24 vs 16

[johnbob]

i have two questions...

does anyone actually notice much of a difference recording in 16 bit vs 24?

and, if i am recording and mixing in 16 bit, when i mix down to a stereo track to do my final touches (no, i won't call it mastering) do i lose sound quality? Should i be putting those final touches on the master fader instead of mixing down?

I would love to hear everyones thoughts....

 

[appleyardrules]

oh i notice quality loss in 24 bit vs 16 bit
i think it had something to do with like that 24 bit is an actual replication of the sound while 16 bit isnt exactly the real sound you recorded idk im confusing myself

 

[littledog]

Most people can hear a difference if they know what to listen for and have a decent monitoring system. With 24 bit you have increased dynamic range, better stereo imaging, smoother reverb tails, and less grainy decays to silence.

You can understand it easily if you look at the math.

The smallest change at sixteen bits would be going, e.g., from:

0000 0000 0000 0000 to
0000 0000 0000 0001

but between those two numbers, you would add 256 more increments at 24 bit, because you would have eight additional binary places for inserting combinations of ones and zeroes:

0000 0000 0000 0000 0000 0001
0000 0000 0000 0000 0000 0010
0000 0000 0000 0000 0000 0011
0000 0000 0000 0000 0000 0100

etc., all the way to -

0000 0000 0000 0000 1111 1111

In other words, 16 bit by definition means 2 to the 16th possibilities between digital silence and the loudest possible value, but 24 bit means 2 to the 24th.

It's kind of like looking at a picture made up of individual pixels. The more pixels per square inch, the closer you get to reality - which can be considered to have infinite resolution. So neither 16 bit nor 24 bit is actual reality - but 24 bit gets you a whole lot closer.

 

[vigormusic]

I'm confused about this too, littledog, thanks for your post, it makes a lot of sense. If you record in 24, you still have to mix down to 16 right? What about sample rate? does that have to match the bit rate? are there good or "correct" combinations for bit rates and sample rates? what about if I already recorded in 16, does it make sense to convert the audio to 24 to mix? or should I just stay with what I have?

thanks

 

[littledog]

I'm confused about this too, littledog, thanks for your post, it makes a lot of sense. If you record in 24, you still have to mix down to 16 right? What about sample rate? does that have to match the bit rate? are there good or "correct" combinations for bit rates and sample rates? what about if I already recorded in 16, does it make sense to convert the audio to 24 to mix? or should I just stay with what I have?

thanks

Sample rates and bit rates have no relation to one another. Bit rate measures the resolution of amplitude of a wave - typically the vertical axis on a wave graph as we usually draw them.

Sample rates measure the resolution of time - how many "snapshots" of the sound are being taken each second. This would be the horizontal axis of a waveform graph.

While more is better in theory, there is a practical limit to how much you can really hear, (and other factors such as the inherent noise floor of electronic equipment) which makes increasing either bit rate or sample rate beyond a certain point not particularly useful.

The advantages to recording at 24 bit versus 16 bit aree pretty much universally accepted. Higher sample rates are not quite as universally agreed upon. Some very respected people insist that recording at multiples of 44.1 (the ultimate CD sample rate) such as 88.2 and 177.4 is better than 96 or 192, because of the math. Others disagree.

Other people, like myself, don't use higher sample rates because of how much bigger it makes all of our audio files (x2 or x4), feeling that the increase in quality is so subtle that most people aren't ever going to hear it. But we still use 24 bits - so in my case I'm recording at 24 bit 44.1k.

The question often asked is, what good is recording at higher resolutions if it is all just going to end up on a CD? This has been discussed many times here, but the short answer is that if you record and mix at 24 bit, then use dither to reduce it to 16 bits as the very last step in the process (which is a method that avoids simply truncating off the last 8 bits), the result will be noticeably better than if you just did the whole project at 16 bits right from the start. There are reasons for this, so you may want to search out discussions on "Dither", for instance, for more information.

 

[littledog]

I realized I didn't answer the last part of your question.

Normally, it does no good to convert 16 bit files to 24 bit - because they will sound exactly the same. The only difference is you are adding 8 zeros to each value.

In decimal, the analogy would be, which number is more precise:

1 or 1.00000000?

In this case we know the numbers are exactly equal.

But, there are cases where it might be useful. For instance, if you are taking raw tracks recorded at 16 bit and are planning to mix them in your computer, all the manipulation you are doing in the mix process (which includes volume changes, EQ, compression, effects, etc.) are performing mathematical calculations on those 16 bit files. If these calculations are done on 24 bit as opposed to 16 bit files, you do gain some advantage due to less rounding errors.

