I’ve tried to glean as much as I can from reading posts about equalizing loudness across media but it’s a complicated subject, the posts are diverse, the terminology is technical, and I’m relatively new to this. So I’ve developed just enough knowledge to be dangerous and would appreciate some feedback before I go too far into a time-consuming process of digitizing several hundred albums.
I have a Rega Fono Mini A2D pre-amp with input from a Sony turntable and a USB connection to my Windows 11 laptop running Audacity 3.1.3. I recorded a couple of test albums with the recording level peaking at somewhere between -6 and 0 and exported the tracks to FLAC at level 8, 16-bit. I’ve also finished ripping a couple of hundred CDs to FLAC using Exact Audio Copy.
When I put the FLAC files from the vinyl and the CDs into a playback app, the CDs are significantly louder. I read that they do something with compression on CDs to flatten out the highs and lows and then boost the volume. When I imported some of the CD FLAC tracks into Audacity, the wave form is much thicker, with the extremes clipped and the playback levels into the red zone. The only way I’ve been able to get the vinyl output remotely close is to turn on Allow Clipping in Effect > Amplify and boost it to 5 or 6 dB.
Given that my primary goal is to put together music mixes from various formats, and that consistent volume is a higher priority than absolute fidelity, I’m thinking I should amplify as mentioned above before exporting to FLAC but keep a copy of the original .aup3 file on an external drive for future use. (I’m playing through a Sonos amplifier which I don’t believe supports replay gain.)
Does this make sense? Or is there a better way to boost the vinyl to CD levels? Or is it possible to re-rip the CDs down to vinyl level? Suggestions welcome!
You may not be able to get as much loudness with as little damage as a professional mastering engineer…
Loudness matching used by the streaming services, ReplayGain (and WaveGain) and Apple Sound Check all work by (mostly) Reducing volume of the loud songs rather than by boosting the quiet songs. This is the only way unless you want to change the “character” of the sound by reducing (compressing) the dynamic contrast.
I don’t think there’s a “FLAC Gain” but you can use WaveGain before converting to FLAC.
First, you should run the Amplify or Normalize effect on the digitized vinyl to “maximize” the level. Amplify defaults to whatever gain is needed for 0dB peaks and Normalize defaults to -1dB. As long as you don’t “try” to go over 0dB this is a linear adjustment that has no effect on sound quality.
Since you are digitizing so many albums you might want to make “pure” archive copies that are not compressed/limited.
There are two reasons that the vinyl is not as loud - Older records from the analog days weren’t mastered with modern digital limiting & compression. There was a Loudness War but they didn’t have advanced '“weapons”. Modern records are often made from the same master as the digital version, or some additional processing is sometimes done.
Then the vinyl cutting & playback process changes the waveshape making some peaks higher and some lower. (This doesn’t affect the sound of the dynamics) But the new higher peaks limit how loud you can go after digitizing.
Something similar happens with MP3 - MP3 also changes the wave shape making some peaks higher. It’s not unusual to rip a CD to MP3 and end-with peaks over 0dB. CDs can’t go over 0dB but MP3 can go over 0dB without clipping (and Audacity will “show red” for potential clipping).
