[Update: December 2016 — I wrote this article six years ago, and I recognize that my explanation was not technically accurate. Part of it was my attempt to simplify a complex concept, part of it was simply ignorance on my part. Here’s what you need to know about bit depth: Record at 24-bit. Make your final masters 16-bit. All the other technical stuff doesn’t matter. There has been great music created at every bit depth and sample rate out there. And not once has the bit depth or sample rate been the deciding factor as to whether the music was good or not. If you want to make better music, focus less on technical stuff that doesn’t matter, and focus more on the stuff that does, like writing great songs, working with great musicians, learning how to record, arrange, produce, mix, and master in a way that is musical. Thank you to the folks who have corrected my technical inadequacies below. PLEASE READ THE COMMENTS if you want to hear smarter people than me explain bit depth. Or you could…y’know…go make some music. 🙂 ]

 

I’ve mentioned numerous times in blog posts and episodes of “Ask Joe” that you need to record at 24-bit. Then I realized that I’ve not written an article specifically on this topic.

When you’re recording digital audio, there are two main settings that you will come across at some point – bit depth and sample rate.

We won’t get into sample rate today. I’ll save that for a future article. To summarize, sample rate measures how many times per second the audio is “sampled,” or measured. Common sample rate values are 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, and 192 kHz. Is higher better? Hmm…I have my own take on this, but that’s for another day. 🙂

For today, just know that if you record at 44.1 kHz, that means the volume of the audio signal gets measured 44,100 times per second. When you put all these tiny measurements together, you get a waveform.

Okay, moving on.

What is bit depth?

Sample rate determines the frequency with which the system measures the volume of the audio. Bit depth determines how many different volume measurements the system has to work with.

In other words, if you think of the audio as being measured by a ruler, the bit depth is how many notches that ruler has. Some rulers only measure in whole inches (low bit rate), while others allow you to measure within one-sixteenth of an inch.

A ruler with more notches allows for a great number of measurement options, and therefore a more accurate measurement.

Comparing Bits to Inches

Okay, so the higher the bit depth the more individual measurements we can achieve. How does that relate specifically to recording?

If you’re recording at 44.1 kHz, then you’re telling your analog-to-digital converter (i.e. your audio interface) to take a volume measurement of the audio once every 1/44,100th of a second. How does it measure the volume? In bits.

1 bit = 6 dB

“dB” stands for decibel. It is logarithmic measurement of volume. If you increase the level of a signal by 6 dB, it will sound twice as loud.

So, for our converter to measure the signal at 2 bit rather than 1 bit, it needs to be twice as loud.

The 16-Bit Ruler

Digital systems don’t have “in between” measurements. Everything is cut and dry in the Land of Didge (shout-out to Slau).

So, the smallest unit of measuring volume in a digital system is 1 bit. There’s no 1.5 bit or 1.42983003 bit.

This means that in a 16-bit system, you have 16 notches on your ruler. 16 potential measurements for your audio. That may not sound like a lot, but keep in mind that these measurements are being taken thousands of times per second.

Alright, we said that 1 bit equals 6 dB of dynamic range (or volume). What is the dynamic range of a 16-bit recording? The answer is 96 dB.

96 dB? That’s great, right? Sure it is…in a perfect world.

Noise Floor

The problem you run into is noise. Every audio system out there has some amount of inherent noise.

In other words, no recording system is perfectly quiet. The electrical components generate a low-level noise. Each piece of your system contributes to the noise party. All of this noise adds up, and it’s called the noise floor.

This doesn’t even take into account any room noise that might get picked up by a microphone.

The noise floor essentially “steals” away some of your dynamic range. Let’s say that all the noise added together was 18 dB. That’s 3 bits.

Since this noise occupies the bottom 3 bits of your system, the level of your audio needs to be recorded ABOVE 3 bits (or 18 dB), or it will be lost in the noise. So instead of having 96 dB of dynamic range, you realistically only have 78 dB (or 13 bits).

The gap between your recorded signal and the noise floor is getting smaller. This means that if you don’t record your signal loud enough, you’ll end up hearing this noise in your recordings. On the flip-side, if you record your signal too loud (to stay well above the noise), you’re in danger of clipping.

24-Bit to the Rescue!

Enter 24-bit recording, super-hero cape blowing in the wind.

Now, instead of giving your converter 16 measurement options, you’re giving it 24. And if you kept your calculator our from earlier, then you know that 24 bits x 6 dB = 144 dB dynamic range!

