About 2 weeks ago, I posted a poll asking what your favorite cassette tape length is, and why it is so. The results were conclusive. An astounding 59% prefer 90 minutes tapes, 18% voted for the 60 minutes ones, and 12% said they favor 100 minutes or longer.

Most of you said that you liked the fact that 90 minutes tapes can fit a full standard 33 RPM vinyl record album on each side, or a double album on a single tape. You believe that 90 minutes tapes are a good compromise regarding tape thickness, with the longer tapes being too thin, fragile, lower quality, and of questionable reliability. Although most of you did not state it explicitly, it was obvious that they felt that 90 minutes tapes offer better value for money as the price difference between the 60-minute and the 90-minute tapes was much less than the relative difference in length.

Many of you who like to record partial albums, or create mixtapes, felt that the 60 minutes tapes offered better quality since the tape could be made thicker, and that 90-minute were ‘too long’ for their liking.

In this article we’ll explain why we believe that 46 minutes tapes are better, for reasons that might surprise you.

Availability in the western world vs. Japan

Most tapes sold outside Japan were either 60- or 90- minute long. It was only late in the game that manufacturers started offering the longer tapes in the west, and even rarer were the shorter varieties. In Japan however, the same tapes were available in a more diverse variety, mostly shorter tapes from 40 minutes to 90 minutes in many increments. 40, 46, 50, 54, 60, 64, 70, 74, 80, 84, and 90 minute were ubiquitous in the Japanese market. The reasons are fascinating and have to do with western culture vs. the Japanese one.

Japanese culture despises waste and will go to extremes to minimize it. Using a tape longer than needed, leaving blank space of unused tape is considered wasteful and is frowned upon. This is true not only for tapes, but also for food, clothes, living spaces, cars, and practically every aspect of life. The average Japanese person would buy a cassette with the closest length to the specific album they intend to record it, even if it means he must go the shop to get one.

In the western world however, and doubly so in the USA, the culture of abundance and size prevails. Food, cars, houses, bigger means better, and if it means more waste, so be it. Why settle for a 46- minute tape when you can get double the length for only a little more money? For the manufacturers, this was an excellent opportunity to minimize production, shipping, distribution, and marketing costs as each different tape length requires its own production line, packaging, graphics, print, and advertising space.

One of the subconscious reasons that so many of us prefer the 60- and 90-minutes tapes is that this is how the manufacturers wanted us to. It was cheaper for them.

Tape thickness

It was interesting to see that although many of you claimed that they avoid tapes longer than 90 minutes because they are thin, fragile, unreliable, and of lesser quality, only few took it in the other direction, that tapes shorter than 60 minutes might offer better quality.

There is some technical truth to that claim. Longer tapes did compromise tape thickness to be able to fit more tape in the same shell, and the difference is quite substantial. 46 minutes tapes are typically ~16µm (micrometer) thick, while 120 minutes may use a tape as thin as 9µm! That is a big difference…

In the early days, these thin tapes did cause reliability challenges, with the longer tapes being more prone to breaking. However, with the evolution of the polymers used for the backing materials, these challenges were mostly overcome. We have many 150-minute tapes from the 90’s and later that are as reliable as their shorter siblings. What did remain true is that the thinner tape could cause an “imprint” of the magnetic field from one winding to the next which caused an “echo” effect when stored for a long period of time. In addition, thinner oxide layers began distorting at lower levels, and wore out faster.

Theoretically, the shorter the tape, the thicker it can be made which is beneficial for both quality and longevity. That doesn’t mean that all manufacturers made tapes of different thickness for each length, which would have been cost prohibitive. It was much more economical to use the same thickness tape for various lengths, and each manufacturer made their own choices on what thickness tape to use for each length, given the physical limitations.

The shorter the tape, the more likely it is that you get a thicker tape, And yes, thicker tapes can deliver higher quality, suffer less from the “imprint echo” phenomenon, and provide longer high-quality playback.

Reel size, friction, and rotational speed

Minimizing the size of the take up and supply reels is another method manufacturers used in the quest to provide longer playing times. This is not always immediately evident as many shells hide a large portion of the hub. Here is an example of two 1987 TDK AR tapes; a 46 minutes tape and 70 minutes one. Dimensions are approximate.

The larger reels look much better than the smaller ones in our humble opinion, especially with decks where the entire cassette tape is visible, but that’s a matter of personal taste. What is not subjective are the physics that determine the rotational speed of the reels (RPM), vs the linear speed of the tape, and how it affects the cassette player. The latter is constant at 1 ⅞  Inch Per Second (IPS), and therefore the rotational speed must vary as the tape moves from the supply reel to the take up reel.

