Talk:Cassette tape/Archive 1

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Data rates

Data rates for cassettes as data storage are from Slashdot. Not verified. Hotlorp 05:09, 10 Jan 2004 (UTC) http://slashdot.org/articles/03/09/18/1857204.shtml?tid=126

4k bps was a typical data rate for digital cassette tape storage in the 1980s. --Blainster 08:56, 19 December 2005 (UTC)

MC

The name "musicassette" or MC refers ONLY to pre-recorded cassette albums, not recordable cassettes. Lee M 01:57, 16 Apr 2004 (UTC)

Dubious dimensions

Is it just me, or do the metric measurements in the article seem overly precise? Is the width of a single track really specified down to tenths of a micrometre? To help visualise it, a single human hair is about 100 micrometres thick. This means that the track width is specified to thousandths of a hair's width.

Conversions from imperial to metric shouldn't just be mechanic calculations based on conversion factors taught by rote in school. They should actually have some perspective to the real-life things that are actually being measured.

Or to put it another way, how would you feel if I (being approximately 186 cm tall) expressed my height as 6 feet, 1.228346457 inches? — JIP | Talk 10:08, 3 Apr 2005 (UTC)

The dimensions currently given in the article look not very plausible:

• As a Dutch company, Philips is unlikely to use foreign, archaic units in their designs. The inch values appear to be crudely rounded versions of the original metric dimensions. The millimetre values given in the article are merely exact back conversions of the incorrect inch values. They contradict other sources that give the width of the tape as 3.8 mm, for example.
• The tape speed is variable. Since the pulling reel is driven with constant angular velocity, the tape speed at the head will increase as the pulling reel fills up. The tape speed therefore must be a wide interval, not the currently given value "17⁄8 inches per second (47.625 mm/s)", which has ridiculous accuracy anyway.

If someone has access to the standards that I added to the reference section, could you please look up the real dimensions and replace the current inch mess? Markus Kuhn 21:04, 18 December 2005 (UTC)

The takeup reel does not pull the tape, it only takes up the slack. The tape speed is controlled by the capstan speed, not the reel motor (if any). Thus the tape speed is constant (within margin). If it wasn't, cassettes could not be used for music. --Blainster 08:49, 19 December 2005 (UTC)

Here is an online example of cassette tape specifications. --Blainster 10:22, 19 December 2005 (UTC)

It's very notable that 1/8 inch is far closer to 3.18cm than 3.81cm. Is the latter really correct? Perhaps it was typed in wrongly. Multiple sources don't necessarily mean much if they all got their wrong information from the same place. Fourohfour 10:46, 19 December 2005 (UTC)

This looks like a typo, as is should be 3.175 mm. The tape width is 1/8", despite Philips being a European (and hence probably metricated) company, because at the time, tape widths were already standardised at fractional inch widths, with 1/4" tape being the most common. Therefore they almost certainly simply halved it which would have required minimal tooling changes for tape manufacturers to adopt. This is only speculation on my part, but as evidence to support this, I just measured a few cassettes with a vernier caliper, and it looks as if they are indeed a fraction under 3.18mm, which is accurate as my gauge can measure (and bearing in mind tape is too bendy to get a very accurate measurement on with calipers). GRAHAMUK 19 December 2005

Good work. The 3.81 mm dimension I copied without measuring is clearly a typo, all though in my defense I note that this number has proliferated across a number of websites. Thanks for checking and correcting it. Isn't Wikipedia great? --Blainster 17:07, 19 December 2005 (UTC)

BASF

The article's second sentence reads: "It consists of a length of magnetic tape from BASF inside a protective plastic shell." This could be interpreted to mean that all cassetes - sold by all companies - contain tape made by BASF. I'm pretty sure that's not the case, and the intended meaning may have been simply that BASF invented the type of tape used in cassetes, but it needs to be clarified.

--4.245.5.118 23:46, 25 Apr 2005 (UTC)

What they meant to say was that the first tape cassette was made by Philips using BASF tape.

External Links

I removed a link that was essentially an ad. I saw the person who added it said it was a good example of the cassette in today's market, but it seems irrelevant. Anyone who feels different, feel free to explain why... methelfilms 03:00, 14 July 2005 (UTC)

Endless loop?

