What Determines Cassette Sound Quality?

The sound quality of a cassette is determined primarily by the magnetic tape inside it, assuming you are listening on a properly adjusted tape deck.

What Is Inside a Cassette?

Inside a cassette there is magnetic tape with a width of 1/8 inch (3.81 mm). Essentially, it is the same type of magnetic tape used in reel-to-reel tape machines but narrower (the standard width of reel-to-reel tape is ¼ inch, which equals 6.35 mm) and with a lower tape transport speed.

Are reel-to-reel machines still used?

Absolutely! Reel-to-reel machines are still in use today, because they offer the highest sound quality achievable with analog media. They are still used in studios, sometimes for recording, but mostly for mastering. Before the digital era, reel-to-reel tape was the only way to record sound at a truly high quality.

Another use of reel-to-reel tape is home listening. Quarter-inch tape is often used to duplicate releases with the highest possible analog quality. In terms of sound consistency and fidelity, it can even outperform vinyl records.

So what’s the difference between cassette tape and reel-to-reel?

To achieve a compact, portable format that’s convenient for listening and storage (simply put, to squeeze the tape into a small box), the creators of the cassette made the tape narrower and the tape transport speeds (TTS) slower.

As a result, the speed of reel-to-reel tape in professional studio machines is 38 cm per second, while in cassettes it is 4.76 cm per second. This speed makes it possible to fit 90 minutes or even a bit more recording time on a single cassette.

The maximum cassette length is determined by tape thickness. For example, C60 tape, meaning 60 minutes total, is about 17 micrometers thick, while C90 tape is around 13 micrometers thick.

How Does Tape Transport Speed Affect Sound?

Lower tape transport speed results in reduced frequency response and lower dynamic range. It also introduces tape hiss. At higher tape speeds, hiss is essentially absent.

Typical cassette specifications are:

• Frequency response: approximately 20 Hz to 16 kHz 
• Dynamic range for ferric tape: 55 to 70 dB 
• Tape hiss: present

Does this mean that cassette tape sounds significantly worse?

Not at all! This is where the genius of Lou Ottens, the creator of the cassette, comes in: the human ear does not perceive the sound of cassette tape as being of lower quality. In fact, the ear usually doesn’t hear frequencies above 16 kHz at all. As for tape hiss, an interesting fact is that after some time of listening, the human ear adapts and effectively filters it out. This allows the listener to focus on the music itself.

This is how Lou Ottens managed to preserve a level of sound quality that is meaningful to the human ear while creating an incredible portable physical medium which, unlike reel-to-reel and vinyl, is convenient to listen to and store, costs less, and offers an endless number of design possibilities.

 

Humanity and Sound

Humanity has always chased better sound quality, and it feels like we have now reached the technical ceiling. Once that ceiling is reached, people begin to realize that what truly matters is not sound quality alone, but the music itself.

The tactile experience of physical media, the act of holding it, touching it, and interacting with it, complements the sound recorded on it in a way that purely digital formats cannot.