WEBVTT Kind: captions Language: en 00:00:00.229 --> 00:00:02.690 So you think you know the cassette tape, eh? 00:00:02.690 --> 00:00:07.140 That 80s and 90s crappy-sounding barely tolerable thing we had before CD’s? 00:00:07.140 --> 00:00:09.550 The ones that got eaten by your car all the time? 00:00:09.550 --> 00:00:11.829 The thing hipsters are pretending to listen to? 00:00:11.829 --> 00:00:15.230 Whatever memories you have of the cassette could probably use some refreshing. 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 00:00:19.119 --> 00:00:20.890 by some interesting technology. 00:00:20.890 --> 00:00:22.210 Let’s have a look. 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 00:00:26.070 --> 00:00:27.359 them to take off. 00:00:27.359 --> 00:00:31.189 The official name for them is the Compact Cassette, and it was the Philips company that 00:00:31.189 --> 00:00:33.590 invented them in 1962. 00:00:33.590 --> 00:00:37.940 They aimed to solve two problems, neither of which had anything to do with music. 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 00:00:41.930 --> 00:00:42.930 widespread. 00:00:42.930 --> 00:00:45.969 But the machines weren’t very portable, and even those that tried to be were still 00:00:45.969 --> 00:00:49.489 plagued by the problem of tape which required being manually threaded. 00:00:49.489 --> 00:00:52.579 In the professional recording studio, these weren’t problems. 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 00:00:55.989 --> 00:00:59.879 wasn’t a hassle compared to all the other hassles that accompany recording music. 00:00:59.879 --> 00:01:04.730 But people saw uses for magnetic tape outside the recording studio, particularly in recording 00:01:04.730 --> 00:01:05.750 speech. 00:01:05.750 --> 00:01:09.880 In those days, men weren’t really expected to know how to type. 00:01:09.880 --> 00:01:13.680 The big-wigs in offices had secretaries to type their letters for them. 00:01:13.680 --> 00:01:17.500 But secretaries had this annoying habit of leaving at the end of the day, thus being 00:01:17.500 --> 00:01:20.830 unavailable to use their stenographic skills. 00:01:20.830 --> 00:01:24.280 Machines like the dictaphone allowed these corporate luddites to record their speech 00:01:24.280 --> 00:01:27.380 at their whimsy so someone else could write it out later. 00:01:27.380 --> 00:01:31.750 The problem with the dictaphone was that it used non-reusable cylinders or belts, and 00:01:31.750 --> 00:01:36.500 mistakes couldn’t be fixed without some sort of added note marking them as a mistake. 00:01:36.500 --> 00:01:40.050 Magnetic tape, though, could be reused and recorded over, since the magnetic signals 00:01:40.050 --> 00:01:42.490 recorded on the tape could be erased. 00:01:42.490 --> 00:01:46.110 Mistakes were easy to correct, just back the tape up and record over the mistake. 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 00:01:50.080 --> 00:01:51.610 them in an office setting. 00:01:51.610 --> 00:01:54.060 The compact cassette fixed that right up, though. 00:01:54.060 --> 00:01:58.660 A number of clever innovations made for a practical, portable tape format. 00:01:58.660 --> 00:02:01.840 The most important innovation was the cassette itself. 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 00:02:06.000 --> 00:02:08.640 access holes at the bottom of the cassette. 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 00:02:12.250 --> 00:02:16.900 the machine to wind the tape with special spindles that mesh with these cogs. 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 00:02:20.180 --> 00:02:21.769 be much thinner. 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 00:02:25.960 --> 00:02:28.610 get too thin or it will break with handling. 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), 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. 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 00:02:41.660 --> 00:02:43.870 of holes that are very important. 00:02:43.870 --> 00:02:47.129 These are what allow the cassette recorder to interact with the tape. 00:02:47.129 --> 00:02:50.939 Cassette recorders work fundamentally the same as a reel to reel recorder, but since 00:02:50.939 --> 00:02:54.049 we’re using a cassette the machine interacts with the tape a little differently. 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 00:02:59.069 --> 00:03:00.069 recorded. 00:03:00.069 --> 00:03:02.900 The parts that interact with the tape are called the transport. 