DMTH4
LECTROSONICS, INC.
34
The DMTH4 has 11 programmable inputs which can
be used to control a wide variety of DMTH4 functions.
Depending on the assigned function, the inputs may
be connected to momentary contact switches, toggle
switches, or potentiometers. When used with a switch,
the inputs are activated by connecting them to ground
through the switch contacts, called a “contact closure”.
When used with a potentiometer, the inputs respond to
the applied voltage in the range 0 to 5 VDC.
The DMTH4 also has a set of 8 programmable outputs
which can be set up to monitor programmable input
status or whether particular presets are active. Normally,
a programmable output is inactive unless the specified
conditions are fulfilled, at which time it becomes active.
However, a programmable output can be inverted so
that the reverse is true - it becomes active whenever
the specified conditions are not fulfilled. Programmable
outputs act as an electronic “contact closure” to ground.
When the output is active, the contacts are closed (con-
ducting to ground), when inactive they are open.
An important application of the rear panel control inter-
face is to manage what is called the rear panel gain for
Programmable
Inputs/
Programmable
Outputs Select
Programmable
Input/Output
Notebooks
Programmable
Input/Output Status
Indicators
Programmable
Input/Output
Function Select
Rear Panel
Input Gain
Control
Rear Panel
Output Gain
Control
input and output audio channels. This is an additional
gain value that is added to the “main” gain value for a
channel to give the total gain applied. Rear panel gain
may be adjusted over the range -60dB to 0dB, or set
to “Off” which silences the channel. It is intended to
function as a variable attenuator for the audio channel.
The purpose is to allow some amount of gain or level
control by the end user in a safe manner, using one
of the programmable inputs. A typical application of
rear panel gain is to allow adjustment of the level of an
audio output (driving a speaker) downward from some
maximum by means of turning a potentiometer con-
nected to a programmable input which has been set
up to use the Analog Output RP Gain Control function
(see description in table).
This tab contains a notebook with two pages, one for
programmable input setup and one for programmable
output setup. If the computer is connected to a DMTH4,
changes made in this tab take effect immediately. As
always, the changes are not permanent unless the
DMTH4 settings are stored to a preset in nonvolatile
memory.
Page Select
Rear Panel Control Tab