So, if you are still working and changing the audio, it wouldn't be a bad idea to switch over to 24 bit.

Also, another recommendation is that if you are sending your mixes out to be mastered, send them out as 24 bit data files. Do not reduce them to 16 - let the mastering engineer do that as the very last step.

 

[xistenz]

24 bit will be able to retain greater fidelity even at lower amplitudes. it's quite superior to 16 bit. it's all about maintaining that fidelity throughout the mixing process. so even if you're going to 16 eventually, it helps to record and mix in 24.

think of it like digital photography. if you start out with an image that has more information, greater detail is preserved throughout the editing process. the fact that the image will ultimately be compressed for the web gives you even more reason to maintain higher quality from the get-go. in the end it assures that even though the image is of lower quality than the original, you've maintained as much detail as possible.

 

[Robert D]

Great answers above, especially littledog. I'll just mention that a practical advantage to recording 24 vs 16 bits is that it gives you more room to work in without having to sweat dynamic range and noise floor.

 

[vigormusic]

little dog, thank you very much for all of that info.

I have been recording digitally for a year now and haven't completely mixed anything down yet. Still working out the kinks of all the new songs. Just this summer I have been getting more into it and reading up on things like this. I am still mixing on most of these songs. So maybe i'll try converting them up to 24 to mix and see how that sounds. Certainly anything new I will start with 24. Thanks again!

xistenx
your analagy made it perfectly clear seeing that I am a web developer. thank you!

 

[vigormusic]

Great answers above, especially littledog. I'll just mention that a practical advantage to recording 24 vs 16 bits is that it gives you more room to work in without having to sweat dynamic range and noise floor.

Will mixing at 24 bit reduce and crackling that I'm having when I apply effects at 16 bit? Or is that more software/interface related?

 

[xistenz]

Will mixing at 24 bit reduce and crackling that I'm having when I apply effects at 16 bit? Or is that more software/interface related?

that sounds like a software problem to me. but you never know, it might.

 

[vigormusic]

that sounds like a software problem to me. but you never know, it might.

Ok, I'll try converting some files that have the crackling and see what happens. thanks again. The crackling is not too much of a concern because it only happens when I re-open a file after mixing it, and does not come out when I bounce a quick mix to disk. By the way, I'm using Digital Performer 4.6 with a Presonus Firepod on a Dual 2gig Powermac G5.

 

[Dogbreath]

It could be that when you turn up the effects, you're maxing out in the headroom and starting to clip. I dunno. I was mixing a tune tracked in 16 bit and it sounded good until I nudged a bit of EQ to it. Then I got the clipping. May not be the same with running effects but worth looking into.
Peace.......

 

[Dogbreath]

hmmm guess we were writing at the same time...
disregard...

 

[vigormusic]

hmmm guess we were writing at the same time...
disregard...

Yes sir we were
I haven't noticed any clipping on my tracks, that's the wierd part, when it first happend that was the first thing I looked for. But it does happen when effects are inserted.

 

[bblackwood]

It's always good to remember that the difference between 24 and 16 bit words is below -90dBFS (assuming dithered)...

 

[vigormusic]

It's always good to remember that the difference between 24 and 16 bit words is below -90dBFS (assuming dithered)...

I'm not sure what that means. What is a dBFS decibels ___ second? Could you clear that up for me please?

 

[bblackwood]

I'm not sure what that means. What is a dBFS decibels ___ second? Could you clear that up for me please?

dBFS = dB Full Scale.

 

[RAK]

bit depth is also tied to dynamic range. 16 bit=90dB. 24 bit=138 dB. We've come along way from cassette tapes, which were around 60 dB.

Another thing to remember when it comes to higher bit depths/sample rates. Every point in your signal path has to be able to reproduce that. Your system is only as good as your weakest link.

Also, and this was touched on, higher bit depths take up more space and have a larger transfer rate. So depending on your hard drive space, that could be an issue. 1 minute of stereo CD quality (16/44.1) takes up roughly 10 MB of space. 1 minute of stereo 24/44.1 takes up roughly 16 MB.

If only society at large would embrace DVD-Audio and SACD instead of highly compressed digital audio files, then we could master 6 channel 24 bit 96k files to our hearts content.

 

[rgraves]

Ah crap, I know this has been answered before, but I just recently found out I'm recording at 32 bit float. What does that float thing mean anyways?

So, if I was going to record and mix and master everything myself (a crappy job no doubt, but what the hay) is there anything different I have to do? Or just mix the tracks, export them as a .wav file. Import the final stereo file from .wav to master??

Also, if I decide to have it professionally mastered, do you always only send a single stereo file per track, rather than individual tracks right??