Thanks for this, Cno. The graphics are very clear, aren't they?
Sadly it confirms what we hear, both on CDs and over the radio. I've got quite a few early CDs with what sound like quite low levels, but no distortion or noise.
I find it ironic that compression of FM and DAB usually helps in the car but is dreadful at home in the peace of one's living room. I suppose it ends up more mp3-like, which is possibly what the majority of listeners expect these days.
I'm just going to copy and past some reading rather than bother to respond to nonsense.
"Dynamic range in analog audio is the difference between low-level thermal noise in the electronic circuitry and high-level signal saturation resulting in increased distortion and, if pushed higher,clipping
. Multiple noise processes determine the noise floor of a system. Noise can be picked up from microphone self-noise, preamp noise, wiring and interconnection noise, media noise, etc. Early 78 rpm phonograph discs had a dynamic range of up to 40 dB, soon reduced to 30 dB and worse due to wear from repeated play. German magnetic tape in 1941 was reported to have had a dynamic range of 60 dB, though modern day restoration experts of such tapes note 45-50 dB as the observed dynamic range. Ampex
tape recorders in the 1950s achieved 60 dB in practical usage, though tape formulations such as Scotch 111 boasted 68 dB dynamic range. In the 1960s, improvements in tape formulation processes resulted in 7 dB greater range, and Ray Dolby developed the Dolby A-Type noise reduction system
that increased low- and mid-frequency dynamic range on magnetic tape by 10 dB, and high-frequency by 15 dB, using companding
(compression and expansion) of four frequency bands. The peak of professional analog magnetic recording tape technology reached 90 dB dynamic range in the midband frequencies at 3% distortion, or about 80 dB in practical broadband applications. The Dolby SR noise reduction system
gave a 20 dB further increased range resulting in 110 dB in the midband frequencies at 3% distortion. Compact Cassette
tape performance ranges from 50 to 56 dB depending on tape formulation, with Metal Type IV tapes giving the greatest dynamic range, and systems such as XDR
and Dolby noise reduction system
increasing it further. Specialized bias and record head improvements by Nakamichi and Tandberg combined with Dolby C noise reduction yielded 72 dB dynamic range for the cassette. Vinyl microgroove phonograph records typically yield 55-65 dB, though the first play of the higher-fidelity outer rings can achieve a dynamic range of 70 dB. The rugged elements of moving-coil microphones
can have a dynamic range of up to 140 dB (at increased distortion), while condenser microphones are limited by the overloading of their associated electronic circuitry. Practical considerations of acceptable distortion levels in microphones combined with typical practices in a recording studio result in a useful operating range of 125 dB.
Audio CDs achieve about a 90-dB signal-to-noise ratio."
MP3 and AAC both contain a global gain adjustment parameter for every block of music data. According to the word length and resolution of thisparameter, the dynamic range of both MP3 andAAC is well beyond the equivalent of a 24 bit D/Aresolution. In short, MP3 and AAC represent theAES 17thInternational Conference on High Quality Audio Coding 7Karlheinz Brandenburg MP3 and AAC explainedmusic in a way that the dynamic range of everyknown audio source is perfectly retained
"MP3 and AAC both contain a global gain adjustment parameter for every block of music data. According to the word length and resolution of this parameter, the dynamic range of both MP3 and AAC is well beyond the equivalent of a 24 bit D/A resolution. In short, MP3 and AAC represent the music in a way that the dynamic range of every known audio source is perfectly retained"