User's Manual

DPR-A
LECTROSONICS, INC.
4
Input Limiter
A DSP-controlled analog audio limiter is employed
before the analog-to-digital (A-D) converter. The limiter
has a range of more than 30 dB for excellent overload
protection. A dual release envelope makes the limiter
acoustically transparent while maintaining low distor-
tion. It can be thought of as two limiters in series, a
fast attack and release limiter followed by a slow attack
and release limiter. The limiter recovers quickly from
brief transients, with no audible side effects, and also
recovers slowly from sustained high levels, to keep
audio distortion low and while preserving short term
dynamics.
Control Panel
The control panel includes five membrane switches and
an LCD screen to adjust the operational settings. Multi-
color LEDs are used to indicate audio signal levels for
accurate gain adjustment, battery status and encryp-
tion key function.
Alternate Recording Function
The DPR has a built in recording function for use in
situations where RF may not be possible or to work as
a stand alone recorder. The record function and trans-
mit functions are exclusive of each other - you cannot
record AND transmit at the same time. When the unit
is transmitting and recording is turned on, the audio in
the RF transmission will stop, but the battery status will
still be sent to the receiver.
The recorder samples at 48 kHz rate with a 24 bit
sample depth. The micro SDHC card also offers easy
firmware update capabilities without the need for a
USB cable or driver issues.
Encryption
When transmitting audio, there are situations where
privacy is essential, such as during professional sport-
ing events, in court rooms or private meetings. For
instances where your audio transmission needs to be
kept secure, without sacrificing audio quality, Lectro-
sonics implements AES256 encryption in our digital
wireless microphone systems. High entropy encryp-
tion keys are first created by a Lectrosonics receiver
such as the DSQD Receiver. The key is then synced
with the DPR via the IR port. The transmission will be
encrypted and can only be decoded if the receiver
and transmitter have matching encryption keys. If you
are trying to transmit an audio signal and keys do not
match, all that will be heard is silence.
General Technical
Description
The Lectrosonics DPR-A digital plug-On transmitter
benefits from a fourth generation design with specially
developed, high efficiency digital circuitry for extended
operating time on two AA batteries. The unique design
provides several distinct features for professional ap-
plications:
• Outstanding UHF operating range
• Superb audio quality
• On board recording
• Corrosion-resistant housing
The transmitter uses a standard 3-pin XLR input jack
for use with any microphone with a mating XLR con-
nector. An LCD, membrane switches and multi-color
LEDs on the control panel make input gain adjust-
ments and frequency selection quick and accurate,
without having to view the receiver. The housing is
machined from a solid aluminum block to provide a
lightweight and rugged package. A special non-corro-
sive finish resists salt water exposure and perspiration
in extreme environments.
The DSP controlled input limiter features a wide range
dual envelope design which cleanly limits input signal
peaks over 30 dB above full modulation. Switching
power supplies provide constant voltages to the trans-
mitter circuits from the beginning (3 Volts) to the end
(1.7 Volts) of battery life, and an ultra low noise input
amplifier for quiet operation.
The DPR-A has an external SMA antenna jack, which
accepts Lectrosonics steel flex wire AMM or AMJ
series antennas.
Low Frequency Roll-Off
The low frequency roll-off can be set for a 3 dB down
point at 25, 35, 50, 70, 100, 120 and 150 Hz to con-
trol subsonic and very low frequency audio content in
the audio. The actual roll-off frequency will vary slightly
depending upon the low frequency response of the
microphone.
Excessive low frequency content can drive the trans-
mitter into limiting, or in the case of high level sound
systems, even cause damage to loudspeaker systems.
The roll-off is normally adjusted by ear while listening
as the system is operating.