Lectrosonics DA4 User manual

DA4
DISTRIBUTION AMPLIFIER MODULE
OPERATING INSTRUCTIONS
and trouble-shooting guide
LECTROSONICS, INC.
Rio Rancho, NM

INTRODUCTION
The DA4 is a 2 width module that provides the means to control and distribute an input signal to four balanced,
high-current output drivers. Each output has a separate level control. The DA4 can supply up to 20dB of gain, so
small signals can be boosted to avoid noise contamination on long cable runs.
TABLE OF CONTENTS
INTRODUCTION .......................................... 1
GENERAL TECHNICAL DESCRIPTION .......................... 2
INSTALLATION ........................................... 2
FRONT PANEL DESCRIPTION ................................ 3
REAR PANEL DESCRIPTION ................................. 3
OPERATING INSTRUCTIONS ................................. 3
SERVICE AND REPAIR ..................................... 4
RETURNING UNITS FOR REPAIR ............................. 4
SPECIFICATIONS ......................................... 5
WARRANTY ....................................... Back cover
1

GENERAL TECHNICAL DESCRIPTION
The DA4 provides an electronically balanced and RF filtered, XLR type input, and four electronically balanced and
floating, RF filtered outputs. In addition, a Through output is provided to allow the input signal to be passed through
the DA4 on to other modules.
The input stage is a unity gain differential amplifier. This stage drives the four level controls. After the level
controls, each output signal is sent to an amplifier stage with 20dB of gain. When the signals have been amplified,
they are then passed to the output drivers. The output drivers can provide ample current to drive loads as low as
600 ohms to +20dBv levels. These drivers are electronically balanced and floating, as well as RF filtered. They
provide most of the advantages of transformer coupled circuits, without the low frequency non-linearities associated
with transformers. Should transformers be desired, however, they are available as options.
DIFFERENTIAL 10 dB BALANCED
AMPLIFIER VOLTAGE GAIN DRIVER
BALANCED
INPUT
THROUGH
OUTPUT
RFI
FILTER
OPTIONAL
OUTPUT
TRANSFORMER
OPTIONAL
OUTPUT
TRANSFORMER
10 dB
VOLTAGE GAIN
BALANCED
DRIVER
OPTIONAL
OUTPUT
TRANSFORMER
10 dB
VOLTAGE GAIN
BALANCED
DRIVER
OPTIONAL
OUTPUT
TRANSFORMER
10 dB
VOLTAGE GAIN
BALANCED
DRIVER
BALANCED
OUTPUT 1
BALANCED
OUTPUT 1
BALANCED
OUTPUT 1
BALANCED
OUTPUT 1
Figure 1 - DA4 BLOCK DIAGRAM
INSTALLATION
The DA4 module is installed from the rear of the Modular Audio Processor mainframe. The printed circuit board
can fit into any of the ten slots provided for Modular Audio Processor modules. Once the module is fit into the card
guides for the slot, it may be slid forward in the mainframe until the female edge connector seats firmly onto the
male pins of the main bus board.
Care should be taken when inserting the edge connector onto the pins to be sure there is correct alignment.
Four #2 machine screws with captive washers are provided to secure the rear panel of the LM3 to the top and
bottom rear rails of the Modular Audio Processor mainframe. Four #2 flat head screws are provided to secure the
front panel of the LM3 to the front panel of the Modular Audio Processor mainframe. Once these eight screws are
in place, the installation of this module is complete.
2

FRONT PANEL DESCRIPTION
OUTPUT LEVEL (1-4) - Controls the output level for
each output. These controls are non-interactive, so all
output levels are completely independent.
REAR PANEL DESCRIPTION
INPUT - Accepts a balanced (or unbalanced) input to
the module.
THROUGH OUTPUT - Provides an output which is
parallel to the input for passing the input signal on to
other Modular Audio Processor modules, if desired.
Note that since the Through Output is directly in parallel
with the input, if an unbalanced input is used, the
Through Output signal will be unbalanced also.
OUTPUT (1-4) - Provides low impedance balanced
outputs to drive long lines.
OPERATING INSTRUCTIONS
Operation of the DA4 is quite straightforward. A
balanced or unbalanced signal is supplied to the input
XLR connector. If an unbalanced signal is used, pin 2
("+") should be connected to the signal or "hot"
conductor of the input signal, and pins 1 and 3 should
be connected together and also connected to the
ground conductor of the input signal. Note that this will
make the Through Output unbalanced as well.
With an input signal properly connected, adjust the
Output level controls for the desired output level.
The output impedance of the drivers is low (40 ohms
balanced) to provide wide band performance over long
cable runs. For instance, with a cable capacitance of
30 pico-farads/foot, the outputs can drive well over a
mile of cable and still provide frequency response to
20KHz. The formula for calculating the maximum
cable run which will still pass signal frequencies to
20KHz is given below:
CC = Cable capacitance/foot
1
Max Cable Length = -----------------------
5,026,000 * CC
FRONT REAR
AMPLIFIER
2
3
4
LEVEL
1
2
3
4
0
1
LEVEL
1
2
3
4
0
LEVEL
1
2
3
4
0
LEVEL
1
2
3
4
0
DISTRIBUTION AUDIO DISTRIBUTION AMPLIFIER
OUTPUTS
INPUT
THRU
1
2
3
4
1 2
3
12
3
12
3
12
3
12
3
12
3
DA4 DA 4
Figure 2 - DA4 FRONT & REAR PANELS
3

