ARX EC-1 User Manual

INTERNATIONAL LIMITED WARRANTY

ARX Systems (ARX) warrants to the first purchaser of any ARX equipment that it is
free from defects in materials and workmanship under normal use and service. ARX’s
sole obligation under this warranty shall be to provide, without charge, parts and
labour necessary to remedy defects, if any, which appear within twelve (12) months
from date of purchase, and for a further twelve (12) months supply parts only.

This is our only warranty. It does not cover finish or appearance items, or if the
equipment has been, in ARX’s sole judgement:

•Subjected to misuse, abuse, negligence or accident;

•Repaired, worked on, or altered by persons not authorized by ARX;

•Connected, installed, adjusted or used for a purpose other than that for which
it was designed.

This warranty gives you and us specific legal rights and you may also have other
rights which may apply.

Warranty Service Procedure

Should it become necessary to have your equipment serviced under the terms of
the warranty, please follow these steps:

1. Call your ARX distributor for a Return Authorization (RA) number;

2. Carefully repack the unit, in its original packaging where possible,

including a note with a description of the problem, and a copy of the
receipt showing date of purchase. Attach these to the actual unit itself.
Don’t forget to write your name and address clearly, and include a phone
number where you can be contacted during normal business hours. Make
it easy for our service technicians to contact you if they have a question.
Also, use plenty of packing material - better to be safe than sorry.

3. Send the unit freight prepaid to ARX Systems, at the address given you
with your RA number. We will pay the return freight when the serviced
unit is returned to you.

4. We strongly recommend you insure the package. We can’t fix it if it gets
lost! Send it by UPS, Fedex, or any similar service that can track the
package. Parcel Post is not recommended

If Warranty Registration Card is missing, please write to ARX in the country of
purchase, stating model and where purchased, or to ARX, PO Box 15, Cheltenham,
Victoria 3192, Australia.

Or you can Email us at: [e-mail]

EC-1 & EC-2

Electronic

Crossovers

OWNER’S
MANUAL

ARX Systems Pty Ltd, PO Box 15,

Cheltenham, Victoria 3192, Australia

Phone: 03 - 9555 7859 Fax: 03 - 9555 6747

International Fax: [phone]
On the Web: http://www.arx.com.au

Email: [e-mail]

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EC-1 and EC-2 Owner's Manual v 1.6CE ©1997 ARX®EC-1 and EC-2 Owner's Manual v 1.6CE ©1997 ARX®

IMPORTANT -

This is a dual voltage unit. It is essential that you check that the voltage on the

fuseholder cover below the AC connector on the rear of the chassis is set correctly

before connecting it to AC power.

THIS IS SET FOR

100 V AC TO 120 V

AC OPERATION

To change, pull fuseholder out and rotate 180o, then push in again. Do not insert
power cable into unit until voltage has been correctly set. Do not plug power cable
into AC power until voltage has been correctly set

PLEASE READ THIS FIRST

THIS IS SET FOR

220 V AC TO 240 V

AC OPERATION

WARNING SYMBOLS USED ON THIS EQUIPMENT

This symbol is intended to alert you to the presence of important
operating instructions contained in this owner's manual

This symbol is intended to alert you to the presence of uninsulated
dangerous voltage within the product's enclosure that may be of
sufficient magnitude to constitute a risk of electric shock.

This symbol indicates that a Slow Blow fuse is used in this equipment.
Replace with same type and value only

Complies with 89/336/EEC Electromagnetic
Compatibility Directive, amended by 92/31/
EEC and 93/68/EEC and meets the follow­ing standards:EN 55013 : 1990, Sections

3.2 and 3.5 EN 55020 : 1988, Sections 4.3,

5.4, 6.2, 7.0, 8.0.

EC-1 and EC-2 Specifications

Input Impedance

Balanced 20 Kohms
Unbalanced 10 Kohms

Input Headroom

+ 21 dB

CMRR

>50 dB, 20 Hz - 20KHz

Output Impedance

Balanced 300 Ohms (EC-2 only)
Unbalanced 150 Ohms

Output Level (Max)

21 dB

Filter Type

Linkwitz-Riley state variable 24dB per Octave

Frequency Response

30Hz(-0.5 dB) to 20KHz(-0.16dB)
Note: 30Hz figure is the High Pass Filter

Signal to Noise ratio

-90 dB Unweighted

-93 dB ‘A’ weighted (Unity gain)

Distortion

.004% THD @0 dB, 1KHz

Dynamic Range

111 dB

Power Requirements

100/120 V AC 220/240 V AC 50-60 Hz
8 Watts (8 VA)

Weight

5 lbs/2.2 Kg

Dimensions

19"W x 1¾"H x 6"D 482 x 44 x 155mm

Input Connector type

Jack (TRS), ( +XLR on EC-2)

Output Connector type

Jack, (XLR on EC-2)

EC-1 and EC-2 Owner's Manual v 1.6CE ©1997 ARX®EC-1 and EC-2 Owner's Manual v 1.6CE ©1997 ARX®2

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•Most crossovers are dedicated i.e. bought and used for a particular purpose. Once
the required frequency is set, there is no need to change it.

