1 00:00:00,229 --> 00:00:02,690 So you think you know the cassette tape, eh? 2 00:00:02,690 --> 00:00:07,140 That 80s and 90s crappy-sounding barely tolerable thing we had before CD’s? 3 00:00:07,140 --> 00:00:09,550 The ones that got eaten by your car all the time? 4 00:00:09,550 --> 00:00:11,829 The thing hipsters are pretending to listen to? 5 00:00:11,829 --> 00:00:15,230 Whatever memories you have of the cassette could probably use some refreshing. 6 00:00:15,230 --> 00:00:19,119 They don’t sound awful, they’re actually much older than you think, and they’re backed 7 00:00:19,119 --> 00:00:20,890 by some interesting technology. 8 00:00:20,890 --> 00:00:22,210 Let’s have a look. 9 00:00:22,210 --> 00:00:26,070 The cassette tape is actually a product of the 1960’s, though it took some years for 10 00:00:26,070 --> 00:00:27,359 them to take off. 11 00:00:27,359 --> 00:00:31,189 The official name for them is the Compact Cassette, and it was the Philips company that 12 00:00:31,189 --> 00:00:33,590 invented them in 1962. 13 00:00:33,590 --> 00:00:37,940 They aimed to solve two problems, neither of which had anything to do with music. 14 00:00:37,940 --> 00:00:41,930 Magnetic tape was not a new thing in 1962, and reel-to-reel tape recorders were fairly 15 00:00:41,930 --> 00:00:42,930 widespread. 16 00:00:42,930 --> 00:00:45,969 But the machines weren’t very portable, and even those that tried to be were still 17 00:00:45,969 --> 00:00:49,489 plagued by the problem of tape which required being manually threaded. 18 00:00:49,489 --> 00:00:52,579 In the professional recording studio, these weren’t problems. 19 00:00:52,579 --> 00:00:55,989 The machine would just sit in one spot in the studio, and having to be threaded manually 20 00:00:55,989 --> 00:00:59,879 wasn’t a hassle compared to all the other hassles that accompany recording music. 21 00:00:59,879 --> 00:01:04,730 But people saw uses for magnetic tape outside the recording studio, particularly in recording 22 00:01:04,730 --> 00:01:05,750 speech. 23 00:01:05,750 --> 00:01:09,880 In those days, men weren’t really expected to know how to type. 24 00:01:09,880 --> 00:01:13,680 The big-wigs in offices had secretaries to type their letters for them. 25 00:01:13,680 --> 00:01:17,500 But secretaries had this annoying habit of leaving at the end of the day, thus being 26 00:01:17,500 --> 00:01:20,830 unavailable to use their stenographic skills. 27 00:01:20,830 --> 00:01:24,280 Machines like the dictaphone allowed these corporate luddites to record their speech 28 00:01:24,280 --> 00:01:27,380 at their whimsy so someone else could write it out later. 29 00:01:27,380 --> 00:01:31,750 The problem with the dictaphone was that it used non-reusable cylinders or belts, and 30 00:01:31,750 --> 00:01:36,500 mistakes couldn’t be fixed without some sort of added note marking them as a mistake. 31 00:01:36,500 --> 00:01:40,050 Magnetic tape, though, could be reused and recorded over, since the magnetic signals 32 00:01:40,050 --> 00:01:42,490 recorded on the tape could be erased. 33 00:01:42,490 --> 00:01:46,110 Mistakes were easy to correct, just back the tape up and record over the mistake. 34 00:01:46,110 --> 00:01:50,080 But with large reel-to-reel machines and their open reel tape, you weren’t about to see 35 00:01:50,080 --> 00:01:51,610 them in an office setting. 36 00:01:51,610 --> 00:01:54,060 The compact cassette fixed that right up, though. 37 00:01:54,060 --> 00:01:58,660 A number of clever innovations made for a practical, portable tape format. 38 00:01:58,660 --> 00:02:01,840 The most important innovation was the cassette itself. 