I don't fully understand recording and signal to noise ratio

Question

I'm recording vocals and acoustic instruments with my shure57 microphone and behringer ultragain pro preamp and I've been trying to reach the best signal to noise ratio. From what I know to achieve this I should turn input gain on my preamp all the way up until it my signal during louders parts is just below the clipping point.

Ok, I get it.

But what if I recorded with, let's say 20dB less gain and then added this gain to already recorded material in my DAW? Would it be more noisy?

Like in these two situations:

1)

Input gain on preamp +40

desired signal hovers around -10dbfs in my DAW

noise signal hovers around -50dbfs in my DAW

So signal is 40dB louder than noise

2)

Input gain on preamp +20

desired signal hovers around -30dbfs in my DAW

noise signal hovers around -70dbfs in my DAW

Signal is still 40db louder than noise, now I can apply 20 dB in my daw and it's the same as the previous recording.

Is this thinking right/wrong? If it's wrong please tell me why. Thanks for reading.

Answer 1

The general rule of thumb when making the initial recording is to get the track recorded as hot as possible without clipping the signal. Once this has been accomplished, the track can be mixed back to the level required to achieve the desired mix with the other tracks. when the track is mixed back at the desired lower level, the noise floor on that same track is also mixed down at the lower level and you can achieve the desired low noise floor in the final mix. Because processors add to the noise floor, it is recommended to record the original track as hot as possible without clipping and then mix back to the desired level in the mix.

Answer 2

This is about adapting to the equipment at hand. In old days, using tape recorders or 16 bit digital, the rule was to record hot but not clipping. The really modern equipment, say Sound Devices Mixpre 3II records 32 bit float all the way through and you can basically forget about gain and fix it in your mixing program.

Now, the SM57 is a dynamic mic with less output than condenser mic and the Behringer is a single gain stage amp. Single gain stage means that the preamp noise will be different depending on gain. My experience is that least noise tend to be mid gain on the preamp with the rest added in digital. You will get less noise from the preamp with a condenser mic. A middle ground might be to add a further preamp step — there are little devices fed from phantom power that you can add at the mic end.

Regardless of theory, the only thing that really matters is if you can achieve the sound you aim for c