This post is a continuation of my series on how I create a typical episode of one of my podcasts: The SportsFathers (TSF).
Other posts in the series:
There are many different setups that people use to record podcasts. The ultimate task is to get the sound from my microphone (and in my case, Skype) into a digital format which can be processed and released as the final product. Many podcasters record everything through a mixer and onto a digital recording device, while others (like myself) use a computer to capture the audio.
As a result, you might find a different method that works better for your situation. What I do is certainly not the only way to do things. I’m essentially using hardware and software which I already was using for recording musical instruments, and it seems to work nicely for podcasting.
This is what I attempt to accomplish with my setup:
- record my microphone audio in a high quality format
- record my guests, who usually join me via Skype
- have the capability of inserting sound effects on the fly in a way that can be both recorded and heard by myself and my guests
- use separate tracks as much as possible to allow for the greatest flexibility in editing the final product
and of course…
- MacBook Pro (15″, mid-2012 model)
I’ll begin by briefly showing how everything is connected, and then we’ll get to my rationale for connecting things this way.
The Hardware Connections
Hardware connection diagram (ack!)
Yeah, it looks complicated. But hopefully it’s not too horrible… Let’s look at this, step by step.
1. Connecting the Microphone
As noted in Part 1, I principally use a Shure SM7B dynamic microphone. I’ve found that this microphone excels at ignoring room echo and other random noises, and overall it produces a great sound. Many other podcasters are using microphones like the Heil PR40, or a microphone with a direct USB connection such as those produced by Blue Microphones. Sometimes my Skype guests simply use the ear buds that came with the iPhone, and the result isn’t all that bad. I don’t think this option would be suitable for myself as the podcast’s host, but as a guest option it works reasonably well.
The microphone is connected to a dedicated preamplifier (preamp), which amplifies the microphone signal before it goes into a mixer or other device. This step isn’t strictly necessary since most mixers already have decent preamps built-in. However, in my case I have a FiveFish Audio SC1mk2 preamp for recording musical instruments. I liked how this preamp sounded with my voice, so I figured I may as well use it for podcasting! :-) But if you don’t have a dedicated preamp, simply connect your microphone directly to your mixer; you should still get great results.
FiveFish Audio SC1mk2 preamp (homemade; I like electronics but I’m not that great of a painter!)
The preamp is connected to my mixer, which then goes to an audio interface (see #3 and #4 below) and gets recorded by my computer.
2. Recording a Skype Call
Until recently, many people would use a special piece of software to record a Skype call directly to an MP3 or WAV file. However, Microsoft recently announced that they are planning to change Skype so that these Skype recording programs will no longer work.
Other pieces of software exist that record everything that is playing on your computer’s speakers. One such piece of software is Audio Hijack Pro, and this would be an option if your budget isn’t too high.
Finally, a number of podcasters use a mixer to mix all of the audio sources together onto one track, and then they use a dedicated recording device such as a Zoom H2 to record everything at once.
To retain greater flexibility while recording, I use a hardware/software setup that records my voice+effects on one track and my Skype guests on a separate track. This allows me to edit the audio and adjust the levels/equalization more easily.
So how do I do this? It’s the Skype Preferences panel to the rescue!
The Skype Preferences panel (Mac version shown above) allows you to set the input device (“Microphone”) and output device (“Speakers”). I’ve set the input to my audio interface, which is a PreSonus Firepod. The output is set to my Mac’s headphone port.
Then I take my Mac’s headphone port and connect it to my mixer, which then sends the audio to the PreSonus Firepod so that I can record it on a separate track (see below).
3. The Magical Mixer
I have a very basic mixer (Behringer UB1002), and this is where most of the magic happens. It combines the different audio signals together and outputs them onto two separate, stereo channels.
Behringer UB1002 mixer
- On the “Main” channel I combine two separate sources:
- The microphone signal that comes via the preamp
- the headphone output from my iPad. My iPad is used to play sound effects while I’m recording.
The “Main” channel (stereo) is then sent to my audio interface, the PreSonus Firepod (see below).
- On the “Control Room” channel I take in the feed from my Macbook Pro’s headphone port. This is the audio from my guests on Skype. I use the mixer’s Control Room section to more easily control the sound levels coming from the laptop.
The Control Room channel is then sent to my audio interface, on a separate track from the Main channel.
Aside: I was having trouble with an annoying, low frequency hum coming from the Control Room connection. It resulted from something called a ground loop between my computer and the mixer. A “ground loop isolator” (seen in the diagram above) is designed to minimize this problem, and it works very well! It was about $25 from a local home electronics store.
4. Audio Interface
So now that my microphone, iPad audio, and Skype audio have been combined in the mixer, how do I get that sound back into the computer so I can record it? This is accomplished by using a device called an audio interface.
I use a PreSonus Firepod (FP10). It is an 8 input unit that uses a Firewire interface. (Other similar devices are available that use USB.) Since I originally bought this device for recording musical instruments, it’s probably overpowered for simple podcasting. However, it does allow for more flexibility, such as on the (rare) occasions when I’ve recorded multiple guests in person with multiple microphones.
