ACX Mastering Process Update: Normalize To -3.0 dB

Hey, there!

More than anything, I want you to have confidence in your ability to narrate audiobooks for ACX.

And part of that confidence is in trusting the process I teach.

Although thousands of books are on sale at Audible using exactly what I’ve described if you’ve taken my Recording for ACX with Audacity class (or the ACX Master Class that Dan O’Day and I teach together), there is one technical detail that we’ve seen talked about as not technically perfect.

So, let’s fix that, and let’s finally put the whole thing to rest.

Here’s the rundown of the issue and the fix, and a video to help you with the process:

1. We use Levelator to do our RMS normalization. It works great.
2. Levelator outputs a file that is measured at -1.0 dB peak volume.
3. However, ACX prefers uploaded MP3 files that are -3.0 dB peak volume, not -1.0.
4. There is an insignificant aural difference between the peak measurement of -3.0 dB and -1.0 dB.
5. ACX has accepted every book that has used Levelator from my studio and all of yours.
6. That doesn’t actually mean others won’t find fault with this part of the process.
7. It’s an easy fix: from now on, we’ll normalize to -3.0 dB just after importing our .output files, and just prior to exporting to MP3.

Here’s what I want you to do: add this one step to the mastering process, between the step of bringing your Levelated file back into Audacity, and the step of exporting as an MP3 file.

The step? Use Audacity’s Normalize… function (found on the Effect menu) to normalize your audio to -3.0 dB. THEN, export as a 192 Mono MP3 file as normal.

Screen Shot 2015-07-31 at 3.36.29 PM

(Click on that image to make it full size.)

Make sure you do this with every body/chapter you create.

Although this is a small change, it is one that will provide one less reason for me to have to reply to criticism that we aren’t doing things exactly the way ACX wants them.

Now, we are.

Oh, and this will be a video demonstration in the new VO2GoGo Labs area I’m constructing.

Hope this helps.


4 Responses to ACX Mastering Process Update: Normalize To -3.0 dB

  1. Kat Negrete August 1, 2015 at 9:12 am #

    Thank you, David. Do you still recommend normalizing to -1.0 for non-audio book jobs, like IVR or radio spots, etc? Just curious. Xoxo

  2. David H. Lawrence XVII August 1, 2015 at 12:51 pm #

    It’s OK to leave it at -3 if it’s easier. The difference is minor.

  3. Donya August 1, 2015 at 2:47 pm #

    Thanks David.

    Seems simple enough.

  4. Gina August 27, 2015 at 11:28 am #

    So, if I’m only seeing this now… Should I:
    1. start incorporating the process HALFWAY thru production of a book,
    2. wait until my NEXT project to start, OR
    3. go back to the beginning of this project and replace the 17 completed chapters with the corrected -3dB mp3’s?
    Just how much of a difference will it make?
    Thank you!!

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