Hi! I'm Tetsuya Japanese audio enthusiast who worked 1977 to 2013 at DENON. And I was in the planning department dev.developed S1 series.
https://minkara.carview.co.jp/smart/userid/2252957/blog/45588389/
00:05:45_Development of ALPHA
00:06:52_ALPHA processing explained
Let me explain,this illustration is incorrect.
These PCM pulses are changing from sample point to sample point.
ALPHA does not work with such signal.
When you upsample 16bit data to 32bit・・
You said AL32 can create 32bit sample point that high resolution signal.
The person who wrote this figure does not understand the technology called "ALPHA processing" in PCM Digital Audio.
The purpose of ALPHA processing is to reduce granuler distortion of the stepped signal.
The person who wrote this figure does not understand the technology called "upsampling" in PCM Digital Audio.
The purpose of oversampling is to share the analog filter when converting PCM data and DSD data with a Burr-Brown PCM-1795.
On the other hand, left stepped signal is 1kHz -90dB 16bit due to lack of resolution,
Right signewave is processed by AL32.
This infomation of AL32 processing is correct.
And you do not understand the basic technology called "interpolation" in PCM Digital Audio.
The mechanism called AL32 is not intended to reduce quantization noise, and there are conditions for its operation.
It is impossible to reproduce the sound that was lost when recording.
ALPHA Processing works when the pulses are seven or more same sampling position on CD.
And ALPHA Processing find automatically the stepped part of the waveform, and repair granuler distortion.
The waveform is stepped because the resolusion in the amplitude direction is insufficient.
Left:Waveform played on a normal CDP.
Right:Waveform played on ALPHA CDP.
Top of 127Hz -20dB sign wave 16bit 44.1kHz
Playback 1kHz -90dB 16bit 44.1kHz on CD.
Basic frequency is 1kHz, and harmonic distortion is occurring.
Playback with ALPHA same signal as above.
Harmonic distortion is suppressed by ALPHA. ALPHA is a technology that impfoves the distortion of stepped
There are conditions under which ALPHA works.
ALPHA works only when the data recorded on the CD has 7 or more consecutive stepped waveform.
However, ALPHA does not work for waveform data that changes frecently as shown below.
ALPHA works normal digital filter.
ALPHA does not work when the discrete pulse changes drastically as Super Bit Mapping or Dithering.
These waveforms are not stepped
Do you know "InterPolation" about PCM Digital Audio？
Impulse responce & Amplitude moduration
This impulse waveform is good for interpolation discrete pulses in PCM digital audio.
Impulse responce of long tap FIR filter
Impulse responce of short tap FIR filter
Impulse responce of ALPHA filter
This is the joke for short tap FIR filter slow roll off lovers.
This is the true PCM digital audio technology called "Interporation"
Impulse responce and waveformes converting discreat pulses.
By the way, DENON AMERICA was proud of PCM-1795.
Sharp roll off long tap FIR filter and slow roll off short tap bad FIR filter are built-inn.
Long TAP sharp rolloff FIR filter
Short TAP slow rolloff FIR filter
But DENON does not use internal digital filter in PCM-1795.
DENON use Automatic Low Pass filter Harmonic Adjustment STRANGE FIR FILTER.
