System 41 is a modular microphone management system that uses card modules in single mainframes. This allows rapid and complex interconnections without external cable connectors. offers more equivalent signal processing per dollar than systems using a grouping of individual units.
The system offers more equivalent signal processing per dollar than a grouping of individual units. IRP card modules are available for Voice-Matic® / Level-Matic® / equalization, mixing, AGC, remote control, filtering and signal distribution.
Complex installations with hundreds of microphone inputs can be assembled in a very compact space. All module adjustments are made from the fronts of the cards. The front of the cards is inaccessible to unauthorized persons with the security panel of the mainframe closed.

The system automatically attenuates microphone channels that do not have an active input. Voice-Matic utilizes a dynamic threshold rather than the fixed threshold common to gated mixers. The mixer generates a DC ramp which searches downward through 80 dB of dynamic range looking for an open microphone. This search takes 10 milliseconds or less. When a microphone is found with a signal present it is given "on" status for 200 millisecondes. The ramp is reset high and again begins to search downward in level. When it sees a second open microphone, it gives it "on" status. Because the NOM (number of open microphones) count has doubled from one to two, it automatically attenuates the 3dB of gain required to maintain feedback margin.

Level-Matic on the other hand provides automatic level control in sound reinforcement systems. Sound system gain is automatically adjusted to maintain uniform output signals by sending changes in average input signal level. Level-Matic senses signal variations between soft and loud talkers or variations in distance between talker and microphone and automatically adjusts the master gain to maintain uniform output signal (gain control voltages in the Level-Matic are based on loudness vs. Frequency and loudness vs. Time response of the ear).
A feedforward control voltage comes from a sampled and averaged input loudness and establishes a quasi-stationary control voltage that is updated only when input is present.
A feedback control voltage comes from the peak output loudness and reacts quickly to transient loudness increases.

A "priority gate" senses and applies the larger of the control voltages to a voltage controlled attenuator.
System gain is controlled by either the feedforward or the feedback control voltage. This enables the Level-Matic to respond with feedback control for temporary increases in level and to return to the gain established by the feedforward control voltage. Gain corrections are made at a constant dB/sec slew rate to minimize gain "hunting".

Distribution Amplifier (2 Input, 6 Outputs),
the DJ-4104A is a dual distribution amplifier with two active balanced inputs and six transformer isolated outputs. All six outputs are pin-jumper programmable to be driven from either of the two inputs. The DJ-4104A is suitable for signal distribution to remote equipment, and for applications requiring power ground isolation, buffering, and extended frequency response.

Level-Matic AGC, 1 Channel, with VCA,
the DJ-4109A senses variation in input level and adjusts gain to maintain a uniform output level and provides up to 15dB of gain reduction. This effectively compensates for differing talker level and varying microphone to talker distance, thus making the DJ-4109A a particularly useful addition to any microphone mixing system.

Voice-Matic Microphone Input Module,
the DJ-4114A is a four microphone/line input automatic mixing module. One or more DJ-4114A modules combined with a single DJ-4115A Voice-Matic ® Master approximates the gain, stability, and noise performance of a single microphone system for multiple microphone installations.

Voice-Matic Master Module,
the DJ-4115A Master Module mixes into two outputs the audio signals from one or more DJ-4114A Voice-Matic microphone input modules. The main sound reinforcement output includes a stepless NOM attenuator. The auxiliary output provides a programmable mix of gated and ungated system inputs suitable for broadcast or recording feeds. Two auxiliary line level inputs are also provided. A linking interface provides a method of combining mixer control signals for room combining applications.

29 Band TEQ Transversal Equalizer,
the DJ-4117A provides 29 bands of Transversal Equalization (TEQ ® ) positioned at 1 / 3 octave ISO frequencies, selectable high-pass and low-pass band-limiting filters, and selectable high frequency shelving pre-emphasis. TEQ ® eliminates the transient ringing, frequency response ripples, and coloration common to tuned filter equalizers.

Voice-Matic Room-Combining Module,
use with modules 4114A and 4115A,
the DJ-4129A Voice-Matic Combiner module allows combining of up to eight independent Voice-Matic mixing systems into one or more larger, fully operational Voice-Matic mixing systems. The DJ-4129A combines the NOM (Number of Open Microphones) and DTS (Dynamic Threshold Sensing) control bus signals from selected DJ-4115A/DJ-4115A-1 Voice-Matic Master modules.
Internal switching logic combines common room-pairs into larger multiple room systems when corresponding switches are engaged.