G.R.A.S. 12AQ User manual

Instruction Manual
Power Module Type 12AQ
Skovlytoften 33, 2840 Holte, Denmark
www.gras.dk [email protected]
SOUND & VIBRATION
G R A S
...
.

Revision 04.12.2019
Power Module
Type 12AQ

G.R.A.S. SOUND & VIBRATION
CONTENTS
1 General Description ..............................................4
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Salient Features ...................................................4
Traditional preampliers ....................................................4
CCP preampliers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Signal Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Gain ...................................................................5
Input ..................................................................5
Ouput .................................................................5
Polarization voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Preamplier supply voltage..................................................5
Syscheck. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.4 Power Supply .....................................................5
2 External Features ................................................6
2.1 Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Manual Control ...........................................................6
2.2 Rear Panel .......................................................8
3 Internal Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1 Battery Compartment ..............................................10

G.R.A.S. SOUND & VIBRATION
4 Remote Control via RS-232 Interface ...............................11
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2 Interface ........................................................11
4.3 Behaviour .......................................................13
4.4 Commands and Responses .........................................13
Setup Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Special Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Special Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.5 Overload Responses ..............................................16
In Latched Mode .........................................................16
In Message Mode (non-latched) .............................................16
4.6 Power-up/down Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5 Service and Repair ..............................................18
6 Specications ..................................................19
7 Optional Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

G.R.A.S. SOUND & VIBRATION
Power Module Type 12AQ
Page 5
1 General Description
1.1 Introduction
The G.R.A.S. Power Module Type 12AQ (Fig. 1.1) is a dual-channel power supply for preampli-
ers (CCP as well as traditional) used with measurement, condenser microphones.
It has facilities for both manual control and remote control. Manual control is via its front-panel
switches and push buttons. Remote control is via its RS232 interface.
The Type 12AQ is for general use in acoustic measurements as well as for intensity measure-
ments; both in the laboratory and in the eld.
Fig. 1.1 The Power Module Type 12AQ
1.2 Salient Features
1.2.1 Traditionalpreampliers
For traditional preampliers such as Type 26AL (¼″) or Types 26AJ and 26AH (½″), the Type
12AQ provides:
• a voltage supply (± 15 V or ± 60 V) for powering up to two microphone preampliers.
• a polarization voltage (200 V or 0 V) for two condenser microphones.
• a SysCheck signal (1000 Hz) for calibration checks.
1.2.2 CCPpreampliers
For CCP (constant-current power) preampliers such as Types 26CB and 26CC (¼″) or Types
26CA and 26CF (½″), the Type 12AQ provides:
• a constant current supply (4 mA) sourced at 28 V DC for two CCP microphone preampliers.

G.R.A.S. SOUND & VIBRATION
Power Module Type 12AQ
Page 6
1.3 Signal Conditioning
Each channel can be set up independently in terms of gain, lter, input, output and polarization
voltage. The bandwidth of the signal conditioner is:
1.3.1 Gain
Type 12AQ has a wide frequency range: the gain can be adjusted in steps of 10 dB from
-20 dB to +70dB.
Frequency response
For gain from – 20 dB to 50dB:
10 Hz to 100 kHz ± 0.1 dB
2 Hz to 200 kHz ± 0.2 dB
For gain 60 and 70 dB:
10 Hz to 20 kHz ± 0.1 dB.
One of a series of front-panel LEDs (e.g. 20 dB) lights up to indicate the current gain setting.
Filter
The lter characteristics (applied to the bandwith of the signal conditioner) can be selected from
one of the following:
Lin for linear response with a high-pass lter of 0.2 Hz.
HP for linear response with a high-pass lter of 20 Hz.
AW for an A-weghted response.
Ext for using a built-in, customised a signal-response network (contact G.R.A.S. for further
details).
Note! The Ext option provides you have installed a customised signal-response net
work (not factory-mounted).
1.3.2 Input
The microphone signal can enter the Type 12AQ via either of the following input sockets on the
rear panel.
BNC sockets for microphones used with CCP preampliers
7-LEMO sockets for microphones used with traditional preampliers
1.3.3 Ouput
The conditioned output signals, via the BNC output sockets on the rear panel, can be made
available as either oating or non-oating.
1.3.4 Polarization voltage
Applicable to 7-pin LEMO preamplier inputs on the rear panel. Can be set to either 0 V or
200 V.
1.3.5 Preampliersupplyvoltage
This can be set to either ± 15 V or ± 60 V. The chosen value will apply to both 7-pin LEMO
preamplier inputs.
1.3.6 Syscheck
This can be set to either SysCheck signal (1000 Hz) on or off. The chosen condition will apply to
both 7-pin LEMO preamplier inputs.
1.4 Power Supply
The Type 12AQ can be powered either by internal standard alkaline cells (6 x LR14 {C}) or from
the included mains/line Adapter for either 115 V AC or 230 V AC * .
* A0002 (EU) or AB0003 (USA)

