Electro-Voice 1700 Series Operating Instructions Manual

1700 Series

Mixer/Power Amplifiers

Operating Instructions

TABLE OF CONTENTS

DESCRIPTION................................................................................................................................................................................... 3

INCLUDED ACCESSORIES: ............................................................................................................................................................. 3

OPTIONAL INPUT OUTPUT ACCESSORY MODULES: .................................................................................................................. 3

ELECTRICAL CONNECTIONS FOR THE 1700 SERIES MIXER/POWER AMPLIFIERS ................................................................ 3

Power Connections (120 Volt, 50/60 Hz) .................................................................................................................................... 3

Power Connections (100, 200, 220, or 240 Volt; 50/60 Hz) 1707C/1715C Only ........................................................................ 3

INSTALLING MODULES IN THE MAINFRAME................................................................................................................................. 4

SHELF OR RACK MOUNTING THE ................................................................................................................................................. 4

Ventiliation .................................................................................................................................................................................. 4

OUTPUT CONNECTIONS (1707C/1715C Only) .............................................................................................................................. 6

MUTE/TONE GENERATOR CONNECTIONS ................................................................................................................................... 6

PREAMP OUT/AMP IN CONNECTIONS .......................................................................................................................................... 7

AUX OUT CONNECTIONS................................................................................................................................................................ 7

BATTERY INPUT CONNECTIONS .................................................................................................................................................... 7

FRONT/REAR-PANEL CONTROLS, SWITCHES, INDICATORS, AND CONNECTORS ........................................................... 8

INITIAL SETUP AND OPERATION OF .............................................................................................................................................. 8

MAINFRAME WITH MODULES INSTALLED .................................................................................................................................... 8

Initial Setup of an Input Module .................................................................................................................................................. 8

Initial Setup of an Output Module ............................................................................................................................................... 8

Initial Setup of the Mainframe ..................................................................................................................................................... 8

OPERATING THE 1700 SERIES MIXER/POWER AMPLIFIERS ...................................................................................................... 8

1781 Mic/ Line Input Module......................................................................................................10

DESCRIPTION................................................................................................................................................................................. 10

INSTALLATION OF OPTIONAL 1785A INPUT ISOLATION TRANSFORMER................................................................................ 10

CONFIGURING THE 1781A ............................................................................................................................................................ 10

PROGRAMMING THE 1781A .......................................................................................................................................................... 10

Mute”Priority” Mode of Operation ............................................................................................................................................. 10

Mute “Slave” Mode of Operation ............................................................................................................................................... 10

Mute “Off “ Mode of Operation .................................................................................................................................................. 11

Phantom Power ........................................................................................................................................................................ 11

REMOTE VOLUME CONTROL CONFIGURATIONS ...................................................................................................................... 11

Remote Volume Control Connections ....................................................................................................................................... 11

Alternative Configurations Using the RVC Circuitry for Preset Attenuation ............................................................................. 12

Simultaneous Remote Volume Control of Several Input Modules ............................................................................................ 12

CONNECTOR OPTIONS FOR THE 1781A ..................................................................................................................................... 12

USE OF HIGH LINE LEVEL INPUT SIGNAL SWITCH THE 1781A................................................................................................ 12

ALTERNATIVES TO THE EXTERNAL RESISTIVE PAD ................................................................................................................. 12

SPECIFICATIONS ............................................................................................................................................................................ 13

1783 Line Output Module...........................................................................................................14

CONFIGURING THE 1783 .............................................................................................................................................................. 14

CONNECTOR OPTIONS FOR THE 1783 LINE OUTPUT MODULE .............................................................................................. 14

INCLUDED ACCESSORIES: ........................................................................................................................................................... 14

INSTALLATION OF OPTIONAL 1786 OUTPUT ISOLATION TRANSFORMER .............................................................................. 15

VOX GATE ...................................................................................................................................16

DESCRIPTION................................................................................................................................................................................. 16

MODIFICATION A (REFERENCE FIGURE 1): ................................................................................................................................ 16

MODIFICATION B (REFERENCE FIGURE 1): ................................................................................................................................ 16

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DESCRIPTION

The 1700 Series Mixer/Power Amplifiers offer a highly flexible
integration of a user configurable six input mixer with a fully
protected power amplifier in one convenient cost effective
package.

