More on Chemically Tailored Crystal Mic Elements

My mention in SolderSmoke # 132 of this technique to custom tailor the AF response of crystal mic elements has already generated a lot of interest. Here's the e-mail from Italy that alerted me to the work of Dr. Andrea Bugiardo:

http://soldersmoke.com/microphone.htm

Check it out!

HomeBREW (literally!) Your Own Microphone!

During those dark days in which I was using my Astatic D-104 mic for podcast purposes (not a popular move) I checked on the mic element inside my chrome lollipop and found it to be the original crystal "Rochelle salt" element. I remember wondering about the Rochelle salt: What the heck was that? Well, this morning, the hippie technologists over at the Make blog explained it all to me via the above embedded video. It turns out that you can MAKE piezoelectric Rochelle salt crystals in your kitchen using -- get this -- soda ash, coffee filters, and -- wait for it: CREAM OF TARTAR sauce! I'm not making this up.

Our New Microphone!

Just kidding... That's actually a mic from an old Heathkit Benton Harbor Lunchbox.

I continue to get good advice from listeners on the mic issue. I hope to put this to rest soon -- then we'll shift away from AF back to RF. Several listeners advised me to stick to SolderSmoke's "homebrew or roadkill" ethos, and to avoid the temptation to solve problems with credit cards. Good advice! People REALLY like the audio with the old decrepit computer mic and the Linux Ubuntu Laptop. So here is what I'm going to do: I'll go back to that combo, but I will attempt to fix up some of the mechanical problems (the old mic is falling apart and it has all kinds of weird things taped on to it) and the electrical problems (it seems to pick up more AC hum than then D-104). It won't be pretty, but it will be a nice homebrew/roadkill device.

A question for those who expressed support for this mic and for the audio in #129: Didn't you hear the AC hum?

Rouges Gallery: Three Possible SolderSmoke mics

One of my New Year's resolutions was to finally, seriously pay some attention to the audio quality of the SolderSmoke podcast. With its roots in the scratchy Echolink connections between Juneau and London, audio quality has long been neglected on our show. With some funds donated by kind listeners (thanks guys!) I was this weekend shopping the internet for a suitable SolderMic. I ran into a lot of audio-fool snake oil. Wait a second, I thought, let's do some checks on the many mics I have around me here in the shack. I made comparison tests using three different mics (pictured above): my venerable D-104 chrome lollipop (with a transistor amplifier in the base), the dilapidated computer mic with improvised pop shield that I've been using for the last several years, and a Turner +2 mic that I gutted a while back (the original element was replaced by a cheap Radio Shack electret element, and the on-board amplifier was disconnected). (NOTE: It is a MYTH -- an ugly myth -- that the D-104 is CB gear. We debunked this hideous lie a while back. The D-104 is definitely ham gear! The Turner +2? Well, I don't know about that one. It does look a bit good-buddyish.)

At first, I thought the re-done Turner would win out. Then I thought the computer mic would keep its job. But then -- surprisingly -- the D-104 started to sound REAL good. The D-104 was especially good at keeping AC hum out of the signal -- that was a problem with the other two.

I found that I could get a very nice-sounding audio by running the D-104 audio through some EQ to knock down the little bit of hum that it did pick up, and to put about 30 db of attenuation on my now infamous SSSS whistles. I also used Audacity's noise remover.

So, the next SolderSmoke may come to you via an Astatic D-104. Kind of appropriate, don't you think? What do you guys think? Maybe I should post an audio sample to get some expert opinion before I chrome lollipop #130...

The SolderSmoke Microphone

As promised, here is the infamous SolderSmoke microphone, featuring duct tape, and supported by a Radio Shack "Third Hand."

Check out the "popping on the letter P" audio filter I made out of a bathroom drain filter, a baby wipe, and duct tape. The previous effort using some foam from an old Walkman headphone is also visible.


Kind of appropriate, don't ya' think? I think this simple filter has helped with the audio problem.
(Let me know what you think.)