Can somebody with more technical expertise that what I have write a section that talks about endless-loop cassettes? Although I think they've fallen out of favor, they were popular in answering machines and in music-on-hold systems. Some had a metalic piece of tape that served as a "marker" for the equipment to know when the tape had made a complete cycle. Any takers to write such a section? Joe 19:49, 3 October 2005 (UTC)

C15?

Am I right in thinking C15 tapes were widely available for a period? I seem to remember using them for ZX Spectrum data.--bodnotbod 12:39, 26 October 2005 (UTC)

They certainly were, as I have several. I also have some C46 (ie. LP-sized) ones. Bastie 14:09, 26 October 2005 (UTC)

Thanks. I'll add them into the article. --bodnotbod 16:25, 26 October 2005 (UTC)

Coleco ADAM

The Coleco_Adam computer used two high-speed drives based on compact cassette technology.

• I remember reading an article about that; apparently the cassettes were not "normal" audio cassettes, although I don't know what the difference was (I assume it was in the tape formulation and not the shell, as it mentioned the possibility that "normal" cassettes could be inappropriately used) Fourohfour 00:49, 31 October 2005 (UTC)

Track layout

"the two stereo tracks lie adjacent to each other rather than a 1/3 and 2/4 arrangement. " -- could someone explain this for the layperson? -- Tarquin

I think it means that the tape is laid out like this:

1111111
2222222
3333333
4444444
<---> direction of tape

rather than:

1111111
3333333
2222222
4444444

Where 1 and 2 are the stereo channels of side one, and 3 and 4 are the stereo channels of side two. How to put that into simple language without taking up half a page is a different matter, however... --Camembert

The second diagram is wrong. Compact Cassette recorded the side A stereo on track 1 and 2 in the first diagram (and side B on tracks 3 and 4. Reel-to-reel recorders, on the other hand recorded the side A stereo on tracks 1 and 3 in the first diagram (and side B on tracks 2 and 4). This meant that although the stereo recording could be played back on 4-track mono machines (provided it permitted replay from both sections of the head), they could not be played back on 2-track mono or stereo machines. Mono 2-track recordings could be played back on mono 4-track machines (and stereo machines if the machine would play from one track only - as most did).

Interesting. But I don't understand how this change is advantageous. Bastie 12:21, 12 October 2005 (UTC)

I think it means that it's easier to build cheap monophonic players because they can get by with only two heads. One head can read both the left and right tracks in one direction and the other head can read the left and write tracks in the other direction. That makes their mechanics simpler and cheaper. I'm not an engineer, but that's how it was explained to me once. If anyone has a better explanation, I'd love to hear it. Joe 13:46, 12 October 2005 (UTC)

This is a good diagram of the types of R2R recording. Bastie 13:15, 23 October 2005 (UTC)

This is how the channels are located. By having the channels this way, makes it possible for mono playes to play stereo recordings (in mono) and vice versa. atmo 23:52, 9 February 2006 (CET)

We should have our own diagrams of this; they should be fairly simple to do. I was thinking of doing some of my own when I get off my lazy ass, but if someone else wants to do them first, no problem with me. Fourohfour 15:21, 10 February 2006 (UTC)

I read somewhere that a Stereo compact audio cassette, actually has five tracks... Tracks 1, 2, 4, and 5 have audio on them. Track 3 is silent... Side one is made up of Tracks 1, 2, and half of Track 3. Side Two consists of The Second Half of Track 3, plus Tracks 4 and 5. The Silent Track in the Center is there to help prevent crosstalk between the two sides.§ —The preceding unsigned comment was added by Garr1984 (talk • contribs).

That's interesting, but can you find a reliable source for it? Fourohfour 11:37, 9 March 2007 (UTC)

It was in some Handyman's encyclopedia, in a section discussing how to repair 8 Track and Cassette Tapes. Garr1984 04:09, 22 March 2007 (UTC)§

Discussion continued at New info on track & tape width dated 22 March, 2007 --Blainster 20:48, 26 March 2007 (UTC)

Article title

Is 'compact audio cassette' a meaningful term? The official name is "Compact Cassette", and it's usually referred to as an "audio cassette" or simply "cassette" nowadays... so where did this hybrid come from? Has it ever been used except as a result of this article?

