Lectrosonics DSP4/4 User manual

DSP4/4
4 In / 4 Out Digital Audio Processor
DSP4/4 DUAL
Dual 4 In / 4 Out Digital Audio Processor
LECTROSONICS, INC.
Rio Rancho, NM
www.lectrosonics.com
OPERATING INSTRUCTIONS
and trouble-shooting guide

2
TABLE OF CONTENTS
INTRODUCTION .................................................................................................. 2
GENERAL TECHNICAL DESCRIPTION ............................................................ 3
INSTALLATION ..................................................................................................... 4
FRONT PANEL DESCRIPTION........................................................................... 5
REAR PANEL DESCRIPTION ............................................................................. 5
DIFFERENCES BETWEEN THE DSP4/4 AND DSP4/4 DUAL ......................... 6
OPERATING INSTRUCTIONS ............................................................................ 7
DSP4/4 CONTROL PANEL SOFTWARE ............................................................ 9
SOFTWARE CONTROL PANEL SCREENS AND FUNCTIONS ..................... 11
USING THE DSP4/4 TO IMPLEMENT AN ELECTRONIC CROSSOVER....... 24
SERIAL CABLE WIRING DIAGRAM ................................................................ 26
AMX CABLE WIRING DIAGRAM ...................................................................... 25
SERIAL PORT COMMANDS AVAILABLE ........................................................ 27
TROUBLESHOOTING ....................................................................................... 30
SPECIFICATIONS .............................................................................................. 31
FCC PART 15 NOTICE ...................................................................................... 31
SERVICE AND REPAIR ..................................................................................... 32
RETURNING UNITS FOR REPAIR ................................................................... 32
WARRANTY ......................................................................................... Back cover
INTRODUCTION
The DSP4/4 offers some of the most versatile multi-channel signal processing
available. With 4 channels of audio signal processing plus Automatic Digital Feed-
back Elimination (ADFE) on each channel, the DSP4/4 is a compact solution for a
wide variety of sound system applications. 8 nonvolatile preset memory positions
mean complete flexibility and reconfigurability.
Individual level control is provided on each input with gain adjustable in 1 dB steps
from -40 to +20 dB. A complete 4 x 4 matrix follows, allowing crosspoint gain to be
adjusted in 1 dB steps from -20 to +10 dB. Each output also includes gain adjust-
ment in 1 dB steps from -40 to +20 dB, with up to 12 signal processing filters. The
filters include a unique ADFE (automatic digital feefback eliminator), shelving,
parametric EQ, compression, limiting and digital delay.
Programmable pin connections on the rear panel allow configuring external level
controls and preset recall functions with simple switches and potentiometers. Any of
the 13 pins can be programmed as “inputs,” which can be used for individual or
grouped channel level control. 8 of the 13 pins can also be programmed as “out-
puts,” used to trigger external indicators or other functions.
The DSP4/4 has an RS-232 port for remote setup or control by a computer or other
RS-232 compatible controller.

3
4 In / 4 Out Digital Audio Processor
Rio Rancho, NM – USA
GENERAL TECHNICAL DESCRIPTION
The DSP4/4 is a 4in/4out audio signal processor that uses a state-of-the-art 32-bit floating point DSP (digital signal
processor). The unit provides powerful and flexible audio processing for all types of sound systems. Superior audio
quality is ensured by the use of 24-bit A/D and D/A converters.
The ADFE system on the DSP4/4 can find and eliminate feedback on each of the four outputs individually, allowing
multi-channel distributed sound systems to have the benefit of ADFE economically. The ADFE system works by
detecting feedback frequencies in the range of 100Hz to 5.6kHz. It places a 1/5 octave notch filter on the offending
frequency with 1/10 octave accuracy. The initial notch depth is 6dB, but is changed to 12dB if the same frequency is
still found to be feeding back.
Figure 1 shows the simplified block diagram of one channel of the DSP4/4. The gain for each input is individually
controlled. Following the input gain control is a 4 x 4 matrix with fully adjustable crosspoint gains. Each of the four
matrix outputs has a complement of 12 user-adjustable filters, a full function compressor, a limiter, audio delay, and
individual output gain control.
13 programmable pin connections on the rear panel allow control of a variety of functions on the DSP4/4. Set up as
“inputs,” external pots or switches can be connected to provide input and output muting and/or level control, or used
to recall of any of the 8 available preset memories. 8 of the 13 pins can also be programmed as “outputs,” which are
used to drive external indicators to signal the state of a programmable input. For example, a programmable output
can be used to light an LED as an indication of whether an output is muted or unmuted.
An RS-232 port is available to allow almost all of the functions of the DSP4/4 to be controlled either by a computer or
a dedicated control system (such as AMX or Crestron systems).
Input Channel (1 of 4)
Matrix Crosspoint
(1 of 16)
Filters/ADFE
(12/output)
Compressor
Balanced Input
Rear Panel
0dB to -30dB, Off
Input Gain
+10dB to -68dB, Off
+10dB to -20dB
and Off
12 Filters +
ADFE
Limiter Audio Delay Output Channel (1 of 4)
Output Gain
0dB to -78dB, Off
Rear Panel
0dB to -30dB, Off
To Balanced
Output Driver
Audio Delay
Limiter
Compressor
DSP4/4 Functional Block Diagram

