Adding dither noise to simulate SACD

[boxerfan88]

For the fun of it, started an experiment to add dither noise to simulate SACD noise.

Approach: setup a DSP chain -- after resampling to 176kHz, add SmartDitherDSP with 17 bits of content + 4bits of high passed dither.

Using DeltaWave to analyze the result, we can see the noise added in the upper frequency range (similar to SACD).

• blue line is the original music track (Birds)
• white line is the modified track with dither
• I can't really hear a difference, but I can see it in the charts.

 

[boxerfan88]

When playing back music, can see the dither noise just peeking up above the floor of of the spectrum display (red box at the bottom right), so I know it's working. Theoretically, the levels are so low, it should not be audible.

Need to monitor a few days ... see of placebo effect is taking place ... and I start hallucinating that the music sounds more analog

 

[boxerfan88]

Audio Dither Example - IAM MediaWiki

imamp.colum.edu

 

[boxerfan88]

 

[boxerfan88]

Need to monitor a few days ... see of placebo effect is taking place ... and I start hallucinating that the music sounds more analog

I think I quite like the post-processing TPDF dithering to 16bits, sounds very slightly "smoother" to me.
Maybe it's placebo effect going on, I donno.
The dithering is now staying on my DSP chain

 

[boxerfan88]

Recently changed to mda dither… even more analog…

foobar2000:Components/mda Dither DSP (foo_dsp_mdadither) - Hydrogenaudio Knowledgebase

wiki.hydrogenaud.io

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[boxerfan88]

Audio Myths - The Ultimate "Myth Buster" Video - Monty Montgomery, Xip

Digital Show & Tell, Monty Montgomery, Xiph.org This Video Busts the Following Myths: Myth - "Digital audio has stairsteps." - Busted! Monty feeds an analog

benchmarkmedia.com

Myth - "Analog tape has more resolution than digital audio." (9:37 - 11:34) Busted! Tape noise and gaussian dither noise are virtually identical. Cassette tape is equivalent to about 6 bits, and the best studio reel-to-reel tapes are equivalent to about 13 bits.

Myth - "Dither masks quantization noise." (11:35 - 13:50) Busted! Dither replaces quantization distortion with a noise spectrum of our choosing. Harmonic distortion (produced by quantization) is removed by dither and this can be seen on the analog test gear.

 

[boxerfan88]

Listening test - quantization noise & bit-depth 🎧

Demonstration of noise shaping and dither. Quantization noise audibility test.

www.tonestack.net

 

[boxerfan88]

 

[boxerfan88]

Used my foobar to convert a sample SACD/DSD track to PCM 176k to analyze ...

Wow ... the amount of ultrasonic noise is really high.

Blue is the decoded DSD into PCM 176k.

Green is the CD version from the SACD.




Orange is my DSP "cooked" version with CD upsampling, bitdepth reduction to 18bits, and dither noise added.
The added noise is at a decently low level, not as high as SACD.

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