Audio Mixer

In part 3 of this series I discussed hardware required to pull audio from our host and his potential guests.  In this part, let us discuss how we’re going to mix those two microphones with various other sources like Skype, my computer (for videos and such) and an MP3 player for some fancy background sounds.

After yet another dose of online research I discovered that an audio mixer was required in order to inject audio from multiple sources into my VidBlaster video mixer software.  This meant a trip to my local audio shop for some physical research.  Based on my previous research I knew I had to ask for a mixer that supported 2 mic inputs (mono) and 3 Line inputs (stereo).  My local shop pointed me to the mixer display room and pointed me at the 5 channel mixers.  I asked a few simple questions and quickly discovered he knew less than nothing on mixers and I was on my own.  After a while of looking around I came across the Xenyx 1002B 5-Channel compact mixer for only $108.  Hashing it out in my head I realized this will perfectly fit my needs. 

Once I got it home I set about calculating the wiring I would need to get everything hooked up.  Visio helped me draw the mixer out and calculate my wiring needs.  According to the diagram and looking at my hardware I determined I would need the following wires which were reasonably priced at my local RadioShack:

(2) 1/8” Stereo Jack to 1/4” Mono Plug Adapter
(1) 6-ft 1/8” Stereo to Stereo Cable
(3) Mono Phono Jack to 1/4” Mono Plug Adapter 2pk
(4) 6-ft 1/8” Stereo to Dual Phono Y-Cable
(2) 1/4” Mono 3-ft Shielded Cable

I wanted to be able to listen to the audio as well.  I already had a simple Logitech headset but had to add a 1/8” Stereo Jack to 1/4” Stereo Plug Adapter.  However if you are buying these parts yourself, I’d suggest something like the Cyber Acoustics Stereo Headphones, it comes with a 1/8” to 1/4” adapter.  This is only for the audio engineer to listen to the output without causing any microphone interference.

It is hard to determine an upgrade path to this device.  The cost of audio mixers allowed me to choose one that would perfectly suit my needs and provide plenty of room to grow.  For example, if I were to have a 3rd in-studio guest, I would only need to purchase a 3rd microphone and cable.  If a 4th were to arrive, a 4th mic/cable and I could push the computer signal over to where the MP3 player is.

The current setup can feasibly handle up to 5 guests, one of them being a Skype guest.  If we would like to have more than 5 guests we would need to upgrade this mixer.  Researching a bit more I would recommend using the Behringer Xenyx X2222USB for $326.  It has room for 8 microphones and includes mixer effects to make the broadcast more fun.  Beyond that I’d probably recommend the 10-mic Xenyx X2442USB or how about the 24-mic EuroDesk SX3282 mixer for some real power at $978.  Of course I’m starting to get a bit silly now… something like that would be overkill for my little 300sqft home office.  Don’t believe I can even fit 24 people into it.

But seriously though.. back to the Xenyx 1002B configuration.  I had various inputs to be dealt with…

1. Microphone 1 for David, our host, connected to Channel 1 Line In on the mixer using the 1/4” Mono 3-ft Shielded Cable.
2. Microphone 2 for me, connected to Channel 2 Line In on the mixer also using the 1/4” Mono 3-ft Shielded Cable.
3. Skype caller.  Skype allows us to specify which audio playing device the Skype audio is sent.  My sound card contains a nice enough sound card that I could feed the front green speaker plug a separate audio signal from the back green speaker plug.  I configured Skype to send its signal to the front plug which is connected to Channel 5/6 on the mixer using the

Mono Phono Jack to 1/4” Mono Plug Adapter 2pk and 6-ft 1/8” Stereo to Dual Phono Y-Cable.  Skype audio is in stereo unlike the microphones.

4. Computer Speakers so we could hear audio from videos I might play from YouTube for example.  The default audio device for my computer is the rear green speaker plug.  Therefore it is connected to Channel 7/8 on the mixer using the Mono Phono Jack to 1/4” Mono Plug Adapter 2pk and 6-ft 1/8” Stereo to Dual Phono Y-Cable.  This is also a stereo signal.
5. My MP3 Player (iPhone) is connected to the RCA output connecters  on Channel 9/10 on the mixer using the 6-ft 1/8” Stereo to Dual Phono Y-Cable.

Next I had to deal with my various outputs…

1. My headphones allow me to hear what everything mixed together sounds like.  Therefore they are connected in the top right plug on the mixer using the 1/8” Stereo Jack to 1/4” Stereo Plug Adapter.
2. Main Mixer Output needs to be fed back into the computer so it can be mixed with the video within VidBlaster.  Thus the main output gets plugged into the rear Line In blue plug on the back of my computer.
3. Main speakers allow David anybody in studio to hear signals from specific sources I configure on the mixer.  In this case, I’d like David to hear anything from the computer, our Skype guest but that’s it.  I don’t want him to hear himself or any of the in-studio microphones since that would cause horrible interference.  Thus the main speakers are connected into the Mon Send plug on the mixer using a 6-ft 1/8” Stereo to Dual Phono Y-Cable and Mono Phono Jack to 1/4” Mono Plug Adapter 2pk.  See the “Red” control knobs for which sources are sent to the main speakers.
4. Skype Caller return signal will need to be plugged into the Rear pink microphone plug.  This is the audio that our Skype caller will hear on their side and is connected to the mixer with the 1/8” Stereo Jack to 1/4” Mono Plug Adapter and the 6-ft 1/8” Stereo to Stereo Cable.  Just like the main speakers you will use the “Orange” control knobs to determine which sources our Skype caller will hear.  In our case I want them to hear all the microphones, the computer and the MP3 player.   I don’t want them to hear themselves.  Since the orange knobs are linked to the volume sliders, they will only hear the sources where the sliders are tuned up.

When I’m not broadcasting, I keep all the source slider knobs tuned down including the Main slider.  Since the computer is turned up on the Red control knob it feeds into my main speakers which are my default for the computer.  I can turn the MAIN Main speaker Red control knob if I need to adjust the volume for anything I’m doing.

Now when I’m broadcasting is when the fun starts.  For this I put on the headphones and adjust the white control knob to adjust those.  I slide up the MAIN slider which affects both my headphones and the main output for the mixer.  Then I can control which sources are listened to by moving up/down their source slider.  Prior to the show I adjust the control knobs as desired for everyone (white knob for me, orange knobs for our Skype caller, and red knobs for David).

Cost Sheet

In part 5 of my How to Produce a Webcast series, I will discuss the video mixer software called VidBlaster.  Show you some interesting features about that software.

Special thanks to JVonD for his video on YouTube for assistance setting up this mixer.