1. CM12
The Wunder Audio CM12 Tube Microphone is targeted to the
professional with the most demanding criteria. The CM12 uses the
larger Hiller T14/1 output transformer that was standard in the early
C12. The beautiful hand made capsule is a CK12 style. These
boutique microphones are hand assembled in Texas per customer’s
order. Tubes are hand tested NOS GE 5-star 6072.
It should be stressed that vacuum tubes, with their heater filaments,
are much more delicate than solid-state components. Consequently,
the user should take great care in handling the microphone. A drop
from even a moderate height may cause the filament to break and
may result in immediate failure of the microphone. It would be
advisable for the user to keep a spare tube – specially selected by
the Wunder Audio Service Department – always ready for
replacement.
It is important to note that the tube may have become slightly
unplugged from the tube socket during shipping. If the microphone
has no audio output, 99% of the time it is a result of a slightly
unplugged tube.
How to Replace the Vacuum Tube
Repairs are to be carried out only by experienced, authorized
service personnel. Unauthorized opening of, or modification to
the equipment shall void the warranty.
The microphone tube requires a high operational voltage.
Contact with the voltages present in the interior of the
microphone and PSU may result in injury or death; therefore,
the microphone and PSU must be opened only by an
authorized, qualified technician.
The microphone must be operated only with the supplied
cable. Because hazardous voltages are generated by the PSU
that may result in injury or death, always ensure that the
microphone cable is undamaged. Damaged cables must no
longer be used.
1. Disconnect microphone from PSU.
2. Turn the three grub screws at the lower end of the microphone
into the body in a clockwise direction until the outer housing can
be pulled off in a downwards direction.
3. The vacuum tube may now be removed by depressing the lower
(rubber) shockmount to free the tube with a forward motion.
Taking the tube socket in one hand and the tube itself in the
other hand will enable you to separate the vacuum tube from
the socket.
4. Insertion of a new tube should be done in reverse order
of the description above.
Operation
The CM12 is equipped with an 8-pin Swivel-Mount connector that
plugs into the base of the microphone and screws tight. Always
make sure that the PSU is switched off when plugging the
microphone connector into the microphone and PSU.
How to Change the Polar Pattern
Locate the white pattern switch on the PSU. Use this switch to
change the directional characteristics: omni-, cardioid-, figure-eight,
and eight intermediate positions. The center position with the
Wunder Audio logo is the cardioid setting.
As you turn from position to position it will take a few seconds for the
polarization voltage to settle and achieve the desired polar pattern.
How to Mount the Microphone
A special swivel mount/stand adapter is provided and should always
be used to mount the microphone on floor stands or booms. The
CM12 can now be placed with the microphone on stands or booms
with standard thread sizes. It may also be swiveled against the
stand axis to suit the recording angle.
Powering of the Microphone
The required PSU is included with the microphone. It is clearly
marked and should be quite obvious by connector type and size
how to connect the microphone to the power unit with the supplied
CM12 microphone cable. The audio signal may be taken from the
transformer-balanced power unit by a conventional audio cable with
standard XLR-type connector.
After connection of the microphone, the power supply, and the AC
line, the main switch may be switched on. Operating condition will
be indicated by the power lamp.
The warm-up time of the CM12 is approximately one minute. When
your CM12 is new, a 24-hour burn-in period is recommended.
The CM12’s tube will “break in” over a period of time enabling the
CM12 to sound subtly better over a period of time.
2. The CM12 Power Supply
This PSU supplies the microphone with the 6.3V filament voltage
and 120V plate voltage for the vacuum tube.
Prior to connecting the CM12 to AC power, check the AC voltage of
the power line you are going to connect to the CM12.
The CM12 PSU has an internal AC voltage selector switch.
To check the CM12 PSU AC voltage selector switch, first unplug the
AC cable (power plug) from the PSU.
Use a flat-blade screwdriver to unscrew the lid to the PSU and
remove.
You will see a small chrome toggle switch located inside the unit
directly next to the large AC transformer.
To set the switch to 115V, toggle the switch towards the
transformer. To set the switch to 230V, toggle the switch away from
the transformer.
Warning: Connecting the CM12 to the wrong AC voltage may
destroy the unit and cause fire and/or electric shock.
Replacing Fuses
The fuse protecting the primary circuit is located outside the PSU.
Unscrew the black fuse cover to open the fuse compartment.
Replace the fuse with a new fuse of the same type (T 500 mA for
115V; 250 mA for 230V) and close the fuse compartment lid.
!
AC Power Connector
If you are using the microphone in a different country, you may
need to connect the unit to a power outlet that does not match the
power connector on the supplied power cable. Purchase a matching
power cable locally that complies with IEC and local safety
standards and has a power connector with a chassis ground pin.
While in the same area, use this “local“ power cable only.
Shutdown and Storage
Before switching off the microphone or disconnecting cables, reduce
the volume of the connected equipment. Only then should the PSU
be switched off.
Disconnect the cables. When disconnecting a cable, always pull only
on the connector housing and not the cable itself.
When the microphone is not in use it should not be allowed to
remain on the stand gathering dust.
A microphone that is unused for a prolonged period should be
stored in a cool, dry place and protected from dust.!
Cleaning
Under normal conditions the microphone body may become dirty
and covered with fingerprints. One or two drops of Lubriderm
unscented hand lotion may be gently rubbed into the nickel finish
with a terry cloth and then wiped clean.
!
Troubleshooting
1. Microphone not operating
Possible causes:
a. PSU not switched on
b. Microphone is not connected to PSU
c. Tube has become unplugged
2. Signal is noisy
!
Possible causes:
a. Tube filament has become damaged.
3. Specifications of the Microphone
Directional Characteristics: omni-, cardioid-, figure-eight, and eight
intermediate positions remotely controlled from the
microphone on the powering unit
Frequency Range: (20 - 20,000 Hz)
Electrical Impedance: 200 ohms
Powering: Via the included powering unit with 115/230 VAC
Maximum Sound Pressure Level: 138 dB
Sensitivity: approx 1 mvolts per dyne / cm sq
Non Linear Distortion: less than or equal to 0.5% at 100 dyne / cm
sq
Equivalent Noise: 16 dB (a-weighted)
Connector: Large-sized swivel, 8 pin
Dimensions: 254 mm (10'') x 41.3 mm (1.625'')
Shipping Weight: Approx. (~12 Ibs.)
!
!
Included Accessories:
CM12, CM12 PSU
NOS GE 6072 Tube, connection cable
CM12 Swivel Mount
Quarter-sawn oak case
!
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