Axel Merlin User manual

Operating Manual
(Rel. 1.3)
Merlin
Broadcast Audio Changeover
Via Caduti Di Sabbiuno 6/F •40011 Anzola Emilia •Bologna •Italy [phone] •Fax. [phone]
e-mail: [e-mail] •web site: www.axeltechnology.com

Merlin -TABLE OF CONTENTS
Pag. 3
1 TABLE OF CONTENTS
1TABLE OF CONTENTS.............................................................................................................................................. 3
2INTRODUCTION......................................................................................................................................................... 5
2.1 MERLIN OPTIONAL MODULES........................................................................................................................ 6
3SAFETY WARNINGS ................................................................................................................................................. 7
4CONNECTING MAINS POWER............................................................................................................................... 8
4.1 EARTHING............................................................................................................................................................ 8
5INSTALLATION........................................................................................................................................................ 10
5.1 UNPACKING AND INSPECTION..................................................................................................................... 10
5.2 AC MAINS VOLTAGE SETTING (220 V / 115 V)............................................................................................ 10
5.3 RACK MOUNTING THE UNIT.......................................................................................................................... 11
5.4 REMOVING THE TOP COVER ......................................................................................................................... 12
5.5 GROUNDING ...................................................................................................................................................... 12
6GENERAL DESCRIPTION...................................................................................................................................... 13
6.1 FRONT PANEL.................................................................................................................................................... 13
6.2 REAR PANEL...................................................................................................................................................... 15
7CONFIGURATIONS.................................................................................................................................................. 17
7.1 INPUT SWITCHING MODES (JUMPER SETTING) ........................................................................................ 17
7.2 SWITCHING-RELATED AUDIO LEVELS....................................................................................................... 19
7.2.1 ‘SILENCE’ THRESHOLD ............................................................................................................................ 19
7.3 INPUT SWITCH TIMING................................................................................................................................... 19
7.3.1 ‘SILENCE’ TIME.......................................................................................................................................... 19
7.3.2 RECOVERY TIME ........................................................................................................................................ 21
7.4 MONO / STEREO INPUT MODE....................................................................................................................... 22
7.5 INPUT B PRE-EMPHASYS ................................................................................................................................ 23
7.6 19 KHZ PILOT TONE ACTIVATION................................................................................................................. 24
7.7 INJECTION OF AN EXTERNAL SOURCE....................................................................................................... 25
7.8 SWITCHING BETWEEN COAXIAL SOURCES (VIDEO, MPX, ETC) .......................................................... 27
8ADJUSTEMENTS...................................................................................................................................................... 28
8.1 REFERENCE TONE LEVEL AND FREQUENCY............................................................................................ 28
8.2 PILOT TONE FREQUENCY............................................................................................................................... 29
8.3 PILOT TONE INJECTION LEVEL ON B-RIGHT & B-LEFT CHANNELS.................................................... 30
8.4 LEVEL OF INJECTION OF AN EXTERNAL SIGNAL ON L&R OUTPUT CHANNELS..............................31
9AUDIO AND REMOTE INTERFACE DESCRIPTION........................................................................................ 32
9.1 AUDIO CONNECTIONS..................................................................................................................................... 32
9.1.1 INPUTS......................................................................................................................................................... 32
9.1.2 INPUT IMPEDANCE SETTING................................................................................................................... 32
9.1.3 PIN RCA CONNECTOR ASSIGNMENT ...................................................................................................... 33
9.1.4 OUTPUT....................................................................................................................................................... 34
9.2 ‘OPTO’INTERFACE............................................................................................................................................ 35
9.3 SPECIAL SWITCHING FEATURES.................................................................................................................. 37
9.4 ‘RELAY’ INTERFACE (OPTIONAL)................................................................................................................ 38
9.4.1 Relay 1, Relay 2 and Relay 3 assignment...................................................................................................... 39
9.4.2 Relay 1 assignment to Dc POWER failure.................................................................................................... 42

Merlin -TABLE OF CONTENTS
Pag. 4
9.4.3 Momentary or Latched Relay setting............................................................................................................ 43
10 VCA OPTION......................................................................................................................................................... 44
10.1 CROSSFADE MODE........................................................................................................................................... 45
10.2 AUTOFADER MODE.......................................................................................................................................... 45
11 BLOCK DIAGRAM............................................................................................................................................... 46
12 TECHNICAL SPECIFICATIONS........................................................................................................................ 47