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 00:03:07.110 --> 00:03:08.550 between them. 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 00:03:12.519 --> 00:03:16.650 pulled out and through the transport before being wound onto the empty reel. 00:03:16.650 --> 00:03:20.959 The tape passes three heads, first an erase head, then the record head, and finally the 00:03:20.959 --> 00:03:22.030 playback head. 00:03:22.030 --> 00:03:25.739 Lastly, the tape goes through the capstan and pinch roller, which are the parts that 00:03:25.739 --> 00:03:27.999 actually pull the tape past the heads. 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. 00:03:32.310 --> 00:03:37.230 The pinch roller, a small rubber wheel, squeezes the tape between itself and the spinning capstan, 00:03:37.230 --> 00:03:39.260 and this is what actually moves the tape. 00:03:39.260 --> 00:03:42.409 The reel on the right only rotates to spool the tape onto the reel. 00:03:42.409 --> 00:03:46.110 See, if I stop it, the tape doesn’t stop moving through the machine. 00:03:46.110 --> 00:03:50.139 Also important to note is the curved path of the tape as it passes the heads. 00:03:50.139 --> 00:03:54.159 This ensures that it stays tightly against the heads, and various tape guides make sure 00:03:54.159 --> 00:03:56.450 it stays in alignment as it passes them. 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 00:03:59.719 --> 00:04:01.459 the same, although smaller. 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 00:04:05.650 --> 00:04:09.950 use one head for both functions), and the capstan and pinch roller are on the right. 00:04:09.950 --> 00:04:13.109 But you might notice some problems that come about with the cassette. 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 00:04:16.650 --> 00:04:17.670 on the other. 00:04:17.670 --> 00:04:19.890 The tape has to somehow get between them. 00:04:19.890 --> 00:04:22.480 How’s that supposed to work when the tape is trapped in a box? 00:04:22.480 --> 00:04:25.500 Well, that’s what the holes on the side of the cassette are for. 00:04:25.500 --> 00:04:28.450 See how the capstan is shaped almost like a spike? 00:04:28.450 --> 00:04:32.420 The capstan goes through this hole and thus ends up behind the tape. 00:04:32.420 --> 00:04:36.590 Then the pinch roller can move upwards and squeeze the tape against the capstan. 00:04:36.590 --> 00:04:39.440 Which brings us to the holes on the bottom of the cassette. 00:04:39.440 --> 00:04:43.460 Rather than bring the tape to the heads, the cassette brings the heads to the tape. 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 00:04:47.970 --> 00:04:51.570 pinch roller can all fit neatly inside the cassette shell. 00:04:51.570 --> 00:04:56.210 The mechanism of the cassette deck lifts these three components together inside the cassette. 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. 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 00:05:05.610 --> 00:05:06.790 firmly on the tape. 00:05:06.790 --> 00:05:10.190 When recording, only half the tape is actually used. 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 00:05:13.860 --> 00:05:17.730 at the end and run in the opposite direction for a second side. 00:05:17.730 --> 00:05:20.940 Part of what made the cassette successful was its simplicity. 00:05:20.940 --> 00:05:25.620 In many recorders, the buttons that you pressed were physically linked to the mechanism. 00:05:25.620 --> 00:05:28.100 This sony stereo is a great example. 00:05:28.100 --> 00:05:31.260 This cassette recorder actually holds the tape upside down. 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 00:05:35.880 --> 00:05:39.020 on the button is what actually pushes the heads into the tape. 00:05:39.020 --> 00:05:43.230 In conventional cassette decks, the buttons are instead levers that sit underneath the 00:05:43.230 --> 00:05:44.230 cassette door. 00:05:44.230 --> 00:05:48.140 They’re often called piano keys, and they did just what this button does. 00:05:48.140 --> 00:05:52.250 The only reason this cassette recorder holds the tape upside down is so that the buttons 00:05:52.250 --> 00:05:54.080 could be on top. 00:05:54.080 --> 00:05:58.600 Higher end machines like this use automatic mechanisms to move the components around, 00:05:58.600 --> 00:06:01.460 rather than directly connect those components to the buttons. 00:06:01.460 --> 00:06:05.990 These were called soft touch controls, and when cassette decks started to get microcomputers 00:06:05.990 --> 00:06:10.450 inside controlling them, the buttons could be placed anywhere on the machine, and these 00:06:10.450 --> 00:06:13.370 machines were said to have full logic control. 