I certainly have been posting more than usual, haven't I?
Sometime last year, my school ditched their old circa-1978 Tandberg Educational Language Lab and replaced it with a newer Sanako lab. The new lab uses PCs instead of cassette tapes and, perhaps most important to this post, new headsets. While they were in the process of getting rid of the old lab, a couple of people and I asked if we could take some of the old headsets. Unfortunately, these old headsets used a 6P6C connector instead of 3.5" stereo connectors, so we couldn't just plug them into a computer and hope to use them in a Skype call, though they were perfect if you wanted to plug them into a phone socket and listen to a call without being heard. And for purely comical purposes, I hooked mine up to the internal modem of my 386 laptop and slapped a piece of paper on the front with an "iPod Mega" scribbled on, then carried it to a couple of classes.
A couple of days ago, I was cleaning and found the headset gathering dust under my desk. After contacting two of the others that had picked up the headsets, nobody had yet been able to interface a pair with standard stereo equipment. Today, I headed out to Radio Shack and picked up solderable TRS and TS connectors. They're sold in packs of two, so technically I only needed one pack of TRS connectors and could have saved $3, but decided to get a pair of mono TS plugs for the sake of distinguishing between the headphone and mic connectors.
When I got home, I slashed the RJ25 connector off the cord to expose the wires. Unfortunately for me, they weren't color-coded to the RJ25 standard, so I had to do some guess-and-check with the connections. To save anybody else that reads this the trouble, the pinout is as follows:
.---. +----------------------------+
_| |_ | pin | color | signal |
| | |----------------------------|
.---~ ~---. | 1 | Blue | Mic out |
| | | 2 | White | Right in |
| | | 3 | Red | Left in |
| | | 4 | Green | Left gnd |
| | | 5 | Black | Right gnd |
+__|_|_|_|_|_|__+ | 6 | Yellow | Mic gnd |
1 2 3 4 5 6 +----------------------------+
After gathering this data, I was ready to start soldering. The wires use four strands of copper with what appeared to be Teflon insulation, which smoked a bit once I applied the iron to it. I soldered the mic to one of the TS connectors first, then proceeded to finish with the TRS connector for the headphones. I then plugged both into my computer, and could record my voice without hearing it on the headphones while recording. Later, to test the headphones, I created a split stereo track in Audacity, then modulated a 440Hz tone to the left speaker and an 880Hz tone to the right. I could hear both of them individually without any crosstalk, so everything was working alright.
As you can see, this headset is a beast. I used duct tape as a stress relief on the connectors, to make sure I can grab it by the cord when taking it out without having the connections break out. Acoustically, the headset performs quite well with vocals, but struggles with music of any sort (given, it's better than the fifty-cent earbuds that come with iPods and the like, though they're still nothing I'd want to use to listen to music). Unlike most consumer headsets, the microphone hangs level with the chin rather than the mouth, so my mouth isn't obstructed. So far, I've had two Skype conversations, both of which have essentially stated that this microphone blows my laptop's built-in mic out of the water. I'll probably be using this for podcasting and Skype conversations more than anything, though I may find some other interesting use for it in the meantime.