The six input ports accept any of the several input modules or
output module. The programmable input modules may have their
muting circuitry configured in either “priority”, “slave” mode, or
may be set to ignore muting commands. When a module
configured in the “Priority” mode is activated, modules in the
“slave” mode will be muted.

Circuitry is also provided to allow remote volume control of
individual inputs.

Multiple mainframes may be dynamically linked together.
Separate preamp-out and amplifier-in jacks allow the insertion
of equalizers or other, signal processing between the mixer and
the power amplifier.

A multi-tone generator and a compressor/limiter are also
provided.

INCLUDED ACCESSORIES:

1 - Operating/Service Instruction documents.

1 - Shorting Bar (Installed on Direct Output to OT in).

1 - “U” Shorting Bar (Installed on Preamp Out to Amp In).

4 - Rubber Feet (installed).

1 - System Configuration Label installed on top cover.

1 - International fuse.

1 - International 220/240 VAC voltage sticker.

1 - International Fuse sticker.

1 - Rack mount hardware kit.

OPTIONAL INPUT OUTPUT ACCESSORY
MODULES:

1781A Programmable Input Module.

1781AT Programmable Input Module with 1785A 600 ohm

to 10 kohm isolation transformer installed.

1783 Line Output Module.

1785A 600 ohm to 10 kohm Input Isolation Transformer.

1786 600 ohm to 600 ohm Output Isolation Transformer.

1791 Female XLR Connector.

1792 Male XLR Connector.

1793 Dual RCA Phono Connector.

1794 5-Lug Screw Terminals.

ELECTRICAL CONNECTIONS FOR THE 1700
SERIES MIXER/POWER AMPLIFIERS

Power Connections (120 Volt, 50/60 Hz)

The mainframe configuration for both mixer/ power amplifiers
comes with the power transformer’s primary line voltage
strapped for 120-volt operation from the factory. Refer to Table
1 for exact strapping details and other voltage options.

NOTE:

Make sure the line voltage corresponds with the

selected line voltage power rating BEFORE you

connect the mainframe to the alternating current

line.
Power Connections (100, 200, 220, or 240 Volt; 50/60 Hz)

1700C/1715C Only

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You may change the mixer/power amplifier’s 120-volt power
connection to a 100-, 200-, 220-, or 240-volt power connection
by restrapping the power transformer’s primary line voltage. Use
the following procedure to change the factory strapping to
another line voltage.

1. If you connected the mixer/power amplifier to an
alternating current power source, disconnect it.

2. Remove and save the nine screws that secure the mixer/
power amplifier’s top cover. There are two screws near
the bottom of each side, two screws on top near the rear
edge of the front panel, and three screws at the top edge
of the rear panel. Refer to Figure 1 for details.

The numbers in Table 1 correspond to the numbered
positions on the alternating current terminal block
connector, which is adjacent to the power transformer. To
select a line voltage, install the colored primary lead wires
into the corresponding numbered positions on the terminal
block.

3. Locate the voltage selection terminal block between the

side of the chassis and the power transformer.

Figure 1. Top Cover Removal

4. While referring to Table 1, disconnect the primary lead
wires from the terminal block. Pull each wire firmly to
disengage the push-on connector. Then reconnect each
lead wire into its designated position on the terminal block
that corresponds to the desired line voltage. Press each
connector to snap into place.

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5. Install the appropriate fuse value from Table 2.

NOTE:
Use of fuses other than those listed in Table 2 will

VOID THE W ARRANTY .

6. If you connected the power transformer’s primary leads
for 200-, 220-, or 240-volt operation, perform steps 7, 8,
and 9 below to prevent future confusion and possible
damage to the amplifier. Otherwise, proceed with step
10 below.

7. Affix the supplied 220/240 VAC label above the power
cord and cover the 120 VAC silkscreened designation.

8. Affix the 2-amp fuse/1707C, (4-amp/

original 3.5 amp/1707C, (7-amp/1715C) silkscreened
designation.

