Sunday, August 16, 2015

Audio Compressors for Podcasters

I recently attended The Podcast Movement Conference in Fort Worth, TX. I don't do a lot of conferences but I thought this one was important, as it happened to take place during an interesting/transitional time in my life... it relates to my work in radio, and my work with , 2BoomerBabes, AARP and audioBoom.

I think you can get most of the "knowledge" part of a conference from a google or twitter search, but you'll miss the best part of a conference... the people. Those other figure-outtters out there you'd never otherwise get the chance to meet. I am so glad I went because I got to meet great people doing great stuff in this platform.

I promised some of my new podcaster friends (you know who you are) I would send some notes on basic compressor settings for improving the sound their podcasts. 

Here are my notes:

You want to use a compressor on your "master fader" (protools lingo) track and/or your vocal tracks to make your volume more uniform. What a compressor does is raise the overall volume of your audio while compressing peaks (volume over a threshold) into a predetermined level. 

This is specially useful for podcasters because you will be listened to in cars, trains, while jogging and while cooking, etc, and it makes for a better user experience if the listener does not have to be rewinding the file to hear something because your volume was too low in some sections... this happens a lot to me  (as a user) while trying to listen to audiobooks or podcasts while riding the #wmata metro. #talkingACX
With a compressor, you have a better chance of getting a steady volume throughout your file and also avoid unpleasant (painful...over 120 dB) surprises in volume, in the listener's ear, when the convos get hot.   

Here are some screen grabs of a typical audio mastering compressor I use:




These are 3 pictures of the same compressor; same settings, just shown in 3 different visual variations... I wanted to show the variations because your software of choice might show you one of these or maybe a VU level but regardless of the visuals, know that you are getting the same results.

I think the "wave" visual explains the function of the compressor best, as the original audio (gray wave) crosses the threshold (orange line) you can see the effect of the compressor (yellow line) pushing peaks (anything above the threshold) down, while raising the volume of anything below the threshold.

So, regardless of what software you use, these settings should help you get started:

RATIO:           1.50:1

ATTACK:        1.00 ms
RELEASE:      100 ms
THRESH:        -21.5 dB
KNEE:             12 dB
OUT (GAIN):   (0-4) dB  

A note about output/gain: In the example above, I didn't give any gain to the compressor, but in real life I have ran the gain up to 9 db for commercial radio. You do have to be careful not to distort though, so if you want to be safe, err towards too little gain instead of too much... distortion is very hard to clean.

Warning: compressors will raise the overall volume of your audio... if your audio is not clean, it will more noticeable. I suggest processing your audio (cutting, EQ, cleaning filters) before you apply the compressor. I use Izotope RX filters for audio repair...also multiband EQs, gates and volume envelops before I apply compression.

I realize all that cleaning might be too much work for some, so if you have an amazing but noisy interview and want me to take a listen, just let me know.

Happy podcasting!