Rme OCTAMIC User Manual
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 Introduction............................................................ 3
2 Package Contents.................................................. 3
3 Brief Description and Characteristics................... 3
4 Technical Specifications ....................................... 3
4.1 Analog................................................................... 3
4.2 ADC Modul ............................................................ 4
5 Power Supply......................................................... 4
6 Operation and Usage
6.1 Controls................................................................. 5
6.2 Mic/Line Inputs...................................................... 6
6.3 Line Outputs.......................................................... 6
7 The ADC Module
7.1 DIP Switches......................................................... 7
7.2 External Synchronization....................................... 8
8 Digital Outputs
8.1 AES – Sub-D......................................................... 9
8.2 ADAT Optical .......................................................10
9 Word Clock
9.1 Operation and Technical Background...................11
9.2 Cabling and Termination ......................................12
10 Technical Background
10.1 DS - Double Speed.............................................13
10.2 QS – Quad Speed..............................................13
10.3 AES/EBU – SPDIF .............................................14
11 Accessories...........................................................15
12 Warranty ................................................................15
13 Appendix ...............................................................15
14 Block Diagram OctaMic ........................................16
15 CE / FCC Compliance............................................17
User's Guide OctaMic © RME
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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. Package Contents
Please check that your OctaMic's package contains each of the following:
• OctaMic
• User's guide
• Power supply 12 V / 1.25 A and power cord
3. Brief Description and Characteristics
• 8 separate microphone inputs with discrete Class-A frontend
• Phantom power 48V, low cut and phase switchable per channel
• 48V, Clip and Level LED per channel
• Gain +10 dB up to +60 dB adjustable per channel
• Reference level switchable Hi Gain / +4 dBu / -10 dBV
• Fully compatible to RME's ADI-8 series and HDSP series
• Servo balanced inputs and outputs
• Wide frequency response with special RF input filters
• Wide operating voltage range
• 100% hum-free via internal switching regulators
4. Technical Specifications
• Current drawn at 12 Volt operating voltage: 850 mA (10 Watts)
• Accepted power supply voltage DC 8 V – 28 V, AC 8 V – 20 V.
• Dimensions: 483 x 44 x 205 mm
• Weight: 2 kg
4.1 Analog
• Inputs: XLR or 1/4" TRS (stereo) jack, servo balanced
• Impedance: 2 kOhm
• Signal to Noise ratio (SNR): 129 dB EIN @150 Ohm
• THD: 0.006% @ 30 dB Gain
• Crosstalk: > 110 dB
• Frequency response –0.5 dB: 5 Hz - 200 kHz
• Line Out: 1/4" TRS (stereo) jack, servo balanced
• Maximum output level: +21 dBu
• Output impedance: 47 Ohm
• Output level switchable Hi Gain / +4 dBu / -10 dBV
• SNR ADC Module: > 110 dBA
• Sample rate range ADC Module: 28 kHz – 200 kHz
• THD ADC Module: < 0.00032 %, < -110 dB
User's Guide OctaMic © RME
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4.2 ADC Modul
AES Input
• 1 x XLR via 25 pin D-sub, transformer balanced, ground-free, according to AES3-1992
• High-sensitivity input stage (< 0.3 Vss)
• SPDIF compatible (IEC 60958)
• Lock range: 27 kHz – 200 kHz
• Jitter when synced to input signal: < 2 ns
Wordclock Input
• BNC, not terminated (10 kOhm), switch for internal termination 75 Ohm
• Automatic Double/Quad Speed detection and internal conversion
• AC-coupling, not effected by DC-offsets within the network
• Signal Adaptation Circuit: signal refresh through auto-center and hysteresis
• Overvoltage protection
• Level range: 1.0 Vss – 5.6 Vss
• Lock range: 27 kHz – 200 kHz
• Jitter when synced to input signal: < 2 ns
AES/EBU Outputs
• 4 x via 25 pin D-Sub, transformer balanced, ground-free, according to AES3-1992
• Output voltage Professional 4.5 Vss, Consumer 2.1 Vss
• Format Professional according to AES3-1992 Amendment 4
• Format Consumer (SPDIF) according to IEC 60958
• Single Wire: 4 x 2 channels 24 bit, up to 96 kHz
ADAT Optical
• 2 x TOSLINK
• Standard: 8 channels 24 bit, up to 48 kHz
• Sample Split (S/MUX): 2 x 8 channels 24 bit / 48 kHz, equalling 8 channels 24 bit 96 kHz
5. Power Supply
In order to make operating the OctaMic as flexible as possible, the unit contains a switching
regulator of the latest technology, which not only has a high efficiency (> 90%), but also prevents internal hum noise by operating at 150 kHz. Another advantage: the OctaMic accepts any
power supply with voltages between 8 and 28 V DC, no matter which polarity, and even between 8 and 20 V AC. Given the power supply can deliver the current needed.
