I have written a few articles recently about my love of analogue formats and yes it’s true that the quality inherent in analogue formats is lacking. However, that is not the crux of my argument for any type of artistic analogue expression. In this article we’ll keep it technical and look objectively (rather than subjectively) at the limitations of various audio delivery formats.
What follows is an analysis of the dynamic range of various audio formats such as cassette, vinyl and digital. What will become clear is that digital is superb at handling dynamic range and analogue formats are not. However, there is a difference between this form of objective analysis which doesn’t take into account the subjective creativity of using lower fidelity mediums to create and record music.
We, as human beings, are capable of hearing a factor of a hundred thousand (100,000) difference in the amplitude of an audio signal, this equates to a factor of ten billion (10,000,000,000) in power! We use decibels, a logarithmic unit to describe this as the numbers get very large very quickly. The dynamic range of our hearing is approximately 140dB from the quietest sound we can perceive, around -9 dB SPL at 3kHz to the threshold of pain at 120-140dB SPL (every +3dB is approximately a doubling in power) . However, we cannot perceive these differences at the same time as the mechanisms of our ears adjust to different auditory stimulus. This is also why you’re more likely to damage your hearing if you work in a loud environment before going to a loud concert.
Moving on to audio delivery formats, it is easy to ignore early phonographs when discussing vinyl. These were often made of Shellac and span at approximately 78 rpm (78.26 rpm and 77.92 rpm). Due to this construction, speed and the hardness of the needle that played them, they had a dynamic range of around 40dB when new which quickly reduced to 30dB through wear.
Modern vinyl with microgrooves (33/45rpm) enjoys approximately 55-65dB with the high fidelity outer rings getting as much as 70dB dynamic range. There are also other limitation of this format such a frequency response which is handled using equalisation (RIAA) hence the need for Phono Pre-Amps.
Compact Cassette/Musicassette averages around 50-56dB depending on tape formulation. Very specialised tape head configurations, noise reduction, XDR and Type IV tape used together, in the right way, may expand that to 70dB but it was a rare and expensive set-up in the 70s, 80s and 90s and is even rarer and still expensive nowadays.
Compact Disc at 44.1kHz sample rate with a bit depth of 16 bits yields a theoretical 96dB but with dither can push to over 120dB of dynamic range. We must also remember that with a reconstruction filter (in the time domain) or anti-aliasing filter (in the frequency domain), digital does not output the stepped (quantised) waveform that many believe it does.
The beauty of the digital audio signal is that noise and distortion can be separated from the audio signal. […] The only real theoretical limitation to the accuracy of a digital signal is the quantity of numbers in the signal representation and the accuracy of those numbers. These are both known and controllable design parameters.Grant Erickson
Compressed audio formats are where it gets more interesting. The right compression even a lossy type (data compression), especially one that employs VBR (Variable Bit Rate) can sound as good as uncompressed digital audio. This has been the subject of technical research papers and listening challenges but is beyond the scope of this particular article (although will be the subject of a future blog).
Thus in terms of dynamic range, the ability to separate noise from a signal and thus, copy fidelity, digital is superior in every technical way. However, I have also heard digital spoken about as “clinical”, “too clean”, “lifeless”, “brittle” and “crystalline”. It’s no accident that so many audio plugins have been created modelled on antiquated analogue gear.
As precise as digital audio is, I would argue that our ears often prefer the sound of analogue formats, despite their countless flaws. The noise, crackle, distortion and added harmonics are often referred to as sounding “warm”, having “character” and being “real”. Perhaps, it is these analogue limitations that define the music .