•Better value. A ten position switch for changing crossover points automatically has
90% of the filter circuitry unused...no matter which frequency you pick, the other 9
will be idle. We think you shouldn’t have to pay for excess circuitry you won’t be
using.

•Wandering fingers can cause immense damage to speakers by either deliberately
or accidentally changing crossover points. Once you have determined the optimum
crossover point and set it, the last thing you want is other people changing it. In
arental situation this can render PA systems unusable; in the studio, arbitrarily
changing the crossover point can drastically upset the room EQ and the final mixes.

The ‘semi fixed’ method adopted in the EC-1 and EC-2 avoids all these problems.

Front Panel Controls

• Marker panel for Channels A and B

• Low output control for Channel A in 2 way and 3 way mode

• High output control for Channel A in 2way mode only

• Low output control for Channel B in 2 way mode, and Mid output control in
3 way mode

• High output control for Channel B in 2 way and 3 way mode

• 2 way/3 way mode LEDs. (EC-2 only)

Rear Panel Connectors

EC-1

2 Way and 3 Way Modes

In 2 way mode, the crossover is a dual channel (stereo) unit. Each of the channels
has a 24 dB, Linkwitz Riley filter which divides the incoming signal into Low and
High at the chosen frequency.

In 3 way mode the crossover is a single channel (mono) unit. The switch on the rear
panel directs the output of the Channel A High frequency into the Input of Channel
B, so that the filter from Channel B can be used as a Mid/High filter.

In order for this to work, Channel B must be set up as a Mid/High filter. If it is left
as a Low/High filter (as in stereo 2 way mode) it won’t work!

So, for single channel 3 way mode, it’s not enough to just press the switch in on the
rear panel! You must set up the filters correctly for 3 way use. The chart in this
manual (Page 6) will give you a choice of typical filter points and their correct
resistor values.

Each crossover point can be changed in the time it takes to change 4 resistors (all of
them the same value). Replace the lid, and the unit is virtually tamper-proof.

Summed Mono Out (EC-2 only)

Many Bass crossover applications (especially Sub Bass) sound a lot better (and often
louder) with a mono feed. This removes small phase and amplitude differences
that can cause unintentional shifting of the stereo image and blurring of the bass
signal. Since frequencies 100 Hz and below are usually agreed to be non-directional,
a mono feed makes a lot of sense.

The EC-2 sums the Low Outputs of Channel A and B and delivers them to a
separate summed mono output on the rear panel. Note: It delivers the same
frequencies that the Low Outputs of Chanel A and B deliver, but in a summed mono
form. It is not a separate Sub Bass output. However, if the crossover has been set up
as a Sub Bass unit (100-120Hz and below), then Sub Bass will come out of the
summed mono output.

EC-2

• Input for Channel A in 2 way mode; Input for 3 way mode

• Low output for 2 way and 3 way modes

• High output for 2 way mode; not used in 3 way mode

• Mode switch: 2 way stereo(OUT), 3 way mono (IN)

• Input for Channel B in 2 way mode; not used in 3 way mode

• Low output for Channel B in 2 way mode; Mid output in 3 way

• High output for Channel B in 2 way and 3 way mode

• A+B Low Frequency sum output (EC-2 only)

• IEC 3 pin AC connector and integral fuseholder. Replace fuse with correct
value only: 100 - 120 V AC 1 amp, 220-240 V AC 0.5 amp. Please also refer
to voltage details on Page 2

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EC-1 and EC-2 Crossover Frequency Selection

WARNING!

THE FOLLOWING SERVICE INFORMATION IS FOR QUALIFIED

TECHNICIANS ONLY. SWITCH OFF AC POWER AT THE WALL AND

REMOVE POWER CABLE FROM THE WALL SOCKET BEFORE
PROCEEDING. FAILURE TO DO THIS CAN EXPOSE YOU TO LIFE
THREATENING VOLTAGES! ARX ACCEPTS NO RESPONSIBILITY

WHATSOEVER FOR PERSONAL DAMAGE CAUSED THROUGH

DISREGARDING THIS ADVICE.