39 00:02:01,840 --> 00:02:06,000 Instead of having an open reel of tape, the tape is sandwiched in a shell of plastic with 40 00:02:06,000 --> 00:02:08,640 access holes at the bottom of the cassette. 41 00:02:08,640 --> 00:02:12,250 The tape was pre-threaded in the shell, and the holes in the middle of the cassette allow 42 00:02:12,250 --> 00:02:16,900 the machine to wind the tape with special spindles that mesh with these cogs. 43 00:02:16,900 --> 00:02:20,180 Having the tape contained so that you didn’t have to touch it meant that the tape could 44 00:02:20,180 --> 00:02:21,769 be much thinner. 45 00:02:21,769 --> 00:02:25,960 With open reels of tape, since grubby little hands are always fiddling with it, it can’t 46 00:02:25,960 --> 00:02:28,610 get too thin or it will break with handling. 47 00:02:28,610 --> 00:02:33,200 But inside a cassette where it won’t get touched (or at least, shouldn’t get touched), 48 00:02:33,200 --> 00:02:37,540 it could afford to be thinner and thus you could pack a longer length of tape inside. 49 00:02:37,540 --> 00:02:41,660 The bottom portion of the cassette is wider than the rest, and it has a standard pattern 50 00:02:41,660 --> 00:02:43,870 of holes that are very important. 51 00:02:43,870 --> 00:02:47,129 These are what allow the cassette recorder to interact with the tape. 52 00:02:47,129 --> 00:02:50,939 Cassette recorders work fundamentally the same as a reel to reel recorder, but since 53 00:02:50,939 --> 00:02:54,049 we’re using a cassette the machine interacts with the tape a little differently. 54 00:02:54,049 --> 00:02:59,069 Let’s take a step back and look at a reel to reel machine to see how ordinary tape gets 55 00:02:59,069 --> 00:03:00,069 recorded. 56 00:03:00,069 --> 00:03:02,900 The parts that interact with the tape are called the transport. 57 00:03:02,900 --> 00:03:07,110 A reel-to-reel recorder has 2 spindles that hold the tape reels, and the transport sits 58 00:03:07,110 --> 00:03:08,550 between them. 59 00:03:08,550 --> 00:03:12,519 When using the machine, a full reel of tape is placed on the left, and then the tape is 60 00:03:12,519 --> 00:03:16,650 pulled out and through the transport before being wound onto the empty reel. 61 00:03:16,650 --> 00:03:20,959 The tape passes three heads, first an erase head, then the record head, and finally the 62 00:03:20,959 --> 00:03:22,030 playback head. 63 00:03:22,030 --> 00:03:25,739 Lastly, the tape goes through the capstan and pinch roller, which are the parts that 64 00:03:25,739 --> 00:03:27,999 actually pull the tape past the heads. 65 00:03:27,999 --> 00:03:32,310 The capstan is one of the most important parts because it regulates the speed of the tape. 66 00:03:32,310 --> 00:03:37,230 The pinch roller, a small rubber wheel, squeezes the tape between itself and the spinning capstan, 67 00:03:37,230 --> 00:03:39,260 and this is what actually moves the tape. 68 00:03:39,260 --> 00:03:42,409 The reel on the right only rotates to spool the tape onto the reel. 69 00:03:42,409 --> 00:03:46,110 See, if I stop it, the tape doesn’t stop moving through the machine. 70 00:03:46,110 --> 00:03:50,139 Also important to note is the curved path of the tape as it passes the heads. 71 00:03:50,139 --> 00:03:54,159 This ensures that it stays tightly against the heads, and various tape guides make sure 72 00:03:54,159 --> 00:03:56,450 it stays in alignment as it passes them. 73 00:03:56,450 --> 00:03:59,719 If you look at the parts inside a cassette deck, you’ll see that they’re fundamentally 74 00:03:59,719 --> 00:04:01,459 the same, although smaller. 