Microphone components for DIY experimenters

CM1 Capsule

-cardioid unidirectional pattern true condenser designed for 20-60V polarization

- insulated case with two terminals allows either direct coupled polarized diaphragm or capacitor coupled
grounded diaphragm connection

- 6 micron pure gold evaporated  diaphragm

-precision lapped backplate

-silk phase shift element acoustic resistance

-individually tested in standard pencil body with response chart supplied

-EASILY DISASSEMBLED. Can be modded to provide different responses and polar patterns
Adjust backplate, rear chamber volume, phase shift acoustic resistance easily if you wish.

-US made
specifications @ 60V polarization
sensitivity: 5mV/Pa open circuit
frequency response: 30Hz-20kHz
polar pattern: Cardioid
self noise: 25 dBA
maximum SPL: 145 dB  (94dB=1 Pascal)

Single capsule $59.95        Matched pair $129.95

figure 8 pattern

Capsule as above tuned for FIGURE 8 polar pattern
-true condenser
-can be used for small diaphragm figure eight microphones and MS arrays
-can be easily disassembled/retuned  if desired
-individual response chart supplied
specifications @ 60V polarization
sensitivity:3mV/Pa open circuit
frequency response: 30Hz-16kHz
polar pattern: Cardioid
self noise: 25 dBA
maximum SPL: 145 dB  (94dB=1 Pascal)

Single capsule $59.95        Matrched pair $129.95

PVK-1 Polarization voltage dc converter kit

As a convenience I offer a small PCB and components for a  15-60V dc converter for polarization voltage for the above capsules
and others. Input voltage is 8-12VDC at 500 microamps. Easily runs on typical pahntom power mic rails. Single resistor output
voltage adjustment for attenuation, etc.

You can easily build your own from perfboard if you wish. It's just  a standard Hartley circuit used in many many mics.

I tried to make this as small as possible with through hole components so it will fit in many mic bodies.  Size is 0.5"X1.062" (12X26.5mm)

FR-4 glass epoxy PTH board and all components are included. along with complete assembly and useage instructions.

Gold diaphragm material

For the few that are scratchbuilding capsules we offer our stock 6 micron gold coated PET
on a 75 mm adjustable precision machined tension ring. The gold is applied with the PET film
under tension so higher tensions don't rupture the conductive film.

The rings can be tuned much like a drum head by turning an inner ring assembly. In our case we then glue ten or more
small rings with special silver conductive epoxy, unclamp the ring, then cut them out.

diaphragm ringsl

Head Amplifier kits

Tranformer coupled:
This kit is basically the head amplifier of our CM-1 SDC instrument microphone. It uses the Linear Systems LS846 Fet for the input stage with a Bipolar emitter follower coupled to a custom
80% nickel core step down transformer. A zener regulator supplies operating current via phantom power. A Hartley type dc converter supplies 20 and 60V polarization for capsules.
The circuit includes a pad that provides attenuation by reducing polarization voltage rather than shunt capacitance for superior distortion rejection. A switched low cut filter is also provided.
A high shelf filter is included for HF peak equalization that can be programmed with alternate component values or simply not used.
The input is direct coupled for use with a non-grounded capsule case. It can also be used for grounded capsule with addition of an extra 1000pF coupling cap and bias resistor supplied.
In that case polarization voltage attenuation can't be done, but the board can be wired for other means such as a capacitor pad.
 It is specifically designed for small capsules such as the CM-1.
Fet input transistor and bias resistors are hand selected.

Two form factors are available....0.5X4 inches as used in our pencil cardioid and 1 X  2 inches as used in our figure eight microphone.

0.5" X 4"
pencil mic board

1" X2"

Complete kit (specify form factor)   $49.95

This kit is a high quality version  of the often used FET phase splitter/PNP bipolar follower configuration. It can be used with large or small diameter capsules using either grounded or non grounded
diaphragm. Terminals are supplied for pad and  low cut external switches. A hartley type DC converter supplies resistor programmable polarization voltage to 60 volts. (can be disconnected for electret capsules)
Fet input transistor and bias resistors are hand selected.