Our experience of the audio engineer’s
situation on the road and in the studio
has shown us that compressor / limiters
and de-esser combinations frequently
prove so inflexible that they create as
many problems as they solve. We have
applied our audio design skills to solve
these problems, and the result - the BSS
DPR-402 - is much more than an
ordinary compressor / limiter.
A quick look at the front panel shows
that as a result each of the two channels
combines a full range of signal level
control facilities a dedicated and
tuneable de-esser section; a compressor
section with comprehensive control of
all main parameters and an AUTO mode
option for general use; a fully informative
LED metering section that never
leaves the engineer ‘in the dark’; and
finally a calibrated and variable peak
The double side-chain and subtractor
architecture of the DPR-402 makes it
predictable enough for conventional
programs, and flexible enough for
unlimited effects. Among the facilities, it
offer are: loudness control for
recording, mixdown, live sound
reinforcement and clubs; peak
amplitude control in disc cutting; split
band and peak amplitude control for
broadcast feeds; dynamic sibilance
control on individual mikes or even on
post-mix production, where remarkable
results are obtained from narrow-band
But the DPR-402 really shows its
colours when its internal filters are
configured to dynamically compress OR
expand individual parts of the audio
band- leaving the rest of the spectrum
unmodified. The endless possibilities
range from low frequency expansion
and narrow band resonance control to
general dynamic equalisation to create
enhancement effect. Further
possibilities include dynamically
controlled mixing, gating and ducking
for new and novel sounds.
The Double Side Chain
The circuit design secret that makes the
DPR-402 so successful is the use of an
extra side-chain. Because of this, only
the subtractor circuit and the gain
control lie in the signal path. The
sophisticated control circuitry -
including a voltage control amplifier -
lies parallel to the signal path, controlling
the subtractor while its components
have no adverse effect on the signal.
This not only ensures a cleaner, purer
signal, but forms the basis of entirely
new possibilities in signal processing.
# It gives hard or soft knee compression
for general purpose loudness
control during recording, mixdown or
# It adds a peak-limiting stage to
normal compression to provide the
protection needed for disc cutting and
# In reverse mode, it expands
previously compressed recorded
material, and is also used for producing
Music often suffers when compressed
over its full range. To overcome this,
the innovative technology of the DPR-
402 introduces a new flexibility in signal
compression, not only giving control of
threshold levels but making it frequency
Compressing selected levels and
frequencies can reduce noise and
distortion problems while leaving other
significant signal elements at full
strength to maximise artistic effects.
The DPR-402 provides two main deessing
options to suit different program
material and means of reproduction.
Broadband de-essing adds to normal
compressor performance the ability to
compress the whole signal when HF
signals exceed the preset de-ess
threshold level, or for greater precision
in demanding applications it can be set
by the main compressor controls.
HF - only de-essing, the other main
option, uses all the compressor control
circuitry to create a dedicated,
frequency-selective de-esser channel
compressing high frequency signals
while leaving low frequency content
Develop new skills to do what other
compressors cannot do
# Combine selective de-essing
sibilance control with compression or
# Control loudness in a way suited to
AM/FM broadcast processing.
# Use the frequency-selective
loudness control to enhance a frequency
spectrum without additional
# Preset LF loudness to maintain club
# Obtain automatic level-controlled
mixing of program sources for special
IMPEDANCE 10KOhm, electronically balanced.
MAX INPUT LEVEL +20dBv.
INPUT CMRR > -50dB 30Hz-20Hz.
INPUT XLR3-31 or equivalent. Wired as
CONNECTOR pin 1 o/c, pin 2 cold, pin 3 hot.
IMPEDANCE Less than 1 Ohm unbalanced,
MAX OUTPUT LEVEL +20dBv into 600 ohms.
OUTPUT GAIN +20dB continuously variable.
OUTPUT XLR3-32 or equivalent. Wired as
CONNECTOR pin 1 earth, pin 2 earth, pin 3 hot.
FREQUENCY +1dB 25Hz-20kHz. Ultrasonic
RESPONSE filter -3dB@ 30kHz.
NOISE Equiv. input noise -86dBv 22Hz -
22kHz, -82dBv CCIR weighted.
DISTORTION Unity gain, + 10 dBm output, below threshold: THD 0.03%
IMD 0.01%SMPTE, 10 dB compression. Threshold 0dB. 1kHz, 5 sec rel. time setting: 2ND
HARMONIC 0.15%. 3RD
HARMONIC 0.05%.IMD 0.25%
Harmonic distortion in this type of
equipment will increase with reduced
frequency and shorter time constants.
CROSSTALK < -85dB 20Hz -20kHz.
THRESHOLD -30 to +20 dBv cont. variable.
RATIO 1:1 continuously variable to infinity:1.
MAX. VCA RANGE 30dB.
ATTACK TIME 11 steps 50μsec-80msec.
RELEASE TIME 10 steps 5ms to 5 sec and AUTO.
Attack times are measured at 63% of final gain reduction with step
signal 8dB above threshold. Release times are measured at 63% of
open gain or removing a signal 8dB above threshold.
AUTO TIME CONSTANT
A two part program-dependent time constant. Typical attack
time is 200 μsec on fast transients, release time 10msec for 63%
recovery from a 10dB 4msec
response, and 1 sec for a 10dB 40 msec response.
THRESHOLD RANGE -30 to +20 dBv continuously variable.
RATIO Infinite, at and above twice the set frequency.
FREQUENCY RANGE 800Hz to 15kHz continuously variable.
Frequency is that at which 3dB of gain
reduction occurs for 10dB of signal overdrive above threshold.
10dB of gain reduction will occur at and above twice this
THRESHOLD RANGE +4dBv to +20dBv continuously
ATTACK TIME Fast setting 150μsec, Slow setting 750μsec.
RELEASE TIME Fast setting 100msec, Slow setting 500msec.
Dimensions and Power
SIZE 482 x 44 x 228mm 19in x 13/4in x 9in overall.
WEIGHT 4.5kg (10lbs) packed.
ELECTRICAL SUPPLY 120-220V +105-20% 50/60Hz 15VA.
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