75 00:04:01,459 --> 00:04:05,650 There’s an erase head to the left, a record and playback head in the middle (cassettes 76 00:04:05,650 --> 00:04:09,950 use one head for both functions), and the capstan and pinch roller are on the right. 77 00:04:09,950 --> 00:04:13,109 But you might notice some problems that come about with the cassette. 78 00:04:13,109 --> 00:04:16,650 The capstan--it needs to be on one side of the tape, and the pinch roller needs to be 79 00:04:16,650 --> 00:04:17,670 on the other. 80 00:04:17,670 --> 00:04:19,890 The tape has to somehow get between them. 81 00:04:19,890 --> 00:04:22,480 How’s that supposed to work when the tape is trapped in a box? 82 00:04:22,480 --> 00:04:25,500 Well, that’s what the holes on the side of the cassette are for. 83 00:04:25,500 --> 00:04:28,450 See how the capstan is shaped almost like a spike? 84 00:04:28,450 --> 00:04:32,420 The capstan goes through this hole and thus ends up behind the tape. 85 00:04:32,420 --> 00:04:36,590 Then the pinch roller can move upwards and squeeze the tape against the capstan. 86 00:04:36,590 --> 00:04:39,440 Which brings us to the holes on the bottom of the cassette. 87 00:04:39,440 --> 00:04:43,460 Rather than bring the tape to the heads, the cassette brings the heads to the tape. 88 00:04:43,460 --> 00:04:47,970 The three holes on the bottom are shaped and sized so that the erase head, play head, and 89 00:04:47,970 --> 00:04:51,570 pinch roller can all fit neatly inside the cassette shell. 90 00:04:51,570 --> 00:04:56,210 The mechanism of the cassette deck lifts these three components together inside the cassette. 91 00:04:56,210 --> 00:05:01,300 A felt pad sits inside the cassette shell, and it helps keep the tape against the head. 92 00:05:01,300 --> 00:05:05,610 The pad is glued to a metal brace that acts like a spring, making sure that the pad pushes 93 00:05:05,610 --> 00:05:06,790 firmly on the tape. 94 00:05:06,790 --> 00:05:10,190 When recording, only half the tape is actually used. 95 00:05:10,190 --> 00:05:13,860 This head is aligned with only one side of the tape so that the tape can be turned round 96 00:05:13,860 --> 00:05:17,730 at the end and run in the opposite direction for a second side. 97 00:05:17,730 --> 00:05:20,940 Part of what made the cassette successful was its simplicity. 98 00:05:20,940 --> 00:05:25,620 In many recorders, the buttons that you pressed were physically linked to the mechanism. 99 00:05:25,620 --> 00:05:28,100 This sony stereo is a great example. 100 00:05:28,100 --> 00:05:31,260 This cassette recorder actually holds the tape upside down. 101 00:05:31,260 --> 00:05:35,880 The play button is directly connected to pinch roller and heads, and the act of pushing down 102 00:05:35,880 --> 00:05:39,020 on the button is what actually pushes the heads into the tape. 103 00:05:39,020 --> 00:05:43,230 In conventional cassette decks, the buttons are instead levers that sit underneath the 104 00:05:43,230 --> 00:05:44,230 cassette door. 105 00:05:44,230 --> 00:05:48,140 They’re often called piano keys, and they did just what this button does. 106 00:05:48,140 --> 00:05:52,250 The only reason this cassette recorder holds the tape upside down is so that the buttons 107 00:05:52,250 --> 00:05:54,080 could be on top. 108 00:05:54,080 --> 00:05:58,600 Higher end machines like this use automatic mechanisms to move the components around, 109 00:05:58,600 --> 00:06:01,460 rather than directly connect those components to the buttons. 