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Topic: Digitizing/cleaning at high sample rate then downsampling? Or not? (Read 2693 times) previous topic - next topic
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Digitizing/cleaning at high sample rate then downsampling? Or not?

To digitize and restore a few vinyl records I'm hesitating between two flows

A) Digitize at 192.000 Hz, 24 bit > Clean at 192.000 Hz, 24 bit* > Archive 192.000 Hz but downsample to 48.000 Hz for "everyday life"
B) Digitze at 48.000 Hz, 24 bit > Clean at 48.000 Hz, 24 bit* > Just use and archive at 48.000 Hz

* cleaning mostly with iZotope RX

Archive disk space and process time are not limited are not a criteria in this case!

To my understanding, processing "may" be better at high sample rate but some quality may be lost when downsampling. Though I would expect that it is neglectable and my priority is quality of archives.
I read stuff like decrackling and declicking may perform better having more sampe per crackle/click... but I don't really know what outweighs what.
(When digitizing at 192.000 Hz, I see frequencies as high as 30 kHz or 50 kHz.)

Re: Digitizing/cleaning at high sample rate then downsampling? Or not?

Reply #1 –
It is an old saying that it is safer to start higher because 44.1k or 48k demand a decent and steep analog filter that might cut into the audible range. That does not mean you will be able to tell the difference, but it kinda guards you against a bad component.

So that is a case for digitize at higher frequency even if you immediately downsample to 48k (= do the low-pass in the digital domain where it is safe) to do the declicking. I don't know if your device does that internally though. Could be.

Re: Digitizing/cleaning at high sample rate then downsampling? Or not?

Reply #2 –
Quote from: Porcus on
I don't know if your device does that internally though. Could be.

Thank you. What I use precisely is Technics SL-1500c (internal phono amp) >  M-Audio Air 192|14 > then I usually record with SoundForge Pro 15, iZotope RX for cleaning, then SoundForge again for fade in/out and sometimes amplify loudness.

But as I understand your reply, it makes sense to do the work at high sample rate then downsampling?

Re: Digitizing/cleaning at high sample rate then downsampling? Or not?

Reply #3 –
Quote from: Porcus on
It is an old saying that it is safer to start higher because 44.1k or 48k demand a decent and steep analog filter that might cut into the audible range. That does not mean you will be able to tell the difference, but it kinda guards you against a bad component.

So that is a case for digitize at higher frequency even if you immediately downsample to 48k (= do the low-pass in the digital domain where it is safe) to do the declicking. I don't know if your device does that internally though. Could be.


This largely depends on the sound card's ADC and the card's implantation.  Many cards have delta-sigma oversampling ADCs which works at higher sampling rates than the rate user has it set to internally to do anti-aliasing filtering digitally.

Re: Digitizing/cleaning at high sample rate then downsampling? Or not?

Reply #4 –
Compare the results of click removal in your software. At high sampling rates clicks can be sharper. You can also more easily visually identify the positions on a spectrogram for repair. With older software a click can become too long/smooth to catch it. I suspect that RX might compensate for it and work well either way.

Re: Digitizing/cleaning at high sample rate then downsampling? Or not?

Reply #5 –
Quote from: j7n on
You can also more easily visually identify the positions on a spectrogram for repair.
Thank you. Well, this looks like a strong argument in favor or high sample rate, from my point of view as some of the vinyls are seriously used with some damages.