Axel Macrotel DIGITAL User manual

Operating manual
(Rel. 1.1)
Via Caduti Di Sabbiuno 6/F •40011 Anzola Emilia •Bologna •Italy [phone] •Fax. [phone]
e-mail: [e-mail] •web site: www.axeltechnology.com
MacrotelDIGITAL
DIGITAL STUDIO TELEPHONE HYBRID

MacrotelDIGITAL
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CONTENTS
1
INTRODUCTION ....................................................................................................................................................4
1.1 MAIN FEATURES.............................................................................................................................................4
2 EQUIPMENT DESCRIPTION...............................................................................................................................5
2.1 FRONT PANEL..................................................................................................................................................5
2.2 REAR PANEL....................................................................................................................................................6
3 WIRING AND CONNECTIONS............................................................................................................................7
3.1 AUDIO INPUT (SEND).....................................................................................................................................7
3.2 AUDIO OUTPUT (RECEIVE AND REC OUT ).....................................................................................................8
3.3 REMOTE INTERFACE.....................................................................................................................................9
3.4 TEL LINE CONNECTION ................................................................................................................................9
3.5 PHONE SET CONNECTION ..........................................................................................................................10
3.6 HEADPHONES JACK.....................................................................................................................................10
4 SETTINGS..............................................................................................................................................................11
4.1 DIP SWITCHES SETTING..............................................................................................................................11
5 OPERATION..........................................................................................................................................................13
5.1 TRAINING THE TELEPHONE ECHO CANCELLER...................................................................................13
5.2 TRAINING THE MIX-MINUS........................................................................................................................13
6 BLOCK DIAGRAM...............................................................................................................................................14
7 TECHNICAL SPECIFICATIONS .......................................................................................................................15
8 WARRANTY ..........................................................................................................................................................15

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1 INTRODUCTION
Macrotel Digital is a single line digital telephone hybrid, especially designed to fit all TV and radio station
requirements.
With the variety of telephone systems in the world today, from cellular mobile phones to analog and to digital,
it’s increasingly difficult to have all callers sound the same on-air in a broadcast environment.
The Macrotel Digital uses digital signal processing (DSP) technology to continually adapt to telephone-line
conditions and to deliver the maximum isolation between the send and receive audio (> 55 dB).
With no echo and no "bottom of the barrel" sound, the Macrotel Digital is thus ideal when the very best audio
quality and uniformity is required for talk shows, news feeds, production, recording studios, and even internet
applications.
Several functions (selectable from front panel DIP switches) greatly expand its operation. Automatic
gain control (AGC) allows each call to be delivered at the same level. Built-in caller Ducking stage
reduces the caller's audio level when the announcer speaks. Auto mix-minus feature allows easy
installation to consoles with no mix-minus capability.
Additionally, the hybrid can automatically answer the telephone line after the first ring and automatically
disconnect it after the caller hangs up. The REC Output can be configured to contain a mix of send and
caller audio or caller audio only.
In accordance to mainland Europe, USA, Canada, and UK compliance standards, the Macrotel Digital is
perfect for your telephone application.
1.1 MAIN FEATURES
•Crystal clear, consistent audio quality
•Continual adaptation to POTS line conditions
•Best isolation between Send and Receive audio
•Selectable caller control (ducking)
•Worldwide compliant
•Full Remote control
•Selectable mic / line level input
•Selectable automatic mix-minus
•Selectable AGC on Receive signal
•Selectable auto-answer / auto-disconnect

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2 EQUIPMENT DESCRIPTION
2.1 FRONT PANEL
Send potentiometer it adjusts the level of audio signal sent to phone caller. At its midpoint (6 o’clock
position), the pot is set for nominal send level (0dBm).
Aux-in potentiometer It adjusts the level of the auxiliary send audio coming from the remote connector
input and going onto the telephone line to the caller. At its midpoint (6 o’clock
position), the pot is set for nominal level (0dBm).
Receive potentiometer it adjusts the phone subscriber audio level which is provided to the user ’s
equipment
Rec-Out potentiometer it adjusts the level of the audio at the Rec-Out connector. At its midpoint (6 o’clock
position), the pot is set for nominal level (0dBm).
DIP Switches
these DIP switches configure the hybrid’s system. Individual switch functions are
defined in Calibration Chapter
Send LED
it indicates the relative level of the send audio into the digital hybrid. Green
indicates nominal level, amber indicates caution, red indicates clipping.
Receive LED it indicates the relative level of the caller audio from the telephone line. Green
represents nominal level, amber indicates caution, red indicates clipping.
Hook button it allows Line hooking i.e. it connects the hybrid to the telephone line
Hook LED it blinks when a call (ring) is coming in and lights firmly while line is hooked.
Please note: led switchs on only if phone line is connected
Off button it disconnects the hybrid from the telephone line and mutes all audio going to and
from the telephone line
Off LED it indicates the hybrid is not connected to an active phone line. The LED
illuminates red when the hybrid is powered
Volume Up / Down these buttons control the audio level on the headphone monitor output. Pressing
once changes the level by 1dB. Pressing and holding a button sweeps the level up
or down