00:06:13.370 --> 00:06:17.310 Now that we understand the mechanical elements of the compact cassette, let’s examine the 00:06:17.310 --> 00:06:18.740 technical details. 00:06:18.740 --> 00:06:23.020 At the time of the cassette’s introduction, standard audio tape sounded pretty awful at 00:06:23.020 --> 00:06:25.820 the slow speed of 1 and seven eights inches per second. 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 00:06:38.880 --> 00:06:40.090 it was fine for speech. 00:06:40.090 --> 00:06:41.090 See? 00:06:41.090 --> 00:06:43.720 I’ve run this sound through the tape recorder and inserted it here. 00:06:43.720 --> 00:06:47.760 It may not sound as good as before, but you can still understand me just fine. 00:06:47.760 --> 00:06:50.700 So this was the speed chosen for the compact cassette. 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, 00:06:55.070 --> 00:06:57.530 which was a great benefit for recording memos. 00:06:57.530 --> 00:07:01.270 Now the corporate luddites we talked about earlier could record their letter to Professor 00:07:01.270 --> 00:07:05.320 Frederick, pop the cassette in an envelope for inter-departmental delivery, and the ladies 00:07:05.320 --> 00:07:09.830 in the transcription department would type up the letter and send it back for approval. 00:07:09.830 --> 00:07:12.100 What a weird time we used to live in… 00:07:12.100 --> 00:07:13.200 But that was it. 00:07:13.200 --> 00:07:15.760 That right there is what Philips invented the cassette for. 00:07:15.760 --> 00:07:19.170 8 track cartridges were just coming out, and they seemed fine for music. 00:07:19.170 --> 00:07:20.700 No need to improve the cassette. 00:07:20.700 --> 00:07:22.580 OK, there actually was a need. 00:07:22.580 --> 00:07:26.270 The 8 track was a weird format plagued with issues, and wouldn’t last. 00:07:26.270 --> 00:07:29.510 Now we had the problem of how to get the cassette ready for music. 00:07:29.510 --> 00:07:32.090 The slow tape speed wasn’t gonna allow for decent music. 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 00:07:37.670 --> 00:07:39.830 that the slow speed wasn’t an issue. 00:07:39.830 --> 00:07:43.550 Cassettes had roughly the same fidelity as the 8 track by the early 70s. 00:07:43.550 --> 00:07:44.790 But then there’s another issue. 00:07:44.790 --> 00:07:46.030 We want stereo! 00:07:46.030 --> 00:07:49.940 To get stereo sound on the cassette, the tape had to be split into 4 tracks. 00:07:49.940 --> 00:07:52.280 2 in one direction, and 2 in the other. 00:07:52.280 --> 00:07:55.650 These narrow tracks were kept compatible with older mono equipment because they were right 00:07:55.650 --> 00:07:59.280 next to each other, and they’d work together for a mono signal. 00:07:59.280 --> 00:08:01.150 But they also introduced a problem. 00:08:01.150 --> 00:08:05.010 The signal to noise ratio of the tape suddenly became much worse. 00:08:05.010 --> 00:08:08.760 Having a narrower track meant that the signals recorded onto the tape became weaker compared 00:08:08.760 --> 00:08:10.260 to the background noise. 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 00:08:14.290 --> 00:08:16.390 improving noise beyond what it was originally. 00:08:16.390 --> 00:08:20.580 Here you’ll find a separate video explaining how Dolby Noise Reduction works. 00:08:20.580 --> 00:08:23.980 By the 1980’s, the cassette was well established as a music format. 00:08:23.980 --> 00:08:26.930 And they sounded really good. 00:08:26.930 --> 00:08:33.570 Have a listen: 00:08:33.570 --> 00:08:35.669 I bet you didn’t think the cassette sounded that good. 00:08:35.669 --> 00:08:37.979 Well, that’s just the tip of the iceberg. 00:08:37.979 --> 00:08:42.659 That recording used normal tape, which uses ferric oxide as the magnetic medium. 00:08:42.659 --> 00:08:46.940 Cassette recorders equipped with adjustable bias circuitry could also record onto chromium 00:08:46.940 --> 00:08:49.009 tapes and metal tapes. 00:08:49.009 --> 00:08:53.379 These special tapes were designated type 2 and type 4, and they sounded even better. 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 00:08:58.290 --> 00:09:00.100 standard type 1 tape. 00:09:00.100 --> 00:09:04.460 It required that the machine record with a higher bias frequency and more volume, but 00:09:04.460 --> 00:09:08.810 the resulting recording had a superior signal to noise ratio than standard tape. 00:09:08.810 --> 00:09:12.560 Type 4 tape was fairly expensive and used pure metal particles. 