ASL INTERCOM PS 230 User manual

January 2017
V1.0
PS 230
DUAL CHANNEL
REMOTE SPEAKER STATION
User Manual

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Table of contents
1.0!GENERAL*DESCRIPTION*.............................................................................................*3!
2.0!INSTALLATION*..........................................................................................................*4!
3.0!FRONTPANEL*CONTROLS*&*CONNECTORS*.................................................................*4!
4.0!SIDE*PANEL*CONNECTORS*.........................................................................................*7!
5.0!INTERNAL*CONTROLS*................................................................................................*7!
6.0!TECHNICAL*SPECIFICATIONS*......................................................................................*8!
7.0!PS*130*BLOCK*DIAGRAM*...........................................................................................*9!
8.0!PARTY*LINE,*TECHNICAL*CONCEPT*...........................................................................*10!
9.0!CABLING*.................................................................................................................*10!
10.0!SYSTEM*CONFIGURATION*.......................................................................................*12!
11.0!EARTHING*CONCEPT*...............................................................................................*13!

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1.0 GENERAL DESCRIPTION
The PS 230 is a dual channel speaker station designed for use in an ASL analog intercom
system and provides full duplex communications.
The unit incorporates a loudspeaker, a gooseneck microphone and a headset connector
The PS 230 RM model has, instead of a gooseneck mic, a small built-in electrets mic.
Each channel has Volume (listen level) Control, a TALK and CALL button with LED indica-
tors and a 2-stage side tone trimmer. There is a trimmer for speaker attenuation and one
for buzzer volume.
The unit is equipped with a limiter for the gooseneck microphone, allowing the user to
speak close into the microphone without giving rise to overload and distortion.
Loudspeaker dimming is automatic if the gooseneck microphone is active.
Private conversation may be carried out via a headset or telephone handset plugged into
the headset connector. If a headset is connected, both the gooseneck microphone and
speaker are disabled automatically.
The XLR-4 headset connector can be replaced (by ASL) by a XLR-6 connector for binaural
use of the headset.
Special attention has been paid to the intelligibility of speech. By applying low noise/high
speed op-amps, a speech presence filter and a specially developed high power bridged
headphone amplifier, communication is very comfortable even in environments with high
back-ground noise level. There is a separate amplifier for the loudspeaker.
The unique ASL CALL system provides both a flashing red LED and a very characteristic
sound signal (the buzzer). Smooth operation is guaranteed with the CALL button. Only a
slight touch makes the red LED flash, whilst holding the button for two seconds activates
the CALL sound signal. The volume of this signal (the buzzer) can be adjusted at the front
panel.
Fully electronic switching allows for 'soft' microphone on switching (latching or momen-
tary), remote Mic Mute facility and automatic speaker attenuation.

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2.0 INSTALLATION
Connect the intercom party lines to the LINE connectors on the side panel of the PS 230.
The necessary DC voltages are derived from a master station or a separate power supply,
via the intercom connection cables. Use professional microphone cable with 2 wires and
1 shield only.
The PS 230 is fully protected against wiring mistakes (reverse power) or short circuit in the
interconnecting cables.
A kit is available for mounting the PS 230 in a 19" rack, taking 2U of rack space.
3.0 FRONTPANEL CONTROLS & CONNECTORS
1 VOLUME control knobs
To adjust the listen level for the headset and the loudspeaker.

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2 TALK buttons
This push buttons (one for each channel) activates the gooseneck or headset micro-
phone. The large green LED indicates if the microphone is switched on.
Momentary switching:
If the TALK button is pushed and held, the microphone signal is sent to the intercom
channel until the button is released.
Latched switching:
If the TALK button is pushed quickly it is electronically latched and the microphone sig-
nal is sent to the intercom channel. If pushed again, the TALK button switches off.
Mic Mute when latched on:
After on the intercom channel a so-called MIC Mute signal has been received from a
PRO Series master station or separate power supply, the connection between micro-
phone and intercom channel is interrupted. By pushing the TALK button the connection
is restored again.
3 CALL buttons
This push buttons (one for each channel) activates the call system. By a momentary
push a visual call signal is sent to all stations connected to the intercom channel and the
call LEDs start flashing. By keeping one of the CALL button pushed for 2 seconds the call
buzzer is activated, provided there is no ‘buzzer mute’ on one or both intercom chan-
nels. After the CALL button is released the LEDs continue to flash for a further 2 se-
conds.
4 SIDE TONE LEVEL trimmer
These trimmers (one for each channel) are for minimizing the speaker feeding back into
the gooseneck microphone (unit feedback). They also determine the level of your own
voice as you hear it in the speaker or headset.
5 SIDE TONE HI trimmer
These trimmers, one for each channel, have the same purpose as trimmer #4, but solely
for the high frequencies.
Adjustment procedure for both side tone trimmers:
• set trimmer in start position: fully clockwise
• switch off the microphones of all connected (speaker) stations
• make sure there is no automatic speaker attenuation (turn trimmer #6 fully