This graph represents the rotational speed variance between the supply (feed) reel and the take up reel as the tape moves from one to the other.

* Image from http://datagenetics.com/blog/march12018/index.html which provides a detailed mathematical explanation.

Why should you care about it?  Well, you might not, but the deck that needs to play these tapes surely does and it has a profound impact on its ability to record and play your precious tapes reliably and faithfully.

This would make no difference to an “ideal” cassette deck that might have separate motors and drivetrain for the reel and/or a dual capstan that guarantees a constant torque across the entire playback spectrum. This significantly increases the complexity and cost of the mechanism and the electronics. Most decks are not ideal and don’t have 4 motors and dual capstans. They might use belts or idler drives to drive the take up reel, and the tension that these provide will vary as the tape moves from the supply reel to the take up reel, depending on the rotational speed.

Longer tapes require smaller reels and a larger tape spool diameter. This means that the torque of the take up reel will vary significantly between the beginning  and the end of the tape. For this reason, some manufacturers discourage the use of long tapes. This largely varying tension causes inconsistencies in wow and flutter and in extreme cases may cause the deck to either stop, or to “tape eating” phenomenon when the deck is unable to maintain the high speed required for the small take up reel.

This is emphasized by the fact that longer tapes also have a larger friction area with the slip sheet, and this friction increases not linearly, but exponentially with the increase in length. Increased friction means that the deck must work harder to pull the tape, results in increased tape noise, and of course higher wow and flutter.

Shorter tapes minimize friction and both the maximal and the variance of rotational speed from start to end, helping maintain a more constant tension which in turn results in reduced wow and flutter and improved reliability.  The larger reels guarantee that the rotational speed is maintained within the deck’s optimal range and less friction means better performance and less wear for the deck.

Musical experience

Recorded music goes back to the early 20th century. It’s interesting to note that even before that, classical compositions’ average duration was typically between 25 and 50 minutes long  due to human attention span. Longer compositions such as operas would include intermissions between acts. Early recording media, such as Edison’s phonograph, were very limited in duration which was one of the reasons they never became a mainstream item. The long-playing 331⁄3 rpm microgroove LP record, introduced in 1948 by Columbia Records was the first media to allow for playback of an entire composition. This was a major factor in it becoming ubiquitous.

Since then, and until the introduction of the CD in the mid 1980’s, artists produced their music to be played back mainly on LP records. An LP record could hold a maximum of 23 minutes per side. This had a profound impact on the way artists wrote and produced their music. Artists knew that listeners would have to take a break when side A ended, and it affected their choices.

For artists who wrote collections of independent songs, the main issue was to make sure the total duration of the songs on each side of the record would fit in that limit. For artists who wrote complete musical compositions, there was much more to it. They wrote their music and segmented it in such a way that the imposed intermission would take place when they wanted their listeners to have some time to reflect and absorb what they’ve just heard.  

Let’s take Pink Floyd’s dark side of the moon for example, where the first side of the album ends with Wright and Clare Torry's soulful metaphor for death, "The Great Gig in the Sky". "Money", the first track on side two, opens with the sound of cash registers and rhythmically jingling coins. The song mocks greed and consumerism with sarcastic lyrics and cash-related sound effects. Listening to the CD version where “Money” start immediately after “The Great gig in the Sky” was uncomfortable and even a bit annoying for us. We often find ourselves naturally pausing the CD so that we have some time to digest before moving on to “Money”.

Recording on a 46-minute cassette tape, specifically designed to hold one LP record, preserves that original intention. It forces the listener to take a break just like with the LP record, enhancing the musical creation’s emotional impact, as the artists intended.

Conclusion

90-minute cassette tapes were the de-facto standard length in the western world. They offered excellent value for money as they could hold two LP records for the price of one cassette tape. They did not suffer from the early illnesses of longer tapes, and most manufacturers designed their decks so that they could play them within specifications.

That said, they are relatively thin which had a potential negative impact on sound quality and durability. Their increased surface area, small reel size and widely varying rotational speed puts unwarranted stress on the deck, and they rob the listener of the full emotional musical experience, the way the artists intended.

When we choose a cassette tape to record on, our first choice is a 46-minute tape for music that was originally produced for LP records. Even for double albums, we prefer to use two 46-minute tapes rather than a single 90-minute one. For music that was produced for CDs, we will choose a 74-minute tape, and if possible, a shorter one to minimize friction, rotational speed, waste, and empty space that needs to be fast forwarded.

If you’ve never used 46-minute tapes, we highly recommend giving them a try!

Wishing you a wonderful and melodious day, and always remember to TAPE IT EASY!