Protech 862B User Manual

PROTECH

MODELS COVERED

®

1/03

INSTALLATION & OPERATION

MANUAL

AUDIO DISTRIBUTION AMPLIFIER CARDS

INTEGRA III SYSTEM

862B
863B
864B
865B

866B
867B
868B
869B

www.protechaudio.com

The 800 Series Audio Distribution Amplifiers are
designed for use in professional audio applications. Each
model is designed to accept an audio signal in, and send
the signal to multiple destinations.
Typical applications are public address announcements that
must be fed to different zones or power amplifiers, program
material that must be fed to different studios, headphone
listening systems where the user can select different program
sources, or audio recording systems where the program
material must be fed to the recorders at the same time it is
being fed to a public address system. The actual application
of the distribution amplifiers is found in such buildings as
airports, factories, courthouses, casinos, convention centers,
libraries, racetracks, training systems, and corporate board­rooms, to mention a few.
The 800 Series Audio Distribution Amplifiers are
designed to incorporate a combination of features that will
allow the units to deliver maximum performance and reli­ability. Each circuit is designed with a minimum of compo­nents, to reduce the possibility of failure, while still maintain­ing perfromance and feature criteria.

Model 865B Shown

The distribution amplifiers are available with a choice of
microphone or line level inputs, and 2 to 5 ouputs. The
microphone input units have a push-on jumper to enable
15VDC phantom power. Modules with 2 to 4 outputs are
linkable, to create larger networks. The link capability is
not available on the 5 output units.
The gain structure of the 800 ADA's allows the level of each
output to be individually adjusted. The output level may be
adjusted up, or down, with respect to the input level. If a low
input level is present, and more gain is required, the input
section has adjustable gain.
The trimpots used to adjust the input and output levels are
mounted on the accompanying backplane assembly. This fea­ture allows the system gain settings to remain adjusted, even
when a distribution amplifier is removed from it,s slot, and a
spare unit is plugged into that slot.
Since the 800 Series ADA's are used to connect multiple pieces
of audio equipment, and there exists the potential for creating
ground loops when doing so, the input section, and each of the
outputs are individually isolated using high quality audio
transformers. This feature provides the maximum in isolation
and ground loop prevention.

Protech Audio Corporation, PO Box 597, 192 Cedar River Road, Indian Lake, New York, 12842, Voice 518-648-6410 Fax [phone]

INSTALLATION

The 800 Series Audio Distribution Amplifiers are designed to
be mounted in the Model 857B Card Frame Package, or the
Model 858B Card Frame Package.
The Model 857B Card Frame Package will accomodate up to 10
audio cards, and requires an external power supply(Model

66708). The Model 858B Card Frame Package will accomodate
up to 9 audio cards, and has a built-in, unpluggable power
supply card.

The determination as to which backplane assembly to use in
your project, was made prior to our factory receiving the order.
The backplane assembly you have received will accommodate
the group of cards you or your designer have specified.

The actual steps necessary for installation of the 800 Series
Microphone Preamplifier and Line Amplifier cards, are compa­rable to those necessary for any of the 800 series cards. They are
as follows:
1 - Mount the card frame in an appropriate EIA 10" width rack,
using 4 screws of sufficient tensile strength to provide secure
mounting.

2 - A determination has been made as to which type of power
supply will be used on your system. Follow the instructions for
the type of power supply you will be installing.

EXTERNAL POWER SUPPLY. If an external power supply
is to be used, terminate the proper supply connections to pins 1,
2, & 3 of the DC barrier connector, as shown in the card frame
layout drawing. Turn on the power supply, and using a DC
voltmeter, check for correct voltage and polarity at pins 1,2 &
3 of the barrier connector.

INTERNAL POWER SUPPLY. If a plug-in power supply card
is to be used, plug in the supply card, and check for proper
illumination of the both the positive and negatrive voltage
LED's, on the power supply card front panel.

3 - Terminate all audio input and output connections, using the
card connection drawing on the facing page. Double conductor
shielded cable is recommended for all audio connections..
Terminate each unused input with a 1K ohm resistor.

4- Unpack each individual card, inspect for shipping
damage, and assuming none is found, slide the card
half-way into the appropriate slot. After all cards have been
installed half-way into the card frame, plug in one card at a time
and turn on the power supply. Make sure no unusual loading is
indicated at the power supply . If loading is noticed, turn off
the power supply, unplug the card and recheck terminations.
If no loading is noticed, continue inserting each card in the card
frame, checking power supply loading as each card is plugged
in. When all the cards have been plugged in, the installation
is complete, and all that remains is the alignment.

ALIGNMENT

Each 800 Series card with line level inputs has been shipped
from the factory aligned for unity gain. The units with
microphone level inputs is aligned for 45dB of gain. This
alignment optimizes headroom. If additional gain is required,
the following alignment procedure is recommended:

1- For microphone level input units that require phantom
power, unplug the red phantom power jumper, and push it on
both pins of the 2 pin phantom power terminal strip. This will
apply 15 volts DC phantom power to the input.

2- Apply a signal representative of the actual signal level to
be used, to the input.

3- While monitoring the #1 output channel, turn the output
#1gain trimpot, clockwise, until the output signal reaches
the desired level.

4- Repeat step #3 for each output on your distribution amplifier.

For any unused output, leave the gain trimpot in the maxi­ mum counterclockwise position.

This completes the installation and alignment of your 800 Series
Audio Distribution amplifiers. The cards may be expected to
deliver years of uninterrupted service.

Note #1­The alignment procedure outlined above will almost always
provide the desired output level. However, when an unusually
low input signal level is present (less than -20dB), the installer
may wish to use the additional gain available in the input gain
stage. This gain should be used only when each output has
already been adjusted to the maximum gain setting. Using this
gain in systems which do not require in excess of 20dB of gain,
will result in reduced headroom.

Note #2­The alignment procedures for 800 Series cards, differ from card
type to card type. Therefore it is necessary to consult the
alignment procedure for each type of card being installed, to
properly align a card frame using different card types.

PROTECH

MORE GAIN

CW

OUTPUT #5 GAIN

(10K)

OUTPUT #4 GAIN

(10K)

OUTPUT #3 GAIN

(10K)

OUTPUT #2 GAIN

(10K)

OUTPUT #1 GAIN

(10K)

INPUT GAIN

(10K)

NOTE: For Link Capability On Models 862B 863B and 864B, Strap Pins 14 Together,
and remove IC from socket nearest card handle, on unit to be used as slave.

Location of IC to be removed when
linking cards. Remove IC on all
“SLAVE” cards.

Phantom power Jumper

®

857B & 858B BACKPLANE CONNECTIONS

H

L

S
H

L

H

L

S

S
H

L

H

L

S

S
H

L

INTEGRA III SYSTEM

CONNECTOR & TRIMPOT DRAWING

MODELS 862B Through 865B

INPUT HI

INPUT LO

GROUND

OUT #1 HI

OUT #1 LO

OUT #2 HI

OUT #2 LO

GROUND

OUT #3 HI

OUT #3 LO

OUT #4 HI

OUT #4 LO

GROUND

OUT #5 HI

OUT #5 LO

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

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