User’s Guide OctaMic II ™ SteadyClock Professional Mic / Line Preamp and AD-Converter 8-Channel Microphone / Line Preamp with Line Outputs 8-Channel Analog to AES / ADAT Interface 24 Bit / 192 kHz Digital Audio AES-3 24 Bit Interface
Important Safety Instructions ..................................3 General 1 2 3 4 5 6 Introduction ...............................................................6 Package Contents .....................................................6 Brief Description and Characteristics.....................6 Accessories ...............................................................7 Warranty.....................................................................8 Appendix .................................................
Important Safety Instructions ATTENTION! Do not open chassis – risk of electric shock The unit has unisolated live parts inside. No user serviceable parts inside. Refer service to qualified service personnel. Mains • The device must be earthed – never use it without proper grounding • Do not use defective power cords • Operation of the device is limited to the manual • Use same type of fuse only To reduce the risk of fire or electric shock do not expose this device to rain or moisture.
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User’s Guide OctaMic II General User’s Guide OctaMic II © RME 5
1. Introduction The OctaMic II's innovative concept allows for amplification and digitization of ALL analog signal sources. Be it high-level stage signals, typical studio signals, lower level and high-impedance instruments, or dynamic, condenser or ribbon microphones: OctaMic II understands them all – in a way that is simply thrilling. When developing the OctaMic II we used all our experience, and also the experience of our customers, to create a unique, excellent and high-quality unit.
4. Accessories RME offers several optional components for the OctaMic II: Part Number Description OK0050 OK0100 OK0200 OK0300 OK0500 OK1000 Optical cable, Toslink, 0.
5. Warranty Each individual OctaMic II undergoes comprehensive quality control and a complete test at IMM 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.
CE / FCC Compliance CE This device has been tested and found to comply with the limits of the European Council Directive on the approximation of the laws of the member states relating to electromagnetic compatibility according to RL89/336/EWG and RL73/23/EWG. FCC This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules.
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User’s Guide OctaMic II Usage and Operation User’s Guide OctaMic II © RME 11
7. Front Panel Controls 7.1 Displays +48V (LED) lights up when phantom power is active. 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. At Hi Gain the LED lights up at +17 dBu output level, selecting +4 dBu it lights up at +11 dBu. SIG (Signal) indicates the presence of an input signal. The LED has a detection range of more than 50 dB using multiple brightness states.
8. Rear Panel 8.1 Connectors MICROPHONE / LINE INPUTS: 8 8 Neutrik XLR / TRS combo jacks. Thanks to the servo balanced designs and a high maximum input level (maximum input level XLR +14 dBu, TRS +21 dBu) the inputs are universally applicable. LINE LEVEL OUTPUTS: 8 TRS (stereo) jacks. The electronic output stage is built in a servo balanced design, handling monaural (unbalanced) and stereo jacks (balanced) correctly. IEC receptacle for power connection.
9. External Synchronization The digital inputs of the OctaMic II 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). The SteadyClock technology of the OctaMic II guarantess exceptional performance in all clock modes.
User’s Guide OctaMic II Inputs and Outputs User’s Guide OctaMic II © RME 15
10. Analog Inputs / Outputs 10.1 Mic / Line In The OctaMic has 8 balanced Mic and Line inputs via 1/4" TRS (stereo) and XLR combo jacks on the rear panel. The electronic input stage is built in a servo balanced design which handles unbalanced and balanced signals correctly, automatically adjusting the level reference. XLR The pin assignment follows international standards. With XLR, pin 2 is + or hot, pin 3 is – or cold, pin 1 is ground. Pin 1 is connected to the chassis directly at the socket (AES48).
10.2 Line Out The 8 short circuit protected, low impedance and servo balanced line outputs are available as (stereo) 1/4" TRS jacks. The electronic output stage is built in a servo balanced design which handles monaural and stereo jacks correctly. The pinout follows international standards. Tip + or hot, ring – or cold. To maintain an optimum level for devices connected to the analog outputs, the OctaMic includes a switch which allows to change the reference level of all 8 outputs simultaneously.
