaker 1: amplifiers on, that's what's doing. It's pushing the strong signal 450 00:25:46,119 --> 00:25:49,439 Speaker 1: out to the speakers. The input circuit's job is to 451 00:25:49,560 --> 00:25:52,919 Speaker 1: use the original weak electrical signal as a way to 452 00:25:53,080 --> 00:25:57,400 Speaker 1: vary the resistance in the output circuit, so the variable 453 00:25:57,440 --> 00:26:01,959 Speaker 1: resistance recreates the voltage fluctuation in the original signal. So 454 00:26:02,000 --> 00:26:05,280 Speaker 1: what you're doing is you've got this strong signal going out, 455 00:26:05,560 --> 00:26:10,359 Speaker 1: use the weak signal to introduce the same fluctuations into 456 00:26:10,400 --> 00:26:14,000 Speaker 1: the strong signal, and then the strong signal will reflect 457 00:26:14,160 --> 00:26:17,320 Speaker 1: the weaker one. It will be exactly the same, except stronger. 458 00:26:18,000 --> 00:26:21,479 Speaker 1: In the good old days, amplifiers relied upon vacuum tubes 459 00:26:21,600 --> 00:26:25,240 Speaker 1: as an integral component, and in fact some amplifiers still do, 460 00:26:25,480 --> 00:26:30,280 Speaker 1: particularly for stuff like professional electric guitar amplifiers. There are 461 00:26:30,640 --> 00:26:34,679 Speaker 1: professional musicians who swear by vacuum tube amplifiers and they 462 00:26:34,680 --> 00:26:38,960 Speaker 1: will not use anything else. Vacuum tubes are pretty interesting technology, 463 00:26:38,960 --> 00:26:41,280 Speaker 1: and they date back to the early twentieth century. So 464 00:26:41,520 --> 00:26:44,560 Speaker 1: let's talk about how they work for just a second. First, 465 00:26:45,040 --> 00:26:47,320 Speaker 1: they look a lot like light bulbs, and in fact 466 00:26:47,400 --> 00:26:51,440 Speaker 1: they operate very similar to light bulbs. They are glass tubes. 467 00:26:51,760 --> 00:26:55,280 Speaker 1: Inside this glass tube is a filament like a light bulb. 468 00:26:55,280 --> 00:26:58,760 Speaker 1: The filament inside uses electrical resistance to heat up. The 469 00:26:58,800 --> 00:27:01,960 Speaker 1: filament either content aines or is somehow wrapped around a 470 00:27:02,080 --> 00:27:06,320 Speaker 1: material like tungsten, which, when it's heated to very high temperatures, 471 00:27:06,600 --> 00:27:10,560 Speaker 1: starts to boil off electrons. That would be the cathode 472 00:27:11,000 --> 00:27:14,159 Speaker 1: of the vacuum tube. It's the source of electrons. The 473 00:27:14,160 --> 00:27:17,480 Speaker 1: electrons accept only so much energy, and then after that 474 00:27:17,520 --> 00:27:21,000 Speaker 1: they effectively jump ship. They're ready to burst off of 475 00:27:21,040 --> 00:27:24,480 Speaker 1: the atoms that they were previously connected to. Now, also 476 00:27:24,520 --> 00:27:27,439 Speaker 1: inside the vacuum tube is a plate that has a 477 00:27:27,480 --> 00:27:31,359 Speaker 1: relative positive charge to it compared to the cathode. That's 478 00:27:31,400 --> 00:27:35,359 Speaker 1: called the anode. The electrons are negatively charged, and so 479 00:27:35,400 --> 00:27:39,560 Speaker 1: they're attracted to the positively charged anode, and the negative 480 00:27:39,600 --> 00:27:44,119 Speaker 1: charged electrons flow towards the positively charged anode. Now, if 481 00:27:44,119 --> 00:27:46,480 Speaker 1: this were all, there were to a vacuum tube, it 482 00:27:46,520 --> 00:27:49,359 Speaker 1: would just be a diode. That means it would be 483 00:27:49,400 --> 00:27:52,000 Speaker 1: an element in a circuit that would allow electricity to 484 00:27:52,000 --> 00:27:55,239 Speaker 1: pass one way from the cathode to anode, but not 485 00:27:55,480 --> 00:27:58,600 Speaker 1: back the other way. However, there's a third element, and 486 00:27:58,640 --> 00:28:02,040 Speaker 1: that's what creates the amplification sho effect. That element is 487 00:28:02,080 --> 00:28:05,800 Speaker 1: a grid of spiral wires or a mesh material. The 488 00:28:05,800 --> 00:28:09,199 Speaker 1: acts as a sort of control grid or cage between 489 00:28:09,200 --> 00:28:14,159 Speaker 1: the cathode and the anode, so it essentially surrounds the cathode. Now, 490 00:28:14,200 --> 00:28:17,119 Speaker 1: if you apply a voltage to this control grid that 491 00:28:17,280 --> 00:28:20,639 Speaker 1: is lower than the cathode itself, it reduces the amount 492 00:28:20,640 --> 00:28:23,960 Speaker 1: of current passing from cathode to anode. By placing a 493 00:28:24,040 --> 00:28:27,760 Speaker 1: large positive voltage on the plate and then feeding a 494 00:28:27,840 --> 00:28:31,240 Speaker 1: signal to the control grid, you can affect the voltage 495 00:28:31,280 --> 00:28:34,440 Speaker 1: across the load on the circuit. So you make tiny 496 00:28:34,520 --> 00:28:37,080 Speaker 1: changes in the control grid's voltage and you get a 497 00:28:37,160 --> 00:28:40,360 Speaker 1: much larger change across the load of the circuit amplifying 498 00:28:40,360 --> 00:28:43,760 Speaker 1: the signal. So again, you you put a large positive 499 00:28:43,840 --> 00:28:48,080 Speaker 1: voltage on this plate, you feed the input signal into 500 00:28:48,440 --> 00:28:53,760 Speaker 1: the the control grid, and then you amplify that signal 501 00:28:54,520 --> 00:28:57,400 Speaker 1: across the entire load, and that load would it typically 502 00:28:57,560 --> 00:29:02,280 Speaker 1: involve speakers or an amplifier or These days most amplifiers 503 00:29:02,280 --> 00:29:06,760 Speaker 1: do not use vacuum tubes. Instead, we use solid state transistors. 