4
LED is on when the programmable output is active
+5VDC (from Pin 14)
380
Ohms
Programmable Output Pin
380
Ohm
s
LED is off when programmable output is active
+5VDC (from Pin 14)
Programmable Output Pin
GND (from Pin 15)
Relay is on when programmable output is active
Programmable Output Pin
GND (from Pin 15)
Relay Coil
Coil current < 100mA 1N4001
or equiv. External DC Voltage
Source (<40VDC)
INSTALLATION
DSP4/4 Audio Inputs
Each of the four DSP4/4 inputs is balanced. The drawing
shows a typical interface between an unbalanced line
level source and the DSP4/4, and a balanced line level
source and the DSP4/4.
DSP4/4 Audio Outputs
Each of the four DSP4/4 outputs is balanced. To use an output in the unbalanced line level mode, take the signal
from the “+”output connection and the output ground. Leave the “-”output floating.
DSP4/4 Programmable Inputs
The DSP4/4 has 13 programmable inputs which can control a variety of DSP4/4 parameters. Each input can re-
spond to either a contact closure or a continuous voltage. The diagram below shows common connections to the
programmable input pins.
Each programmable input is internally pulled up through a 100K resistor to +5V, so no external pull up resistors are
necessary. When using a continuous voltage with one of the programmable inputs, the Function of the program-
mable input must be set to either Analog In Control or Analog Out Control. See the Programmable I/O tab for setting
all programmable input parameters.
DSP4/4 Programmable Outputs
The DSP4/4 has 8 programmable outputs which can indicate the current state of a programmable input. Each
programmable output is the electrical equivalent of a contact closure to ground. When a programmable output is
active , it conducts current to ground. When the programmable output is inactive , no current flows to ground. The
maximum usable voltage for the programmable outputs is 40V, and they will safely conduct up to 100mA DC continu-
ous. The following diagram shows some typical uses for the programmable outputs:
It is permissible to run LEDs from the +5VDC pins on the programmable input connector, as long as the total LED
current for all LEDS on does not exceed 100mA. Similarly, 5V relay coils may also be run from the +5VDC pins on
the programmable input
connector, as long as the
total coil current for all
relays on does not exceed
100mA. Note that the
diagram shows an external
DC source powering the
relay coil. This will be
necessary if coil voltages
above 5V are needed.
Unbalanced Line Level Source
Input +
Input -
Gnd
Input +
Input -
Gnd
Balanced Line Level Source
Pot Connection for Analog Control of Gain
10K Linear Pot
CCW CW +5V
To Programmable Input Pin
Gnd
Contact Closure as Programmable Input
To Programmable Input Pin
Gnd
DC Voltage Source as Programmable Inpu
t
To Programmable Input Pin
0VDC (Off) to +5VDC (On)
Gnd

5
4 In / 4 Out Digital Audio Processor
Rio Rancho, NM –USA
FRONT PANEL DESCRIPTION
INPUT LEVEL 1-4 (1A-4A on the single version and 1B-4B on the dual version) –Indicates the audio input level
of each input. The green Signal Present LED indicates an audio level of at least –20dBu is present. The green –12
LED indicates 12dB of headroom before the maximum input level is reached. This is equivalent to an audio level of
+8dBu. The yellow –6 LED indicates 6dB of headroom before the maximum input level is reached. This is equivalent
to an audio level of +14dBu. The red Clip LED indicates 0dB of headroom, i.e. the input is overloaded and clipping.
This is equivalent to an audio level of +20dBu.
RESET DEFAULTS –When held down during power-up, resets the preset memories to their factory defaults. Note
that this will overwrite any user information which may have been stored in the preset memories.
REAR PANEL DESCRIPTION
INPUTS 1A-4A (and 1B-4B on the Dual) - Accepts balanced or unbalanced signal. Fully balanced differential input,
RF filtered.
OUTPUTS 1A-4A (and 1B-4B on the Dual) - Provide balanced system outputs. The Line Outputs may also be used
in an unbalanced mode by connecting the “+”terminal of the Line Output to the signal lead of the unbalanced device,
and the ground terminal of the Line Output to the ground of the unbalanced device. Do not ground the “-”terminal of
the Line Output.
PROGRAMMABLE INPUTS - Allows remote control of a number of DSP4/4 functions. Pins 1-8 on the 15 pin D-Sub
connector may be programmed to be either programmable inputs or programmable outputs. Pins 9-13 are program-
mable inputs only.
Each of the 13 programmable inputs can utilize either continuous DC voltages (0VDC-5VDC) or contact closures,
depending on the particular function chosen. For continuous voltages, either 10K ohm linear pot or an adjustable DC
control voltage may be used. The volume control action is internally scaled in software to provide an “audio taper”
characteristic to a linear pot. When using a DC control voltage, the control constant is .167V/dB (or 6dB/V) from 0V
to 5V. At 0V, the channel is turned completely off. The control voltage should not exceed 5V.
4 IN / 4 OUT DIGITAL AUDIO PROCESSOR
RIO RANCHO, NM –USA
POWER
INPUT 1 INPUT 2 INPUT 3 INPUT 4
Signal
Present
–12 –6Clip Signal
Present
–12 –6Clip Signal
Present
–12 –6Clip Signal
Present
–12 –6Clip
RESET
DEFAULTS
+
–– + + –– +
43 21
OUTPUTS
+
–– + + –– +
43 21
INPUTS
PWR
IN
(CH40)
OUT IN
20 VAC
LecNet
(RS232)
EXPANSION PROGRAMMABLE
INPUTS / OUTPUTS
1
15
8
9
1 - Prog I/O 1
2 - Prog I/O 2
3 - Prog I/O 3
4 - Prog I/O 4
5 - Prog I/O 5
6 - Prog I/O 6
7 - Prog I/O 7
8 - Prog I/O 8
9 - Prog IN 9
10 - Prog IN 10
11 - Prog IN 11
12 - Prog IN 12
13 - Prog IN 13
14 - +5V
15 - GND
POWER
INPUT 1A INPUT 2A INPUT 3A INPUT 4A
Signal
Present
–12 –6Clip Signal
Present
–12 –6Clip Signal
Present
–12 –6Clip Signal
Present
–12 –6Clip
INPUT 1B INPUT 2B INPUT 3B INPUT 4B
Signal
Present
–12 –6Clip Signal
Present
–12 –6Clip Signal
Present
–12 –6Clip Signal
Present
–12 –6Clip
DUAL 4 IN / 4 OUT DIGITAL AUDIO PROCESSOR
RIO RANCHO, NM –USA
RESET
DEFAULTS
RESET
DEFAULTS
+
–– + + –– +
4A 3A 2A 1A
OUTPUTS
+
–– + + –– +
4A 3A 2A 1A
INPUTS
PWR
IN
(PS60)
OUT IN
16.5 VAC
LecNet
(RS232)
EXPANSION PROGRAMMABLE
INPUTS / OUTPUTS
1
15
8
9
1 - Prog I/O 1
2 - Prog I/O 2
3 - Prog I/O 3
4 - Prog I/O 4
5 - Prog I/O 5
6 - Prog I/O 6
7 - Prog I/O 7
8 - Prog I/O 8
9 - Prog IN 9
10 - Prog IN 10
11 - Prog IN 11
12 - Prog IN 12
13 - Prog IN 13
14 - +5V
15 - GND
+
–– + + –– +
4B 3B 2B 1B
OUTPUTS
+
–– + + –– +
4B 3B 2B 1B
INPUTS
PROGRAMMABLE
INPUTS / OUTPUTS
PROCESSOR A PROCESSOR B