The supplied high-quality switching power supply, 12 V / 1.25 A, not only accepts any mains
voltage between 100 V and 240 V (usable world-wide), but is also fully regulated against voltage fluctuations. Additionally it only weighs 150 g in spite of its high power of 15 Watts.
The large voltage range of the OctaMic also allows for the use of a rechargeable lead-battery
instead of a power supply, for completely independent mobile operation. A matching connection cable (power jack to terminals 6.3 mm) is available from RME. A Panasonic LCR122R2PG battery, 12 V 2.2 Ah, can operate the OctaMic for 2 hours.
User's Guide OctaMic © RME
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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. 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. With this, SIG acts as useful level control, helping
to set GAIN correctly.
GAIN allows for a stepless and very precise adjustment of the amplification between +10 dB
and +60 dB.
+48V (switch) activates phantom power. Phantom power should only be activated when using
condensor microphones which require such a power supply, and only on the specific channel.
LO CUT activates a hi-pass at 80 Hz, 18 dB per octave. This filter can remove rumble and
other low frequency noise.
PHASE changes the polarity. Phase cancellations and sound changes can be caused by using
multiple microphones at different places, or wrongly soldered cables. In such cases PHASE can
eliminate the error by adding an additional phase inversion.
Clip Hold is activated by pressing the key for two seconds. As soon as an overload is detected,
the corresponding Clip LED begins to flash once per second. With this, a momentary overload
stays visible for a longer time. Pressing the key once resets the Clip display. Pressing the key
again for two seconds deactivates the Clip Hold mode.
Hi Gain / +4 dBu / -10 dBV: Defines the reference level of the Line Level Outputs. See chapter 6.3, Line Outputs.
The back of the OctaMic has the 8 analog inputs and outputs, the power supply connector
AUX, the analog D-sub output, or the optional ADC module (see chapter 7) with all the digital
inputs and outputs.
MICROPHONE / LINE INPUTS: 8 Neutrik XLR / TRS combo jacks. Thanks to the servo balanced designs and a high maximum input level (+10 dBu), the inputs can be used balanced or
unbalanced, with XLR or TRS jack, with microphone or line levels – nearly everything is possible.
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.
AUX: Connect power supply, lead-battery or battery. See chapter 5, Power Supply.
User's Guide OctaMic © RME
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6.2 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 pinout follows international standards. XLR pin 2 + or hot, pin 3 – or cold, pin 1 ground.
TRS tip + or hot, ring – or cold.
6.3 Line Outputs
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. When used unbalanced it automatically corrects
the gain by 6 dB.
The pinout follows international standards. TRS tip + or hot, ring – or cold.
To maintain an optimum level for devices connected to the analog outputs, the OctaMic in-
cludes a switch which allows to change the reference level of all 8 outputs simultaneously.
The OctaMic can generate a maximum level of +21 dBu without distortion. However, the CLIP
LED has been designed to act like the OVR LEDs of the ADI-8 series. It lights up 2 dB before
the reference level selected on the back of the unit, plus a headroom of 9 dB, is reached. At Hi
Gain the LED lights up at +17 dBu output level, selecting +4 dBu it lights up at +11 dBu, selecting –10 dBV it lights up at 0 dBV.
Setting Reference Clip LED True Clip ADC Level
Hi Gain +19 dBu +17 dBu +21 dBu -2 dBFS
+4 dBu +13 dBu +11 dBu +15 dBu -2 dBFS
-10 dBV +2 dBV 0 dBV +4 dBV -2 dBFS
This also means that the CLIP LED lights up 4 dB before the OctaMic actually reaches the
maximum level. Such an additional headroom is considered to be useful in real world operation.
The chosen reference level has no meaning for the ADC module. The ADC modul is designed
for a level of –2 dBFS as soon as the Clip LED lights up.
Selecting +4 dBu the output signal is attenuated by 6 dB, so for the same output level the amplification has to be increased via GAIN. With this trick the OctaMic reaches the maximum
signal to noise ratio on +4 dBu based inputs (like our ADI-8 series), because microphone preamps have better EIN values at higher amplification. In case of an extreme recording situation,
where the gain of the OctaMic is no longer sufficient, selecting Hi Gain will again provide the
highest amplification possible.
The same is true and even more efficient at –10 dBV. In this case the output level is reduced
by around 14 dB – the same happens to the basic noise of the unit!
User's Guide OctaMic © RME
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