DIY Studio Condenser Mic

Getting Started

This Mic can be built in about 30 min - 1 Hour, as long as you have everything handy. Make sure that you have everything on the parts list available. It is also a good idea to plan out how you want to run the circuits on the board before you get started. This will help prevent confusion, and crossed circuits.

I try to keep the ciruits as simple as posslibe, and try to have them flow in the easiest to follow, most logical way possible. I'll add some markers to the photos as soon as possible, but for now note how every thing is lined up from right to left on the board. Compare the above photo to the Schematic below. Notice that they are arranged in almost the exact same fashion. By arranging all of the componants on the board before you start soldering alllows you to make sure everything is correct.

I like to use a piece of foam to lay everything out. I use a few small pieces of wire to hold the board. I start with the Ground circuit, since it is the most complicated. I prefer to leave the leads that go to the XLR and Mic capsule for last, so they they don't get in the way. NOTE THAT THE ZENER DIODE AND THE 330OHM RESISTOR ARE TRANSPOSED IN THE PHOTO. The ground lead will connect to the "-" side of the tantalum capacitor

Next is the "-" circuit. The 22KOhm resistor should be between the "-" lead, the 1uf capacitor, and the "+" side of the Tantalum capacitor. Next Place the 1uf Capacitor (the bigger one), and then the 2.2KOhm resistor. The 2.2KOhm resistor should be between the 1uf Cap, the Mic capsule, and the "+" side of the ground circuit, at the 0.1uf Cap.

Next is the "+" circuit. This is the same as the "-" circuit, with one difference. The 2.2KOhm resistor for this circuit goes to the "-" side of the Ground circuit, at the 0.1uf Cap. You'll notice in this photo the Zener Diode is in the correct place also.

Lets Start Soldering!

A pair of "Helping Hands" can be very useful (and only cost about $15-$20 at Radio Shack). I like to start from the XLR side, and begin the ground circuit, since it is the most complicated. The tantalum capicitor, and the Zener Diode are polar. That means that you CAN NOT put them in backwards. The Capcitor is marked with a "+". The diode is a little more confusing. Diodes have an anode, and a cathode, in place of a standard "+" and "-". The annode is the "+" and the cathode is "-". The cathode end of the Zener Diode is marked with a black band.

Make sure that the "-" side of the tantalum capacitor goes to your ground wire (pin 1). On the XLR connector, Pin 2 is designated as "Hot" or as "+". Since phantom power is used as a reference to produce a signal, both pins 2 and 3 are techincaly "Hot" leads.

Depending on the Mic Capsule that you get, it may have 2 or 3 pins/wires. The capsules I used are the 3 wire type. When using these you will notice there is a red, a white, and a ground wire. For these types, connect the white and the red wires together. The "+" side of the Mic will connect to "-" on the board (Pin 3). The "-" side of the capsule will connect to the "Hot" ciruit.

Testing

Now, before you get too carried away thinking of cool ideas for things to put the mic into, lets test it and make sure everyhthing was done correctly. For this you will need either a +48 inline phantom power supply, or a mixer that provides phantom power.

Make sure the volume and gain are turned down all the way, plug in the mic, and turn on the phantom power. Slowly increase the volume and gain until you hear a signal. If you turn it all the way up, and your still not getting anything, that means something is wrong. Turn everything back down, turn off the phantom power, and then unplug the mic. If your mic wasn't working, go back and make sure all the connections are soldered correctly , and that all the nessasary connections have been made.

If your mic is working, Congratulations, now you can start thinking about what you want to put it into.

Here are some samples so you can hear what they sound like:


Slow BLues Harp.