An audiologist will tell you that our ears aren’t even capable of hearing a full 144 dB of dynamic range. However, having this much available dynamic range allows you to create greater separation between the recorded audio signal and the noise floor.

When you add in the 18 dB of noise we have in our make-believe system, and you drop the usable dynamic range down to 126 dB, you still have a TON of breathing room left.

Check out this diagram:

As you can see, the 16-bit system is still fairly close to the noise floor. The 24-bit system, however, towers above the noise floor, making it much less of an issue when recording.

In a 24-bit system, you don’t need to record the levels super-hot, because you’re signal is not nearly as likely to drop down into the noise floor. This leads to better sound quality, less noise, and less stress when recording.

Do you record at 24-bit? Leave a comment.

[Photo by internets_dairy]

  • John Morris

    Nonsense. 16 bit is more than enough and if you are pushing your meters close to zero you don’t know what you are doing. Most professional engineers know the following:

    When you record at 16 bit you want to your levels at -12dbs rms (not peak) and to n fgggfffdffff

    Pink Floyd’s Dark Side Of The Moon was recorded on a 2 inch 16 tack. Twoctually. Alan Parsons bouncedono a second tape to make room for sound effects, more overdubs, etc.

  • 16 bit is what most people make music at and save their MASTER file in and that’s all well and good. Film and TV however usually require 24 bit, and that ‘s for the samples used in your song as well. If you do everything in 24 bit, assuming your song is good, you can just slide it over with a licensing deal. Otherwise they may pass on your song or pay you chicken scratch for the rights then hand it over to a producer who will earn the big dollars rerecording your music and getting a producer credit on it. Think of 16 bit like a photo on the internet, which are great at 72 dpi. But if you try to print that photo it comes out the size of a postage stamp?! And if you attempt to enlarge it then it comes out pixelated. Print requires a higher quality, 300 dpi. Movies and film are their best at 24 bit. And there is the dilema because you never need 24 bit until your hit is blowing up the charts and someone wants to put it in a film or on TV and now you’re scratching your head wondering what you should have done and hoping upon hope that someone made a 24 bit master and saved it somewhere.

  • Jon S. Kristoffersen

    Hi! I have gotten the master in 24 bit, but it needs to be 16 bit if I want to upload it to a digital distributer. My question is simply, can I just put the master files into a project in ableton and then bounce it with 16 bit? Or will I then f**k up something up I am not aware off? Do I have to do something before i put the files into ableton (set the bit rate 16 bit before i put them in the project for example?).

    I will be thankful for a simple answer to this.

    • If Ableton applies dither on export, then yes. If it doesn’t, then you’ll need to find a dither plugin to apply. Or have the person who delivered the file to you give you a 16-bit version.

      • Jon S. Kristoffersen

        Thanks Joe for the answer. Ableton does apply dither, but I get a few options up, is there an easy answer to which I should choose? Rectangular, Triangular, POW-r 1, POW-r 2 and POW-r 3 are the alternatives I get.

        • I’d pick one of the POW-r ones and move on. 🙂

    • John Morris

      When you knock it down to 16bit make sure you dither your 24bit file to 16bit. Without dither your 16bit copy might end up sounding not to good. Dithering – very important.

  • Hey everyone. I’ve written an update to this article (see the top). Apologies for any misinformation I presented here. Thanks for all your feedback!

  • Lee Spencer

    I stopped reading after you idiotically said that 16 bits means that there are only 16 possible levels of sound. You sir, are retarded. 16 bit audio gives you 65,536 increments, or possible volume levels, not 16. 24 bit gives you 16,777,216 possible levels. How could you possibly feel you could write an article on a subject and get something SO basic SO wrong?! Absolutely pathetic. You taught me absolutely nothing.

    • You’re probably right. I oversimplified it. Not sure it warrants this much anger and name-calling. My guess is you’ve got a lot going on and are taking it out on me. I get it. I’ve done it, too. Maybe we can still be friend. 🙂

      • Lee Spencer

        lol just a bit of well earned internet trolling, enjoy & don’t take it too seriously. p.s. edit your article!

        • Wanna edit/rewrite it yourself?

        • Seriously, though. You should try being a part of the solution instead of trolling. Saw a video today where someone trolled lady’s site, telling her to dye her gray hair so she doesn’t look so old. Turns out she has an auto-immune disease that causes her to age quickly, and she won’t likely live to an “old age” anyway.

          Words are powerful. I try to use them to help people. You should try that next time you want to write things like, “You sir, are retarded.” or “Absolutely pathetic.”