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PROGRAMMABLE OUTPUTS - 8 of the 13 programmable pins can be configured to work as “outputs,”which are
used to indicate the state of a programmable input. For example, an LED can be driven from one of these output
pins to indicate activity at one of the audio inputs. Each of the 8 programmable outputs is the electronic equivalent of
a contact closure. The logic output will sink up to 100mA at voltages up to 40VDC, however, the total current draw of
all logic outputs should not exceed 100mA if the internal +5V supply in the DSP4/4 is used.
RS-232 SERIAL PORT - Provides access to and control of some of the operational features of the DSP4/4. The port
is compatible with the serial port of a PC, or other controllers with RS-232 type serial ports. For hardware intercon-
nection and software details, see Appendix 1, “Serial Port Hardware and Software”.
EXPANSION IN/OUT - Allows other LecNet devices to be connected to the DSP4/4. Also used when multiple DSP4/
4s are connected together to bus the RS-232 serial connection between DSP4/4s.
Pin Expansion In Function Expansion Out Function
1 Main In Main Out
2 Mix Minus Out Mix Minus In
3 NOM In NOM Out
4 NOM Total NOM Total
5 RS-232 RX RS-232 RX
6 RS-232 TX RS-232 TX
7 round round
8 N/C N/C
PWR IN - Connects to the CH40 (for the DSP4/4) or the PS60 (for the DSP4/4 DUAL) power supply to provide power
for the unit.
DIFFERENCES BETWEEN THE DSP4/4 AND THE DSP4/4 Dual
The DSP4/4 Dual is simply two DSP4/4s in one box sharing a common power supply. Audio inputs and outputs are
labeled 1A through 4A on one unit and and 1B through 4B on the other unit. There are no internal bus connections
between the A and B units. Each unit operates as an independent device with a unique serial address. The follow-
ing outlines the important differences between the DSP4/4 ad the DSP4/4 Dual.
LecNet Port and LecNet Address
A DSP4/4 has a single LecNet address whose factory default is 143. A DSP4/4 Dual has two LecNet addresses
whose factory defaults are 143 (for channels 1A-4A) and 144 (for channels 1B-4B). Both addresses for the DSP4/4
Dual are accessible from the LecNet port on the DSP4/4 Dual.
Programmable Inputs and Outputs
The DSP4/4 Dual has two 15 pin D-sub connectors for the programmable input/output function. Each of the connec-
tors controls only the four channels with which it is associated. For example, assume a programmable input is set
for the preset recall function. In order to recall a preset for all eight channels of the DSP4/4 Dual, the programmable
inputs should be at both LecNet addresses should be set to the recall preset function. In addition, the contact
closure to ground to effect the preset recall should be electrically connected to the programmable inputs on both
connectors.
Power Supply
The DSP4/4 uses a Lectrosonics CH40 power supply. The DSP4/4 Dual uses the Lectrosonics PS60 power supply.
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
OUT IN
EXPANSION

7
4 In / 4 Out Digital Audio Processor
Rio Rancho, NM –USA
OPERATING INSTRUCTIONS
Since all of the parameters used to set up the DSP4/4 are adjusted using the DSP4/4 Software Control Panel, the
operating instructions include instructions for the use of the software. It is recommended that you have the software
running, either live or in the demo mode, as you read through this section.
Using the DSP4/4 PC Hosted Control Panel
The DSP4/4 control panel may be used in one of two ways. When launched from the LecNet Master Pro application,
you can control all the parameters of the DSP4/4 in real time. Needless to say, your PC must be connected to the
DSP4/4 using the supplied LecNet serial cable in order for this to happen. Alternatively, you can launch the DSP4/4
control panel directly and it will automatically come up in the demo mode. The demo mode is useful for doing system
setup (and saving the setups to a disk file) without the need to be connected to a DSP4/4.
System setup and audio signal flow follows the order of the tabs on the control panel from left to right. Start at the
left tab and work your way to the right Please refer to the DSP4/4 Control Panel Software section of this manual for
a complete description of each control panel tab.
The DSP4/4 Block Diagram on page 3 represents the signal flow of one input to one output through one matrix
crosspoint. Illustrated are all the gain control points in the signal path.
To adjust this parameter: Use this control:
Input Gain Input gain tab on DSP4/4 control panel software
Rear Panel (Input) Gain Programmable inputs on DSP4/4 rear panel
Crosspoint Matrix Gain Crosspoint Matrix tab on DSP4/4 control panel software
Output Gain Output gain tab on DSP4/4 control panel software
Rear Panel (Output) Gain Programmable outputs on DSP4/4 rear panel
Each input channel has two gain control points. The input control point labeled “Input Gain”is adjusted using the
Input Gain tab on the DSP4/4 control panel. This control is used to adjust the sensitivity of each line level input to
the desired gain. The gain adjustment range is +10dB to -68dB plus off.
The input control point labeled “Rear Panel”represents the gain adjustments which can be made from the rear panel
programmable inputs. The rear panel gain control is attenuation only, starting at a maximum gain of 0dB. The rear
panel input gain controls may be limited in their adjustment range using the Input Gain tab on the DSP4/4 control
panel. In addition, you may set a rear panel preset gain value that will be applied to any inputs which are being
controlled by a programmable input. The preset gain is applied at power up. Note that if there are no limits applied
to the rear panel gain range, the input channel may be turned completely off. The current gain value of the rear
panel controls is displayed on the Input Gain tab.
Matrix crosspoint gain can be set using the Matrix tab. Input-to-output gains are set based on the requirements of
the application. The factory default matrix setting is In1 to Out1, In2 to Out2, In3 to Out3, and In4 to Out4, all at 0dB
crosspoint gain.
System equalization and feedback control are manipulated in the Filter Setup tab. The frequency response of the
sound system is adjusted with parametric filters, followed by an automatic digital feedback elimination (ADFE)
process that uses narrowband notch filters. The equalization should be set first, then several ADFE filters as follows.
Normally, several filters (2 to 4) are set to the ADFE function and deployed to notch out the worst feedback frequen-
cies in the room, and then the setup is stored into memory. Any time the setup is stored into the DSP4/4 memory or
to disk, the frequency of any ADFE filter that has been deployed will also be stored. To deploy the filter (or “ring out”
the system), gradually raise the volume of the sound system using the ADFE Setup window in the computer screen
control panel. When feedback begins to occur, the DSP4/4 will automatically detect it and set a notch filter to cancel
it. Continue to increase the volume until the next feedback frequency is detected and the next filter is deployed, and
so on. After all the designated ADFE filters have been deployed, store the settings to memory or disk to preserve
the frequency setting on each filter. These filters will then operate at these fixed frequencies every time the system is
powered up. If the volume has been increased the full 10dB allowed in the window on the screen and no further
feedback occurs, the system is likely to be very stable and not need any additional filters.