I'm not convinced that it's worth changing the title of the article now (too much hassle with links), but if this is simply a neologism, wouldn't it be preferable to discourage its use elsewhere?

Fourohfour 10:14, 26 September 2005 (UTC)

I'd strongly favor "Compact Cassette" too, because it's the official name, and this would keep it in line with Compact Disc, and Digital Compact Cassette, the name of both of which derives from Compact Cassette. But it might be a pain with all the links.  ProhibitOnions  ^(T) 09:41, 14 May 2006 (UTC)

That's the only reason I didn't change it long ago... I'm sure that with the proper tools and/or admin powers it would be fairly simple, but I haven't looked into it yet. Fourohfour 20:38, 14 May 2006 (UTC)

Being an admin, it was no problem, so I did move it. Quite a lot of articles linked to "Compact Cassette" anyway, but I fixed all the redirect pages, of which there were many; less than half of articles linked to the previous article title "Compact audio cassette" so it was a problem that needed fixing anyway. I'll fix as many article links as I can but might look into getting a bot to do it instead.  ProhibitOnions  ^(T) 13:20, 23 May 2006 (UTC)

Great stuff, nice to see you changed it anyway! Fourohfour 12:26, 10 June 2006 (UTC)

"Tape" was the most common referal in my corner of the globe (Central United States).

Image of cassette types

Anyone else feel that this since the shells for the different tape-types aren't standardised, and what you can see of the tape inside looks the same, it doesn't actually add to the point it's meant to be illustrating?

OTOH, it's a fairly good technical shot (much better than the slightly-out-of-focus, non-colour-corrected, flash-reflections-showing, clutter-in-the-background stuff that sometimes appears on Wikipedia). Perhaps it should simply be rebadged as a general shot? Perhaps I'm nitpicking...

Fourohfour 10:03, 26 September 2005 (UTC)

I agree — while an excellent photo, it doesn't help to explain the differences between types of cassette. Laypersons might think that the differing appearances of the shells have something to do with the different tape types, which is not the case at all. Slicing 04:40, 4 December 2005 (UTC)

I've changed the caption; we now have an illustration of the differences between the types elsewhere anyway. Fourohfour 16:00, 4 December 2005 (UTC)

I added a second image of a higher quality cassette, A TDK MA-X to compliment the existing phito of a low end tape, the TDK D series. Teamgoon 23:28, 19 August 2006 (UTC)

I wouldnt mind seeing a timeline of casette types (as images), as they varied significantly over time. I've no images to offer though :( Tabby 16:01, 9 September 2007 (UTC)

8-tracks vs. the audio cassette

There should be some mention of the 8-track in here. I'd like to know how the 8-track ever got off the ground if, in addition to an inferior design, it was launched five years after the aduio casette. -Litefantastic 23:58, 12 March 2006 (UTC)

Bear in mind that cassettes were not originally intended for musical use, and that until the late 1960s their audio quality was (apparently) pretty ropey. I assume that the 8-track was marketed for musical use from the beginning. Whether it was actually better than the early cassettes, I don't know (doubly so because they never took off in Europe and I've never heard one). Fourohfour 00:05, 13 March 2006 (UTC)

The 8-track cartridge was introduced in 1964, only about a year after the cassette. But at the time the cassette was not much good for music, while the 8-track's 3.75 ips speed gave it a more tolerable high frequency response. Since 8-track tape was 1/4 inch wide, the track width was about the same as a 4-track stereo cassette. From 1964 until 1972 or possibly later, if you wanted to play music other than radio in your car, the only factory option was 8-track tape. The 8-track would play endlessly while the cassettes you had to flip over before auto-reverse came out. The two drawbacks to 8-track were its larger size (about 4x cassette), and its proclivity to tape wow due to friction in the tape layers which had to slip past each other in the endless loop. --Blainster 10:27, 13 March 2006 (UTC)

In addition to the above, cassettes were pretty fragile back in the early days - 8 tracks were much more robust and could be kicked around the floor of a truck without too much harm coming to them, and they were easy to slam into the deck without any problem. Ideal for mobile use. In car cassettes were at first very delicate little precious things that would throw a hissy fit at the slightest provocation, spilling the tape all over their prissy little innards! In-car units in the early days also cut silly corners like putting the tape in endways to save space but then not having any spigot for the supply reel and thus no back-tension on it. This was recipe for tape spillage. Also the fiddlyness of cassettes was considered too dangerous for in-car use compared to the chunky 8-track that could be loaded without taking your eyes off the road. Basically, cassetees simply weren't seriously considered as an in-car music format until the mid to late 70s. Graham 10:58, 13 March 2006 (UTC)