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clockwise)
• push the TALK button
• slowly turn up the listen volume
• speak into the gooseneck microphone
• adjust the speaker listen level to a minimum by turning the side tone trimmers
counter clockwise (first trimmer #4 and then trimmer #5; repeat this a few times)
• Connect a headset to the PS 130 (the speaker and gooseneck mic are now auto-
matically disabled) and speak into the headset microphone
• Check whether the level of your voice in the headset can(s) is sufficient. If not,
push up the listen level a bit by turning side tone trimmer #4 clockwise.
The trimmers operating area is between fully clockwise and minimum level. Adjusting
the side tone does not affect the level of your voice as it is heard by other stations.
6 SPEAKER ATTENUATOR trimmer
To adjust the extent to which the speaker is automatically dimmed if the gooseneck mi-
crophone is switched on. It prevents unit feedback if side tone rejection is not sufficient.
It also minimizes system feedback or a 'hollow' sound when the gooseneck microphones
of other speaker stations on the intercom channel are switched as well.
Adjustment procedure:
• make sure there is no headset connected
• feed an audio signal into the intercom channel (via an AUX input on a master sta-
tion or a separate power supply)
• turn up the listen volume
• activate the gooseneck microphone (push the TALK button)
• adjust the desired degree of speaker attenuation (turning the trimmer counter-
clockwise increases the attenuation)
7 BUZZER VOLUME trimmer
To adjust the volume of the internal buzzer. The buzzer is activated if a CALL button of
the PS 230 is pushed (or a CALL button of any other station on a channel to which the PS
230 is connected) longer than 2 seconds, provided there is no ‘buzzer mute’ on one of
the channels.
8 HEADSET connector
An XLR-4 connector for the connection of a local headset when private conversation is
desired. The headset must have a can with an impedance of 200 ohms minimum, or
have two cans in parallel each 400 ohms minimum. The headset microphone may be a
dynamic or electret type.

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XLR-4 pin assignments:
pin 1. Shield mic. (GND)
pin 2. mic. +
pin 3. phones +
pin 4. phones
When a headset is connected, the speaker and gooseneck microphone are disabled au-
tomatically.
9 GOOSENECK MICROPHONE
An electret noise canceling gooseneck microphone. A limiter prevents the microphone
preamplifier from clipping when speaking close into the microphone
10 LOUDSPEAKER
A high quality 16 Ωloudspeaker
4.0 SIDE PANEL CONNECTORS
11 LINE connectors
These connectors are for connecting
the PS 230 to the intercom system.
XLR-3 pin assignments :
1. 0 V /ground shield
2. +30V power wire
3. audio wire
The female connector is for input, the
male connector for extending the in-
tercom line to other stations.
5.0 INTERNAL CONTROLS
Inside the unit there are two trimmers to adjust the mic gain of the gooseneck micro-
phone and the headset microphone separately. The trimmers are located on the PC
board.

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The trimmers can be reached as follows:
• remove the screws of the bottom plate
• slide the plate to one side and take it out
• take away the plastic isolation plate
The two trimmers are labeled :
‘GOOSE’ for the gooseneck microphone
‘HEADS’ for the headset microphone
6.0 TECHNICAL SPECIFICATIONS
System
• Dynamic range: 80 dB (1 kHz, THD < 1%)
• Frequency response: 200 Hz - 15 kHz (-3 dB)
• Call signal: 2.8 mA
• Call signal threshold (receive): +2.4V DC
• Operating voltage: 24 – 32 V DC
• Power interrupt time (mic mute): 0.1 sec
Intercom Line
• Line Impedance: 350 Ω(1 kHz) / 2.2 kΩ(DC)
• Audio level: nom. -18 dBu, max. 0 dBu
Mic pre-amp
• Gain: 40 – 60 dB (adjustable internally, separately for the headset mic and the
gooseneck mic)
• Presence filter: +6 dB at 5 kHz
• Power to electret mic: +9V DC
• Limiter range (gooseneck mic): 30 dB
Headphone Driver Amps
• Max output level: 16 Vrms @ 200 Ω
• Max output power: 1.3 Wrms @ 200 Ω
Speaker Driver Amp
• Max. output power: 1.6 Wrms @ 16 Ω

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Side Tone
• Rejection: 0 – 30 dB adjustable
Buzzer
• Max. SPL: 85 dBA
PS 230 Power Consumption (@ 30V DC)
• 35 mA quiescent, 70 mA signalling
• 190 mA at max. output + signaling
PS 230 Dimensions & Weight
• Width: 230 mm / Height: 88 mm
• Depth:42/48 mm sloping / Weight: 1300 grams
0 dB is defined as 775 mV into open circuit
ASL reserves the right to alter specifications without prior notice
7.0 PS 130 BLOCK DIAGRAM

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8.0 PARTY LINE, TECHNICAL CONCEPT
User stations and power supplies in an ASL intercom system are connected via one or
several 'party lines'.
A party line offers two-way (‘full duplex’) communication and consists of standard micro-
phone (multi-pair) cable. One wire is used as an audio line, one as a power line and the
screen of the cable functions as earth/return.
Current drive is used for signal transfer.
Each station utilizes a current amplifier to amplify the microphone signal. That signal is
put on the common audio line. Due to the constant line impedance, a signal voltage is
developed which can be further amplified and sent to the headphones or loudspeakers.
This principle has three advantages:
• the use of a single audio line allows several stations to talk and listen simultane-
ously
• due to the high bridging impedance offered by each station, the number of sta-
tions on the party line has no influence on the level of the communications audio
signal
• power and audio to the intercom stations use the same cable
The Call signal is sent as a current, on the audio wire. It develops a DC potential over the
line impedance which is sensed by each intercom station and interpreted as a Call sig-
nal.
9.0 CABLING
The intercom lines (the ‘party lines’) in an ASL analog intercom system are of the shielded two-
conductor microphone cable type. The intercom line connectors are of the XLR-3 type. Audio and
Call signals are on pin 3, DC power is on pin 2 and pin 1 is connected to the shield of the cable
which functions as the common return for audio and power.
The audio signal is transferred in an unbalanced way (see ‘Party Line, Technical Concept’).
To avoid earth loops (hum), the possible effect of electromagnetic fields and to minimize power
loss, certain rules have to be obeyed when installing the cabling of an intercom system :