8
It is also normal practice to then set two or so additional filters as ADFE types, but not deploy them before the setup
is stored to memory. These two filters will then function as dynamic feedback elimination and be available to notch
out any new feedback frequencies that might occur during subsequent operation. After a filter is deployed to notch
out feedback, it will remain on that frequency until the DSP4/4 is powered down. At the next power up, the filter will
again be available to be deployed as any other feedback occurs.
Set up the sound system so everything is operating normally. Refer to pages 12-13 and follow the summary below to
use the ADFE system.
1) Start with the ADFE system off for all outputs, using the ADFE On/Off radio buttons;
2) Click on the ADFE Setup main menu item to bring up the ADFE Setup window;
3) Using the Out1 - Out4 radio buttons on the Filter Setup tab, select Out 1;
4) Assign as many ADFE notch filters as you want for fixed room modes (typically two or three). This is done by
clicking on the gain label (above the scroll bar) on an unassigned filter, then using the Filter Type dropdown
list to pick ADFE Notch;
5) Using the ADFE On/Off radio buttons, set the ADFE system On for Out 1;
6) Using the Output Gain scroll bar on the ADFE Setup window, raise the system gain until feedback occurs;
7) Wait for a notch to be placed on the offending frequency (usually within one or two seconds), and then
increase the gain again until feedback again occurs;
8) Repeat step 7 until all the ADFE filters you have assigned have been deployed;
9) Turn the ADFE system Off using the ADFE On/Off radio buttons;
10) If you want any dynamic ADFE notch filters, assign them now as in step 4 above;
11) Repeat steps 1-10 for the other outputs;
12) After all outputs are rung out and the system is functioning normally, turn the ADFE system On for all outputs
using the ADFE On/Off radio buttons;
13) Save the active state of the DSP4/4 to preset 1 (the power up default) to preserve the frequencies of the
ADFE filters using the Save Active Setup to DSP4/4 Preset... File menu option.
The compressor may be set up using the Compressor tab. Compression can be used to restrict the dynamic range
of the audio source without crushing the life out of it. Several options exist for compression ratio from light compres-
sion (1.5:1) to fairly heavy compression (5:1). Lower values of compression ratio will be less audible in their com-
pression action, but will exert less dynamic control. Some tinkering with compression ratio and threshold will be
necessary in any given venue to optimize the compressor. The default attack and release times are generally good
places to start, and indeed may not need to be adjusted at all. The maximum gain reduction that can be exerted by
the compressor under any circumstance is 25dB.
The limiter may be set up using the Limiter tab. Limiting is used to protect power amplifiers, loudspeakers, and any
other downstream equipment from overload. The limiter has a compression ratio of “infinity-to-one”above threshold.
This means that the threshold setting constitutes a ceiling for the audio signal. The limiter threshold is generally set
higher than the compressor threshold at a level that provides system protection.
When audio delay is necessary in a system, use the Audio Delay tab for set up. Delay can be added to any of the
four outputs up to 182.625mS, in 20.83uS increments. The delay is displayed in milliseconds, feet and meters. In
addition, on the right side of the tab is a Time/Distance calculator which will convert any of the three quantities
entered to the other two.
The output gain structure is identical to the input gain structure, with the exception that the output gain range is 0dB
to -78dB plus off. The output gain is adjusted using the Output Gain tab. Rear panel output gain control ranges may
be set in a similar fashion to the input control ranges in the Output Gain tab.

