You are confusing the ADC quantization noise floor with the FFT noise floor.
ADC RMS quantization noise = FFT noise floor + 10*log(65536/2) = -160dB + 45dB = -115dB
which is nothing outstanding for a 24bit ADC (theoretical 6.02*24+1.76 = 146dB). The magic starts under -120dB
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I did take a look at the ADS127L0, this is quite noisy ADC SNR 115db, if you'll check other ADCs(over 120db range) like PCM4222 or AK5578 you'll find much less than -140db noise-floor without Boltzmann constant trimming or elementary charge boosting in the flux-capacitor
Do you have a SNR frequency sweep of the ES9822PRO @192KHz SR? I would like to see it.
not sure if I understand what exactly you are asking to show.. At 1k or 10k or at 20Hz 0dbfs will refers to the same input voltage, why we should expect a different result of a Signal(all frequency at the same level) to Noise Ratio?
I want to see if the ES9822PRO has any audio band noise shaping. That would make it useless for instrumentation purposes, which is what I am looking for (and the reason why I used the ADS127L01). The only audio grade ADC I've seen, not having some form of noise shaping, was the AK5394, now defunct.
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Thanks, no noise shaping, this is great. All other audio ADCs available today look more or less like in the attachment. This is for an otherwise very good audio ADC, from AKM. Perhaps the ES9822PRO has a programmable digital filter to implement (or not) noise shaping, hope to find out when I'll get the datasheet.
Attachments
Unrelated, there is hope:
AK4499EQ | Audio D/A Converters | PRODUCTS | Asahi Kasei Microdevices (AKM)
AK4499EQ | Audio D/A Converters | PRODUCTS | Asahi Kasei Microdevices (AKM)
...after noise shaping, which is, in my book, only a trick to get the audio band SNR datasheet bragging rights.
Check the PCM4222 noise floor over 50KHz @192KHz sampling rate. Then care to integrate the noise up to 90KHz and figure out which has actually the lower noise. Hint: the ADS127L01 is much better with its apparently poor 115dB SNR spec, the PCM4222 doesn't go over 110dB before noise shaping..
Don't tell me SNR at these levels matters for audio, it's well under the CD SNR anyway, and I don't recall anybody complaining about CDs being noisy.
strange that you guys are mostly from Canada, BTW, the design group of ESS is also in Canada BC.
On the ismosys webshop, when you click on the es9822 page, there's a link that says product datasheet (NDA required). I clicked on that and filled it in. That set the balls in motion for signing the NDA although it wasn't straightforward. The EU representative had to pull some strings to get things to happen and that's something I'm very grateful for.
Good luck.
Hi IVX,
Simple, it's cold up here in the winter and all we can do is think and play with electrons.