Merlin -INTRODUCTION
Pag. 5
2 INTRODUCTION
The Merlin is designed to provide sophisticated changeover of audio signals, such as stereo pairs and even FM
multiplex and video composite signals. Incoming signals are constantly monitored and if a fault is detected on
the signal applied to a set Input, it will switch to a stand-by source (such as a CD), in order to keep
transmissions running.
The Merlin fulfils the needs of every radio station for manual or automatic (emergency) switching between
different audio sources. Multiple switching mode are provided (switch on stand-by input only when active,
switch and stay on the second input, etc). Up to 7 internal relays can be associated to the audio switching for
further alarm signalling, external signal routing, starting CD players etc.
Using internal and front settings, the Merlin can be easily re-configured for a variety of applications, either in the
radio or in the video field. The delay times before switching and before returning to the normal state (recovery)
are easily set by trimmers and jumpers.
The Merlin features both XLR balanced and PinRca audio inputs for an easier connection to either professional
or consumer equipment. Each pair of PinRca inputs can be also reverted to unbalanced ‘foldback’ outputs. The
balanced XLR output stage incorporates high-current line drivers capable to always deliver optimal signals
even down long cable runs and with low load impedance. Bnc, 75 Ohm terminated connectors are available for
video and Mpx signals.
Expressly designed for broadcast applications, Merlin features an hardware bypass (via relay) which connects
the Input 1 pair (and the Coaxial Input 1 as well) to the Output (both XLRs and Bnc) in case of AC power failure
or whenever the unit is unintentionally turned off. This prevents the transmission chain from any audio
interruption.
The electronically balanced stereo inputs feature individual left / right gain controls with two bi-color LEDs
enabling quick recognition of input status (no audio, audio ranging between - 6 and + 3 dBm or audio higher
than + 3 dBm dB).
The Merlin is very easy to install and to operate. A ‘0 dB gain’ mode can be selected for each output channel
via front panel accessible slide switches. For fine calibration of the outputs, the source signal can be replaced
by an internal 1kHz / 0 dB oscillator.
The rear panel includes a remote control / monitoring socket (optoinsulated) which may be used to connect
external warning circuit. The contacts are open during normal operation and close during failure. These relays
may be used to activate an external alarm in the event of a failure - even in case of missing power. An external
control may be also applied to force the switching from remote.
The Merlin can be equipped with plug-in, optional modules which greatly improve its application fields: MPX
decoder, Video monitor, Serial monitor and Crossfade module.
Merlin highlights:
• Audio changeover 2 inputs /1 output
• Double Audio Detector fully user-settable
• Fully configurable for a range of applications
• Wide remote control capabilities
• Complete control of stereo audio, FM multiplex / Video composite source failures
• Hardware Bypass in case of AC Main failure
• Internal 1kHz / 0 dB oscillator
• Automatic / manual operation

Merlin -INTRODUCTION
Pag. 6
2.1 MERLIN OPTIONAL MODULES
MPX An MPX decoder is applied to the incoming MPX signals, resuming the Left and Right audio
channels form the composite signal and routing them to the Input A for regular detection (see
above). A pilot detector is also provided (which can be disabled), switching to the backup
signal if pilot is lost.
SERIAL
A decoder is provided which constantly monitors serial RS 232 connection activity and
provides contact closures (f.i. a RESET command) in case of connection freezing lasting
more than a pre-set time. A dedicated software application running on Windows platforms
comes with the unit.
VCA It allows cross-fades between sources, with fully configurable rising / fading times and levels.
VIDEO A special stage watches after video sync switching to the backup signal if it is lost
RELAY Set of 5 internal relays

Merlin -SAFETY WARNINGS
Pag. 7
3 SAFETY WARNINGS
A correct installation and an optimum level setting are crucial for a good operating and the exploitation of all the
equipment capabilities. Please pay attention to the following notes:
The installation and servicing instructions in this manual are for use by qualified
personnel only.
This symbol alerts you to the presence of dangerous voltage inside the closure –
voltage which may be sufficient to constitute a risk of shock. Do not perform any
servicing other than that contained in the operating instructions. Refer all servicing to
qualified personnel
• Read All Instructions. All safety and operating instructions must be read before operating the product.
They also must be retained for future reference, as it contains a number of useful hints for determining the
best combination of equipment settings for Yr particular application.
• Heed All Warnings. All warnings on the product and those listed in the operating instructions must be
adhered to.
• Heat. This product must be situated away from any heat sources such as radiators or other products
(including power amplifiers or transmitters) that produce heat.
• Power Sources. This product must be operated from the type of power source indicated on the marking
label and in the installation instructions. If you are not sure of the type of power supplied to your facility,
consult your local power company. Make sure the AC main voltage corresponds to that indicated in the
technical specifications. If a different voltage (ex. 110/115 VAC) is available, open the equipment closure
and set the voltage switch on the main supply circuit, located behind the AC socket.
• Power Cord Protection. Power supply cords must be routed so that they are not likely to be walked on nor
pinched by items placed upon or against them. Pay particular attention to the cords at AC wall plugs and
convenience receptacles, and at the point where the cord plugs into the product.
• Lightning. For added protection for this product during a lightning storm, or when it is left unattended and
unused for long periods of time, unplug it from the AC wall outlet and the audio connections. This will
prevent damage to the product due to lightning and power line surges.
• Installation. Configuration and installation should only be carried out by a competent installation engineer.
• Cabling. Using high quality wires, well protected. Make sure the cable integrity.
• Equipment design. This manual images could differ a bit from the equipment actual design.