PreSonus Firepod (FP10) computer audio interface
I’ve connected my mixer’s main outputs (left and right) to inputs 1 and 2 on the Firepod. Skype shares what it receives from input 1 with everyone in the conversation. So, this means that everyone in the Skype call can hear both my voice and my iPad’s sound, which have been combined by the mixer.
Aside: I usually record in mono to save disk space and processor horsepower. However, if I desire to record in stereo, this setup gives me the option of doing so. In stereo, Input 1 is the left side, and Input 2 is the right side.
The audio from my guests on Skype gets routed through my mixer’s control room channel and is sent to inputs 3 and 4 on the Firepod. As with my voice/effects track, I usually record my Skype guests in mono (input 3), but I can add input 4 for a stereo recording if I desire.
Pretty much, at least for the hardware side of things! I’ll discuss software in my next post.
Was this as clear as mud? Please feel absolutely free to ask any questions below!
Do you have any better ideas or other comments? Please share those as well! I love learning about this stuff!
Other posts in this series:
One of the things that I’ve found to be a lot of fun in recent years is the creation of podcasts. Podcasts are like a radio show, but distributed over the internet. Once your phone or computer subscribes to the show (using something like iTunes), then new episodes will be delivered to your device(s) automatically and you can listen to/watch the content at your own convenience.
The podcasting that I’ve done so far is in the audio realm. Some people create video podcasts, though that can be much more difficult to do well. For me, I’ve been focusing on creating the highest quality audio that I can — and I’m constantly learning about how to improve!
I’ve had a number of questions in the past few months about how I put these podcasts together. So, here begins a series of blog posts about how I create a typical episode of The SportsFathers (TSF). TSF is a show consisting of priests who talk about sports. We connect via Skype and it is all recorded using Logic Pro on my Macbook Pro.
This post is dedicated to microphones. Nowadays I use a Shure SM7B dynamic (moving-coil) microphone. It has a great sound (especially in my smallish office with hard walls) and, because I already had a preamp and audio interface for music recording, it didn’t break the bank.
And so without further ado, here is some of what I’ve learned about microphones:
Capturing the highest quality audio from the source is essential for producing a quality result. Trying to fix audio issues in post-production can be very difficult (if not impossible)!
The crucial piece of equipment for capturing the sound is the microphone. Essentially, the microphone turns the sound into an electrical signal, which can then be recorded and digitized.
There are many types of microphones available. They can be classified according to the mechanism through which they turn the sound into an electrical signal, and also by the direction(s) from which they can pick up the sound (called the “pattern” of the mic).
Dynamic (also called “moving coil”) microphones are essentially like a loudspeaker run backwards. A coil of wire is placed around a magnet. In a loudspeaker, an electrical signal is fed to this coil, causing it to vibrate – and sound is produced. In a dynamic (moving coil) microphone, the opposite happens: as the sound waves hit the coil, it vibrates. The vibration of the coil around the magnet produces an electrical signal, which can then be amplified or recorded.
Dynamic microphones are often fairly inexpensive and rugged. There are videos on YouTube of people generally abusing a Shure SM58 by dropping it from the top of a building or driving over it, and it still works! Dynamic microphones can also be very good at rejecting sound reflections from the walls of a room, and they can be very good at rejecting feedback in a live situation.
However, cheaper dynamic microphones might not capture the same range of sound frequencies that other mics can capture. Ideally, people are able to hear in the range of 20-20,000 Hz. Cheaper dynamic microphones often pick up only about half of that range.
Having said that, medium-level dynamic microphones can pick up a wide frequency range. I personally use a Shure SM7B, which I purchased on eBay for about $300. Since I’m typically recording in a smaller office, I find this microphone to excel at eliminating the echo that comes from the walls in the room. A Shure SM57/SM58 can also be a great choice, and they can be had for about the $100-$120 range. (The SM57/58 microphones are almost identical, except that the 58 has a ball-shaped windscreen built in.)
Dynamic microphones are often sensitive to picking up sound in a cardioid pattern (see below).
Condenser microphones operate using a principle called capacitance. Essentially, a thin film of plastic (mylar) is sputtered with a metal film (often gold or nickel), and this is placed very close to another metal plate. As the sound waves interact with the film, it vibrates. The electrical signal resulting from the change in capacitance is amplified and can be recorded or put through a loudspeaker.
Condenser microphones require a power source of some sort to power the electronics inside the microphone. This is usually provided either from a battery or from the mixer, which uses something called “phantom power” (a 48 volt signal which is provided on a couple of the wires in a standard microphone cable). More high-end microphones use an external power supply, but I’m guessing you wouldn’t be using those for podcasting… :-)
Because the mylar film is very thin, condenser microphones tend to be very sensitive to sound over a wide range of frequencies. This is desirable in some circumstances. However, I’ve also found that it can make cheap condensers less suitable where the room is small or has hard surfaces: they can really pick up echo from the walls of the room.
They can also be manufactured to pick up a variety of directional patterns – cardioid, figure-8, and omnidirectional are common (see below).
Cheaper microphones can introduce a noticeable amount of noise (hiss) into the signal, so be aware of this when you’re shopping. Fortunately you don’t need to spend a whole lot to have a microphone that has very little noise.
