Applying Gain to 16-bit Recordings Options

[Engelsstaub]

I have a few questions regarding some 16/44.1 recordings I have that could be a bit louder. I wanted to boost the gain to somewhere around the point where peaks will be around -1dB without clipping. (It seems that typically the peaks are around -3dB and the meat of the recording is around 6dB and often lower.)

The files will first be upsampled to 32-bit(float)/44.1 and edited in iZotope RX2 Advanced. (Editing consists of light declicking, some possible noise removal between tracks, etc. and then resampling/dithering back.) My questions are these:

1. Is there any reason why applying gain would effect the quality of the original recording in the resulting product? (Would it have just been better to get the level set closer in the first place ?) I know that reducing the volume is "losing bit depth," as I've read this from members in older threads while searching earlier. Is there a reduction in bit depth (or perceivable sound quality) when increasing the volume when using a quality program at the upsampled bit rate?

2. Should the gain be applied before or after the editing (or does it even matter) assuming that number one isn't a boneheaded way to approach this with respect to quality?

Basically I believe it would be ideal to make this...



...look about like this. (About 3dB louder.)



(Sorry if these questions are a bit noobish. I've been reading my ass off through the archives and still can't quite get a grasp.)

[Arnold B. Kruege...]

1. Is there any reason why applying gain would effect the quality of the original recording in the resulting product? (Would it have just been better to get the level set closer in the first place ?) I know that reducing the volume is "losing bit depth," as I've read this from members in older threads while searching earlier.

Consider the context. The source object (vinyl) has about 12 bits of resolution. Your editing environment has from 16 to 24 bits of resolution. The weakest link is obvious. As a rule of thumb, if there are about 3 bits of difference, the difference is less than a tenth of a dB which is deep into audibly negligible.

Is there a reduction in bit depth (or perceivable sound quality) when increasing the volume when using a quality program at the upsampled bit rate?

As long as you haven't lost usable resolution by recording the track at too low of a volume originally, no. If you are adding more than 20 dB of gain, you really should redo the origional transcription.

2. Should the gain be applied before or after the editing (or does it even matter) assuming that number one isn't a boneheaded way to approach this with respect to quality?

In general, if anything makes a difference and it usually doesn't, the most important thing is getting the signal levels up, but not so far up that anything you subsequently do causes digital clipping. I like to see peaks within 3 to 10 dB of FS at any step in the processing.

It appears that you are concerned about gain changes on the order of 3 dB which should always end up being moot, even with average software.