User Manual

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User’s Guide OctaMic XTC © RME
9. The Input Channel in Detail
9.1 Gain
The OctaMic’s GAIN can be set in steps of 1 dB per channel. Setting the amount of amplifica-
tion is done digitally, therefore being very accurate and 100% reproducible. The gain change
itself is performed within the analog domain.
The range of the adjustable gain is
65 dB. Additionally an attenuator
(PAD) of -20 dB is available. The
total gain range is therefore 85 dB.
The TRS Line input gain range is
shifted by about 9 dB. The AD-
converter in the OctaMic XTC
reaches full scale already at an input
level of –53 dBu (Gain 65 dB, XLR
input), but also at +32 dBu (Gain 0
dB, PAD active). Therefore the inputs
are both sophisticated microphone
and line types.
The picture to the right shows levels
and gains in an overview and in
relation to the different inputs. The
instrument input has no PAD, and a
gain range of 55 dB.
XLR and TRS Line have a gain
range of 55 dB in steps of 1 dB, and
another step of 10 dB. Additionally a
PAD of -20 dB with XLR and -18 dB
with TRS Line is available.
9.2 Phantom Power
The LED +48V indicates activated phantom power for the XLR input. Phantom power should
only be activated when using condenser microphones which require such a power supply.
Connecting and disconnecting microphones while phantom power is active causes a high
voltage surge, which can destroy the microphone input stage! Switch phantom power off
before connecting/disconnecting any external device.
The OctaMic XTC turns on the phantom power smoothly during one second, from 0 to 48 Volts.
This technique is advantageous for the connected microphone as well as the OctaMic XTC.
The phantom power of the OctaMic XTC is short-circuit proof. With a maximum load on all eight
channels the internal voltage from the power supply does not drop below 47 Volts.