00:09:12.560 --> 00:09:16.629 These could hold a lot of signal, but only higher-end cassette decks could record onto 00:09:16.629 --> 00:09:17.629 them. 00:09:17.629 --> 00:09:20.950 Metal tapes sounded better than vinyl records, and indeed they sound just as good as any 00:09:20.950 --> 00:09:23.550 CD, provided you’ve got a good enough tape deck. 00:09:23.550 --> 00:09:26.029 So we have type 1, 2, and 4. 00:09:26.029 --> 00:09:28.810 Astute viewers may have noticed we skipped 3. 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. 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. 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 00:09:41.860 --> 00:09:43.589 apart automatically. 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. 00:09:48.370 --> 00:09:51.300 Metal tapes have yet another notch closer to the center. 00:09:51.300 --> 00:09:56.370 Sensors in the tape deck would detect these notches and adjust the record parameters automatically. 00:09:56.370 --> 00:09:58.879 This deck, though, has a manual selector switch. 00:09:58.879 --> 00:10:01.529 Let’s listen to the difference each tape type makes. 00:10:01.529 --> 00:13:51.059 Here’s the same song recorded with the same level on each of the three tapes. 00:13:51.059 --> 00:13:54.660 Because people are so lazy, auto reverse became a priority. 00:13:54.660 --> 00:13:58.970 Early machines used elaborate mechanisms to actually remove the cassette from the transport, 00:13:58.970 --> 00:14:01.069 flip it over, and then put it back. 00:14:01.069 --> 00:14:04.499 These were quickly superseded by machines that used a rotating head. 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. 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 00:14:12.069 --> 00:14:13.749 would start moving in the other direction. 00:14:13.749 --> 00:14:18.160 The change in direction happened due to a pair of capstans which turn in opposite directions. 00:14:18.160 --> 00:14:22.589 Depending on the direction selected, the pinch roller corresponding to that direction would 00:14:22.589 --> 00:14:25.129 come up and squeeze the tape against the capstan. 00:14:25.129 --> 00:14:30.480 Interestingly, Nakamichi, the fairly undisputed champion of high quality cassette decks, returned 00:14:30.480 --> 00:14:34.230 to a mechanism which actually flipped the tape around because of concerns that the rotating 00:14:34.230 --> 00:14:38.139 head mechanism could over time bring the heads out of alignment. 00:14:38.139 --> 00:14:41.240 Whether or not this happens in practice is up for debate. 00:14:41.240 --> 00:14:44.520 Part of why the cassette took off was that it was so portable. 00:14:44.520 --> 00:14:49.819 The Sony Walkman was the first portable cassette player, and it was introduced in 1979. 00:14:49.819 --> 00:14:54.119 Later models like this one would add dolby noise reduction, tape formulation selection, 00:14:54.119 --> 00:14:55.410 and even auto reverse. 00:14:55.410 --> 00:14:58.250 All in a machine barely larger than the tape itself. 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. 00:15:03.490 --> 00:15:07.749 One interesting note here is that auto reverse walkmans actually have 4 heads. 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 00:15:12.069 --> 00:15:16.569 the forward heads (the other heads are listening to side B backwards). 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 00:15:20.329 --> 00:15:24.490 direction, and then switched electronically to the other set of heads. 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 00:15:28.170 --> 00:15:32.459 erase head like this conventional auto reverse machine has on each side. 00:15:32.459 --> 00:15:35.509 The cassette died a slow death into the 2000s. 00:15:35.509 --> 00:15:39.279 It stuck around in car stereos for a while since road vibrations didn’t affect tapes 00:15:39.279 --> 00:15:43.149 like they did CDs, but eventually they pretty much faded away. 00:15:43.149 --> 00:15:45.260 The cassette never really disappeared though. 00:15:45.260 --> 00:15:48.689 It’s not really dead, and in fact is receiving somewhat of a revival. 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 00:15:53.529 --> 00:15:55.939 have a physical thing that contains the music. 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. 00:16:00.309 --> 00:16:02.940 Thanks for joining me on Tech Explorations. 00:16:02.940 --> 00:16:06.750 Be sure to subscribe for more videos like this, or our series Technology Connections.