A DIY Boom Mic with a Shock Mount

N1GY- The Simple Approach to Ham Radio

A DIY Boom Mic with a Shock Mount

This is a project that worked out quite well.

Here is the finished boom mic in its shock mount at my operating position. You can see that the elastic cords are twisted on all four sides of the mic body both front and rear. This adds more tension to the bands and holds the mic more firmly.

This project started out because I was looking around for something new to build. I have admired those fancy boom mics that have an elastic shock mount around them, but of course the prices of the commercially available ones would have destroyed my budget.

I do, however, know how to assemble a simple microphone using PVC pipe and fittings for the shell and an inexpensive electret element for the working part of the mic. So I did just that. I used a 6" piece of 3/4" PVC pipe and a PVC cap to create a shell. Drilling an appropriately sized hole in the cap gave me a place to put the electret or condenser mic element. The element I used had a rubbery grommet like fitting around it so the hole was sized to make a snug fit for the device.

I added the necessary 2.2 K resistor and 47 uF polar capacitor as shown in the circuit diagram below and spliced in an inline 3.5 mm jack into the CAT-5 cable so that I could bring the PTT line out to a floor mounted PTT switch operated by my right foot under the operating position desk. I used one end of a foam spool from my wife's sewing box to close up the back end of the mic shell, drilling the center of the spool out to accomodate the strain relief and the CAT-5 jumper. Once everything was wired up and working a few dabs of "hot glue" holds everything together.

Testing was an enjoyable experience since all of the signal reports I got from other hams were excellent. Sometimes I get really lucky. I picked that element at random from the "junque" drawer and it worked great. If you build this project you may have to do some trial and error experimentation to find the right one.

A foam "wind screen obtained from a local music store and a little gold paint to disguise the PVC pipe and the mic was almost complete. The next item was the shock absorbing mounting system. A lengthy perusal of the info on the Internet was very helpful. I found several YouTube videos on how to build the shock mount. I culled a design using elements from several and came up with the one you see in the pictures on this page.

The start for the shock mount was a 2 inch PVC connector from Home Depot at a total cost of $0.97. Some careful planning and then drilling, cutting and sanding resulted in the shock mount with four "fingers" to the front and another four to the back. I carefully drilled a small hole at the end of each "finger" and screwed in a small screw-eye. These are available at craft stores and are not expensive. I already had a sufficient supply on hand left over from an old project.

The next step was to paint the mount, again to cover the white PVC. This time I chose an acrylic paint my wife had on hand called "Anthracite". It is really just a dark gray but you know how the art companies love to give colors fancy names. Once the paint was thoroughly dry I added four elastic hair bands purchased (in a package of 12 for $1). two to the front fingers and two to the back fingers so that they cross in the center of the mount.

The microphone was inserted into the square at the center where the elastic bands cross. I found that I did have to twist each end of each band 180 degrees between the mic body and the "finger" that the band was attached to to make the tension enough to keep the mic centered in the mount.

The next phase was to figure out a way to suspend the mic and its shock mount over the operating position so it could be used. A quick trip to a local office supply store and I was homeward bound with an "Architect" style lamp that had an articulated arm and a base that could be clamped or screwed to a surface. I removed the lamp assembly and removed the electrical cord from the articulated arm. I had thought about feeding the mic cable through the channel where the electrical wire used to be but eventually I decided to simply wire-tie the cable under the lower arms of the device, leaving sufficient slack around the hinge points to allow the arm (or boom) to move freely.

I screwed the base down to a bookshelf over my operating position desk. Becuse of the limitations in the range of motion with the articulated arm I had to mount the base at the right end of the bookcase to allow the mic to be properly positioned in front of the operator. These lamps were made to be moveable mostly above the base position and some allowances must be made when the base winds up higher than the other end of the articulated arms.

Testing and use since finishing the project shows it to have great audio and it is very easy to operate. If you have been wanting a boom mic for your station, why not build it instead of buying it. You will save some money and be able to say " I built it myself"

This circuit shows a foot operated PTT switch. The same circuit could of course be used for a hand held PTT switch or a PTT button mounted on the operating desk. The components shown are those necessary to match the electret element to my IC-706 MkII G. If you have a different rig you can substitute component values appropriate for your radio. Some Yaesu FM rigs may also require a 22K resistor on the PTT line.

This shows the electret element press fitted into the hole drilled in the PVC cap.

This project looks complicated but it really isn't. The shaping of the shock mount just requires patience and a little "elbow grease" but it is not hard to do with a step drill and a saber saw followed by a lot of sanding and de-burring.

Here is the "finished" shock mount prior to painting. The illustration clearly shows how the elastic hair bands cross making a "square" at the center of the mount. The mic is inserted through the squares fore and aft and then the elastics are twisted 180 degrees at each end of the elastic to increase the tension so the mic is firmly held.

This is the completed mic before the addition of the wind screen and paint. Perhaps not as pretty as some but with the windscreen and a little gold color paint it doesn't look too bad in my personal opinion. The cable used to connect it to the IC-706 is a standard seven foot CAT-5 jumper with one modular connector cut off so that the mic element and components could be wired in.