Overload LED: on when
overload present; off
when absent, unless
latched to remain on
after overload.
Filter switch: rotate switch
to make a selection.
CCP Input
Floating Ouput
Polarization 0 V
buttons: LED on only
when function is active,
otherwise off.
Gain LEDs: showing the selected
gain in dB. Rotate switch
clockwise to increase gain and
vice-versa.
SysCheck button: LED
on when SysCheck
active, otherwise off.
On/Off button
Power LED: green on; yellow
standby, otherwise
Battery LED: green on; red low.
Remote LED: when on (manual
switches disabled, except power).
Channel numbers.
Filter LEDs: showing the selected lter.
Lin(Linear)
HP (high-pass)
AW (A-weighted)
Ext(Extension) optional customised
lter.
Latch button: LED on
only when Latch is
active, otherwise off *
Preamp. ±15 V
button: LED on only when
value is set to ±15 V,
otherwise it is ±60 V.
G.R.A.S. SOUND & VIBRATION
Power Module Type 12AQ
Page 7
2 External Features
2.1 Front Panel
Front-panel details are shown in Fig. 2.1.
2.1.1 Manual Control
Manual control is via toggle-buttons and rotary switches. Green LEDs indicate the current set-
tings and red LEDs are overload warnings (Power and Battery LEDs apart).
With the exception of Remote, the Type 12AQ can be manually-controlled via its front panel.
Remote can be selected only via the RS232 interface. Note: when Remote is active, manual
control is disabled (except power off). Only remote control via the RS232 interface is permitted.
Power button
Note: when external power is connected, it will take precedence over battery power.
With external power connected, the Power LED shows:
• Yellow for standby
• Green for switched on
With only battery power available, the Battery LED shows:
• Green for switched on
• Red for insufcient battery power, only when powered on (see chapter 3 for changing
batteries)
Fig. 2.1 Front-panel details of the Power Module Type 12AQ
* Behaviour modied if the latch command has been sent via the RS232 interface.

G.R.A.S. SOUND & VIBRATION
Power Module Type 12AQ
Page 8
Remote LED
Can be selected only via the RS232 interface. When on, all manual switches (except the Power
button) are disabled. Control is only via the RS232 interface. Cancelled either via the RS232
interface or by switching off/on.
Latch button
When activated, Overload LED(s) will remain on after detecting an overload, even after the
overload ceases. Latched Overload LED(s) can be cancelled by pressing the Latch button
once. Press the Latch button once (double push if overloaded) to cancel Latch.
The manual user controlled overload system:
The manual-user overload system can be disabled by the command: Ovlled n.
The system will be enabled on the next power on or by the command: Ovlled y.
Note: The overload system consists of two independent systems, a manual user system and a
remote controlled system.
In non-latched mode:
When the overload detector is in the non-latched mode, the respective overload LED will follow
the overload status, unless disabled by the command: Ovlled n.
The Overload LEDs will light during an overload condition; they will turn off about one second
after the overload condition ceases. This time can be changed via the command: Ovltm m or
by Ovltm #.
In latch mode:
For each of the overload detectors, an LED indicates the actual overload condition. The over-
load LED will be turned on when an overload occurs.
Pressing the latch button while no overload-LED lights will change the mode to non latched.
Pressing the latch button while an overload-LED is turned on and no overload condition is
present will turn off the overload-LED, if an overload condition is present nothing will happen.
To skip out of latch mode during an overload condition press latch button twice within a space
of 0.5 sec.
Gain in dB
Rotary switch for increasing or decreasing the gain of the conditioning amplier of this channel.
Rotate clockwise to increase gain or anti-clockwise to decrease gain. The range of gain settings
is from – 20 to 70 in steps of 10 dB.
Filter
Rotary switch for selecting the signal response of the conditioning amplier for this channel.
There are four settings, the rst three can be selected manually via the rotary switch, these are:
Lin for linear response with a high-pass lter of 0.2 Hz.
HP for linear response with a high-pass lter of 20 Hz.
AW for an A-weighted response.
Ext for an optional built-in, customised signal-response network
(contact G.R.A.S. for further details).
CCP Input button
When activated, the incoming signal for this channel is expected via the corresponding CCP
Input socket (BNC) on the rear panel. When cancelled, the incoming signal is expected via the
corresponding Mic Input socket (7-pin LEMO) on the rear panel.

