DMTH4
LECTROSONICS, INC.
10
Input Processing
Each input channel provides individual stages for gain,
filtering and compression.
Input Gain
The input applies software controllable gain with a level
indicator and clipping indicator.
Filters
Up to six filters can be implemented at each input and
each output to idealize the signal equalization.
The filter types include:
Low pass
High pass
Band pass
Parametric EQ
Low shelving
High shelving
Filter slopes can be selected with 6 or 12 dB per octave
Butterworth or Bessel parameters. Multiple filters can be
assigned to creater steeper slopes in 6 dB steps.
Input Compressor
The compressor implementation is a unique “soft knee”
type based on an RMS level detector controlled by a
single time constant parameter. This is a new design
which responds to varying rates of change in the signal
level by dynamically adjusting the attack and release
times for best performance. Adjustment is simplified by
entering a single value (half of the desired release time).
The attack time is then applied by the DSP to vary with
the signal.
The default value is 100 ms, which sets the release
time at about 200 ms. The attack time is signal con-
trolled and varies from about 2 ms to about 100 ms as is
needed to handle the signal dynamics. See page 14 for
a closer look at this unique and effective compressor.
Compressor adjustment parameters include:
Threshold
Time Constant
Compression ratio
Makeup gain
LecNet2 Software
Software is included with the DMTH4 and available
for download from the website at: www.lectrosonics.
com. The software is used primarily for setup, with the
configuration saved on file and into the unit’s memory
for actual operation. Once configured, the DMTH4 runs
without a host computer.
The software is user-friendly, with a variety of screens
provided for each section of the signal flow and system
design. The software runs under Windows® XP, Vista
and 7 operating systems using a familiar tabbed layout.
A few sample screens are shown below.
*Windows is a registered trademark of Microsoft Corp.
Six Filter
Stages
Compressor
Level Meter
Clipping
Detector
Gain Reduction Indicator
Fine Gain & Polarity
-10 to 10 dB,
1 dB steps
Threshold
Comp. Ratio
Time Constant
Off, LP, HP, BP,
PEQ, LS, HS
6 or 12 dB/oct.
ButteRworth or Bessel
when applicable
One of 3 Input Signal Processing Blocks
Indicator
Indicator
Activity Indicator
A/D
Input Gain & Polarity
-10 to +60 dB
1 dB steps
Coarse Gain
0 to 12 dB,
3 dB steps
Typical Input Signal Processing Blocks