1715C) label over the

9. Replace the standard AC line fuse with the 2-amp fuse/
1707C, (4-amp/1715C) supplied. You should find the
labels and the fuse enclosed in the plastic bag with this
manual. Refer to Table 2 for an AC fuse selection chart.

10.If you are not installing additional modules in the
mainframe right now, reinstall and secure the top cover
with the nine screws previously removed in step 2 above.

NOTE:
Y ou can buy and install additional modules into the

mixer/power amplifier , which has six ports that you
can configure as input or output modules.

INSTALLING MODULES IN THE MAINFRAME

1. Remove and save the two screws that secure the access
panel to the top cover. Refer to figure 1 for details.

2. Plug the input or output module into one of the six channel
positions with the controls facing the rear as shown in Figure

Figure 2. Module Installation

2. Secure the module with the two screws provided.

3. Remove the blank cover panel as shown in Figure 3. Install
the selected connector assembly with the screws provided.

Figure 3. Removal of Blank Cover Panel

Figure 4. System Configuration Label

Plug the pigtail connector (from the main connector
assembly) onto its appropriate male mating connector on
the module’s printed circuit board.

4. On the top cover is a System Configuration Label. Use it to
indicate the module type, configuration, and any options for
future reference. Write directly on the label with a permanent
marker. Refer to Figure 4 for a sample of this label.

SHELF OR RACK MOUNTING

You may shelf mount or rack mount the mainframe. For shelf or
countertop applications, four rubber feet on the bottom of the
chassis will protect resting surfaces and provide elevation for
air flow underneath the unit. For rack or cabinet applications,
remove the four rubber feet from the bottom of the chassis. Then
install the unit in the rack with the screws and shoulder washers
provided. The unit must have 1.75" of blank space both above
and below it.

Ventiliation

The mixer/power amplifier generates minimal heat during normal
use. Although the amount of generated heat is low, make sure
the mainframe is property ventilated to prevent an excessive
temperature rise. Because the output power devices (transistors)
are sensitive to heat, you should not place the amplifier between
other heat generating equipment or in areas where the ambient
temperature exceeds 50°C (122°F).

If you mount the mainframe in an equipment rack or cabinet
with other heat producing equipment, provide adequate space
between the units. Otherwise, the equipment may become too
warm.

If a rack or cabinet contains several amplifiers, you may need
to check the ambient air temperature. To determine the ambient
air temperature, operate the system until the temperature
stabilizes. Measure the ambient air with a bulb-type thermometer
held at the bottom of the uppermost amplifier.

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Figure 5. Block Diagram of 1707C / 1715C Mixer/Power Amplifiers

CAUTION

Don’t let the thermometer bulb touch the metal
chassis. The chassis might be hotter than the
ambient air.

CAUTION

If the air temperature exceeds 60°C (140°F), place
the equipment farther apart or install a blower to
provide air movement within the cabinet. Make sure
you don’t block the air intake holes located on the
bottom of the chassis or the exhaust holes on the
top cover.

Figure 5 above displays a block diagram of the mixer/power
amplifier mainframe. Study it carefully. To use the system’s full
capabilities, you’ll need a good understanding of the inner
workings of the mainframe. Brief explanations of how the inside
of the mainframe works follow in the text below.

The signal coming from each additional input module
simultaneously routed to the mixer/power amplifier’s front-panel
nominal/peak LED indicators and to the input channel level

controls. The dual LED nominal/peak displays are pre-fader and
designed to monitor the output level from the corresponding
input module. The nominal (green) LED indicators have an
approximate 10 dB window over which they will illuminate. This
makes it easy to properly adjust the gain for each input module
while efficiently using the rest of the system in terms of
performance and headroom.

The mixer/power amplifier then sums the signal at the wiper of
each input channel level control into a true virtual ground
summing node or bus. The summing amplifier has eight input
channels - input channels one through six on the front panel,
tone generator output, and the link input or LINK IN on the rear
panel. The summing amplifier’s output signal drives the link
output, or LINK OUT, located on the rear panel of the mainframe.
The E.Q. and compressor/limiter sections are in series with each
other, as shown in Figure 5. The compressor/limiter’s output
signal drives the preamplifier output, or PREAMP OUT, located
on the rear panel which then provides the input signal to the
main amplifier section.