Two Inputs for CCP
Preamplifers with pre-
polarized Microphones
Two Inputs for Pream-
plifers with externally-
polarized Microphones
Signal Output for
Channel 2
RS232 Control
Input for external
power supply 8 - 18 V
DC
Locking screw for
base plate
Signal Output for
Channel 1
Channel numbers
Adjusments for
Preamplifers with
SysCheck facilities and
externally polarized
Microphones.
G.R.A.S. SOUND & VIBRATION
Power Module Type 12AQ
Page 9
Fig. 2.2 Rear-panel details of the Power Module Type 12AQ
Floating Ouput button
When activated, the output signal of the conditioning amplier for this channel (via the corre-
sponding BNC Output socket on the rear panel) is set to oating. When cancelled, it reverts to
non-oating.
Polarization 0 V button
Applies to the Mic Input sockets (7-pin LEMO) on the rear panel.
When activated, the polarization voltage for this channel is set to 0 V. When cancelled, it reverts
to 200 V. The polarization voltage is applied to pin 3 (Fig. 2.3).
Preamp. ± 15 V button
Applies to the Mic Input sockets (7-pin LEMO) on the rear panel.
When activated, the supply voltage to the preamplier of this channel is set to ± 15 V. When can-
celled, it reverts to ± 60 V. The preamplier voltage is applied across pins 6 and 7 (Fig. 2.3).
SysCheck button
Applies to the Mic Input sockets (7-pin LEMO) on the rear panel.
When activated, a SysCheck * signal of 1000 Hz is applied to pin 1 (Fig. 2.3) of the Mic Input
socket. When cancelled, the SysCheck signal is removed.
2.2 Rear Panel
Rear-panel details are shown in Fig. 2.2.
* This requires the use of a preamlpier which can make use of the SysCheck facility, e.g. Type 26AL (¼″) or
Types 26AJ and 26AH (½″).

G.R.A.S. SOUND & VIBRATION
Power Module Type 12AQ
Page 10
Fig. 2.3 7-pin LEMO female socket 1B
(external view)
Fig. 2.4 9-pin female D-sub connector socket for
connecting directly to an RS232 computer
port (external view)
SysCheck
Adjustment potentiometer
Use a small screwdriver to adjust the level of the SysCheck signal applied to pin 1 (see Fig. 2.3) of
this Mic. Input socket. Signal adjustment ranges from 0 to 5.6 V RMS.
The SysCheck signal is activated via the SysCheck button on the front panel (Fig. 2.1) or via the
syschk command.
CCP Input
BNC input socket for driving IEPE transducers such as G.R.A.S. CCP Preampliers Type 26CB
(¼″) and Type 26CA (½″), as well as G.R.A.S. Array Microphones. Source voltage and current are
respectively 28 V and 4 mA.
Mic. Input
7-pin LEMO input connector for microphone preamplier. Wiring diagram shown in Fig. 2.3.
Output
BNC socket for the output signal via the current settings of the conditioning amplier.
Ext. Supply
Input socket for an external power supply of 8 - 18 V DC; centre pin +terminal. The use of an exter-
nal power supply automatically disables power from the batteries.
RS232
9-pin female D-sub connector socket for connecting directly to an RS232 computer port. Wiring
diagram shown in Fig. 2.4.