1. Check that the unit is disconnected from the power at the wall socket.

EC-1 and EC-2 Owner's Manual v 1.6CE ©1997 ARX®EC-1 and EC-2 Owner's Manual v 1.6CE ©1997 ARX®

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2. Remove the four (4) self tapping screws (2 each side) holding the lid to the
chassis, and lift off the lid.

3. Turn the unit around so the knobs are facing you .

4. You will see two areas with eight (8) rectangular pads, with an ‘R’ marked beside
each 4 pads. Resistors are surface mounted horizontally between these pads.

The crossover frequency is changed by varying the value of these 4 resistors per
channel. The value of the resistors is the same for all 4. For accuracy we recommend
the use of 1/4 watt 1% metal film resistors.

For 3 way operation the Channel A frequency is the lower crossover point (eg. Low
to Mid) and the Channel B frequency is your upper crossover point (eg. Mid to
High). Remember, too, that for 3 way use the 2 way/3 way switch on the rear panel
must be pushed IN.

To change your crossover point simply select the frequency required from the
following table, obtain the correct value resistors and carefully solder them between
the pads. The table lists 18 commonly used crossover frequencies, which have been
carefully chosen to enable you to use easily obtainable resistor values.

Crossover Point Frequency/Resistor Value Chart

Frequency Resistor Value

80 Hz 510 K ohms
100 Hz 390 K ohms
125 Hz 330 K ohms
150 Hz 270 K ohms
200 Hz 220 K ohms
250 Hz 160 K ohms

500 Hz 82 K ohms
800 Hz 51 K ohms
1 KHz 39 K ohms

1.25 KHz 33 K ohms
2 KHz 20 K ohms

2.4 KHz 18 K ohms

2.8 KHz 15 K ohms

3.5 KHz 12 K ohms
5 KHz 8.2 K ohms
6 KHz 6.8 K ohms
8 KHz 5.1 K ohms
10 KHz 3.9 K ohms

Introduction

Thank you for choosing this ARX Electronic Crossover. We hope you enjoy using it
as much as we enjoyed creating it. As with all ARX equipment, it has undergone
extensive factory calibration and ‘burn in’ before shipping. To ensure continued
trouble free use, please familiarise yourself with the contents of this manual,
especially if you are planning on modifying the crossover points.

About the EC-1 and EC-2

The twin keynotes of any active crossover, or frequency dividing system, would be
accuracy and transparency. For accuracy, the crossover point must exactly
complement the requirements of the drivers, and for transparency the crossover
must not colour the sound in any way.

With this in mind, ARX design engineers have developed the EC-1 and EC-2,both
flexible, ‘user friendly’ 24 dB per octave, Linkwitz Riley, Phase Correct electronic
crossover in a single rack unit.

They have 2 modes of operation: as a Stereo 2 way crossover, or a Mono 3 way
crossover, with user variable crossover points. A switch on the rear panel selects
either mode.

Despite their compact size, the EC-1 and EC-2 are not short of features. All controls
are clearly labelled on the front panel for either mode of operation; Low/High
Channel A, Low/High Channel B for 2 way mode, and Low/Mid/High for 3 way.
Other features include Balanced TRS inputs, and a preset 12 db per octave High
Pass filter to remove Subsonics that can damage speakers and waste amplifier
power.The EC-2 has Balanced XLR Inputs and Outputs, plus a Low Frequency sum
output in 2 way mode, which provides a mono A+B output.

True Linkwitz Riley 24 dB per octave (Fourth Order) State Variable Filters are used
throughout, ensuring a smooth transition through the crossover region, with up to 6
dB of gain available to compensate for amplifiers and speakers of differing
sensitivities.

In addition to this, as on all ARX single rack unit equipment, there is a numbered
marker panel you can write on for easy ‘at-a-glance’ confirmation of crossover
assigns.

About Electronic (Active) Crossovers

Electronic crossovers are inserted into the signal chain directly before the amplifier.
In 2 way mode they divides the frequencies into LOW and HIGH; in 3 way mode
into LOW, MID and HIGH.

Each of these audio bands will require its own amplifier; in 2 way mode, one for
LOW and one for HIGH; in 3 way mode, one for LOW, one for MID and one for
HIGH.

The EC-1 and EC-2 crossover points are determined internally by the value of 4
resistors per filter. We call this ‘semi fixed’ and believe it is a far more reliable
method of changing crosover points than switching or infinitely variable controls
for the following reasons:

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EC-1 and EC-2 Owner's Manual v 1.6CE ©1997 ARX®EC-1 and EC-2 Owner's Manual v 1.6CE ©1997 ARX®

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