First post here. Please be gentle. Windows 7, Audacity v 2.0.
After searching for quite a bit I couldn’t find a comprehensive answer to my question so here goes…
I’ve got a new truck (2018 Ram 1500 with UConnect 8.4 audio system) that has a USB port for playing music stored on USB flash drives. The truck’s audio system has the ability to execute voice commands to play music, i.e. “Play song ‘Stairway to Heaven’” or 'Play album ‘Led Zepplin IV’. I’m in the process of ripping a bunch of my CD’s using Windows Media Player into lossless WAV files, then importing the songs into Audacity. When I have the WAV files in Audacity I use the function Effect > Amplify to bring the sound level of each song to the maximum allowed sound level without clipping. Apparently it’s the default setting of the Amplify function and it brings the peak amplitude to 0.0 db. I then convert to mp3 files at 320 kbps, export the song to my PC, and finally copy them on a USB stick so I can play the songs in my truck.
I’ve found when I play the mp3 files I have to turn the volume up in my truck to higher than usual levels to reach the desired volume level. For example, I might listen to music on the radio at a volume setting of 16 but to get an mp3 song from the USB stick to play at the same perceived loudness level I have to turn the volume up to 26, for example. (Volume control goes up from 1 to 39)
I’ve gone back into Audacity and repeated the process but this time applied the Amplify function to more than 0.0 db levels. For example, I might set the ceiling at +0.5 db, checkmark the box “allow clipping”, and then depending on the song I might see a few vertical red lines here and there or I might see a LOT of red lines, so much that it practically obscures the blue waveforms underneath. I tend to be a bit afraid of the red vertical clipping indicator lines so I will set the levels just a bit higher than 0.0 db, say 0.3 db, which produces maybe 10-15 “red clipping lines.” However when I export the file and then play it in the truck it is a bit louder but I might still have to set the volume to 22 or so. Except for the elevated volume setting the song sounds fine but I swear I’m hearing distortion when I crank up the volume to, say 30 or so. (Or am I imagining that distortion?)
Is there a solution for this? How can I get my mp3 files from ripped CD’s to play louder in my truck’s audio system at the same volume setting as the radio? Can I set the Amplify function to higher levels and not get distortion? Or, to put it another way, how much red is tolerable in the waveform when using the Amplify function?
Side issue–When I purchase mp3 songs and albums from Google Play Music, they play louder in my truck than ripped CD’s converted to mp3 files, but when I import these songs into Audacity and look at the waveform, it’s almost solid red! What’s going on with that?