Condensers can be less sturdy than a comparably-priced dynamic (moving coil) microphone, but this shouldn’t be a problem in most settings.
Ribbon microphones are also sometimes called dynamic microphones because their principle of operation is similar to that of a moving coil mic. However, instead of a coil of wire, a thin strip (or “ribbon”) of metal is placed between the poles of a magnet. The sound waves cause the metal strip to vibrate. This vibration of the metal interacts with the magnetic field and produces an electrical signal which can be amplified and recorded.
Because the metal strip is often very thin, ribbon microphones can be more fragile than a moving coil or condenser microphone. However, the resulting signal can sound fantastic, smoothing out the higher frequencies from sources like electric guitars or horns.
A good ribbon microphone can be pretty expensive. I’ve never tried one for podcasting, nor have I heard of anyone using them for podcasting, though older ribbon microphones were apparently very common in radio in the mid-20th century. Their directional pattern is generally a figure-8 pattern (see below).
Other microphone mechanisms exist (e.g. piezoelectric), but they are used far less commonly for podcasting.
2. Directional Patterns
The directional pattern (sometimes called “polar pattern”) of a microphone describes the direction(s) in which the microphone is sensitive to sound. For more in-depth information, check out this Wikipedia page (which is where the graphics below are from).
Also note that some microphones let you switch between patterns, which can be useful in some situations (usually for live sound).
Cardioid microphones are sensitive to sound in front of and to the sides of the microphone capsule. When this pattern is plotted on a graph, it looks sort of like a valentine heart – hence the name, cardioid.
Cardioid pattern (Wikipedia)
Microphones with this pattern are excellent at picking up what is in front of them, while rejecting what is behind them. For this reason they are great for smaller rooms and for live sound (e.g. they are great at rejecting feedback at the pulpit in a church).
Condenser and dynamic (moving coil) microphones are often manufactured with this pattern.
Omnidirectional microphones pick up sound all around the microphone capsule.
Omnidirectional pattern (Wikipedia)
They are often sensitive to a very wide range of sound frequencies at relatively equal levels. This makes them valuable in situations where one wants to hear a wider distance and have a more natural sound than what is sometimes possible with a cardioid pattern microphone (e.g. for a choir or for some instruments).
This can make them more difficult to use in a podcasting setup, however, because the usual desire is to only pick up the voice of the person speaking into the microphone while rejecting everything else.
It is common for certain types of condenser microphones to be manufactured with an omnidirectional pattern.
Figure-8 microphones are so named because they can hear sound from the front and the back of the microphone, but not from the side.
Figure-8 pattern (Wikipedia)
This can be valuable in live situations where a monitor speaker is beside the microphone. Some sound technicians that I’ve read also like this pattern because it can sometimes create a signal that sounds more like what the human ear hears – especially when two microphones are used in a stereo setup called M/S.
I’ve often seen condenser microphones with this pattern. Ribbon microphones also naturally have this pattern, since the thin, metal ribbon will naturally vibrate to sound coming from both the front and the back of the ribbon but not from the sides.
More patterns exist (usually some variation of the cardioid pattern). Check out the Wikipedia page for more information about these.
3. Using your microphone
Once you have your microphone and everything is all connected (I’ll get into that process in the next post), it’s important to set it up in a way that works well and reduces noise in your environment.
The first thing is to use a microphone stand of some sort. Table-top stands exist, and some microphones (typically small condensers) are built into a headset. I use a cheap, boom stand, like what you see in typical church or hall setting. Because my Shure SM7B is so heavy, I’ve tied a 2lb counterweight to the other end of the boom.
Depending on the microphone you use, you may want to use a shock mount to attach the microphone to the stand. This is usually a contraption with elastic bands or bungee cords that helps remove any unwanted vibrations when you move the microphone. Part of why I use the Shure SM7B is because it doesn’t really need a shock mount. It’s pretty good at rejecting those vibrations on its own. Other mics, such as the Heil PR40 do benefit greatly from a good shock mount.
You may also wish to use a windscreen (pop filter) of some sort. This removes excessive “pop” sounds from when you speak a “P” or “B” sound into the microphone. The Shure SM7B and SM58 microphones come with very effective foam windscreens, but other microphones need some help in this area. This can be especially important for some condenser microphones; excessive pop or wind noise can actually damage some microphones!
It is possible to build a cheap pop filter using a small fabric loop and by stretching a piece of nylon (e.g. from nylon stockings) across the loop. Then, a stiff wire (e.g. a pipe cleaner) can be used to attach the fabric loop/nylon to the mic stand so that the stretched nylon sits just in front of where you will speak into the microphone.
You can also purchase relatively cheap pop filters from most music/audio supply stores.
So that’s a very brief primer on microphones. I’ve had the chance to build a few condenser microphones (called “electret” type condensers, because part of the capsule has a permanent charge), and that was a fun learning experience. The resulting mics sound pretty good, though I find the Shure SM7B to be much better for podcasting in my smaller office because of how well it rejects this room’s natural echo.
In the next post I’ll talk about how I take that SM7B and record it on my laptop, along with the audio from the Skype call.