504 00:29:06,960 --> 00:29:10,920 Speaker 1: To describe all those transistors work gets a little complicated, 505 00:29:10,960 --> 00:29:13,720 Speaker 1: but in general, and basic transistor has three components. You've 506 00:29:13,720 --> 00:29:17,760 Speaker 1: got an emitter, a base, and a collector. The emitter 507 00:29:17,840 --> 00:29:22,440 Speaker 1: and the collector are both in type UH semiconductors, meaning 508 00:29:22,440 --> 00:29:26,200 Speaker 1: that they have more electrons. They have a surplus of 509 00:29:26,240 --> 00:29:28,160 Speaker 1: electrons there. You can think of it almost like a 510 00:29:28,200 --> 00:29:32,040 Speaker 1: negative charge. The base is a P type semiconductor. It's 511 00:29:32,040 --> 00:29:35,600 Speaker 1: sandwiched between the emitter and the collector. It has what 512 00:29:35,720 --> 00:29:39,280 Speaker 1: would we would call a positive charge or holes for electrons. 513 00:29:39,840 --> 00:29:42,880 Speaker 1: Feeding the input current between the emitter and the base 514 00:29:43,280 --> 00:29:46,080 Speaker 1: creates a much larger output current between the emitter and 515 00:29:46,120 --> 00:29:49,800 Speaker 1: the collector, thus amplifying the signal. Now, the output signal 516 00:29:49,880 --> 00:29:54,720 Speaker 1: should ideally match the input signal exactly, except again everything 517 00:29:54,800 --> 00:29:58,440 Speaker 1: is just bigger as an amplified and that signal would 518 00:29:58,440 --> 00:30:00,560 Speaker 1: be strong enough to do the work of moving those 519 00:30:00,600 --> 00:30:05,440 Speaker 1: speaker diaphragms and generating the sounds we enjoy. Well, I 520 00:30:05,480 --> 00:30:09,600 Speaker 1: hope you enjoyed health speakers and amplifiers work. Like I said, 521 00:30:09,760 --> 00:30:12,520 Speaker 1: next week we're going to have the story of San 522 00:30:12,640 --> 00:30:16,400 Speaker 1: Sui and it's rise and fall and what the company 523 00:30:16,480 --> 00:30:20,360 Speaker 1: did and UH the various products that it produced and 524 00:30:20,400 --> 00:30:24,840 Speaker 1: why they were important. Why certain audio files to this day, 525 00:30:24,960 --> 00:30:29,680 Speaker 1: we'll seek out San Sui UH components like receivers in particular, 526 00:30:29,680 --> 00:30:34,640 Speaker 1: there's certain receivers that are highly prized among audio files. 527 00:30:34,680 --> 00:30:40,240 Speaker 1: Even though spoiler alert, this company doesn't exist anymore. So 528 00:30:40,760 --> 00:30:43,000 Speaker 1: that will be next week's episode. But I'm glad that 529 00:30:43,040 --> 00:30:45,400 Speaker 1: I did this so that way you know, I'm not 530 00:30:45,520 --> 00:30:48,360 Speaker 1: just repeating something I've already done in the past. I 531 00:30:48,360 --> 00:30:50,760 Speaker 1: know that can be very frustrating, and due to my 532 00:30:50,960 --> 00:30:55,360 Speaker 1: terrible memory, it happens pretty frequently without me even being 533 00:30:55,360 --> 00:30:58,920 Speaker 1: aware of it. So I hope you enjoyed this episode. 534 00:30:58,920 --> 00:31:02,200 Speaker 1: If you have suggestions for future topics, because San Sui 535 00:31:02,280 --> 00:31:04,560 Speaker 1: is actually going to be that's a listener request. I'll 536 00:31:04,560 --> 00:31:07,040 Speaker 1: talk about that more next week. So if you have 537 00:31:07,080 --> 00:31:10,160 Speaker 1: a request, like if there's a specific topic in tech 538 00:31:10,240 --> 00:31:12,960 Speaker 1: you want me to talk about. Maybe it's a particular company, 539 00:31:13,560 --> 00:31:16,880 Speaker 1: a trend in technology of particular type of tech, and 540 00:31:16,920 --> 00:31:19,840 Speaker 1: you want to know more about it, send me a message. 541 00:31:20,240 --> 00:31:22,640 Speaker 1: I love getting those. It always gives me a great 542 00:31:22,680 --> 00:31:25,880 Speaker 1: starting point to jump into some research, and the best 543 00:31:25,920 --> 00:31:28,160 Speaker 1: way to do that is to send it over on Twitter. 544 00:31:28,400 --> 00:31:31,240 Speaker 1: The handle for the show is tech Stuff hs W 545 00:31:32,120 --> 00:31:40,800 Speaker 1: and I'll talk to you again really soon. Tech Stuff 546 00:31:40,880 --> 00:31:44,040 Speaker 1: is an I Heart Radio production. For more podcasts from 547 00:31:44,040 --> 00:31:47,840 Speaker 1: my Heart Radio, visit the i Heart Radio app, Apple Podcasts, 548 00:31:47,960 --> 00:31:49,920 Speaker 1: or wherever you listen to your favorite shows.