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Recording and Mixing Tips for Audio Podcasting

July 7, 2013

Over the last six months, I’ve been working with Justin Davis, user experience designer and founder of Madera Labs (http://maderalabs.com). We publish a one-hour weekly podcast about design and technology, wherein we drink bourbon and talk about the interaction between human and machine. If you’re reading this, there’s a good chance you’ll enjoy the podcast. It’s called Distilled. Find it on iTunes (https://itunes.apple.com/us/podcast/distilled/id574867062).

Along the way, I’ve learned a lot about audio recording, mixing, and editing. Justin was the front man for a band called Quarter to Nine, so he has a bunch of audio equipment. At some point, we looked at each other and said,

“why the hell are we using an iPhone to record this podcast?”

Once we went from mono to stereo recordings, the editing task changed. It was no longer about redacting sensitive content or trimming uninteresting segments. Instead of recording whatever we wanted and cutting it down to an hour, we started training ourselves to record only an hour. This really helps cut down on the mixing and processing time. Having a routine also really helps, especially when you do it every week. Let’s dig into the details.

Gear and Settings

We’re using a Zoom H4n recorder¬†with Shure SM57 and SM58 XLR mics. Justin uses the SM57, which survived a studio fire and still sounds great. I use the SM58. I’m not entirely sure, but I believe we typically record Justin on the left channel and me on the right. We use 44.1kHz sample rate and 16-bit resolution, resulting in a 60min WAV file about 650MB in size. This file is stored on a SD card, which makes it easy to transfer to my MacBook Pro for post-processing.

Production Style

Until very recently, we recorded everything in high quality and published a mono clip, optimized for voice. This merges everything from left and right channels together evenly into one track. The primary reason for this was originally file size. Mono requires half the data of stereo. Recently, we started publishing in stereo. However, without any mixing, the result is Justin in your left ear and me in your right. That’s not really what we are going for. We added an extra step in the post-processing workflow to mix the two channels inward toward the center. In other words, each channel bleeds over into the other.

Mixing Strategy

First, I run the raw audio through Levelator to smooth out the dynamic range. Next, I open the output file in Audacity. This shows two distinct channels together as a stereo track. I split the track to mono, leaving two distinct mono tracks. I pan Justin’s track 30% left and mine 30% right to give the track a bit more depth. I export to the same quality as the source. Finally, I import into GarageBand for transcoding.

Distribution

It’s important to include meta data about the clip before publishing. We use Podomatic for hosting and delivery of episodes. Most hosting providers will include meta content from ID3 tags in the published RSS feed. iTunes uses only the information in the RSS stream to describe your podcast to listeners, so you want to make sure the content in your RSS feed is accurate and relevant to the episode content. I like to write the title and description for each episode as soon after recording as possible. Otherwise, I’m left listening to the whole hour again to make sure the title matches the discussion.

 

I typically spend about an hour in post-production each week. I’m certain the process could be completely automated, taking the raw audio file and producing MP4 as output. I’d also like to see an automated voice recognition layer that would annotate the conversation with time-stamped tags. I’m picturing a media player with a tag cloud visualization overlay. You could see on a timeline when the conversation topic changes, making it easy to navigate to the segment that interests you.

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One Comment leave one →
  1. August 6, 2013 6:34 am

    Thank you so much for sharing your tips. I am just starting out in audio mixing and I didn’t know about Levelator for instance. I would upload the raw tracks directly into Audacity.

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