The USM 69 i stereo microphone
has two separate dual-diaphragm
capsules. These are mounted vertically and rotate against each other. The directional polar patterns
can be selected separately for each capsule
. The capsules operate independently from each other.Applications
The USM 69 i condenser stereo microphone
is a studio microphone
for intensity stereo
recording. It is suitable for XY
consists of the amplifier
section and the capsule
head. The amplifier
section contains two microphone
amplifiers operating independently from each other. They have an extremely low self noise
Two completely separate microphone
capsules are positioned closely above each other within the capsule
head. Their diaphragms are made out of gold-sputtered polyester film. The upper capsule
rotates against the lower one over a range of 270. Color markings on the lower capsule
system help to identify the angle by which the upper capsule
has been rotated.
waves reach the microphone
capsules from different directions they will generate audio
signals with different intensity only, but not with time differences, since the capsules are in close proximity and the sound
arrives at both capsules simultaneously. The result is an intensity stereo
signal that can be summed together for excellent mono
compatibility without causing interference.Polar patterns
The USM 69 i
has two built-in rotary switches. The five polar patterns
of both capsules can be selected at the microphone
itself. Therefore, no special AC
power supply units or powering adapters are necessary.
The two outputs attach directly to any 48 V phantom powered connectors.
In addition to the usual polar patterns
, and figure-8
, we have added a hypercardioid
and a wide-angle cardioid
A built-in DC
converter generates the required capsule
polarizing voltages.Electrical features
The amplifiers feature high output capability and extremely low self noise
. Distant sound
sources, as well as very loud sound
sources at close range can therefore be recorded without any problem.
has an active filter
. It effectively suppresses subsonic interference as caused by wind or structure borne noise
. At the same time, the filter
prevents the output transformers from overloading through very low frequency
energy.Use as a mono microphone
The microphones may also be used as completely independent mono
microphones. There are many applications when it is important to have a second mono microphone
as a backup, or when the outputs of microphones with different polar response characteristics must be available simultaneously.
The outputs of the two microphone
channels can be linked (cascaded). In addition to the individual directional
patterns, other characteristics are available through the combination of both channels.Operational safety
systems operate completely independent from each other.
The second amplifier
will be unaffected, even in case of a faulty ground
of the supply voltage
for one of the channels, or a short circuit in one of the outputs.
is reliable in mono
usage, even if only one of the systems is operated and connected. Its simple and redundant circuitry guarantees a low failure rate.
Should the DC
converter ever fail, a diode circuit within the microphone
ensures that both systems will remain operational. The cardioid
pattern is automatically chosen. The sensitivity
is reduced by 3 dB