11. Digital Outputs 11.1 AES/EBU The four AES/EBU outputs are provided on the rear of the OctaMic II via a 25 pin D-sub connector with Tascam pinout (also used by Digidesign). A digital breakout cable will provide 4 male (and 4 female) XLR connectors. Every output is transformer-balanced, ground-free and compatible to all devices with AES/EBU ports. Besides the audio data, digital signals in SPDIF or AES/EBU format contain a channel status coding, which is being used for transmitting further information.
AES/EBU Sync The input AES 1 (channel 1/2) found on the D-sub connector can not be used for audio with the OctaMic II, but as clock source. The input is transformer-balanced and ground-free. Thanks to a highly sensitive input stage, a SPDIF signal can also be fed by using a simple cable adapter phono/XLR. (see above). Pinout of the D-sub connector, Inputs 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 GND is connected to pins 2, 5, 8, 11, 16, 19, 22, 25.
12. Word Clock 12.1 Operation and Technical Background In the analog domain one can connect any device to another device, a synchronization is not necessary. Digital audio is different. It uses a clock, the sample frequency. The signal can only be processed and transmitted when all participating devices share the same clock. If not, the signal will suffer from wrong samples, distortion, crackle sounds and drop outs.
12.2 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. Actually you will find all the necessary components (T-adapters, terminators, cables) in most electronics and computer stores. The latter usually carries 50 Ohm components.
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User’s Guide OctaMic II Technical Reference User’s Guide OctaMic II © RME 23
13. Technical Specifications 13.1 Analog Microphone/Line 1-8 • Input: Neutrik XLR/TRS Combo jack, electronically balanced • Input impedance: XLR 2 kOhm, TRS 10 kOhm balanced • Frequency response –0.1 dB: 20 Hz – 100 kHz • Frequency response –0.3 dB: 10 Hz – 150 kHz • THD @ 30 dB Gain: < -106 dB, < 0.0005 % • THD+N @ 30 dB Gain: < -100 dB, < 0.
Word Clock • BNC, not terminated (10 kOhm) • Switch for internal termination 75 Ohm • Automatic Double/Quad Speed detection and internal conversion to Single Speed • SteadyClock guarantees super low jitter synchronization even in varispeed operation • Transformer coupled, galvanically isolated input • Not affected by DC-offsets within the network • Signal Adaptation Circuit: signal refresh through auto-center and hysteresis • Overvoltage protection • Level range: 1.0 Vpp – 5.
13.6 Connector Pinouts The pinout of the 25-pin D-sub connector uses the widely spread Tascam scheme, which is also used by Digidesign. Out of the four AES inputs only the first one is used by the OctaMic (Sync). Tascam / Digidesign: 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.
XLR sockets analog input and output The XLR connectors of the analog inputs and outputs are wired according to international standards: 1 = GND (shield) 2 = + (hot) 3 = - (cold) The servo balanced input and output circuitry allows to use unbalanced connections with no loss in level. For this to work, pins 3 (-) and 1 (GND) have to be connected inside the XLR connector.
14. Technical Background 14.1 Terminology Single Speed Sample rate range originally used in Digital Audio. Typical applications are 32 kHz (digital radio broadcast), 44.1 kHz (CD), and 48 kHz (DAT). Double Speed Doubles the original sample rate range, in order to achieve higher audio quality and improved audio processing. 64 kHz is practically never used, 88.2 kHz is quite rare in spite of certain advantages. 96 kHz is a common format. Sometimes called Double Fast.
14.2 DS - Double Speed When activating the Double Speed mode the OctaMic II 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.
14.4 AES/EBU - SPDIF The most important electrical properties of 'AES' and 'SPDIF' can be seen in the table below. 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.
14.5 SteadyClock The SteadyClock technology of the OctaMic II guarantees an excellent performance in all clock modes. Its highly efficient jitter suppression refreshes and cleans up any clock signal, and provides it as reference clock at the word clock output. Usually a clock section consists of an analog PLL for external synchronization and several quartz oscillators for internal synchronisation. SteadyClock requires only one quartz, using a frequency not equalling digital audio.
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