110 00:06:01,460 --> 00:06:05,990 These were called soft touch controls, and when cassette decks started to get microcomputers 111 00:06:05,990 --> 00:06:10,450 inside controlling them, the buttons could be placed anywhere on the machine, and these 112 00:06:10,450 --> 00:06:13,370 machines were said to have full logic control. 113 00:06:13,370 --> 00:06:17,310 Now that we understand the mechanical elements of the compact cassette, let’s examine the 114 00:06:17,310 --> 00:06:18,740 technical details. 115 00:06:18,740 --> 00:06:23,020 At the time of the cassette’s introduction, standard audio tape sounded pretty awful at 116 00:06:23,020 --> 00:06:25,820 the slow speed of 1 and seven eights inches per second. 117 00:06:25,820 --> 00:06:38,880 Here’s an example of what that sounds like: This speed wasn’t very good for music, but 118 00:06:38,880 --> 00:06:40,090 it was fine for speech. 119 00:06:40,090 --> 00:06:41,090 See? 120 00:06:41,090 --> 00:06:43,720 I’ve run this sound through the tape recorder and inserted it here. 121 00:06:43,720 --> 00:06:47,760 It may not sound as good as before, but you can still understand me just fine. 122 00:06:47,760 --> 00:06:50,700 So this was the speed chosen for the compact cassette. 123 00:06:50,700 --> 00:06:55,070 The slow speed allowed for recording times of up to 60 minutes per side on the cassette, 124 00:06:55,070 --> 00:06:57,530 which was a great benefit for recording memos. 125 00:06:57,530 --> 00:07:01,270 Now the corporate luddites we talked about earlier could record their letter to Professor 126 00:07:01,270 --> 00:07:05,320 Frederick, pop the cassette in an envelope for inter-departmental delivery, and the ladies 127 00:07:05,320 --> 00:07:09,830 in the transcription department would type up the letter and send it back for approval. 128 00:07:09,830 --> 00:07:12,100 What a weird time we used to live in… 129 00:07:12,100 --> 00:07:13,200 But that was it. 130 00:07:13,200 --> 00:07:15,760 That right there is what Philips invented the cassette for. 131 00:07:15,760 --> 00:07:19,170 8 track cartridges were just coming out, and they seemed fine for music. 132 00:07:19,170 --> 00:07:20,700 No need to improve the cassette. 133 00:07:20,700 --> 00:07:22,580 OK, there actually was a need. 134 00:07:22,580 --> 00:07:26,270 The 8 track was a weird format plagued with issues, and wouldn’t last. 135 00:07:26,270 --> 00:07:29,510 Now we had the problem of how to get the cassette ready for music. 136 00:07:29,510 --> 00:07:32,090 The slow tape speed wasn’t gonna allow for decent music. 137 00:07:32,090 --> 00:07:37,670 Well, it might not have in 1962, but by the 1970’s the actual tape was improved so much 138 00:07:37,670 --> 00:07:39,830 that the slow speed wasn’t an issue. 139 00:07:39,830 --> 00:07:43,550 Cassettes had roughly the same fidelity as the 8 track by the early 70s. 140 00:07:43,550 --> 00:07:44,790 But then there’s another issue. 141 00:07:44,790 --> 00:07:46,030 We want stereo! 142 00:07:46,030 --> 00:07:49,940 To get stereo sound on the cassette, the tape had to be split into 4 tracks. 143 00:07:49,940 --> 00:07:52,280 2 in one direction, and 2 in the other. 144 00:07:52,280 --> 00:07:55,650 These narrow tracks were kept compatible with older mono equipment because they were right 145 00:07:55,650 --> 00:07:59,280 next to each other, and they’d work together for a mono signal. 146 00:07:59,280 --> 00:08:01,150 But they also introduced a problem. 147 00:08:01,150 --> 00:08:05,010 The signal to noise ratio of the tape suddenly became much worse. 148 00:08:05,010 --> 00:08:08,760 Having a narrower track meant that the signals recorded onto the tape became weaker compared 149 00:08:08,760 --> 00:08:10,260 to the background noise. 