This project has been in my mind for a couple of months and I have finally reached a simple yet (cost-) effective solution. I would like to share my steps of making it and hope that someone out there would find this instructable useful.
Step 1: Mounting the Condenser Mics
6.3mm Right Angled Plug x 2 (I took them off from a fender patch cable)
Panasonic WM-61A Electret Condenser Microphone x 2
Silicon Earphone Bud x 2
Some Silicone Sealant
It is easy if you have the right parts of the right size.
- Put the silicon earphone bud to the end of the right angled plug. It should be a tight fit as the bud is slightly smaller than the end opening of the plug.
- Apply some silicone sealant to the inside of the plug to secure the bud.
- Solder the wires to the mic and to the connectors of the plug. Remember to run the wires through the bud and the plug housing before soldering (which I often forget to do...).
- Insert the mic to the bud and it should be another tight fit. Remember to push the wires with some tool in instead of forcing it in by pushing the mic, or you may break the soldered joints.
Step 2: The Electronics
Velleman "Super Stereo Ear" (MK136) Kit
2.2K ohm resistors x 2
This project is based on the Velleman "Super Stereo Ear" (MK136) Kit. I only changed the value of 2 resistors that connect to the + side of the mic and +V (R1 and R2 if you refer to the kit). The value of these 2 resistors should be chosen according to the impedance of the mic. For WM-61A, it should be 2.2K, but some other Electret Condenser Microphones may have a different value.
Building this kit is easy and is well illustrated in its manual. If you design your own circuit, then probably you do not need to follow any further instructions here.
Step 3: Housing and Assembly
Metal Box x 1
On-Off Switch x 1
LED (with housing) x 2
6.3mm Stereo Jack x 1
6.3mm Mono Jack x 2
Plenty of Wires
I have a metal box that I planned to use for making guitar effects. The size is just right for this project.
The concept of this project is to make the toe-in/ toe-out angle adjustable, and the idea was to use the right angled plug coupled with the jacks, so I can set the angle while keeping the mics connected to the circuit. This is reliable and cost effective, and I can also replace/ fix the mics easily in future if they are broken.
I first gather all the parts and put them inside the box to visualize the spacing, make sure that they will not clash with each other before drilling the holes (which is a mistake I often made in the past when building guitar effects). I only have a hand drill at home so drilling the holes is a tiring and time consuming process for me.
Another tiring and time consuming process is to connect the off board components to the PCB. I used shielded wires for the main signal paths so most of the time was spent cutting and preparing the wires.
After soldering all the parts, test and check that everything is in working order. When you are satisfied, you can then mount the off board components to the box and finish it up.
Step 4: The Result
P.S. I still have no idea how I should test and match the Electret Condenser Microphones. Please let me know if you have any ideas. Thanks.