Protech 899B User Manual

PROTECH

MODELS COVERED

899B

®

1/02

DUAL AUDIO DISTRIBUTION AMPLIFIER CARD

INTEGRA III SYSTEM

INSTALLATION & OPERATION

MANUAL

Model 899B Shown

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(s)
in, and send the signal(s) 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.

The Model 899B is a dual, 1 input by 2 output device. Each
of the two identical circuits may be used to “split” an audio
feed to two different locations.
The gain structure of the Model 899B 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 an additional 15dB of 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, or the Model 858B Card Frame.
The Model 857B Card Frame will accomodate up to
10 audio cards and requires an external power supply.
(Model 66708). The Model 858B will accomodate up to
9 audio cards and has an internal power supply. (Model
2000-PS-A)

Both card frame assemblies bus the DC power to the in­dividual card slots, and provide screw-type barrier termin­ation points for audio and DC connections.

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
Audio Distribution 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 19" 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.

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
card at a time and turn on the power supply. Make sure no
unusual loading is noticed 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.

half-way into the card frame, plug in one

ALIGNMENT

Each 800 Series card with line level inputs has been
shipped from the factory aligned for unity gain. This
alignment optimizes headroom. If additional gain is
required, the following alignment procedure is recom­mended;

Apply a signal representative of the

1 -

actual signal level to be used, to the
input.

While monitoring the #1 output chan-

2 -

nel, turn the output #1 gain trimpot
clockwise (increased gain), or coun­terclockwise (decreased gain) until
the output signal reaches the de­sired level.

3 -

Repeat step #2 for each output on
your distribution amplifier. For any
unused output, leave the gain
trimpot in the maximum 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.

PROTECH AUDIO

857B & 858B BACKPLANE CONNECTIONS

OUTPUT 2B

OUTPUT 2A

INPUT 2

OUTPUT 1B

OUTPUT 1A

INPUT 1

INPUT 1 HI

INPUT 1 LO

GROUND

OUT 1A HI

OUT 1A LO

OUT 1B HI

OUT 1B LO

GROUND

INPUT 2 LO

INPUT 2 HI

OUT 2A HI

OUT 2A LO

GROUND

OUT 2B HI

OUT 2B LO

INTEGRA III SYSTEM

CONNECTOR DRAWING

MODEL 899B

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

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 both the positive and negative
voltage LED's, on the power supply card.

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.

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 INTEGRA III 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.

Page 2

NOTES.