This older song was recorded in 24 bit mostly. Currently I have Sonar set to 24 bit for all projects but when I am mixing Multitrack down to stereo track (for mastering), do I Export audio at 24 bit or 16 bit?
 
For my newer projects that recorded at 24 bit I was recommended to Export at 24 bit, Master it with Izotope Ozone in new project, and then Export it from that project at 16 bit and MP3. Is it how you would do it?
 
In case of 16 bit audio- I just exported it in 24 bit stereo track for Mastering and now I am thinking- if it was recorded at 16, shouldn't I export it at 16 so it would not need to truncate it again from 24 to 16 after mastering? Exporting 16 bit in 24 bit would not improve it but that 24 bit new clip will be compressed to 16 bit after mastering with new loss. So should I initially (before mastering) export at 16 or 24? Thank you.

Sonar defaults to rendering in 32 bit. All processing seems to be such. 
But wait,  My audio interface seems to decide for me that I'm working in 24 bit. . 
I guess this applies to all audio recorded. 
So some people keep 32 bit in the export to wave which seems to be Sonars default, then master in 32 bit and only render to 16 bit when burning the CD.
I myself export to 16 bit and master in 16 bit. But then nothing I'm doing these days will ever be played on a high end audio system. Those guy's only listen to Steely Dan. 

I used to record in 16 bit because my audio interface only offered 16 bit. I then switched to recording in 24 bit but was mixing for Mastering in 16 bit. But was told that it is better to export first in 24 bit, master and then render to 16 bit.
 
But this particular song is recorded in 16. I just listened what it exported at 24 bit- I can not tell if it would be any different if I set it to 16. But who knows, I am just thinking- if I export in 24 what recorded in 16, and then truncate 24 to 16 again, wouldn't I have losses as it has to take something out to make it 16 out of 24?

If you master in a separate software tool  (or send your mix to a mastering engineer) you should definitely export at 24 bit and only AFTER the final mastering step reduce bit depth to 16 bit (using dither) i.e. you should not truncate to 16 bit early as you will lose resolution (i.e. mix depth), you should not dither more than once ...

vladasyn
I just listened what it exported at 24 bit- I can not tell if it would be any different if I set it to 16. 

And you won't. When you export to a longer word length, all SONAR's doing is tacking on some zeroes to pad it out. It will sound exactly the same.
 
The reason for exporting 24- or 32-bit audio is so that the next software that gets it (e.g. a mastering program) will receive the maximum resolution. But if you're doing the mastering within the same project, there is no benefit to exporting 24- or 32-bit files, and no penalty for leaving it at 16 bits.

Will it sound the same when I render from 24 back to 16? 

Yes of course. But make sure you select a suitable dithering algorithm.
 
The only time I render from 24 bit to 16 bit is if I want to burn a CD

It's worth mixing at 24 bits even with 16 bit audio files, in case calculations caused by processing within SONAR while mixing create words with longer than 16-bit lengths. 24 bits minimizes the possibility of rounding errors. 

I nominate this thread for the SurfBoard section of the next eZine.

 But make sure you select a suitable dithering algorithm. The only time I render from 24 bit to 16 bit is if I want to burn a CD

What algorithm are you referring to? I pic my Ozone mastering present, make minor adjustments and then just Export audio the same procedure as with multitrack mixing to stereo track. I just set it to 16 or 24 (if I wanted to) and it makes a track. I do not select any algorithms. Should I? The ozone actually offers Dizering but I am not sure how I supposed to use those settings in Sonar if all I have to do for Sonar is export audio and set it to 16.
 
How do you use 24 bit files? it would not even play on anything (or may be it only applies to 32 bit? Every time I render file at 32 bit bi accident, it would not open by Windows media player). Do you convert 24 bit wav file to MP3? I thought you have to have 16 bit file to convert to MP3. There is a thread under my profile with specification requirements for online streaming services. I do not remember if It has to be 16 bit for MP3 or not.