Branchlist

I've noticed that in addition to the "Compact Cassette" logo, the branchlist was added, and now keeps getting moved around. The problem is that with the branchlist, contents table, cassette image and logo image, there isn't enough room for all of them near the start without the layout suffering. Frankly, the way the intro looks just now isn't good, and I wish we could just settle on something that is a bit more presentable than this. Fourohfour 12:28, 2 April 2006 (UTC)

Mixed up article!

This article doesnt know whether its about the cassete tape or cassette recorders. Which is it? It cant be both and needs to be split!--Light current 01:08, 6 May 2006 (UTC)

Who says it needs to be split? Surely the two are mutually necessary? Of course, the general concepts of audio tape and audio tape recorders probably warrant separate articles, but for the Compact Cassette.... nah. Fourohfour 20:38, 6 May 2006 (UTC)

I don't think a split is appropriate. You can't really meaningfully discuss the development of the cassette in total isolation from the machines because improvements in both were necessary for the medium's success. There is an article at cassette deck which serves the need for focusing specifically on the machines, but I think this article as it stands has a good balance. Graham 13:20, 7 May 2006 (UTC)

Third world

From the article:

Although its use in the West has declined as a result of more advanced technologies, it remains widespread, and is still the dominant medium for listening to music in many third world countries.

Really? I don't think so. Where does the author got this information from? —The preceding unsigned comment was added by 200.153.183.111 (talk • contribs) 12:31, 14 May 2006 (UTC)

I've seen this discussed in several articles and TV programmes. As I can't specifically remember where this was however, I did a quick search of the web and found back up for it here:-

And outside of the music stores of the West, cassettes do continue to survive as a music format, in countries such as Afghanistan and India. In some markets, performers record directly onto cassette. [..] Turkey still sells 88 million cassettes a year, India 80 million, and that cassettes account for 50% of sales in these countries. In Saudi Arabia, it is 70%. (Source: BBC Article, June 2005)

and here

In Africa, India, and parts of the Middle-East, the cassette is still king. (Source: seemagazine.com article, 2004)

Hope this clears things up. Fourohfour 17:25, 10 June 2006 (UTC)

Mix Tape

What, no mention of mixtapes? That was one of the biggest things about cassettes was that you could make a mix tape for your girlfriend. Ah, nostalgia. —The preceding unsigned comment was added by 204.87.87.170 (talk • contribs) 08:21, 16 May 2006 (UTC)

Ummm, in the "See also" there is Mix tape. Graham 04:21, 17 May 2006 (UTC)

Mixtapes were not exclusive to cassettes. It has been done on reel to reel in the 50's & 60's. When I was a kid in the late 70's & early 80's, I would make mix tapes on 8 Track to play on the portables in the cars. And people now do it on CD-R. So mixtapes have no exclusivity to cassette. Teamgoon 12:29, 19 August 2006 (UTC)

True in theory, but not how it was in practice. For 99+% of the population, the cassette was for a long time the only accessible way to make music compilations. Tabby 15:59, 9 September 2007 (UTC)

"Actual size" image

In reference to the thumbnail of the Compact Cassette, Blainster's edit summary says he put it back to being large (300px) so that it's close to actual size. I've no wish to get into an edit war, so I've not made it smaller again, but I do think it wrecks the page for people with lower screen resolutions, by consuming potentially half of the available content space. (Some people still use 640x480!) This lack of accessibility is a shame. I'd see your point though, if it were possible to make things look actual size; that might be useful. But it's not what you've done here by specifying a number of pixels. The tape looks about half actual size on my widescreen laptop, for example, because it has very small pixels. If it looks actual size to you, that's a factor of your monitor. I'd suggest taking a new photo of a tape alongside a ruler or reference object. – Kieran T ^{(talk | contribs)} 00:48, 11 June 2006 (UTC)

A ruler only demonstrates something that should already have been explained verbally; e.g. if we're told that a tape is 12cm wide, having a ruler "show" this adds nothing. Why? If someone can't visualise 12cm, then showing it on a ruler isn't that helpful, unless the ruler represents an object of well-known size. And we often don't get to see the whole thing anyway.