9
4 In / 4 Out Digital Audio Processor
Rio Rancho, NM –USA
DSP4/4 CONTROL PANEL SOFTWARE
The following section is a description of the File menu and each of the tabs in the DSP4/4 Control Panel application.
File Menu Options
Copy Preset(s) to DSP4/4 from Disk File... - Allows any preset stored to a disk file (.dsd file extension) to be
loaded to the corresponding DSP4/4 memory preset. The Preset 1 through Preset 8 selections copy a single preset,
while the All Presets selection copies all 8 presets to the DSP4/4. After a preset is loaded to the DSP4/4, it will be
transferred to the active DSP4/4 setup. If all 8 presets are loaded, preset 1 will be made the active preset. This
option is helpful in restoring DSP4/4 settings if they have been accidentally corrupted. Note that this option will
overwrite any data stored in the DSP4/4’s preset memory with the new preset data from disk.
Save Preset(s) from DSP4/4 to Disk File... - Allows any preset currently stored in the DSP4/4’s preset memory to
be saved to a disk file. The Preset 1 through Preset 8 selections copy a single preset, while the All Presets selection
copies all 8 DSP4/4 presets to the selected disk file. This option is used to copy the Preset parameters to an exter-
nal disk file for archiving the final settings for the DSP4/4 in a particular installation.
Load Active Setup from Disk File... - Allows the active DSP4/4 setup to be loaded from a disk file. Loading the
active DSP4/4 setup from a disk file will not overwrite any DSP4/4 preset memory data. This option is helpful when a
basic DSP4/4 setup has been generated off-site and needs to be “tweaked”on-site.
Save Active Setup to Disk File... - Allows the active DSP4/4 setup to be stored to a disk file. You select which
preset position in the disk file to which to store the active DSP4/4 setup. This option has no effect on the DSP4/4
preset memories.
Select Active Setup from DSP4/4 Preset... - Allows any of the DSP4/4 preset memories to be recalled and made to
be the active DSP4/4 setup. This option does not affect any of the preset memory data.
Save Active Setup to DSP4/4 Preset... - Allows the active DSP4/4 setup to be stored in one of the 8 preset memo-
ries in the DSP4/4. Note that this option will overwrite any preset memory data stored in the selected preset memory
position.
Enter Input/Output Names... - Allows names to be assigned to the 4 inputs and the 4 outputs of the DSP4/4. These
names may be up to 15 characters long and are stored in nonvolatile memory in the DSP4/4. In addition, the names
are stored in any disk files generated with any of the save to disk options above. Inputs or outputs with no assigned
names are listed as “No Name”. To change a name, simply click on the desired text box and enter the desired name.
While you are permitted to enter more than 15 characters in the text box, only the first 15 will be stored. To save the
changes to the DSP4/4’s nonvolatile memory, click the Apply button. If you click the Cancel button, the changes you
have made will not be applied. The shortcut key for this option is Ctrl+E.
Enter Disk File Notes... - Allows you to add any notes that you want to be included in a file saved to disk. These
notes could be installation instructions, operational instructions, names, dates or any other information which might
be helpful to associate with a saved file.
After you enter the desired text into the text box, choose OK to save the changes you’ve made. Cancel will ignore
the changes you’ve made since the last time you clicked OK. Note that to save your changes to a disk file, you must
still either use Save Preset(s) from DSP4/4 to Disk File... or Save Active Setup to Disk File... to store the notes in a
disk file. The shortcut key for this option is Ctrl+D.
Print Setup... - Allows the active printer to be changed using the standard Windows printer setup dialog. This will
set the printer which is used with the Print Tabs... menu selection. The shortcut key for this option is Ctrl+P.
Print Tabs... - Allows any or all of the DSP4/4 control panel tabs to be printed for documentation purposes.
Update DSP4/4 Firmware from Disk File - Allows newer firmware revisions to be loaded into the DSP4/4. From
time to time, new features or bug fixes will be added to the DSP4/4’s firmware. These changes will be distributed
with the LecNet installation disks and available on the Lectrosonics Web site (www.lectrosonics.com). The firmware
file will have a “.s19”extension. When installing from the installation disks, the firmware files will automatically be
placed in the LecNet directory (default: c:\lecnet). If new firmware is downloaded from the Web site, the file should
be placed in the LecNet directory. Anytime the DSP4/4 Control Panel is run, it will check for .s19 firmware files which
are more recent than the firmware revision in the DSP4/4. You will be alerted that the DSP4/4’s firmware can be
updated, and you can select whether or not to let the update proceed. If no firmware file is available in the LecNet
directory which is newer than the DSP4/4 firmware, this option will be disabled. The shortcut key for this option is
Ctrl+U.

10
Update DSP4/4 DSP Software from Disk File - Allows newer DSP software revisions to be loaded into the DSP4/4.
From time to time, new features or bug fixes will be added to the DSP4/4’s DSP software. These changes will be
distributed with the LecNet installation disks and available on the Lectrosonics Web site (www.lectrosonics.com).
The DSP software file will have a “.cnv”extension. When installing from the installation disks, the DSP software files
will automatically be placed in the LecNet directory (default: c:\lecnet). If new DSP software is downloaded from the
Web site, the file should be placed in the LecNet directory. Anytime the DSP4/4 Control Panel is run, it will check for
.cnv DSP software files which are more recent than the DSP software revision in the DSP4/4. You will be alerted that
the DSP4/4’s DSP software can be updated, and you can select whether or not to let the update proceed. If no DSP
software file is available in the LecNet directory which is newer than the DSP4/4 DSP software, this option will be
disabled. The shortcut key for this option is Ctrl+T.
Exit - Ends the application. The shortcut key for this option is Ctrl+X.

11
4 In / 4 Out Digital Audio Processor
Rio Rancho, NM –USA
SOFTWARE CONTROL PANEL SCREENS AND FUNCTIONS
Input Gain Tab
The Input Gain tab allows the input gain and input
rear panel (i.e. programmable input) parameters
to be set.
Input Gain 1-4 - Allows the input gain level to be
trimmed between +10dB and -68dB, or Off. In
addition to the gain scroll bar, 6 “quick gain set”
buttons will set the input gain to the indicated
levels. The background color of the input gain
box will change from white to red if the input is
muted by actuation of the Mute Input function of a
programmable input. The input gain scroll bar
and gain set buttons will also be disabled while
the channel is muted.
Short Cuts: A left mouse click on the gain box
will set the input gain to 0dB, while a right mouse
click will set the input gain to Off.
Level Meter - Indicates the input level, taking into
consideration the Input Gain and rear panel (i.e.
programmable input) gain contributions.
Rear Panel Input Controls - Allows both a preset level and limits to be placed on the gain range available for control
of input gain using the programmable inputs. The Gain Preset scroll bar sets the power-up attenuation applied to all
inputs controlled by the Increment Input 1dB or Decrement Input 1dB programmable input function. This attenuation
will be added to the individual input gains to derive the actual input gain value. The maximum adjustment range of
the rear panel input control goes from 0dB to -30dB (in 1dB steps) plus Off. The Min Gain scroll bar allows the gain
adjustment range below 0dB to be limited as needed for the application. “Off”signifies no lower gain limit. 0dB is the
maximum value available for Min Gain, and is equivalent to making rear panel input control inactive. The Min Gain
value also applies to inputs being controlled by the Analog Input Control programmable input. In this case, the Min
Gain value represents the attenuation applied when the pot connected to the programmable input is fully counter-
clockwise (or a control voltage applied to the programmable input is at 0VDC).
Short Cuts: A left mouse click on the Min Gain box will set the minimum gain to Off (i.e. no limit on the minimum
gain), while a right mouse click will set the minimum gain to 0dB.
The 4 boxes below the scroll bars show the current rear panel input gain setting for each input.

