Monday, November 06, 2006

Lecture Podcasting Kit

Here's something I put together a month or so ago that seems to work well for recording lectures:

At the top left is the Samson AL1 AirLine Micro wireless transmitter. It has a built-in mic, you can easily clip the whole unit to someon's shirt or lapel (while they are running away from you!). It also has a separate lav mic, which optionally plugs into the transmitter, this can then be clipped to your belt. There is a third way to use the transmitter, with a lanyard that clips on to it and goes around your neck. Then you don't need the lav.

At the bottom left is the small AM1 Wireless Receiver. It has a line out, but is low in volume, so I use the headphone out. The advantage is that you can control its gain with a small screwdriver. Next comes a small adapter, from 1/8" (3.5 mm) to 2.5 mm, the usual line-out is 2.5 and a male-to-male 2.5 to 2.5 mm cable is supplied. I'd like to clean up the system a bit by getting a 3.5 to 3.5 cable. This goes into the Belkin TuneTalk ($70), set to line input, which connects to the bottom of the iPod, and can record over 3 hours at "low" quality, 22.5 KHz 16 bit mono, which is fine for speech.

Street price for the AirLine transmitter/lav/receiver is $270, a good bargain indeed. Here's how it sounds

The nice thing about the Belkin is that it comes with a USB cable which plugs into its bottom. This can be used to power the iPod from its AC adapter, you could then record all day long if you wanted.

For important lectures, I have my "backup kit", which I slap on to the podium just before the talk. I used to use the Sony MiniDisc MZ-B10, but once it locked up on me at an important lecture, and I don't trust it any more. So, I went back to using my old iPod Photo, with the Griffin iMic. One of my associates here has never had problems with MiniDisc, and uses them often, but one critical failure is too much for me when there are alternatives.

One of our faculty used the wireless mic kit connected to his laptop, and recorded voice and the laptop's PowerPoint screen with Camtasia. However, he did not match the output of the receiver very well to the laptop input, and got some distortion.
It's important to set these levels beforehand, with a bit of experimenting. I made a podcast out of this at
The "Glow..." has the distortion, the later "Fluorescence" came out much better, after we tweaked the levels.

All in all, I like my little rig, and plan on using it more in the future. The only improvement I'd want is a way to monitor the audio while I am recording, and a VU meter on the iPod would be REAL nice!


Frank Fulchiero said...

I notice Sony recently came out with a $100 wireless lav-mic/transmitter and receiver. This sounds very appealing from a cost standpoint. If I could only have one I would still buy the AirLine, the built-in mic in the small transmitter is nice. Most presenters seem to prefer to clip the mic/transmitter to their lapel than to deal with a lav, the cord, and the transmitter clipped to their belt, when I give them the choice.

The clipped-on transmitter may look a bit clunky on the VIP's wearing white, is the only thing.
Maybe Samson can come out with a few different colored "skins": white, tan, etc!

I think we'll buy the Sony when we get a chance to evaluate it, though, the price is right.

Frank Fulchiero said...

I was very disappointed in the Sony. It looks like a toy made by Fisher-Price, and made me pine for the days when Sony stood for quality. Very cheap. I guess you get what you pay for. Would not recommend it to anyone unless they were TOTALLY desperate and only had $100 to spend.