Soundflower is one of the most powerful free audio tools available for OS X. Not only does it give you the ability to route audio from one program to another, but to record that audio in addition to your primary input device. Screencasting, podcasting, and even basic video recording can benefit from the added flexibility that Soundflower provides.

Soundflower is a favorite among podcasters working with OS X. I’ve used it extensively for audio projects in the past, both along and in conjunction with additional audio routing software to create a virtual mixer board allowing me to feed a virtual mix minus to guests on Skype while capturing everything that needs to be captured on the same system.

Recording a Podcast with a Guest Via Skype or Google Hangout (Multi-track Recorder)

How to Set Up Soundflower for Audio RecordingUnfortunately, Soundflower’s configuration app (Soundflowerbed) can be a little confusing from time to time. I use both an external audio input device and system audio to record, so that means that I both need to transmit clean audio to the guest and record that audio locally.

Doing this is relatively simple, though it’s very easy to overthink the process.

First, you’ll need to make sure Soundflower is properly installed and Soundflowerbed is loaded in your system’s task bar located at the top-right corner of your desktop. Then, you’ll need to left-click the Soundflowerbed icon and select Built-in Output under Soundflower (2ch). This will allow you to hear the built-in output in your speakers or headphones later on.

Next, you’ll want to open your Mac’s Sound Preference Pane via the System Preferences menu located under Applications > Utilities. Here, you’ll want to make sure that Soundflower (2ch) is selected as your Output device. Your input device can remain whatever microphone you plan to use as your primary.

How to Set Up Soundflower for Audio RecordingDoing this accomplishes two different things. First, it routes your system’s primary audio to Soundflower, enabling you to assign Soundflower as your audio source in the recording application. Secondly, it doesn’t interfere with your primary audio input, allowing you to send and record a clean channel with just your voice on it.

If your recording program of choice has the ability to have a specific sound device assigned as the input device, you will be able to capture system audio by selecting Soundflower (2ch). Alternatively, you can choose your primary input device for your track. This is especially helpful for multi-track recording apps such as Audacity and GarageBand.

Meanwhile, your guest should be able to hear you without hearing themselves with a minor delay — a very confusing and often difficult situation for any speaker.

There is another method in which you keep all of your system sound settings the way they are and just route audio for the program you wish to record to Soundflower. Doing so will remove it from your main output mix, so you’ll need to set an external listening device (USB headset, for example) to receive audio from Soundflower in order to hear your caller. This will reduce the likelihood of other system noises (new email, notifications, etc.) from interrupting the recording.

Add Both Your Microphone and System Audio to the Soundflower (Single-track Recorder)

This is a handy trick if you’re not working with a multi-track recorder, but still want to capture what you and your guest are saying. This requires a little extra effort, but the results are well worth it.

To accomplish this, you’ll need an additional audio program that routes audio from one source to another called LineIn. This, like Soundflower, is free and offers exceptional audio quality without the need of additional hardware on your part.

LineIn enables you to route one single input device’s audio to another through a simple pass through. You’ll need to create a second instance of LineIn before anything else. This can be done by duplicating the LineIn app in your Applications folder and naming it something slightly different. For example, you could call the duplicate copy “LineInB.”

The end result of this setup should enable you to hear audio without your microphone in it while recording both you and a secondary source. This is a technique which usually requires an external mixer, though it’s not necessary here.

To summarize, this is what you’ll need to be running to record an audio podcast using Skype and Audacity. This setup would also work if you exchanged Skype for another VoIP or audio communications program that permits custom audio input and output settings.

  • Skype
  • Audacity
  • Soundflowerbed
  • LineIn Instance A
  • LineIn Instance B

To set this up, do the following:

  • Open System Preferences and select Sound.
    • Set the Output to Soundflower (16ch).
    • Close the sound preferences, leaving your primary microphone as the default Input device.
  • Fire up both copies of LineIn.
    • Set the Input of the first instance to your primary microphone.
    • Set the Output of the first instance to Soundflower (2ch).
    • Click Pass Thru.
    • Set the Input of the first instance to Soundflower (16ch).
    • Set the Output of the first instance to Soundflower (2ch).
    • Click Pass Thru.
  • Left-click the Soundflowerbed icon in the task bar at the top of your desktop.
    • Select None (OFF) under Soundflowerbed (2ch).
    • Select your preferred listening device (Built-in Output works for most cases) under Soundflower (16ch).

After following these instructions, you should be able to hear system audio, but not your microphone. Anything you assign Soundflower (2ch) as an input device to will hear both system audio and your microphone, making it the optimal recording device.

You might be wondering how you can send your guest audio with only your microphone on it. Since your microphone is still set as the default recording device, it should still work just fine for this purpose.

Final Thoughts

Recording a solid podcast has often been associated with the tedious and expensive task of setting up a mixer board and routing mix minus back to your system through some complex cable manipulation and audio wizardry. This isn’t always the case, and you should be able to accomplish quite a bit without having to purchase external audio equipment.

That said, the money you save on a mixer may be better spent by investing in a better microphone. Often, the microphone itself is the weakest link in any home audio production.

What about you? Do you have any tips or tricks to help make the most of Soundflower and its various features?