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Bit Depth of Logic Project?


Cobalt

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So I've heard that when you're bouncing an unmastered song it's best to bounce at the same bit depth you're working in, and save the dithering process (i.e. 24 bit to 16 bit) til the end of mastering so you only do it once.

 

What's confusing me is I'm not sure what bit depth I'm working at, as my song is mostly Logic's virtual instruments. There are also a few audio files in there, some 16 bit, some 24 bit. I looked in the preferences and project settings, but only found a "24 bit recording" option.

 

What bit depth is my song file playing at by default? Should I bounce my unmastered files in 24 bit or 16 bit if they're mostly VIs? Or does bit depth not apply to VIs?

 

Thanks!

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So I've heard that when you're bouncing an unmastered song it's best to bounce at the same bit depth you're working in

 

You're not necessarily "working in" a certain bit rate. Instead, the audio files used by your project each have their own bit rates. The bit rates can be the same for all your audio files - but then again they could be different ones. You could use 16 bit samples but 24 bit audio files. Or the opposite. Or some 16 bit and some 24 bit audio files. Logic's audio engine is processing everything at 32 bit floating point, independently of the original format of the audio files. Logic does not allow you to bounce 32 bit floating point audio files, which would be unnecessary for that application anyway as long as you are using "reasonable" digital audio levels (meaning you're not bouncing your project at -55 dBFS for example).

 

Assuming you only worked with 16 bit audio files, you'd still want to bounce a 24 bit file.

 

So in conclusion I would always bounce a 24 bit audio file if I want the best quality possible.

 

and save the dithering process (i.e. 24 bit to 16 bit) til the end of mastering so you only do it once.

Dithering should occur when converting from 24 bit to 16 bit. And that conversion should be the last thing you do at the end of the mastering process - but if you did that conversion before, then dithering also should occur before (although I can't think of any situation when you'd want to convert to 16 bit before the end of the mastering process).

 

What's confusing me is I'm not sure what bit depth I'm working at, as my song is mostly Logic's virtual instruments.

Logic's virtual instruments all generate 32 bit floating point signal.

 

There are also a few audio files in there, some 16 bit, some 24 bit. I looked in the preferences and project settings, but only found a "24 bit recording" option.

That option determines what bit depth will be used for any new recordings you make - it does not affect anything that is already recorded.

 

What bit depth is my song file playing at by default?

32 bit floating point.

 

Should I bounce my unmastered files in 24 bit or 16 bit if they're mostly VIs? Or does bit depth not apply to VIs

VIs or not you should always bounce unmastered files in 24 bit.

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  • 1 year later...

So to follow up on this great thread, is there any advantage of me taking a mobile audio interface over just using the built-in CoreAudio sound card in my Macbook Pro if I'm mainly using Logic Pro's virtual instruments, realizing that those instruments are 24-bit? I was of the logic that I needed to carry a mobile audio interface because of the unit's 24-bit recording capabilities. But from what I've been reading on this thread, having that interface would only be necessary if I'm using inputs to record vocals, guitars, etc., which are then converted into 24-bit samples. Am I correct? Sure, I'll have my mobile interface in my bag when I need it, but otherwise the fewer items I need to do my work, the better.

 

Thanks!

V.

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Hi Velanche,

 

First, your Mac's built-in audio interface supports 24 bits recording, even with the built-in microphones. So the bit depth is not a factor when deciding between the built-in audio interface and an after market external audio interface. In any case, comparing bit depths doesn't give you much information - I'd rather use a very good quality 16 bit audio interface vs a low quality 24 bit audio interface! Having said that, I can only think of a single example of a 16 bit audio interface being manufactured today, pretty much all audio interfaces are now 24 bit.

 

So what's the difference between the built-in interface and an external interface? Or, more generally...

 

What makes two audio interfaces different?

• The quality of the converters (both A/D and D/A).

• The quality of the analog circuitry.

• The quality of the clock.

• The quantity and type of audio inputs and outputs.

 

If you're only using software instruments, then the sound is generated by Logic, and you're not using your interface's A/D converters... you are however monitoring your work through your audio interface's D/A converters. So while your audio interface doesn't affect the sound produced in Logic, it does affect how you hear it as you work in Logic. Kinda like the size and quality of the display you use wouldn't affect the quality of a digital photograph you're editing in Photoshop - but it would affect the amount of detail you can actually see as you're working.

 

Hope that helps.

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You won't run into any bit depth related problems using the built-in audio, which is capable of 24 bit / 96kHz operation.

 

That said, it sounds horrible and there is bad interference from other components in the computer. I'd be using the mobile interface every chance I got! (or something more compact - the DACport et al)

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Very, very good points, David. My interface does display audio levels, and of course I have both my headphones and my monitors (as well as my mic) attached when I use it at home. But even away, the ability to watch the levels and listen to true production simultaneously is crucial.

 

As ever, David, you've been very helpful! Much appreciated.

V.

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