Merlin -CONNECTING MAINS POWER
Pag. 8
4 CONNECTING MAINS POWER
WARNING: Make sure the power supply voltage is correctly set to match your local mains voltage. Refer to
the Power Supply Chapter in this operating manual. Before connecting the unit to mains power, determine the
actual mains voltage and confirm that it has been configured correctly. As could be expected, an incorrect
mains configuration could seriously damage the unit. Should it be necessary to change the unit’s operating
voltage refer to the Power Supply Chapter in this operating manual.
The Power Supply unit accepts mains voltages 100 and 230V AC by setting the position of an internal switch..
4.1 EARTHING
WARNING: THIS EQUIPMENT MUST BE EARTHED
The connection to earth (ground) in an audio system is crucial for two reasons:
1. SAFETY
2. AUDIO PERFORMANCE
For safety it is important that all equipment earths are connected to mains earth so that exposed metal parts
are prevented from carrying high voltage which can injure the operator.
The same earth is also used to shield audio cables from external interference such as the hum fields
associated with power transformers, lighting dimmer buzz, and computer radiation. Problems arise when the
signal sees more than one path to mains earth. An earth loop results causing current to flow between the
different earth paths. This condition is usually detected as a mains frequency audible hum or buzz. To ensure
safe and trouble-free operation we recommend the following:
Use a clean mains outlet for the audio system: Be sure to use a 'clean' power outlet, i.e. one that
is fed directly from the mains, including earth. "Polluted" mains are caused by changing currents on the outlets,
such as air-conditioners, coffee machines, fridges, computers, dimmer packs etc. DO NOT connect any of
these types of items to the Merlin main power outlet.
Use star point earthing: It is best to install a ‘star point’ system where the individual earths to the
equipment racks and equipment areas are separately run from a solid central reference earth point.
Have your mains system checked by a qualified electrician.
Do not remove the earth connection from the Merlin mains plug: The Merlin chassis is
connected to mains earth through the power cable to ensure your safety. If problems are encountered with
earth loops disconnect the audio cable screens at one end, usually at the destination. Equipment such as CD
players do not have a mains ground connection. In this case the shielding can be connected on both sides of
the connection - a ground loop will not occur. Try to choose a CD player with metal housing.
Avoid induced interference: To prevent interference pickup keep audio cables away from mains power
units, cables and distribution boards, motors, lighting and computer cables and equipment, and any other
heavy duty electrical equipment. Where this cannot be avoided cross the audio and ‘dirty’ equipment cables at
right angles to minimise interference.

Merlin -CONNECTING MAINS POWER
Pag. 9
Use balanced connections where possible as these provide further immunity by cancelling out
interference that may be picked up on long cable runs. To connect an unbalanced source to a Merlin input
(balanced), link the cold input (XLR pin 3 or jack ring) to 0V earth (XLR pin 1 or jack ground) at the Merlin side.
To connect the Merlin output (balanced) to an unbalanced destination, link the cold output to 0V earth at the
changeover side.
Use good quality cables and connectors and check for correct wiring and reliable solder joints.
Allow sufficient cable loop to prevent damage through stretching.
If you are not sure ... Contact your Axel Technology agent or Axel Technology tecnical support
([email protected]) for advice.

Merlin -INSTALLATION
Pag. 10
5 INSTALLATION
5.1 UNPACKING AND INSPECTION
If you note obvious physical damage, contact the carrier immediately to make a damage claim. Packed with the
unit are:
1 Operating Manual
1 Line Cord
Save all packing materials! If you should ever have to ship the unit (e.g., for servicing), it is
best to ship it in the original carton with its packing materials because both the carton and
packing material have been carefully designed to protect the unit.
Under normal conditions no user maintenance or calibration are required. Internal links and preset controls may
be set to configure the unit during installation. Any service work required should be carried out by qualified
service personnel only.
We are able to offer further product support through our worldwide network of approved dealers and service
agents.
To help us provide the most efficient service please would you keep a record of the unit serial number, and
date and place of purchase to be quoted in any communication regarding this product.
5.2 AC MAINS VOLTAGE SETTING (220 V / 115 V)
BE SURE THAT THE UNIT IS SET TO THE CORRECT MAINS/LINE
VOLTAGE FOR YOUR COUNTRY BEFORE PLUGGING IT INTO THE
WALL OUTLET !
The actual Mains voltage is indicated on the label stuck on the equipment closure.
If, for some reason, the unit is to be operated at a mains input voltage which is different to that as supplied, you
need to open the top cover and set properly the voltage change-over switch which is located inside, close to
the transformer (on the right hand). You also need to replace the AC main fuse (rated at 500mA T for both AC
tensions)