The BASS and TREBLE E.Q. controls are ideally suited to make
adjustments to the overall response of the mix. The low and
high frequency shelving equalizers provide ±12 dB of boost

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and cut with the maximum boost occurring at 100 Hz and 10kHz
respectively.

The compressor/limiter section features variable release time,
compression ratio, and threshold. The circuit uses a feed-forward
topology that will minimize level differences for a more nearly
constant output level. The compression ratio can approach ¥ :1,
and the attack time is fixed at approximately 10 ms.

The main amplifier section protects itself and the load against
radio frequency interference, spurious oscillatory waveforms,
excessive temperatures, direct current, turn-on/turn-off
transients, and excess voltage/current phase shift due to reactive
loading.

A signal overload circuit monitors the level at the output stage
of the amplifier section. The front-panel CLIP LED indicator
illuminates when signal levels are high enough to cause
significant output clipping.

A dual slope V-I limiter protects the output devices. It keeps the
output devices operating within their SOA (safe operating area)
as defined by the device manufacturer.

A special integrated circuit function block monitors the heatsink
temperature, powersupply voltage, and the amplifier’s output.
When it detects a problem, it immediately disengages the output
relay.

Output Connections (1707C/1715C Only)

Make output connections to the seven-terminal barrier strip
connector located on the lower-left side of the mainframe’s rear
panel.

The 1707C main output connections include an 8 ohm direct
output (24.5 vrms) and three transformer balanced outputs; 4
ohm (17.4 vrms), 25 vrms (8.3 ohm), and 70.7 vrms (66.6 ohm).

The 1715C main output connections include a 4 ohm direct
output (24.5 vrms) and a 25 vrms (4.2 ohm), an 8 ohm (34.6
vrms), and a 70.7 vrms (33.3 ohm) balanced transformer output.

Refer to Figure 6 for a display of the direct output connections
and Figure 7 to see the transformer output connections.

Figure 6. Direct Output Connections

Output Fuse: A fuse in series with the output of the amplifier
section protects the amplifier from excessive current
consumption by a load. If this output fuse blows, replace it only
with a fuse that matches the same type and rating as
silkscreened on the rear panel of the unit. If the fuse continues
to blow. check the load to see if it shorted or is exceeding the
rated power consumption. If the problem continues, have a
qualified service technician service the unit.

Mute/Tone Generator Connections

The seven-lug screw terminal connector located on the mid-left
rear of the mainframe provides access to the system mute and
tone generator. For connection details, refer to Figure 8.

Figure 8. Mute/Tone Generator Switch Connections

A switch closure between the mute and common (COM)
terminals will mute any input modules configured in the slave
mode. You can use the remaining switches to select one of the
following sounds:

A single-tone chime (S/T),
A repeating-tone chime (R/T),
A buzzer, or

A yelp (siren).
For the duration of a tone, the tone generator automatically
mutes any input modules configured in the slave mode.

Output-Level Control:

The tone generator’s output-level control is conveniently located
on the rear panel of the mainframe. To increase the tone
generator’s output level, rotate the screwdriver-slotted control
shaft clockwise.

NOTE:
Optional External Mute, (connected at the factory)

allows external muting of the tone generator. If
disconnected, the tone generator cannot be
externally muted.

Figure 7. Transformer Output Connections

To use a transformer balanced output, install a U shorting bar
between the direct (+) output and the output transformer’s input
(OT IN).

NOTE:
When using the output transformer, you may use

any combination of output connections as long as
the total connected load does not consume more
than 75 watts for the 1707C or 150 watts for the
1715C.

Resistance Effects of Long-Cable Runs on Mute/Tone
Generator Circuits:

Table 3 shows the maximum allowable cable resistance (total

resistance) that the mixer/power amplifier can support.
Resistances greater than these values, resulting from
excessively long-cable runs or small gauge wire, may cause
the mute or tone generator circuitry to fail to operate. Please
make sure all cable resistances are less than the values shown
in Table 3.

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