SERVICE AND REPAIR
If your system malfunctions, you should attempt to correct or isolate the trouble before concluding that the
equipment needs repair. Make sure you have followed the setup procedure and operating instructions. Check out
the inter-connecting cords and then go through the TROUBLE SHOOTING section in the manual
We strongly recommend that you do not try to repair the equipment yourself and do not have the local repair shop
attempt anything other than the simplest repair. If the repair is more complicated than a broken wire or loose
connection, send the unit to the factory for repair and service. Don’t attempt to adjust any controls inside the units.
Once set at the factory, the various controls and trimmers do not drift with age or vibration and never require
readjustment. There are no adjustments inside that will make a malfunctioning unit start working.
LECTROSONICS service department is equipped and staffed to quickly repair your equipment. In-warranty repairs
are made at no charge in accordance with the terms of the warranty. Out of warranty repairs are charged at a
modest flat rate plus parts and shipping. Since it takes almost as much time and effort to determine what is wrong
as it does to make the repair, there is a charge for an exact quotation. We will be happy to quote approximate
charges by phone for out of warranty repairs.
RETURNING UNITS FOR REPAIR
You will save yourself time and trouble if you will follow the steps below:
A. DO NOT return equipment to the factory for repair without first contacting us by letter or by phone. We need to
know the nature of the problem, the model number and the serial number of the equipment. We also need a
phone number where you can be reached 8 am to 4 pm (Mountain Standard Time).
B. After receiving your request, we will issue you a return authorization number (R.A.). This number will help
speed your repair through our receiving and repair departments. The return authorization number must be
clearly shown on the outside of the shipping container.
C. Pack the equipment carefully and ship to us, shipping costs prepaid. If necessary, we can provide you with the
proper packing materials. UPS is usually the best way to ship the units. Heavy units should be "double-boxed"
for safe transport.
D. We also strongly recommend that you insure the equipment, since we cannot be responsible for loss of or
damage to equipment that you ship. Of course, we insure the equipment when we ship it back to you.
Mailing address: Shipping address: Telephones:
Lectrosonics, Inc. Lectrosonics, Inc. [phone]
PO Box 15900 581 Laser Rd. [phone]
Rio Rancho, NM 87174 Rio Rancho, NM 87124 FAX: [phone]
USA USA
World Wide Web: http://www.lectrosonics.com email: [email protected]
4

SPECIFICATIONS
Maximum Gain: 20dB
THD @ +4dBv, 20-20KHz: Less than .05%
IMD @ +4dBv, 60/7KHz: Less than .05%
Noise @ Unity Gain: 20-20KhzLess than -82dBv
Maximum Input Level: +20dBv
Maximum Output Level: +20dBv for loads greater the 600 ohms
Input Impedance: 20K ohms, balanced or unbalanced
Input Type: XLR electronically balanced, RF filtered
Pin 2 is "+" input
Pin 3 is "-" input
Pin 1 is "gnd"
Output Impedance: 40 ohms balanced,
20 ohms unbalanced
Output Type: XLR electronically balanced and floating
RF filtered
Pin 2 is "+" input
Pin 3 is "-" input
Pin 1 is "gnd"
5

LIMITED ONE YEAR WARRANTY
The equipment is warranted for one year from date of purchase against defects
in materials or workmanship provided it was purchased from an authorized
dealer. This warranty does not cover equipment which has been abused or
damaged by careless handling or shipping. This warranty does not apply to
used or demonstrator equipment.
Should any defect develop, we will, at our option, repair or replace any
defective parts without charge for either parts or labor. If we cannot correct the
defect in your equipment, we will replace it at no charge with a similar new item.
We will pay for the cost of returning your merchandise to you.
This warranty applies only to items returned to us, shipping costs prepaid, within
one year from the date of purchase.
This warranty gives you specific legal rights. You may have additional legal
rights which vary from state to state.
LECTROSONICS, INC.
581 LASER ROAD
RIO RANCHO, NM 87124 USA August 17, 1996