150 00:08:10,260 --> 00:08:14,290 But Dolby noise reduction would save the day and bring the noise back in line, in fact 151 00:08:14,290 --> 00:08:16,390 improving noise beyond what it was originally. 152 00:08:16,390 --> 00:08:20,580 Here you’ll find a separate video explaining how Dolby Noise Reduction works. 153 00:08:20,580 --> 00:08:23,980 By the 1980’s, the cassette was well established as a music format. 154 00:08:23,980 --> 00:08:26,930 And they sounded really good. 155 00:08:26,930 --> 00:08:33,570 Have a listen: 156 00:08:33,570 --> 00:08:35,669 I bet you didn’t think the cassette sounded that good. 157 00:08:35,669 --> 00:08:37,979 Well, that’s just the tip of the iceberg. 158 00:08:37,979 --> 00:08:42,659 That recording used normal tape, which uses ferric oxide as the magnetic medium. 159 00:08:42,659 --> 00:08:46,940 Cassette recorders equipped with adjustable bias circuitry could also record onto chromium 160 00:08:46,940 --> 00:08:49,009 tapes and metal tapes. 161 00:08:49,009 --> 00:08:53,379 These special tapes were designated type 2 and type 4, and they sounded even better. 162 00:08:53,379 --> 00:08:58,290 A type 2 tape uses chromium dioxide as its medium, and this can hold more signal than 163 00:08:58,290 --> 00:09:00,100 standard type 1 tape. 164 00:09:00,100 --> 00:09:04,460 It required that the machine record with a higher bias frequency and more volume, but 165 00:09:04,460 --> 00:09:08,810 the resulting recording had a superior signal to noise ratio than standard tape. 166 00:09:08,810 --> 00:09:12,560 Type 4 tape was fairly expensive and used pure metal particles. 167 00:09:12,560 --> 00:09:16,629 These could hold a lot of signal, but only higher-end cassette decks could record onto 168 00:09:16,629 --> 00:09:17,629 them. 169 00:09:17,629 --> 00:09:20,950 Metal tapes sounded better than vinyl records, and indeed they sound just as good as any 170 00:09:20,950 --> 00:09:23,550 CD, provided you’ve got a good enough tape deck. 171 00:09:23,550 --> 00:09:26,029 So we have type 1, 2, and 4. 172 00:09:26,029 --> 00:09:28,810 Astute viewers may have noticed we skipped 3. 173 00:09:28,810 --> 00:09:33,730 Type 3 tapes used a mixture of chromium dioxide and metal, but they really never took off. 174 00:09:33,730 --> 00:09:38,370 They’re so uncommon you’ll probably never find a machine with a setting to use them. 175 00:09:38,370 --> 00:09:41,860 The types of tapes have notches on the back so that higher end machines could tell them 176 00:09:41,860 --> 00:09:43,589 apart automatically. 177 00:09:43,589 --> 00:09:48,370 Right next to the write-protect tab is another notch indicating that this is a chrome tape. 178 00:09:48,370 --> 00:09:51,300 Metal tapes have yet another notch closer to the center. 179 00:09:51,300 --> 00:09:56,370 Sensors in the tape deck would detect these notches and adjust the record parameters automatically. 180 00:09:56,370 --> 00:09:58,879 This deck, though, has a manual selector switch. 181 00:09:58,879 --> 00:10:01,529 Let’s listen to the difference each tape type makes. 182 00:10:01,529 --> 00:13:51,059 Here’s the same song recorded with the same level on each of the three tapes. 183 00:13:51,059 --> 00:13:54,660 Because people are so lazy, auto reverse became a priority. 