Tape Saturation

Tape saturation is a phenomenon that describes the moment when the voltage level exceeds the tape’s ability to record. This phenomenon focuses specifically on analog tapes.

Tape Saturation: the Process

The signal and the voltage travel at the same time. The signal is being sent to the tape while the voltage is sent an electromagnet in the recording head. To be able to record, the recording tape and the head of the recorder have to be magnetized. For this reason, they use oxide iron powder particles that vary through time. As the original current changes, saturation occurs.

When the input voltage is greater than the saturation threshold of the tape, the iron oxide particles reach their maximum magnetic potential. When this happens, they can’t either polarize or hold a greater amplitude. Hence, the signal distorts and compresses.

The Studer J37: a Perfect Example

Will Studer, a Swiss recording pioneer, created the Studer J37. The Studer J37 was a very popular tape recorder and many used it for many legendary recordings. This pioneer launched his device around 1960. Immediately, it became a great success because of its functionality, versatility, and simplicity. Abbey Road Studios purchased several J37 machines and used them for almost every recording. This record label improved the device by adding wheels for easy transportation, installing a Bulgin 3-prong socket to enable the connection of an oscillator, and including an equalizer switch. However, the device became quite obsolete around 1969 when 8-track machines first became available. 

The frequency response of the J37 was amazing. Its particular configuration allowed it to produce a wide variety of tonal colors. Abbey Road Studios used special tape formulas to add distinctive sounds to its recordings. EMI developed exclusive tape formulas such as EMI TAPE 888, EMI TAPE 811, and EMI TAPE 815. Each involved its own unique frequency response and harmonic distortion behavior, which resulted in a distinctive timbre to recordings. 

Musicians used the J37 tape recorder on many famous recordings. One of the most popular ones is being The Beatles’s “Sgt. Pepper’s Lonely Hearts Club Band.” Producer George Martin employed the device as a creative production tool, which conveyed layers of sound to achieve innovative sonic textures.