12
Input/Output Crosspoint Matrix Tab
The Input/Output Matrix tab sets the input to
output assignments for the DSP4/4.
Input/Output Crosspoint - Allows the input/
output crosspoint gain to be set. Each of the 4
rows of 4 crosspoint boxes represent input
connections which may be set from inputs to
outputs 1-4. To set a crosspoint gain, simply click
on the crosspoint box at the intersection of the
desired input and desired output. The crosspoint
box will turn yellow, and the Crosspoint Gain
frame in the lower left hand portion of the Matrix
tab will be enabled. At this point, the current
crosspoint gain is shown. Choose a new gain by
clicking on the desired crosspoint gain value. If
you decide not to change the crosspoint gain,
you may click on the crosspoint box again to
disable the Crosspoint Gain frame without
changing the crosspoint gain.
Short Cuts: A right mouse click on a crosspoint
gain box will set the crosspoint gain to 0dB. A middle mouse click (for those with a three button mouse) will set the
crosspoint gain to “Off”.
Clear Matrix (Clr) Button - Clears all matrix crosspoints to the “Off”state.

13
4 In / 4 Out Digital Audio Processor
Rio Rancho, NM –USA
Filter Setup Tab
The Filter/ADFE Setup tab is the heart of the
DSP4/4’s signal processing capability. This tab
allows the almost limitless modifications to the
system frequency response. In addition, the
Automatic Digital Feedback Eliminator system is
set up in this tab. Note that the main menu item
“ADFE Setup”is active when in the Filter Tab.
Clicking on this menu option brings up a small
auxilliary window which allows output gains to be
increased until feedback happens for system
ringout. The recommended procedure for system
ring out is found in the DSP4/4 Installation,
Setup, and Troubleshooting section.
Filter Setting Frame:
Out 1-4 - Selects the output to which the filters
will be applied. Each of the four outputs may
have different filter arrangements as necessary to
meet the system requirements.
ADFE On/Off - The ADFE system may be set on
or off for each output. The Off position stops the ADFE system from placing notch filters on feedback frequencies,
but does not bypass ADFE notches that have been previously placed. Leave the ADFE system Off while other filters
are being adjusted for equalization purposes. After the EQ is finished, the ADFE system can be set to On for ringing
out the system.
ADFE Reset - ADFE filters which are currently assigned by the DSP4/4 to feedback frequencies may be reset using
the ADFE Reset button. All ADFE filters will be reset when the button is clicked. Some care should be taken when
using the reset button that feedback does not occur.
Filter Type - Selects the filter function to associate with the active filter (the active filter is the one whose Boost/Cut
gain label has a yellow background). The following filter types are available:
1st Order Low-Pass - 6dB/octave low-pass filter with adjustable corner frequency
1st Order High-Pass - 6dB/octave high-pass filter with adjustable corner frequency
2nd Order Low-Pass - 12dB/octave low-pass filter with adjustable corner frequency
2nd Order Band-Pass - Unity gain band-pass filter with adjustable corner frequency and bandwidth
2nd Order High-Pass - 12dB/octave high-pass filter with adjustable corner frequency
1st Order Shelving Bass - Bass tone control with adjustable turnover frequency and boost/cut
1st Order Shelving Treble - Treble tone control with adjustable turnover frequency and boost/cut
2nd Order Shelving Bass - Bass tone control with adjustable turnover frequency and boost/cut. The 2nd order tone
control has a higher slope rate than the 1st order tone control.
2nd Order Shelving Treble - Treble tone control with adjustable turnover frequency and boost/cut.
The 2nd order tone control has a higher slope rate than the 1st order tone control.
Parametric - 2nd order parametric filter with adjustable center frequency, bandwidth, and boost/cut.
ADFE Notch - Assigns the filter for use by the ADFE system to detect and eliminate feedback. No user adjustment is
allowed on an ADFE notch. Note that as the DSP4/4 assigns ADFE notch filters to feedback frequencies, the notch
frequency and notch depth (either 6dB or 12dB) will be reflected in real time on the screen.
Short Cut: An ADFE notch filter can be reset by right clicking the Boost/Cut gain label associated with the filter.
Some care should be exercised when resetting an ADFE notch, since feedback could occur as a result.

