User's Guide OctaMic / OctaMic D Portable Professional Mic Preamp 8-channel Microphone / Line Preamp with Line Outputs Universal Power Supply Input Optional 8-Channel 192 kHz 24 Bit ADC AES-3 24 Bit Interface
Contents 1 2 3 4 Introduction............................................................ 3 Package Contents .................................................. 3 Brief Description and Characteristics................... 3 Technical Specifications ....................................... 3 4.1 Analog................................................................... 3 4.2 ADC Modul............................................................ 4 5 Power Supply ....................................................
1. Introduction Thank you for choosing the OctaMic. This unique Mic Preamp allows to connect any kind of microphone to any line level inputs. Thanks to the option of battery-powered operation and removable rack ears, the OctaMic makes an ideal companion to the Hammerfall DSP System in mobile recording situations. But excellent signal/noise ratio, sophisticated discrete Class-A technology, and lots of professional features make the OctaMic your first choice also in studio use! 2.
.2 ADC Modul AES Input • • • • • 1 x XLR via 25 pin D-sub, transformer balanced, ground-free, according to AES3-1992 High-sensitivity input stage (< 0.
6. Operation and Usage 6.1 Controls The front of the OctaMic has the gain knobs, switches for low cut, phantom power and phase, Clip Hold, Reference Level and several status LEDs: +48V (LED) lights up when phantom power is active. Phantom power should only be activated when using condensor microphones which require such a power supply. The CLIP LED has been designed to act like the OVR LEDs of the ADI-8 series. It lights up 2 dB before the chosen reference level plus a headroom of 9 dB.
.2 Mic/Line Inputs The OctaMic offers 8 balanced Mic and Line inputs via 1/4" TRS (stereo) and XLR combo jacks. The electronic input stage is built in a servo balanced design which handles monaural and stereo jacks correctly. When used unbalanced it automatically corrects the gain by 6 dB. When using unbalanced cables with stereo TRS jacks, the 'ring' contact of the cable's jack should be connected to pin 1 (ground). Otherwise noise may occur, caused by the unconnected negative input of the balanced input.
. The ADC Module The ADC Module replaces the analog D-sub output by a high quality digital converter card. The card includes clock generation, clock recovery (SteadyClock) and AD-conversion. 7.1 DIP Switches The DIP switches are used to configure the ADC Module. The following diagram, also printed on the back of the unit, shows the function controlled by each switch.
7.2 External Synchronization The inputs of the ADC Module are used for external synchronization only. In case the clock shall not be generated internally (operation mode Master), an external synchronization (operation mode Slave) is available via word clock or AES (SPDIF). SteadyClock, integrated into the ADC Module, guarantess exceptional performance in all clock modes.
To achieve this, pins 2 and 3 of an XLR plug are being connected to the two contacts of a Phono/RCA plug. The ground shield of the cable is only connected to pin 1 of the XLR plug. Using the AES input, a synchronization is again possible at half, quarter, double and quad sample rates, see above. 8. Digital Outputs 8.1 AES – D-sub The ADC Module provides the four AES/EBU outputs via a 25 pin D-sub connector. The D-sub connector uses the widely known and often found pinout of the Tascam recorders (TEAC).
Pinout D-sub Signal D-sub Signal D-sub In 1/2+ 24 In 1/212 In 3/4+ 10 In 3/423 In 5/6+ 21 In 5/69 In 7/8+ 7 In 7/820 Out 1/2+ 18 Out 1/26 Out 3/4+ 4 Out 3/417 Out 5/6+ 15 Out 5/63 Out 7/8+ 1 Out 7/814 GND is connected to pins 2, 5, 8, 11, 16, 19, 22, 25. Pin 13 is not connected. 8.2 ADAT Optical The ADC Module provides two digital outputs in ADAT optical format.
9. Word Clock 9.1 Operation and Technical Background Correct interpretation of digital audio data is dependent upon a definite sample frequency. Digital signals can only be processed or transferred between devices if these share the same clock. Otherwise the signals are misinterpreted, causing distortion, clicks/crackle or dropouts. AES/EBU, SPDIF and ADAT are self-clocking, so an additional line for word clock could be considered redundant.
9.2 Cabling and Termination Word clock signals are usually distributed in the form of a network, split with BNC T-adapters and terminated with resistors. We recommend using off-the-shelf BNC cables to connect all devices, as this type of cable is used for most computer networks. You will find all the necessary components (T-adapters, terminators, cables) in most electronics and/or computer stores.
10. Technical Background 10.1 DS - Double Speed When activating the Double Speed mode the ADC Module operates at double sample rate. The internal clock 44.1 kHz turns to 88.2 kHz, 48 kHz to 96 kHz. The internal resolution is still 24 bit. Sample rates above 48 kHz were not always taken for granted, and are still not widely used because of the CD format (44.1 kHz) dominating everything. Before 1998 there were no receiver/transmitter circuits available that could receive or transmit more than 48 kHz.
10.2 AES/EBU - SPDIF The most important electrical properties of 'AES' and 'SPDIF' can be seen in the below table. AES/EBU is the professional balanced connection using XLR plugs. The standard is being set by the Audio Engineering Society based on the AES3-1992. For the 'home user', SONY and Philips have omitted the balanced connection and use either Phono plugs or optical cables (TOSLINK). The format called S/P-DIF (SONY/Philips Digital Interface) is described by IEC 60958.
11. Accessories Part number Description 37011 Power supply for HDSP CardBus card Robust and light weigth switching power supply, 100V-240V AC, 12V 1.25 A DC. 12. Warranty Each individual OctaMic undergoes comprehensive quality control and a complete test at RME before shipping. The usage of high grade components allow us to offer a full two year warranty. We accept a copy of the sales receipt as valid warranty legitimation. If you suspect that your product is faulty, please contact your local retailer.
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15. CE / FCC Compliance Statements CE This device has been tested and found to comply with the EN55022 class B and EN50082-1 norms for digital devices, according to the European Council directive on counterpart laws in the member states relating to electromagnetic compatibility (EMVG). FCC This device has been tested and found to comply with the requirements listed in FCC Regulations, part 15 for Class ‘B’ digital devices.