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2.2 REAR PANEL
ON/OFF main switch the led inside switchs on/off accordingly. If it is off while the switch is ON, please
check the supplied AC cord and the fuse
AC cord receptacle the power supply socket has an integral fuse drawer containing the power fuse
and a spare one
- for 220/230 V AC the fuse is rated at 250 mA T
- for 110/115 V AC tension the fuse is rated at 500 mA T
the voltage change-over switch is located inside, close to the transformer
Remote connector This DB25 female connector provides remote control and status of the hybrid.
Unbalanced send in, Receive out ,and Rec out audio are also available at the
remote connector. See Connector Pinouts at Chapter 3.3
Headphone Monitor 1/4" jack. It provides connection to a headphone or to a small loudspeaker for
monitoring the caller audio signal. Capable of 1 watt into an 8 ohm load
Send connector
This balanced, female 3-pin XLR input receives audio from the source
(microphone or mixer) and sends it to the caller. Audio sent to the caller must be a
mix-minus.
Receive connector This balanced, male, 3-pin XLR output contains the audio from the caller
Rec Out connector This balanced, male, 3-pin XLR output contains a mix of caller and send audio or
caller audio only. See DIP switches at Chapter 4. This connector can feed a
recording device to record both the caller and send audio
Line socket
This RJ11 connector provides connection of the telephone line to the hybrid
Set socket This RJ11 connector allows connection to a standard analog telephone set. The
telephone line is present at this connector when the hybrid is off. The telephone
line is not present at this connector when the hybrid is on

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3 WIRING AND CONNECTIONS
We suggest to use high quality wires, well protected, and balanced connections to avoid external EMD.
3.1 AUDIO INPUT (SEND)
The equipment features electronically balanced XLR female inputs (line level).
XLR pinout: Pin 1 Gnd
Pin 2 Signal
Pin 3 Return
If any balanced connection is possible, please connect the cold pole (Pin 3) to the ground (Pin 1).
Factory preset input impedance is 10 kΩ. Input impedance of 600 Ωis also available, simply setting jumpers
on the main board (see Chapter 4).
NOTE: The SEND female, 3-pin XLR input receives audio from microphone or mixer. If using
a single microphone that needs phantom power to operate, you must supply this power to
the microphone. The digital hybrid does not supply phantom power. Line/Mic input level
selection is done through front panel DIP switch # 4.

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3.2 AUDIO OUTPUT (RECEIVE AND REC OUT)
The equipment features XLR analog outputs electronically balanced by high-quality buffers, capable of
withstanding even low-impedance loads (600Ω), with levels of up to +20 dBu.
XLR pinout: Pin 1 Gnd
Pin 2 Signal
Pin 3 Return
In case of unbalanced connections, connect the cold pole (Pin 3) to the ground (Pin 1).

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3.3 REMOTE INTERFACE
Remote Connector Pinout
Pin Description
1 Remote Hybrid On
2 Remote Hybrid Off
3 Not used
4 Not used
5 Switch / Indicator Common
6 Not used
7 Not used
8 + 5 Volt dc (supplied via an internal 100 Ohm protection resistor)
9 Unbalanced AUX –IN Audio Input (0dBu nominal)
10 Unbalanced Receive Audio Output (0dBu nominal)
11 Unbalanced Rec Audio Output (0dBu nominal)
12 Monitor Mute Control*
13 Audio Common
14 Hybrid On Indication
15 Hybrid Off Indication
16 Not used
17 Not used
18 Switch/Indicator Common
19 Hybrid Send Presence Indicator
20 Hybrid Receive Presence Indicator
21 Switch/Indicator Common
22 Audio Common
23 Audio Common
24 Audio Common
25 Switch/Indicator Common
* Remote control provided via contact closure to Switch/Indicator
Common
** Remote indicators provided via open collector outputs to Indicator
Common (<15V, <39mA)
3.4 TEL LINE CONNECTION
Macrotel Digital hybrid operates on standard POTS (Plain Old Telephone Service) / PSTN (Public Switched
Telephone Network) analog telephone lines or an analog extension from a PBX via a standard RJ11
modular jack.
The RJ11 socket will accept 6 conductor modular plugs, but only the 2 central conductors (typically Red &
Green ) are used.

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3.5 PHONE SET CONNECTION
This RJ11 connector will accept 6 conductor modular plugs, but only the 2 central conductors (typically Red
& Green ) are used for connection to a standard analog telephone set. The telephone line is present at this
connector when the hybrid is off. The telephone line is not present at this connector when the hybrid is on
3.6 HEADPHONES JACK
1/4. Stereo Jack - Headphone plug allows connection to an external headphone
set.
Tip = + phase,
Ring = ground,
Sleeve = ground
1W output into an 8 Ohm load