MightyOhm » Audio

New podcasting setup for The Amp Hour

Jeff — Tue, 25 Oct 2011 18:47:39 +0000

After being hassled by Chris about my audio quality on The Amp Hour for the past year, I finally broke down and upgraded my podcasting microphone setup. Here are some photos of the new setup and some notes about my approach.

Here are most of the big (expensive) parts. Clockwise from the upper left:

Audio Technica AT2020 Condenser Microphone ($60 on eBay, I got the XLR version, not the USB version that Chris uses)
ART Tube MP Microphone Preamplifier ($55 on eBay)
Samson SP01 Shockmount Spider Mount ($24 on Amazon)
Swing Arm Magnifying Lamp ($28 from Harbor Freight Tools)

A few more miscellaneous bits:

20 foot XLR M-F cable ($5 on eBay)
10 foot 1/4″ to 1/8″ cable ($0, made with spare parts)
Nady MPF-6 6″ Pop Filter ($15 on Amazon)

I got the idea to convert a swing-arm desk lamp (often called an Architect’s Lamp) into a mic boom from the awesome site IKEA Hackers. (Today I discovered that ham radio guys have been doing this for years.)

The closest IKEA is 40 minutes away, so instead I went to Harbor Freight Tools and bought the cheapest swing arm lamp I could find. I removed the lamp portion (after you remove the adjusting knob, the shoulder-bolt can be removed and the lamp pulls out). Then I cut the power cord and unthreaded it from the lamp.

The swivel mount on the Samson SP01 comes apart easily, exposing a handy flat mounting tab that could be used to bolt the spider mount to all sorts of things…

…including the desk lamp. I used a 1/4″ nylon spacer to fill the gap left by the narrow tab on the shock mount and some lock-washers to keep the mount from rotating when the adjustment is tightened. The original shoulder-bolt stripped (oops) so I replaced it with a beefier 10-32 bolt and corresponding nut.

While my initial tests with just the AT2020 mic were promising, I found that the swing-arm sagged under the extra weight of the shock mount. To solve this problem, I drilled two extra holes at 1″ intervals from the original spring perch on the swing-arm. This allows me to adjust the spring tension to balance the arm. Now the mic stays where I put it.

Here is the finished setup. I removed the heavy bracket and gooseneck from the pop filter and zip tied it to the front of the shock mount. The spacing between the pop filter and the mic comes out just about right.

Here’s the mic preamp. It’s got tubes! The microphone connects to the preamp through the XLR cable. The output of the preamp is connected to my PC’s line input through the junkbox 1/4″ to 1/8″ cable.

The best part about the swing arm setup is that when I’m not using the microphone, I can just swing it out of the way:

I’m really happy with the new setup, but you can judge it for yourself on this week’s episode of The Amp Hour (Xenomorphic Xerox Xebec).

Gary’s Wifi Radio Project

Jeff — Tue, 19 Jan 2010 16:01:41 +0000

Gary Dion (N4TXI) created a Wifi Radio to match his entertainment center. His project is inspired by my original Wifi Radio project and shares several of the same parts (such as the Asus WL-520gU wireless router) and design philosophy.

Interesting features of Gary’s version of the radio:

Very cool 4 line VFD display allows more information to be shown at once (and it’s blue!)
AVR sends actual shell commands to the router, which allows the serial console to remain enabled for debugging/other purposes – brilliant!
Nice custom PCB for the ATmega8 microcontroller
Rotary encoder and significantly more advanced control menus
IR remote control support!

More details, photos, and source code are available on Gary’s site.

Thanks to the Make: blog for bringing this project to my attention!

Inside the SYBA SD-CM-UAUD USB Stereo Audio Adapter

Jeff — Wed, 29 Oct 2008 15:21:36 +0000

I am using this tiny USB-audio adapter as part of my Wifi Radio project. It’s a ridiculously cheap $8 at Newegg.com and contains a C-Media CM119 chip targeted at VoIP applications. I have no idea why they chose to use a VoIP chip for this application because it contains a lot of bells and whistles that are not being used in this device, such as support for a matrix keypad!

Unfortunately, I have not been able to locate a datasheet for the CM119 so for now I will be using it only for it’s intended application – adding an audio output to a wireless router with USB. Come to think of it, that is probably not it’s intended application, but it’s close enough. Hooray for embedded Linux!