184 00:13:54,660 --> 00:13:58,970 Early machines used elaborate mechanisms to actually remove the cassette from the transport, 185 00:13:58,970 --> 00:14:01,069 flip it over, and then put it back. 186 00:14:01,069 --> 00:14:04,499 These were quickly superseded by machines that used a rotating head. 187 00:14:04,499 --> 00:14:07,970 When the tape was playing in the forward direction, the heads would sit like any other deck. 188 00:14:07,970 --> 00:14:12,069 But when the tape got to the end, they heads would quickly flip around and then the tape 189 00:14:12,069 --> 00:14:13,749 would start moving in the other direction. 190 00:14:13,749 --> 00:14:18,160 The change in direction happened due to a pair of capstans which turn in opposite directions. 191 00:14:18,160 --> 00:14:22,589 Depending on the direction selected, the pinch roller corresponding to that direction would 192 00:14:22,589 --> 00:14:25,129 come up and squeeze the tape against the capstan. 193 00:14:25,129 --> 00:14:30,480 Interestingly, Nakamichi, the fairly undisputed champion of high quality cassette decks, returned 194 00:14:30,480 --> 00:14:34,230 to a mechanism which actually flipped the tape around because of concerns that the rotating 195 00:14:34,230 --> 00:14:38,139 head mechanism could over time bring the heads out of alignment. 196 00:14:38,139 --> 00:14:41,240 Whether or not this happens in practice is up for debate. 197 00:14:41,240 --> 00:14:44,520 Part of why the cassette took off was that it was so portable. 198 00:14:44,520 --> 00:14:49,819 The Sony Walkman was the first portable cassette player, and it was introduced in 1979. 199 00:14:49,819 --> 00:14:54,119 Later models like this one would add dolby noise reduction, tape formulation selection, 200 00:14:54,119 --> 00:14:55,410 and even auto reverse. 201 00:14:55,410 --> 00:14:58,250 All in a machine barely larger than the tape itself. 202 00:14:58,250 --> 00:15:03,490 In fact, one walkman was smaller than a cassette, and the machine expanded around it when playing. 203 00:15:03,490 --> 00:15:07,749 One interesting note here is that auto reverse walkmans actually have 4 heads. 204 00:15:07,749 --> 00:15:12,069 When playing in one direction, the heads listening to the other side are muted and you only hear 205 00:15:12,069 --> 00:15:16,569 the forward heads (the other heads are listening to side B backwards). 206 00:15:16,569 --> 00:15:20,329 Then when the it got to the end of a side, it switched pinch rollers, thereby reversing 207 00:15:20,329 --> 00:15:24,490 direction, and then switched electronically to the other set of heads. 208 00:15:24,490 --> 00:15:28,170 I’ve often wondered why Nakamichi didn’t just do this, with 4 heads and a miniature 209 00:15:28,170 --> 00:15:32,459 erase head like this conventional auto reverse machine has on each side. 210 00:15:32,459 --> 00:15:35,509 The cassette died a slow death into the 2000s. 211 00:15:35,509 --> 00:15:39,279 It stuck around in car stereos for a while since road vibrations didn’t affect tapes 212 00:15:39,279 --> 00:15:43,149 like they did CDs, but eventually they pretty much faded away. 213 00:15:43,149 --> 00:15:45,260 The cassette never really disappeared though. 214 00:15:45,260 --> 00:15:48,689 It’s not really dead, and in fact is receiving somewhat of a revival. 215 00:15:48,689 --> 00:15:53,529 I admit I like the ability to make a mixtape (the modern equivalent being a playlist) and 216 00:15:53,529 --> 00:15:55,939 have a physical thing that contains the music. 217 00:15:55,939 --> 00:16:00,309 And they do have a retro quality to them that’s hard to replicate with a playlist on a smartphone. 218 00:16:00,309 --> 00:16:02,940 Thanks for joining me on Tech Explorations. 219 00:16:02,940 --> 00:16:06,750 Be sure to subscribe for more videos like this, or our series Technology Connections.