Related Manuals for G.R.A.S. 12AU
Summary of Contents for G.R.A.S. 12AU
- Page 1 Instruction Manual 12AU 1-Channel Power Module with Signal Conditioning and Power Amplifier www.gras.dk LI0083 – Revision 22 June 2017...
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Page 2: Revision History
Revision History Any feedback or questions about this document are welcome at gras@gras.dk. Revision Date Description 7 November 2012 Tentative version 14 December 2012 First publication 18 December 2012 Minor corrections to General Description 29 November 2016 Correction to page 10, amplifier input impedance 22 June 2017 Specs. -
Page 3: Table Of Contents
Preparing the 12AU for Measurements ..........21 Cables and Connections ................21 Multi-channel Measurements ..............22 Operating the 12AU via its PC Application ........23 Using the Graphical User Interface ............. 23 The Setup Menu ..................24 The Tools Menu ..................24 The Help Menu .................. -
Page 4: General Description
By design, it avoids system-generated noise, e.g. from ground loops. In a measurement set-up, the 12AU controls both the paths of the signal sent out to the loudspeaker and the resulting acoustic signal picked up by the microphone. -
Page 5: Microphone Conditioner
100 Ω. Input for Externally Polarized Microphone or Pre-polarized Microphone (CCP) The 12AU has a 7 pin LEMO socket for a microphone with a LEMO type preamplifier and a BNC socket for a CCP microphone set. The polarization voltage can be set to 200 V or 0 V, a green LED on the front indicates the currently selected polarization voltage. -
Page 6: Speaker Amplifier
Monitor Section The signals that are fed to and taken out of the 12AU can be monitored via the monitor BNC output socket. Front panel LEDS indicate the actual selection: Mic Out, Amp In., Amp Out,... -
Page 7: Physical Interface
Fig. 2. Green LEDs show the operational status and red LEDs warn about overload. When the 12AU is switched on, the default settings will be applied. All LEDs are lit for a few seconds to show that the 12AU is working properly. After approximately 10 seconds, it switches to operational mode. - Page 8 (– 3 dB). When fast settling is enabled, the High Pass LED will flash during settling. Input Overload LED. Lit when microphone signal overloads the 12AU. Overloads can be latched and read via the USB interface, in which case they are cleared when read.
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Page 9: Amplifier Section
Amplifier Section These LEDs indicate the status of the amplifier which is controlled via the USB interface connec- tion on the rear panel. The amplifier can be set to voltage or current amplification, with separate gain and overload settings for each mode. G.R.A.S. -
Page 10: Rear Panel
Rear Panel Mains Input and Voltage Setting Ampli er Current Output Output Serial No. XXXXXX Voltage Setting Switch for either 115 VAC or 230 VAC. Mains Input and Fuse Holder. Input socket for either 115 VAC or 230 VAC mains supply. Fuse holder for 1 A slow fuse. Monitor and Amplifier Sockets Ampli er Current... -
Page 11: The 12Au Behavior And Protocol Specification
Reset<crlf> is submitted. Behavior A watchdog is enabled. It will restart 12AU if the processor stops working – this will send the string Reset<crlf> to the host. In this case the host knows that the fault has occurred and will be able to reinitialise 12AU. -
Page 12: List Of Commands And Responses
List of Commands and Responses Microphone Conditioner CCP Y<cr> CCP input enabled. CCP N<cr> CCP input disabled. Gain G0<cr> set the conditioning amplifier gain to 0 dB. G10<cr> set the conditioning amplifier gain to 10 dB. G20<cr> set the conditioning amplifier gain to 20 dB. G30<cr>... - Page 13 OVLLED Y<cr> set the conditioning amplifier to display overload. (default). OVLLED N<cr> set the conditioning amplifier to not display overload. (not recommended). Speaker Amplifier SG-20<cr> set the speaker amplifier gain to –20 dB. SG-10<cr> set the speaker amplifier gain to –10 dB. SG0<cr>...
- Page 14 Monitoring Monitor Conditioning<cr> sets monitor to Conditioning Amplifier Output. Monitor Speaker in<cr> sets monitor to Speaker Amplifier Input. Monitor Speaker out <cr> sets monitor to Speaker Amplifier Output. Monitor Current<cr> sets monitor to Current Amplifier Output. MLATCH<cr> set the Speaker Amplifier to latch current overloads. Overload’s are latched, and cleared when read.
- Page 15 Speaker in, Speaker out or Current. Name<cr> returns: User selected name of the unit. Name “text” saves the text in 12AU as a user selected name of the unit, the USB connection is disabled during this and 12AU restarts when ready. Pol<cr>...
- Page 16 Special Responses Reset<crlf> submitted when 12AU is powered on. OVL_on<crlf> submitted when OVL is received or in message mode when conditioning amplifier overload status changes. It reflects the overload status. OVL_off<crlf> see OVL_on<crlf>. SOVL_on<crlf> submitted when SOVL is acquired or in message mode when speaker voltages overload status changes.
