Podcasting Gear.

On a fairly regular basis I get asked about the equipment used for the various podcasts that Gavin and I produce (e.g., Confab and Podcasting Liberally). I, personally, have no notable background in audio engineering. When it came to shopping for our podcasting equipment, I had to piece together information from many different sources. Our goal was probably more ambitious than most, and included the requirement of supporting four or more participants from the very first recording. Luckily, only a few, minor mistakes were made on the path to achieving what we produce today.

In the most basic terms of podcasting, you need a way to record audio and convert it to a file format compatible with digital audio players. This typically means a microphone, computer (with audio recording software), and the MP3 file format. Distribution of the resulting podcast usually implies the Internet and Real Simply Syndication (RSS), but that's a whole other blog post. Let's stick with the production side for now, and start with microphones.

Following a series of recommendations and some testing, I decided on the Sennheiser HMD25-1 headphone and microphone combination. It includes a dynamic, super-cardioid microphone that, in the words of Sennheiser's marketing literature, "...has been specifically designed for use in noisy environments." They absolutely live up to the claim. Also, the benefits of a microphone and headphone combination should not be understated. For one thing, they tend to keep the microphone an equal distance from the participant at all points during the podcast recording, despite how much the participant moves their head. Although the MSRP for the Sennheiser HMD25-1 is $519.00 (USD), you can usually find them for ~$400.00 (USD). Be forewarned that the cable ends are going to be your additional responsibility - the HMD25-1s ship with bare wire ends to the headphone and microphone cables. Soldering male 1/4" jacks for the headphones, and male XLR connectors for the microphones prepared our HMD25-1s for actual use.

To improve the audio quality even further, our microphones connect to a series of tube pre-amps before feeding into the mixer. Although the mixer has built-in pre-amps for the microphone channels, their "gain" range is fairly limited. The tube pre-amps provide the necessary range, but also what audiophiles refer to as "warmth". Since each incoming microphone requires its own channel, we bought four of the 2-channel Behringer Ultragain Pro MIC2200s tube pre-amps. MSRP for the Behringer MIC2200s is $129.99 (USD), but you can readily find them for ~$99.00 (USD).

The eight, separate channels coming from the tube pre-amps feed individually into our mixer. In most traditional applications of a mixer, the input channels are all combined -- at various levels -- to produce a right and a left "main" channel (the output). Effects processors and EQ functions may also be added to modify the audio as it is being combined. The two resulting "mains" would normally be what get recorded for a podcast. In our case, we purchased a mixer that included a digital, Firewire (IEEE 1394) interface. The Firewire interface connects to our computer and delivers each of the input channels directly to our audio recording software. We not only use the mixer to combine the input channels, we also use audio software on a computer to perform the exact same task after the recording. Why? There are really two reasons. First, we need the ability to return the mixed channels to the participants' headphones in real time during the podcast recording. That's done through the mixer. Second, we want the ability to add effects and control levels on the individual channels in software, during or after the recording. The mixer and computer combination give us this remarkable flexibility.

In the very beginning, I purchased the Alesis Multimix 16 Firewire mixer. What I really wanted was the Mackie Onyx 1620 with Firewire option (~$1,300.00), but it (pictured) was more than twice as expensive as the Alesis (~$600.00). (You have to be somewhat conservative when you don't know how serious you'll be about a new hobby.) After almost eight months of regular podcasting, I felt that it was serious enough to warrant the Mackie Onyx 1620 purchase. The Onyx has several advantages over the Alesis, including visual level meters and low-cut filters for each of the eight microphone channels. It also produces better sounding audio.

For anyone considering a mixer for their podcast production, there are several Firewire and USB models from a handful of manufacturers. The number of channels delivered to your computer is the most significant difference between the Firewire and USB versions. In every model I've reviewed, the USB versions only deliver the left and right mixed channels to your computer - not each of the individual, pre-mixed channels. The lower cost of the USB versions is likely the result of this difference. Vendors need to make this difference more apparent in their marketing literature if they expect to have high rates of customer satisfaction within the podcasting community. There's absolutely nothing wrong with using a USB version, as long as you know about their limitation prior to spending the money.

The final piece of the system (excluding the computer and software) is the headphone distribution amp. The mixer has a right and left channel output, but definitely can't drive a series of headphones. To solve this challenge, I purchased the Behringer PowerPlay Pro-8 HA8000 (MSRP $179.99 / Street $140.00), which is an 8-channel headphone amp. The output from the mixer feeds into the amp, and the headphones connect to the individual distribution channels. Each channel of the distribution amp has the added benefit of it's own volume control. I eventually purchased two of the HA8000s. One is used to support the headphones of the podcast participants; one is used to support a set of headphones for listeners. This second headphone distribution amp is really important for Podcasting Liberally because it's held, weekly, at the Mountlake Alehouse. Anyone wishing to listen in on the live recording needs headphones to hear over the background noise.

All of our podcasts are recorded to disk using Apple's GarageBand software on my 17" Apple Powerbook. (I hope to be using a 17" Apple MacBook Pro in the very near future.) GarageBand's ability to perform compressor/limiter functions on a per-channel basis is the second most influential factor in making our podcasts sound good. We would have to spend another $2,000 to perform the same task in audio hardware. Gavin has been mixing and converting the shows on a Core Duo Mac Mini since the beginning of March, and I can't wait to have that sort of power in a portable form. All told, we've spent ~$6,300.00 (not including my laptop) on the podcasting gear. It has been worth every penny that we've spent to hang out with good friends for smart conversation on a weekly basis.

Go forth and podcast!