RME OCTAMIC XTC [22/62] The input channel in detail

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.