If it's really necessary to have measurements on the photograph, then (e.g.) double-ended arrows with lengths marked for width, height and depth would be less intrusive. Fourohfour 22:18, 15 June 2006 (UTC)

I don't entirely agree, but I wasn't trying to be an advocate of rulers, I was merely hoping to be constructive rather than just negative. But it's moot anyway — Blainster revisited the page and decided to specify a smaller thumbnail. – Kieran T ^{(talk | contribs)} 22:26, 15 June 2006 (UTC)

Tape lengths

I wasn't aware that C46 was ever a common or popular cassette tape length, as the article suggests. C60, C90 and C120 have always been the standard lengths, but quite a few manufacturers produced "odd" sizes from time to time. AdorableRuffian 09:46, 21 September 2006 (UTC)

C46 was very common for use with data storage and indie recording artists. I'll try to find a cite for that. I do know that a lot of punk tapes from the 70s and 80s are on C46. Kafziel 11:32, 21 September 2006 (UTC)

I recall TDK C46s from the 1980s (they always had the widest range). They were sold reasonably widely, but I still reckon their sales were dwarfed by C60s and C90s. Nor do I know if anyone else sold them. Common? It's all relative. As for data, wasn't that those short C12/C15 cassettes? Fourohfour 01:13, 6 November 2006 (UTC)

The point of the C46 was that it was exactly the length of a typical LP. Drutt 12:05, 31 August 2007 (UTC)

C45 & C96 are missing on that list. Maybe it would be helpful to split the list into 3 sections: most common (60,90), fairly common (45,46,74,120) and others also in use (all sorts) Tabby 14:57, 9 September 2007 (UTC)

In the audiobooks application, where recordings may span several hours, cassettes also have the advantage of holding up to 120 minutes of material whereas the average CD holds less than 80.[12]

I'm not clear how cassette's 60 mins a side beats CD's 80. CDs take up less space and cost less per minute than tapes - though this wasnt always the case of course. Tabby 16:20, 9 September 2007 (UTC)

µS?

In the section on "Cassette Types" it talks about 120 and 70 µS playback equalization -- does this mean microsecond? If so, isn't the recongnized SI symbol for second a lowercase s, which means it should say µs? It might be better to just say "microsecond" anyway for those who don't know what μS means.

I would change it myself but i want to be 100% sure that μS means microsecond.

"1 microsecond (1 μs) – cycle time for frequency 1 MHz, radio wavelength 300 m (AM mediumwave band)" --Microsecond

--Robert 19:41, 22 October 2006 (UTC)

Yes it means microsecond, and so should have the lower case 's'. I've always found this nomenclature a bit odd really - because what it's really saying is that the playback equalization curves have a rolloff point at a certain frequency, corresponding to those values - 14,285Hz for 70µs, and 8333Hz for 120µs. Graham 03:15, 26 October 2006 (UTC)

Oh, thank you for that. I was at a total loss as to what a µs had to do with equalization -- especially since the equalization article didn't mention µs at all! Do you think it would be okay to put Hz in the main article instead of µs? --Mdwyer 04:08, 27 October 2006 (UTC)

For some reason, this is the terminology used in the industry, so we should probably stick to it. It might be worth adding a footnote explaining the situation (putting it in the main text would probably bloat things out too much). Fourohfour 01:20, 6 November 2006 (UTC)

OK, this one has always been a mystery, even to me. And converting 120 or 70 "microseconds" to Hertz taking them as period durations would give 8.33 KHz and 14.285 KHz accordingly, which means that if those were AC bias frequencies they should be pretty audible and far from "high frequency" standards (they would double if they were taken to mean semi-periods, though). Then again, tape bias works exactly by mixing a high-frequency AC signal to the recorded signal...only that those AC bias frequencies appear too low compared to the intended frequency response (20HZ-16KHz for Chrome tape, somewhat worse for Ferric tapes). Maybe then the "S" refers to some other kind of unit like e.g. magnetic induction? EpiVictor 14:55, 6 November 2006 (UTC)

