What is hi-fi? Easily explained

Hi-Fi is a term from the audio world. In this practical tip, we explain what exactly it means, what demands it places on sound reproduction and how the meaning of hi-fi has changed in language usage.

What is hi-fi?

Hi-Fi is primarily attached to the sizes of acoustics and electrical or communications technology:

• Hi-Fi stands for "high fidelity", ie "high accuracy" or fidelity.
• This is a quality standard for devices for recording, transmission and playback of audio.
• In Europe since the 1960s, standards have stipulated which sound parameters may differ from the original sound signal and to what extent if they want to be considered hi-fi.
• In accordance with the technology at that time, DIN 45500 was created in the 1990s, which made certain demands on sound studio equipment, namely FM tuners, tape recorders, microphones, amplifiers, loudspeakers and radio receivers.
• Even before the 1990s, these minimum requirements were easily achieved even by inexpensive devices. This is how DIN EN 61305 was created in 1996, which now only specifies measurement methods and comparative values ​​that can be used to compare the properties and quality differences of audio equipment.
• The quality requirements concern, for example, the bandwidth, dynamics, frequency response and channel separation.
• Internationally and also in German colloquial, the term Hi-Fi is used for all devices that reproduce the majority of the audible frequency range with high accuracy, little noise and other artifacts.

What distinguishes hi-fi?

High-fidelity was anyone who met the following requirements. Precise requirements vary between technologies such as tape recorders, FM transmitters, microphones and speakers:

• The bandwidth should range from around 40 Hz to 12.5 kHz to represent the majority of the frequencies audible to humans.
• Much of this frequency range should have a dynamic accuracy of at least ± 1.5 dB. So no frequency range is overemphasized.
• The distortion factor, i.e. nonlinear distortion, should be below 2%. Anyone who still knows shellac records is familiar with the harsh sound that a distortion factor of 10% and more produces.
• Calender separation should be largely 26 dB and more for FM transmission, and at least 15 dB for records. In the 1960s that was still a big challenge. Even today's record players often only have a channel separation of 25 to 30 dB.
• The signal-to-noise ratio should be at least 46 dB. The signal-to-noise ratio of today's high-end devices is about a million times better and is more like 110 dB. But even a 1-euro electret microphone in your cell phone has a signal-to-noise ratio of over 80 dB.
• Of course, parameters of perception are actually more important than physical quantities. This is why there are now psychoacoustic parameters and methods for comparing the sound quality of spatial audio systems or compression algorithms. This includes, for example, how bright, rough and sharp a signal sounds, how exactly a sound source can be located, how big it sounds, how much the surround sound envelops, and whether comb filter effects or artifacts are audible.

In further CHIP online practical tips we compare the sound quality of CD and record, show you the optimal parameters for your power amplifier and explain how to set up your surround speakers correctly.