The only definitive answer is to not exceed 0 dB.
Many commercial CD have a maximum peak level of 0 dB, though some people prefer to make their own CDs peak a little lower. It’s unlikely that the difference will be noticeable whether you normalize to 0 dB or -1 dB or anywhere between.
thats about what I was thinking but somewhere along the line ive been told a little over 1/2 is better…i personally cant hear the difference except that I have to turn the volume up a bit to hear it when i record like that when i play it back...the sound quality is similar but i havent spent an extensive amount of time listening to them side by side to compare them
When Dominic Mazzoni, the original developer of Audacity, wrote the Normalize effect he set the default level for normalization (usually the last thing done in the production workflow before exporting the finished audio) to be -3dB.
A while back the old Team discussed this and decided that -1 dB might be a more suitable default - and so it was changed to that.
First, this is a very minor thing to worry about. The most important thing is to get good recording of a good performance in a good room with as little background noise as possible.
Personally, I’m not “afraid” of 0dB so I generally normalize to 0dB. With acoustic guitar it’s probably helpful to go as “loud” as possible but 1dB isn’t much difference.
Some people worry about “inter-sample overs”. There is nothing in-between the digital samples but the reconstructed continuous-analog peak might go higher than the digital levels. The digital-side of the DAC (digital-to-analog converter) is absolutely limited to 0dB, but there’s no reason the analog side has to be limited to 0dB so I don’t know if this is a real problem or not.
And, MP3 compression makes some peaks higher and some lower, so some people leave headroom for that. Probably most of the MP3s I’ve ripped from CDs "show clipping’ in Audacity. They aren’t really clipped, and MP3 can go over 0dB without clipping. But if you play them at “full digital volume” into your DAC, you’ll clip the DAC. As far as I know this slight-clipping isn’t audible and if you hear a compression artifact it’s probably something else. So again, It’s not something I worry about… And if you want “perfection” you shouldn’t be using lossy compression…
when I started somewhere I read .6 is about the proper level
Just in case you might be confused, there is a common recommendation of recording with -6dB (50%) peaks. That’s to allow headroom so you don’t clip the analog-to-digital converter during recording. Headroom is a funny thing… If you don’t use it you didn’t need it. And if you do use it, it’s no longer headroom! But, acoustic guitar (or with most “live” recording) the levels are less predictable so you may need more headroom. Digital recording levels aren’t critical as long as you avoid clipping and pros typically record around -12 to -18dB. …It can be helpful to get a strong acoustic signal into the mic and a strong electrical signal into the preamp for a good signal-to-noise ratio, but after that It’s OK to turn-down the knobs on your mixer.