14
All filters (with the exception of the ADFE Notch) have adjustable frequencies from 20Hz to 20kHz. For filters which
support adjustable bandwidth, the bandwidth adjustment range is .05 octaves to 2.55 octaves. Filters which support
adjustable boost/cut have an adjustment range of +/-15dB.
Frequency - Allows the filter frequency to be adjusted. For frequencies less than 200Hz, the Up and Down buttons
increment or decrement the filter frequency by 5Hz. For frequencies between 200Hz and 2kHz, the increment value
is 20Hz. For frequencies above 2kHz, the increment is 100Hz.
Short Cuts: A left mouse click on the frequency label will set the filter frequency to 100Hz. A center mouse click (for
those with a 3 button mouse) will set the frequency to 1kHz, and a right mouse click will set the frequency to 10kHz.
Bandwidth - Allows the filter bandwidth to be adjusted, on those filter types which support bandwidth adjustment.
Adjustment range is from .05 octaves to 2.55 octaves in .01 octave steps.
Live Update on Freq/BW - Sets the filter update mode. When checked, the frequency response graph will be
updated at each frequency or bandwidth step while the Up or Down buttons are held. This provides conntinuous
feedback about the effect of the parameter change on the filter response, but is rather slow since many calculations
must be made at each iteration. A faster alternative is to leave the box unchecked. Under this circumstance, the
frequency response graph will only be updated when the Up or Down buttons are released.
Boost/Cut Gain Label - Indicates the value in dB of filter boost or cut. Click this label to make one of the twelve
filters the active filter so that it may be adjusted. The active filter label will have a yellow background, while inactive
filters will have a white background. When a filter type is selected for a given filter, the frequency label (F1 - F12) will
change to one of the following (depending, of course, on the selected filter type):
1st Order Lowpass - LP6
1st Order Highpass - HP6
2nd Order Lowpass - LP12
2nd Order Bandpass - BP12
2nd Order Highpass - HP12
1st Order Shelving Bass - SB6
1st Order Shelving Treble - ST6
2nd Order Shelving Bass - SB12
2nd Order Shelving Treble - ST12
Parametric - P
ADFE Notch - ADFE
Short Cut: An ADFE notch filter can be reset by right clicking the Boost/Cut gain label associated with the filter.
Some care should be exercised when resetting an ADFE notch, since feedback could occur as a result.
Boost/Cut Scroll Bars - Allow adjustment of boost/cut gain in filters which support adjustable gain. Gain adjustment
range is -15dB to +15dB.
Frequency Response Frame:
Frequency Response Graph - Shows either the frequency response of the active filter or the composite response
of all filters.
Show Response For Radio Buttons - Selects the display mode of the Frequency Response graph. Current Filter
shows only the response of the active filter, while All Filters shows the composite response of all filters together.
Note that when you have a live connection to a DSP4/4, the ADFE notch filter responses will automatically be shown
as they are deployed by the system.
Y Axis Range - Changes the Y axis scale from +/-15dB to +/-30dB.

15
4 In / 4 Out Digital Audio Processor
Rio Rancho, NM –USA
Compressor Tab
The Compressor Setup tab allows the setting of
the compressor parameters. These parameters
include attack time, release time, threshold, and
compression ratio. In addition, the gain reduction
introduced by the compressor is shown on the
gain reduction meter for each output.
Threshold - Sets the signal level at which
compression starts. Threshold range is adjust-
able from -40dBu to +20dBu, in 1dB steps.
Attack Time - Sets the attack time of the com-
pressor. Attack times range from .5mS to
128mS, in .5mS steps.
Release Time - Sets the release time of the
compressor. Release times range from 10mS to
2.56S, in 10mS steps.
Compression Ratio - Sets the compression ratio
of the compressor. Compression ratios of 1:1 (i.e
no compression), 1.5:1, 2:1, 3:1, 4:1, 5:1 are
available. As the compression ratio is increased,
more gain reduction will be applied to any signal whose level is above threshold.
Gain Reduction Meter - Shows the instantaneous amount of gain reduction being applied by the compressor to the
audio signal. Compressor gain reduction is limited to 25dB maximum, irrespective of the signal level and threshold.
Limiter Tab
The Limiter Setup tab allows the setting of the
limiterr parameters. These parameters include
attack time, release time, and threshold. The
compression ratio of the limiter is infinity:1
above threshold. In addition, the gain reduction
introduced by the limiter is shown on the gain
reduction meter for each output.
Threshold - Sets the signal level at which
limiting starts. Threshold range is adjustable
from -40dBu to +20dBu, in 1dB steps.
Attack Time - Sets the attack time of the limiter.
Attack times range from .125mS to 32mS, in
.125mS steps.
Release Time - Sets the release time of the
limiter. Release times range from 2mS to
512mS, in 2mS steps.
Gain Reduction Meter - Shows the instanta-
neous amount of gain reduction being applied
by the limiter to the audio signal. The limiter is
allowed to apply as much gain reduction as is necessary to keep the audio signal at or below threshold.

16
Audio Delay Setup Tab
The Audio Delay Setup tab allows the setting of
audio delay for each output channel. There is
also a distance/time calculator to make conver-
sions between audio delay time and distance.
Audio Delay Scroll Bar - Allows the audio delay
to be set within the range of 0mS to 182.625mS.
Time increment size is 20.83uS. The equivalent
distance in both feet and meters is also given.
Time/Distance Calculator - Converts between
Milliseconds, Feet, and Meters. Fill in any one of
the text boxes and press the Calculate button.

17
4 In / 4 Out Digital Audio Processor
Rio Rancho, NM –USA
Output Gain Tab
The Output Gain tab allows the output gain levels
to be set.
Output Gain 1 - 4 - Allows the output gain to be
set between 0dB and -78dB or “Off”. In addition
to the gain scroll bar, 6 “quick gain set”buttons
will set the output gain to the indicated levels.
The background color of the output gain box will
change from white to red if the output is muted by
actuation of the Mute Output function of a pro-
grammable input. The output gain scroll bar and
the gain set buttons will also be disabled while
the output is muted.
Short Cuts: A left mouse click on the gain box
will set the output gain to 0dB, while a right
mouse click will set the output gain to Off.
Level Meter - Indicates the output level, taking
into consideration the Output Gain and rear panel
(i.e. programmable input) gain contributions.
Rear Panel Output Controls - Allows both a
preset level and limits to be placed on the gain range available for control of output gain using the programmable
inputs. The Gain Preset scroll bar sets the power-up attenuation applied to all outputs controlled by the Increment
Output 1dB or Decrement Output 1dB programmable input function. This attenuation will be added to the individual
output gains to derive the actual output gain value. The maximum adjustment range of the rear panel output control
goes from 0dB to -30dB (in 1dB steps) plus Off. The Min Gain scroll bar allows the gain adjustment range below 0dB
to be limited as needed for the application. “Off”signifies no lower gain limit. 0dB is the maximum value available for
Min Gain, and is equivalent to making rear panel output control inactive. The Min Gain value also applies to outputs
being controlled by the Analog Output Control programmable input. In this case, the Min Gain value represents the
attenuation applied when the pot connected to the programmable input is fully counter-clockwise (or a control voltage
applied to the programmable input is at 0VDC).
Short Cuts: A left mouse click on the Min Gain box will set the minimum gain to Off (i.e. no limit on the minimum
gain), while a right mouse click will set the minimum gain to 0dB.
The 4 boxes below the scroll bars show the current rear panel output gain setting for each output.
Master Output Section
The Master Output section provides a convenient way to apply gain changes to more that one output at a time. The
six buttons (Set to Off, Set to 0dB, Decrease by 1dB, Increase by 1dB, Decrease by 5dB, and Increase by 5dB)
facilitate several common gain manipulations. Their action is applied to any output whose check box is checked. The
Select All and Unselect All buttons provide a quick way to apply gain changes to all channels simultaneously. Note
that the Increase and Decrease buttons are push-and-hold, and will increment or decrement the output gain for as
long as they are held down.