          I’ll agree this article needs to be updated, but I also long for a world where people are more focused on helping people than tearing them down.

      • John Morris

        I don’t understand.?? I don’t agree with everything you say but that doesn’t mean I get to insult you. Why did he feel the need to result to name calling?

        I must say sir I am impressed with your restraint.

        • Haha. I’ve been doing this for a long time…

          • John Morris

            Still impressed.

    • Baran Galocy

      Hey Lee,

      Way to go! Are you raising the little one to be a master troller like his daddy? Does it make you feel powerful and knowledgeable to belittle someone else? My guess is you desperately need a life and are seeking one anyway you can – even if it means making other people wrong. Troll on, but remember what goes around . . .

    • John Morris

      I agree that Joe made an error. Couldn’t you have just said he was incorrect instead of the inappropriate word you used?

      • Lee Spencer

        Yes. This was a year ago. I thought there were more replies to this comment including a reply from myself, perhaps they were removed, but there was some discussion back and forth regarding the comment. The jist of it was that this is the internet, and there was a good amount of sarcasm involved. if you’re going to post something like this publicly the most basic of research and calculations should be done. I will now delete the comment.

  • Guest

    So, does any one record ambient room noise first? Like if I put a SM57 up to a 4×12 cab, let the ambient his and room run for the length of the song, then record the actual guitar cab and reverse the phase of the ambient room track – won’t that add head room? Or simply, in the digital medium, erasing all the unnecessary dead space on a track in between passages?

    • I suppose there are people who do that, but it seems like a waste of time to me. Noise isn’t all that bad.

      • John Morris

        Interesting. I use to be very religious on my use of noise gates. Now, unless the noise is crazy I don’t use them much.

  • Shaun McGrail

    Hi joe / everyone,

    Thanks for this, really helpful. My knowledge on recording is very basic. I record our church service every week on audacity at 44.1kHz/32-bit float. No idea what this means. Just wondering if anyone can tell me how I can get the bit rate down in audacity. The default Sample Format is set at 32-bit float. I ask as the upload time to the website takes forever, and I want to reduce it.

    If anyone wants to help a noob, that would be awesome 🙂

    • Start off recording at something like 24-bit. Then Audacity should have a way to export an mp3, which will be much smaller.

  • shai

    great article. i encourage to write more

  • Stoneage

    R U guys getting tired of the digital quest yet? I am recording thru a Soundcraft 800B into a 16 bit digital recorder. Oh Yea! Does that shake things up here?

    • Not sure what you mean by digital quest?

  • Thank you. Nice and clear.

  • Don Hayek

    I’m experiencing the criteria now in sampling an organ for use in making a sampled virtual organ. Thank you for the simple answer to why I am having problems getting timid high notes above the noise floor.

  • Thanks for this article! I have not seen a piece like this explained in such a, in my humble opinion, clear way!

  • kirk anderson

    Unfortunately, this is too good to be true. Increasing the bit rate doesn’t magically increase your “effective” dynamic range as the poster suggests. Otherwise, the solution to noise would simply be to increase the bit rate to say, 32 bits.

    Your effective dynamic range is limited by saturation or clipping on the top end and noise on the bottom end and neither is changed or modified by the bit rate.

    The only time that an increased bit rate from 16 to 24 can make a difference in this regard is if your effective dynamic range exceeds 96 dB (say it is 110, for the sake of argument). In this case, increasing the bit rate to 24 bits will allow you to exploit the full dynamic range of your system whereas using 16 bits would have effectively thrown away 14 dB of usable dynamic range.

  • Brian Hoerner

    I just wanted to say thank you for your helpful and informative article. I’m trying to get into podcasting, and I’ll tell you with no exaggeration that this has been one of the most useful things I’ve read thus far. People often write articles about recording assuming you know everything else about audio aside from their chosen topic, and even two or three foreign concepts or terms makes the rest of the article practically unreadable for a layperson. The ruler analogy was wonderful and the chart helped clarify that was I was imagining in my head was in fact what you were trying to express. Again, thanks a thousand times. I’ll be reading more of your content.

  • m3k

    24 bit might be useful for really dynamic orchestral recordings, but a guitar/footpedal/amp with a 30db range? Not really. Blind listening tests at 16/44.1 and beyond are inconclusive, half the people think the lowest actually sounded better. You could probably make some sweet tunes at 12bit/36kHz (remember old samplers now revered for their sound?)

    Who refuses to listen to mp3s, soundcloud, youtube, and vinyl because of the resolution/dynamic range? No-one. If you like the tune you forget about all that.