First off you might wonder what the heck is a Hamfest. Well it’s a get together of Ham radio operators and enthusiasts interested in Amateur Radio. During these festivals, Amateur Radio operators or “hams”, like to setup swap meets to buy and sell Ham radio related items as well as talk shop and provide ham radio courses and lectures. Recently, as in this year, I discovered the term Hamfest and found out that people bring some of their older vintage and antique microphones to swap and sell. This was my first ever Hamfest and I wasn’t disappointed. Most of the stuff there was way over my head and I had really no idea what I was looking at other than it was related to amateur radio equipment. This happened to be a perfect venue for not getting distracted when looking for mics. I only had one mission, to find microphones, and as such, I could really focus on what to look for without getting too distracted and finding something unrelated. Sure enough I spotted something in the clutter that stood out. A 1920’s or 1930’s double button carbon ring microphone. It looked absolutely gorgeous with springs intact, a stand and authentic cord. Yep this is exactly what pickers look to find when on the hunt. This particular microphone was the last in this man’s collection. Apparently he had a heart attack and decided it was now time to part with microphone collection he had acquired over many years of collecting. He said the microphone I was about to purchase had been with him for over 30 years and obviously from it’s condition was in fantastic shape.
Ring Microphones or Double Button Carbon Microphones or Spring Microphones are some of the most recognizable early 1920’s – 1930’s microphones. These microphone elements are suspended by springs to isolate them from noise and vibration. Even today you will find many broadcast microphones suspended by what is called a shock mount. I have one that supports my Heil PR-40 mic called the PRSM. These are now usually attached to some type of boom and in my case, the boom is a PL2T by Heil.
I couldn’t find out much about this particular microphone other than it was made by Universal Microphone Co. Ltd out of Inglewood California. It appears they did manufacture microphones for the war time effort in WWII, but after that, I couldn’t find any more reference to them.
Many of these ring microphones had covers on both the front and back, which I assume was supposed to protect the microphone from damage.
The drawback to these early carbon microphones is their limited frequency response, giving them the inherent hiss during recording. This “carbon hiss” is caused by the electrical resistance of the carbon when not compressed. The advantage were they yielded higher output levels with low impedance, which eliminated the need for added amplification. As better technology became available by the late 30’s, the ring microphones would be phased out for the newer better performing microphones.
Normally I can hook up my microphones to my Focusrite Scarlett 2i2, but it appears that with Spring microphones you need to do things a bit differently. From what I have read, they need a little power running through them using something like a 6 volt battery. When you look at the double button spring carbon mics there are usually 3 wires connected to them. Chris Sanchez over at Preservation Sound has a nice article that goes into a bit more detail on this. He also makes a Power Supply/Audio Interface for these mics, which supplies the power you would need to actually use them. The cost is around $200.
Another company making a power supply unit for carbon microphones makes one for the Bing Carbon Microphone.
Here is how they work. As you talk into the microphone, there is a thin metal disk that vibrates. As the vibration occurs, this compresses the carbon granules inside. Speaking loudly squishes them more than speaking softly. The carbon granules form part of the electrical circuit. Using a 6 volt battery will supply sufficient voltage across the carbon granules to allow an electrical current to pass through them. As the carbon granules are compressed due to sound, it reduces the electrical resistance, allowing more current to flow. This in turn means that depending on the volume of sound hitting the microphone, the electrical current flow will also change.
Before the Double Button, there were what is referred to as single button. These just had one circular plate verse 2 sandwiched together. These single button microphones were generally found in the 1920’s and then replaced by the double button by the late 20’s early 1930’s.
Here are just a few of the manufactures who made Ring Microphones during the 1920’s – 1930’s
- American Microphones
- Continental Microphone
- Knight Microphone
- Lifetime Microphones
- Shure Brothers
- The Webster Company
- Universal Microphones
- Western Electric
Here is recent video with Justin Timberlake singing What Goes Around Comes Around. He is using what looks like a Double Button Carbon Microphone.
I have found one company that doesn’t make carbon mics, but does have a cool new aged ring microphone.