The Christian Music Web
How to build a condenser microphone... a DIY project.
Mic Components
This page details a pair of Condenser Mics I built and tested.
The original circuit plans were from a project published in Tape-Op magazine.
They are online at ProSoundWeb.com

Changes I made were to use an Omnidirectional Panasonic WM-61A Mic cartridge which has a freq range of 20-20kHz, Sensitivity of -35dB and a Signal to noise ratio >62dB. My first mic was built in a metal project box and has a 1/4" jack which an instrument cable is used for the mic cable. The second mic uses a male XLR plug as the original plan called for, but all components and the 9v battery is located near the mic (epoxied on the back of a 9v. battery holder). The male XLR plugs into an unbalanced XLR to 1/4" Mic cable.

Schematic


PARTS LIST
Condensor Mic Components from Digi-key www.digikey.com PH 1-800-344-4539

(1) P9925-ND PANASONIC WM-61A MIC CARTRIDGE $3.20
(2) 2.21KXBK-ND 2.21K OHM 1/4W 1% METAL FILM RES 10/ $1.08
(3) EF1106-ND 10.0UF/100VDC METAL POLY CAP $4.58
(4) 1325PH-ND CAP 1000PF 100V CERAMIC DSC N750 10/ $1.40
(5) BS6I-HD-ND SNAPS 9V 6" LEADS I-STYLE HD 10/ $3.06
(6) FP018K-R75-ND HEATSHRK 3M FP301 1/8X0.75"50PC BL $1.50
(7) BH9V-W-ND BATTERY HOLDER 9V. WITH LEADS $0.88
(8) L114-ND ALUMINUM BOX, 4X2X1.6" SNAP TOGETHER $4.84

NEUTRIKS MALE XLR PLUG FROM PROAUDIODESIGN.COM PH. 781-982-2600
(9) P6386 NEURTIKS #CA-NC3MX MALE XLR PLUG $2.25

RADIO SHACK WWW.RADIOSHACK.COM PH 1-800-THE-SHACK
(10) 274-252 1/4" PANEL MOUNT PHONE JACK MONO 2/ $1.99
(11) 64-2802 PENCIL SOLDERING IRON SET 30-WATT $7.99
(12) 64-017 .032" ROSIN CORE SOLDER 60/40 .5 OZ. $1.49
MISC. ITEMS
5 MINUTE EPOXY, FORCEPS, FINGER NAIL CLIPPERS OR SCISSORS FOR TRIMMING WIRE AND COMPONENT LENGTHS ...

Components soldered in box. Mic element glued in rubber bushing at one end... 1/4
Components soldered in box. Mic element glued in rubber bushing at one end... 1/4" jack on the other.

Soldering wires to the tiny element required that only 1/8" insulation was stripped from wires. Then they were tinned with solder... the solder iron tip was kept clean using a piece of 220 grit sandpaper. A fine pencil tipped iron, .032" solder and patience is needed for this part.

Wires in XLR connector boot prior to soldering.
A hole was burned in the side of the XLR connectors boot with the soldering iron and wires passed through prior to soldering. The hole at the end of the boot was also enlarged to the width of the mic element which will be epoxied in place after its wires are soldered carefully in place. Two wires from the XLR plug are also brought through this hole.

The mic element is soldered carefully and then the wires drawn through the boot and the element epoxied in place. Care is made to twist the boot from the threaded portion as the XLR plug is assembled (So that wires don't get twisted).
The mic element is soldered carefully and then the wires drawn through the boot and the element epoxied in place- (a pencil tip of mixed epoxy placed in end of boot and then the mic element positioned). Care is made to twist the boot from the threaded portion as the XLR plug is assembled (So that wires don't get twisted).

Here are both mics. The one in the project box with a jack for an instrument cable. The other mic requiring an XLR female end of a mic cable.
Here are both mics. The one in the project box with a jack for an instrument cable. The other mic requiring an XLR female end of a mic cable. The XLR mic has its components epoxied to its side and the XLR plug is epoxied onto a 9v battery box. Electrical tape was used to cover holes in the battery box to prevent epoxy from running and also to wall off or mold the epoxy untill it was dry. Not very pretty, but simple and functional.

My third and fourth mics were constructed in AA flashlight housings. One uses a neutrix XLR connector and the other a 1/4" instrument cable. Holes were drilled in the flashlight lenses and elements epoxied in place. I used rubber mounts purchased with the mic elements on these two.

Mic construction in flashlight housing Mic on left uses XLR connector. Mic on right uses 1/4

Testing the Mics !

Mic testing. The two condensers and a Shure SM58 to compare it to.
Mic testing. The two condensers and a Shure SM58 to compare it to. The mics are plugged into a Fostex Vf-16 digital recorder. The signals are recorded flat, without equalization.

Hear Microphone Tests - MP3

Panasonic WM-61 Specs (PDF format)        Digikey Catalog- Condenser Mic elements (PDF format)

Guitar Wiring/Mods - Photos !      Vintage Guitar Effects Schematic Archive

Powering Microphones- a collection of information

Questions,(or if I can help you) email me.
Jim Corliss
e-mail me !

 

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