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Page 17: Default Settings
COVL_on<crlf> or COVL_off<crlf> or MOVL_on<crlf> or MOVL_off<crlf>. If an overload occurs while a command is sent to the 12AU, the overload status will not be read and no response sent back until the command has been processed. Restart and Default Restart<cr>... -
Page 18: Installing The Usb-Driver And Control Software
30 for information on how to do this. Installing the USB Driver Prior to connecting the 12AU, you must install the dedicated USB device driver on the PC that you will use to operate the 12AU. Important. The installation requires that you are logged in as administrator on the PC. -
Page 19: Installing The Control Software
Installing the Control Software Introduction The control software for the 12AU is installed from the installation USB. Windows XP , Windows Vista, or Windows 7 is required. Screen resolution must be set to 1024 x 768 or higher. Important. The installation requires that you are logged in as administrator on the PC. - Page 20 In the example above, that folder is GRAS. You can operate the 12AU using its graphical interface and a mouse. How to do this is described in “Using the Graphical User Interface” on page 23. Alternatively, you can enter commands in the View Log window.
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Page 21: Preparing The 12Au For Measurements
Preparing the 12AU for Measurements Cables and Connections Important. Before connecting the 12AU to your PC, you should install the USB driver. Refer to “Installing the USB Driver” on page 18 for instructions. A typical set-up for testing the loudspeaker of a telephone is shown in Fig. 3 below. -
Page 22: Multi-Channel Measurements
Physically, all 12AUs are connected as shown in Fig. 3 on page 21, but all connected to the same PC via USB. You can launch a separate instance of the control software for each 12AU connected to the PC. The control software will automatically look for a 12AU and lock to its serial number. -
Page 23: Operating The 12Au Via Its Pc Application
Operating the 12AU via its PC Application This section describes how to operate the 12AU using its graphical user interface. Alternatively, you can use commands. How to do this is described in “Operating the 12AU Using Commands” on page 28. -
Page 24: The Setup Menu
• Select Enable advanced, allowing you to – assign a name to 12 AU, See “Assign a Name” on page 26. – save actual settings as default setup in 12AU. See page 27. – choose to operate the 12AU using commands. See page 28. - Page 25 View Log Selecting the View log option lets you monitor the communication to and from the 12AU. In Fig. 9 an example of this is shown, The example shows how the default setup used by 12AU upon power up is displayed.
- Page 26 Selecting the Enable advanced option activates a number of functions that otherwise are hidden and therefore inaccessible. • You can give the 12AU a name. This is useful if you will be operating more than one 12AU from the same PC.
- Page 27 2. Click on Enable advanced to remove the disable Enable advanced option. Fig. 16. The 12AU interface with name in the status bar. Enable dvanced is disabled and the name cannot be edited. To edit the name or access the other Enable advanced functions, you need to proceed as described in “Enable Advanced”...
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Page 28: The Help Menu
Tools menu as shown in Fig. 19. Fig. 19. The G.R.A.S Type 12AU log window is accessed from the Tools menu. Here you can enter commands and view responses. When command mode is used, the graphical user interface disappears from the screen. -
Page 29: Dealing With Overload In A Production Setup
Dealing with Overload in a Production Setup Overload Caused by Handling In a setup with product testing in an automated production line, overload due to handling between measurements may occur. Minimizing Overload You can minimize overload by following these guidelines: • Keep the gain as low as possible. -
Page 30: Appendix
Appendix Updating the USB driver The 12AU uses a dedicated USB driver, it will not work with Windows’ own default USB driver. If you connect the 12AU to tour PC before installing the USB driver, the installation software cannot install the driver. - Page 31 4. Right-click CDC RS-232 Emulation GRAS and select Properties. 5. Select the tab General and click the Update Driver button. 6. Click Browse my computer for driver software to access the 12AU installation USB. LI0083 – Revision 22 June 2017...
- Page 32 7. Select usb_driver on the Installation USB. 8. Ignore the authenticity warning. The USB driver will now be updated with the Microtech USB driver required by the 12AU. The installation is complete when confirmed by Windows. LI0083 – Revision 22 June 2017...
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Page 33: Technical Specifications
Technical Specifications All outputs except speaker amp. output have fixed 100 kHz (3 dB) low pass filters to minimize the need for anti-aliasing filtering in the following analyzing equipment. There is no phase shift between microphone input and output due to prepolarized or external polarized microphones. -
Page 34: Warranty And Service
Warranty All G.R.A.S. products are made of high-quality materials that will ensure life-long stability and robustness. The 12AU is delivered with a 2-year warranty. The warranty does not cover products that are damaged due to negligent use, an incorrect power supply, or an incorrect connection to the equipment.