S/PDIF Cable Analyzer - a physics-based simulation tool (free, browser-based)

[JulienFromParis]

Hi ASR,
The project :

S/PDIF Cable Analyzer - a physics-based simulation tool (free, browser-based) : French and English. It's responsive.

https://spdif.onrender.com/



​

I built a small web tool to simulate and analyze S/PDIF coaxial, AES/EBU and optical signal integrity: https://spdif.onrender.com/ . You can compare 2 cables (different lenghts).

What it does

The analyzer models what happens to a BMC-encoded S/PDIF signal (IEC 60958-3) as it travels through a cable. Five physical phenomena are modeled sequentially: bandwidth limitation (skin effect + dielectric losses), amplitude attenuation, impedance mismatch reflections, EMI noise, and ISI jitter. You can also import real oscilloscope captures (CSV) and short audio files (WAV).

Key parameters

• CER (Cell Error Rate): the fundamental metric - are the bits arriving correctly?
• Jitter RMS / Peak-to-Peak: temporal deviation of transitions from the ideal grid, in nanoseconds
• Eye diagram: the classic signal integrity visualization, built from 2-UI windowed segments
• V_PP, noise RMS: amplitude and noise level after cable degradation
• PLL transfer model: shows how much interface jitter actually reaches the DAC, across five receiver presets (CS8412, VCXO, WM8805, ASRC, Word Clock)

Cable presets include Belden 1694A, Belden 1505A, Canare L-5CFB, Mogami 2964, Sommer SC-Vector, generic 75Ω coax, non-spec RCA, plus AES/EBU cables (Belden 1800F, Canare DA202/DA206). A custom cable mode lets you enter your own datasheet values.


The takeaway the tool consistently demonstrates

Any 75Ω coaxial cable under ~5m delivers CER = 0%, ISI jitter < 0.5 ns RMS, and attenuation < 0.1 dB. Two cables both showing CER = 0% transmit bit-identical data to the DAC - there is no physical mechanism by which one can "sound better" than the other. The only things that genuinely matter are impedance (75Ω), shielding (relevant in high-EMI environments), and not using an unmatched RCA cable beyond a few meters.


The full technical documentation (formulas, physical models, calibration against Dunn 1992/1994 and AES-12id) is at:

https://spdif.onrender.com/doc

a plain-language version at
https://spdif.onrender.com/doc/simple.​

Ps :

• it's free, if you want to pay me a coffee why not. I pay the hosting.
• Privacy note: no cookies, no analytics platform, no data stored. Just a raw hit counter to know if anyone actually uses this.
• AI helped me of course. Essentially to implement formulas in Javascript and a little for the front and the translation (too complex manually).
• Maybe they are some mistakes, so you can help me

Your feedback matters : feel free to share it.​

I found this. Maybe the same author ) : A parody

https://scam-audio.netlify.app/.
​

 

[JulienFromParis]

I’ve modeled the principle of non-standard connectors—for example, a reliable but standard cable (Belden) fitted with 50 Ohm RCA/BNC connectors.

As a result, there is a new section in the app:

It covers echo and triple transit effects; since these are explained in detail within the app and the documentation, I’ll skip the technicalities here as it’s quite complex. The idea actually came from someone over at a Mélaudia forum (french).

I’ve added a 75 Ohm coax with 50 Ohm connectors to the cable list. Otherwise, you can use the "Custom" option. This will help you understand the phenomenon and realize just how much the plugs matter. You can play around with the Custom cable and input your own values. Again, this is designed to help you grasp the impact of specific parameters: take two custom cables and tweak the variables to compare them. You’ll see the effects of shielding, length, attenuation, velocity, and, of course, impedance.

Finally, I’ve included a sensitivity matrix showing which parameters impact which results (Error Rate, jitter, etc.) and to what extent.

It's a translated message I posted on a french forum a few minutes ago.​

 

[voodooless]

This is really cool. Did you validate the results with actual measured data? Because such a tool is only useful if it can reliably predict real-world performance.

 

[JulienFromParis]

It's very difficult because you really need specialized equipment (not an oscilloscope like mine); there's impedance management on the oscilloscope and the signal generator (okay, a streamer will do), and you need the right cables and lengths. Nevertheless, I've included the option to import measurements saved as CSV files.
That’s why I’ve included cables with very, very precise specifications. Belden, for example : https://fr.belden.com/products/cable/video-cable/coaxial-video-cable/1694a

Belden also manufactures military-grade and medical-grade cables.

Frequency-dependent attenuation, velocity, impedance, shielding, etc. Everything is described in professional detail. With low-quality or unprofessional cables, this is impossible.

It’s an educational tool, but a very precise one. I even factor in EMI to see if it affects the signal and to evaluate the shielding. You can adjust various parameters using a custom cable that you can configure to understand how each parameter impacts the signal. And the matrix provides a visual representation of this as well.

 

[JulienFromParis]

I've included the backgrounds of the people who created, conceived, and designed the tools I used to carry out this project. They include leading researchers as well as audiophiles. https://spdif.onrender.com/doc/en#author-biographies