1. CM50
The Wunder Audio CM50 Tube Microphone comes with the original
spherical capsule. "Simply one of the most wonderful sounding
room mics in the world." The CM50 represents the pinnacle in a
revered line of microphones that stretches back to the very earliest
days of the Pro Audio. The inspiration is classic, the execution is
cutting-edge. We have successfully recreated the small pressure
transducer (similar to the capsule for the KM series microphones)
embedded in the surface of a 40 mm diameter perspex sphere.
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.
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.
The microphone must be operated only with the supplied
cable. Since hazardous voltages are generated by the PSU that
can result in injury or death, always ensure that the
microphone cable used is undamaged. Damaged cables must
no longer be used.
Operation
The CM50 is equipped with a 8-pin Tuchel 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.
Polar pickup pattern
The capsule of the CM50 is equipped with a small diaphragm and
mounted inside a perspex sphere. It operates as an omni-directional
pressure transducer. The frequency response of the microphone
rises at the high frequency end evenly by about 5 dB without
becoming too directional. With a diffuse sound field, this results in
an almost linear frequency response from 40 Hz to 15 Khz.
How to mount the microphone
A special Yoke mount/stand adapter is provided and should always
be used to mount the microphone on floor stands or booms.
To mount the microphone, fully unscrew the knurled knob on the
side of the metal belt. Place the microphone into the metal belt
making sure that the white jewel on the front of the microphone is
centered into the center hole on the yoke belt. Make sure that the
there is no black rubber grommet in the center hole on the belt, if it
is present, remove it.
Close the metal belt carefully around the microphone making sure
that the leading edge of the metal belt does not scratch the body of
the microphone. Screw the knurled knob clockwise to tighten the
belt around the microphone.
The CM50 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
CM50 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 AC line,
the main switch may be switched on. Operating condition will be
indicated by the power lamp.
The warm-up time of the CM50 is approximately one minute. When
your CM50 is new, a 24-hour burn-in period is recommended.
The CM50’s tube will “break in” over a period of time enabling the
mic to sound subtly better over a period of time.
2. The CM50 Power Supply
This PSU supplies the microphone with the 4V filament voltage and
115V plate voltage for the vacuum tube.
Prior to connecting the CM50 to AC power, check the AC voltage of
the power line you are going to connect to the CM50.
The CM50 PSU has an internal AC voltage selector switch.
To check the CM50 PAU 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 the lid.
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 CM50 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 which 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 can 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
2) Signal is noisy
!
Possible causes:
a. Tube filament has become damaged.
3. Specifications of the Microphone
Directional Characteristics: Omnidirectional
Frequency Range: (40 - 20,000 Hz)
Electrical Impedance: 200 ohms
Powering: Via the included powering unit with 115/230 VAC
Maximum Sound Pressure Level: 128 dB
Sensitivity: approx 0.7 mvolts per dyne / cm sq
Non Linear Distortion: less than or equal to 0.5% at 100 dyne / cm
sq
Connector: Large-sized swivel, 8 pin
Dimensions: 163 mm (6.42'')!!!!!!!!80 mm (3.15'')
Shipping Weight: Approx. (~12 Ibs.)
!
!
Included Accessories:
CM50, Plush Oak Box, Historical Yoke Mount, Historical Power
supply, Original large Tuchel-connected mic cable.
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