18
Programmable Input/Output Setup Tab
The DSP4/4 has 13 programmable pins on the 15 pin D-Sub connector on the rear panel which allow control and
indication of a wide variety of DSP4/4 functions. Pins 1-8 on the rear panel D-Sub connector can be programmed to
be either programmable inputs or programmable outputs, while pins 9-13 are only programmable inputs.
Only the parameters in the “Applies To”section which are associated with each specific programmable input/output
function will be enabled as you select different functions. All other parameters are disabled. This eliminates invalid
Function/Applies To settings. Each of the available functions is explained below.
Hint: If the function (or any associated inputs, outputs, etc.) of a programmable I/O is changed on the control panel,
the Apply button will be enabled. The Apply button is located in the lower right hand corner of the Programmable I/O
tab. The Apply button must be clicked before any changes are actually applied to the active DSP4/4 setup. Note that
you should use the Select Programmable Input Radio Buttons to select the programmable input you’d like to config-
ure before doing any configuration.
Select Programmable Input Radio Buttons 1-13 - Allows selection of which programmable i/o to change. Note
that the frame caption “Programmable I/O ...”(upper left in blue) will change to indicate which programmable I/O is
currently being changed.
Push Input Button - Allows a contact closure to be simulated for the current programmable input. This is useful
when testing to see that the changes you’ve made to each programmable input indeed have the intended effect.
Each click on the “Push Input...”button has the same effect as a momentary contact closure on the current program-
mable input. Note that the caption on the Push Input button always reflects the current programmable input. The
Push Input button will be disabled for any programmable inputs which are “Not Used”, “Analog In”control, or “Analog
Out”control.
Apply Button - Applies the current setting of “Function”and “Applies To”to the current programmable input. When
the Apply button is enabled, this indicates that the setting of “Function”and “Applies To”in the DSP4/4 does not
match the setting of “Function”and “Applies To”shown on the control panel screen. Clicking the Apply button will
load the control panel setting into the active DSP4/4 setup. This does not store the changes to a memory preset!
That must be done explicitly from the File/Save Active to DSP4/4 Preset... file menu option. If changes are made to
a programmable input but not applied (by clicking on the Apply button), and another programmable input is selected
(by clicking on of the Select Programmable Input buttons), all the changes to the first programmable input which
were not applied will be lost.
Select programmable input here
Active Programmable I/O indicated here
The “Applies To” section
The “Apply” button
Select programmable function here

19
4 In / 4 Out Digital Audio Processor
Rio Rancho, NM –USA
Programmable I/O Status “LED”- Shows the current state of a programmable i/o. The status indicator only has
meaning for the following programmable input functions:
Analog In: LED ON - Analog In attenuation < 15dB
LED OFF - Analog In attenuation >= 15dB
Increase In 1dB: LED ON - Contact closure on prog input
LED OFF - No contact closure on prog input
Decrease In 1dB: LED ON - Contact closure on prog input
LED OFF - No contact closure on prog input
Analog Out: LED ON - Analog Out attenuation < 15dB
LED OFF - Analog Out attenuation >= 15dB
Increase Out 1dB: LED ON - Contact closure on prog input
LED OFF - No contact closure on prog input
Decrease Out 1dB: LED ON - Contact closure on prog input
LED OFF - No contact closure on prog input
Preset Recall: LED ON - Associated memory is active
LED OFF - Associated memory is not active
Mute In: LED ON - Associated input(s) not muted
LED OFF - Associated input(s) muted
Mute Out: LED ON - Associated output(s) not muted
LED OFF - Associated output(s) muted
Programmable Output: LED ON - Associated prog input is active
LED OFF - Associated prog input is not active

20
Controlling Audio Inputs
Analog Input Control - Allows one or more input
gains to be controlled by an analog voltage on a
programmable input pin. Analog input gain
control goes from a maximum of 0dB gain to a
minimum of 30dB attenuation, plus “Off”. The
gain change resolution is 1dB. The Analog Input
Control mode is ideal for using a pot (or some
other source of analog voltage) to control input
gain. The valid voltage range in the Analog Input
Control mode is 0VDC to 5VDC. 0VDC corre-
sponds to “Off”(or Rear Panel Minimum Input
Gain, if it is programmed for less attenuation than
“Off”), and +5VDC corresponds to 0dB. In
addition to analog control, this mode can be used
to perform input “muting”using a simple toggle
switch. To mute input(s), simply connect the
toggle switch to connect the programmable input
to ground (GND pin). The screen shown here
indicates that the function of programmable I/O
number 1 is set to provide an analog input control
of inputs 1, 2, and 4. Notice how multiple inputs
may be controlled by a single programmable input.
Increase In 1dB / Decrease In 1dB - Allows one or more input gains to be controlled by a contact closure on a
programmable input pin. Increase and Decrease input gain control goes from a maximum of 0dB gain to a minimum
of 30dB attenuation, plus “Off”. The gain change resolution is 1dB. In the case of Increase In 1dB, each contact
closure will increment the input(s) gain by 1dB until 0dB is reached. Decrease In 1dB will decrement the input(s)
gains by 1dB until either “Off”or Rear Panel Minimum Input Gain is reached. If the contact closure is pushed and
held, it will continue to increment or decrement until it is released or the gain reaches its high or low limit.
Mute In (Toggle) - Allows one or more inputs to be temporarily muted. The first momentary contact closure on the
programmable input pin will mute the specified input(s), and the next momentary contact closure will unmute them.