JOSEPHSON ENGINEERING • C725 USERS GUIDE
Josephson C725 microphones are a new direction for Josephson Engineering, representing a
hybrid of our solid-state technology with the dynamic characteristics of a vacuum tube. More than
five years of development have gone into perfecting the circuit. The capsule is the current revision
of our dual-diaphragm multi-chamber design made since 1989 and used in the C700 and C716
microphones, but is provided with directional pattern control that can be adjusted using a switch
on the power supply. Five selectable patterns from omni through cardioid to figure-8 are provided.
On the front of the power supply is also a selector labeled with the symbols for sun and moon. The
“sun” or
position indicates full level operation with many of the sonic attributes of classic
vacuum tube microphones. In the “moon” or
position the microphone output is reduced, and the
overload characteristic changes to provide a more linear characteristic.
Microphones are typically used like musical instruments, as tools to create an acoustic experience.
While the internal electronic parameters are designed, numerically analyzed and precisely
controlled to give repeatable results, we encourage users of our microphones to use their ears
rather than numbers to determine settings for using our equipment. Switching to the “moon” setting
results in about a 10 dB drop in sensitivity, and 10 dB increase in the overload point of the circuit.
But, the circuit is not an attenuator, the whole sonic character changes even at low levels. It's more
useful to think of this change in sonic character, and we hope that the sun/moon (big and warm
versus smaller and cool) will help you remember the sonic experience you had when selecting one
or the other. To compare the two settings and explore their sonic character, be sure to increase the
gain of your recording channel so the levels match for the comparison.
The power supply will operate from 100 to 250 volt AC power by changing the setting on the
power input module. To change from 100-120 to 220-240 volt, open the door next to the power
input connector and pull out the selector board. It is marked 120 on one edge, 240 on the other.
Insert whichever edge corresponds to the local line voltage. Carefully slide the white plastic
indicator around in the slots in the board so that when the power input module door is gently
closed, the indicator pin will extend through the hole in the door corresponding to the voltage
selected. Do not force the indicator or door. A normal grounded IEC power cord is used. A green
LED indicator light on the front panel will illuminate when power is switched on. A 2 amp fuse is
provided and is used for both voltage settings.
Allow at least two minutes for the microphone to warm up, and ten minutes before using it for
critical recording. There are several internal power supply rails that must stabilize to achieve
proper operating conditions. A few seconds are also required when switching from one pattern to
another. The sun/moon switch may be operated at any time but creates a significant "click" in the
output, so be sure the gain of your recording channel is reduced if you switch modes in use.
Output impedance is nominally 150 ohms and can be used with any transformer or
transformerless input stage. Sensitivity is quite high, the signal level may exceed several volts on
peaks, so it may be appropriate to use a line level input or an attenuator if loud sound is expected.
The output is balanced and floating and does not require phantom power. While the circuit will not
be damaged if phantom power is applied, it is recommended to keep it off.
C725 Users Guide
Summary of Contents for C725
Page 1: ...C725 Users Guide ...
