Not sure the right place to post this, but this looks the closest. Turning a set of live recorded shows on DAT to flac files… Running on MacOS. Very much an Audacity newbie…
Tascam DA-20 → optical SPDIF → USB → Mac… Audacity project at same bit rate as the DAT tape (mostly 44K). Export as flac files after labeling the start of the songs. Assuming that this way is the least processing of the DAT tape output - staying in the digital domain.
Now, these tapes are not all recorded at the same level - live concert recording and probably some different people who did the recording. I don’t see any way to adjust the input volume on a straight digital input like this - and I probably want as identical a copy of the tape as I can get anyway.
My question is about “amplify” - which clearly would allow me to save the data/project at a particular volume level. But for what I’m doing - which is fundamentally transcribing (not editing or multi-track or…), it seems like the amplify effect wouldn’t do anything much different than the listener adjusting the volume on playback (on my Oppo or VLC on the computer).
Am I making any fundamental mistakes here? Getting DAT to flac is a bit of a pain - not worth paying a professional studio - just for personal enjoyment and for the band itself.
It may not be possible (depending on the device drivers). If it is possible, then all it will be doing is scaling the digital data (multiplying each sample value by an amount greater than 1.)
You’re right, it’s not much different, though there may be a slight difference, depending on how the app implements playback volume.
Audacity implements amplification as a 32-bit floating point operation. This provides excellent accuracy, though converting back to 16-bit integer (on export to 16-bit FLAC) introduces a tiny bit of noise. The noise is (by default) at a predictable level (around -84 dB rms fs) and lies mostly in the very high frequency range where hearing is least sensitive for low level sound - in practice this noise should be inaudible.
Playback volume in other apps may be implemented in exactly the same way, or in a way that is sonically inferior (such as scaling the 16-bit data using integer multiplication). I don’t think there’s any way that an app can produce sonically better amplification than the way that Audacity does it. The short answer is that other amps may be the same or worse than using Audacity’s Amplify effect.
The worst option would be turning up the volume on the amplifier / speakers as this will introduce a little more noise due to analogue noise in the input stage of the amp.
For best accuracy in your copies, don’t apply any effects, and when you export as FLAC, temporarily turn off “dither” (set dither to “None”) in “Preferences > Quality”. Normally “dither” should be set to “Shaped”, but this is a special case as all samples will be exact 16-bit values so long as you don’t amplify or apply any other effects between digital recording and exporting.