This is a very tardy reply to your question, but I saw it here and thought I'd better correct your confusion. The frequencies corresponding to 70µs and 120µs are indeed those quoted, but this is the rolloff frequency of the fixed audio band preemphasis and deemphasis that is applied to these tapes, and has nothing to do with the AC bias signal. The bias typically runs up at around 100kHz and while that also varies in AMPLITUDE with tape type (the bias switch selects both the AC bias amplitude and the audio de-emphasis rolloff) its frequency is pretty much irrelevant, as long as it's way above the audible range. 203.87.74.230 (talk) 05:42, 8 January 2008 (UTC) (formerly GRAHAMUK)

The bias frequency should at least be 3 times the highest frequency to be recorded, better even 4 or even 5 times the value. Early reel to reel used 60-70kHz later types and cassette recorders for High Quality recording used 80-100kHZ. Although the whole Bias effect was never fully understood, the experiments and subsequent patents of B&O with the Dolby HX Pro system led to the conclusion that the higher frequencies of the audio signal also had a Bias side-effect. So clear separation of these signals in the frequency domain makes perfect sense. Donvr (talk) 11:04, 4 February 2008 (UTC)

Magnetic tapes are recorded with constant magnetic flux indepent of the frecuency. Magnetic flux is directly related to the current through the coil in the recording head, so this current should be constant regardless of the frecuency being recorded. The recording head is inductive, this means that its impedance increases linearly with frecuency. Hence to achive the goal of a constant, frecuency-independent magnetic flux on the tape, the signal is pre-emphasized. This pre-emphasis, called NAB, means + 6dB/octave (=doubled frecuency) so increasing frecuencies are increasingly emphasized.

During playback, the higher the frecuency, the more magnetic flux lines pass under the playback head gap so the output voltage from the coil will increase with frecuency linearly, or +6 dB/octave. Hence a NAB des-emphasis is required. This is not a complement of that pre-emphasis at the recording stage, which was needed to get a magnetic tape recorded at constant-flux. This comes from Faraday's law. There will be a maximum response frecuency, but it will decrease beyond that, because the size of the playback head gap (around the micrometer); let's put it like this: frecuencies higher are recorded on tape as alternating positive and negative half-cycles; if two or more half-cycles of opposite polarities fill the gap the resulting flux will substract.

NAB equalization uses 'time-constants' rather than frecuencies to define 'zeroes' and 'poles'. Those are the micro-second values given with cassettes, and they are not the inverse of a frecuency as said in former commentaries: the relation is rather t=1/2.pi.f. So ecualization of 120 us stands for a pole at 1433 Hz and equaliation of 70 us stands for that pole at 2273 Hz. The 'zero' is at 3180 us or 50 Hz in both cases.

The NAB playback response decreases at the 6 dB/octave from 50 Hz to 1433 Hz, because of the zero to compensate the higher response with increasing frecuencies already explained . At this frecuency the pole compensates the zero so the frecuency response becomes plain. Change 1433 Hz to 2273 Hz for chromium and metal tapes.

There are many sources about this NAB equalization such as the datasheetss from chip manufacturers (check for example National Semiconductor's LM1897 section 'Application Hints/Design Equation', Sony's CXA1498S/M, KIA's KIA6225P/S and many more) or books devoted to magnetic recordings such as 'Consumer Electronics for Engineers' by Philip Hoff et Philip Herbert Hoff.

To record tapes a 'bias current' is added to the signal to linearize the hysteresis curve, which is S-shaped rather than linear. It relates the remanent magnetism left on the tape versus the applied magnetic field (directly related to the current through the head's coil). Low-end cassette recorders add a direct current so the recording only uses one branch of the hysteresis curve; better cassette recorders rather use a.c. at a frecuency well above the maximum signal recorded. Even the own signal's higher frecuencies have a biasing effect, Dolby/B&O HX recording system handles this effect to modify the a.c. biasing amplitude to improve the quality of the recording. Ferro tapes need lower amplitude of biasing than chromium and metal tapes, but these will provide a maximum-output-level higher if recorded with the proper, higher, biasing than ferro tapes.

Biasing current is not related with playback nor recording equalization. Perhaps the cassette tape makers used a very compact syntax to summarize the features of their products: material (= biasing current) and equalization poles.

—Preceding unsigned comment added by 194.224.48.91 (talk) 22:28, 14 November 2008 (UTC)