RME Audio M-16 AD, User Manual

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User’s Guide M-32 AD
© RME
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8.5 Limiter
For the reference converter ADI-8 QS, RME developed a new fully symmetrical circuit design
with digitally controlled release time. The same circuit has been added to the M-32 AD. While
the analog limiter is constantly within the signal path, it operates fully transparent as long as
there is no control signal generated, so does not cause noise or distortion. This special feature
made it possible to define a threshold of +3 dB in deactivated mode, preventing an overload of
more than 3 dB of the AD-converters. This avoids not only extreme overload effects, but also
prevents the AD-converters from being damaged.
Both the fully symmetrical design and the digitally controlled release time
contribute to the reduction of the unavoidable distortion of a peak limiter
(linearity errors of the control elements, generation of the control voltage).
The distortion value of about 0.3% stays the same at any level and any
frequency.
Another exceptional feature is the ability to handle extremely high levels. At
the level refe24 dBu, +19 dBu and +13 dBu up to +30 dBu can be
fed, the signal is still limited correctly (-3 dBFS), THD is still 0.3%. At the
s4.2 dBu the maximum unclipped input level is +24 dBu. So there is
more than 20 dB overload possible!
Note: As with all such basic designs, increasing dynamic ratio and gain reduction causes audi-
ble pumping effects.
8.6 Clock Section
The source and frequency of the unit's clock is configured in the CLOCK SECTION. The key
CLOCK lets you step through the options external clock (Word, MADI, ADAT) and internal clock
(44.1 kHz or 48 kHz). The button STATE sets internal, but also the external sample rate to dou-
ble or quadruple of the basic sample rate.
WCK, MADI, ADAT (Slave Mode)
Sets the corresponding input to work as clock
reference. A missing or invalid clock source signal
is indicated by flashing of the corresponding LED.
44.1, 48 (Master Mode)
Activates the internal clock with a sample rate of
44.1 kHz or 48 kHz.
DS, QS
With the DS LED additionally lit, the sample rate
will be 88.2 or 96 kHz, with QS lit it will be 176.4
or 192 kHz.
A selection of DS and QS is also possible when using external clock (Slave). If the M-32 AD
should operate at 192 kHz, but receives a synchronous word clock of 48 kHz, the button STATE
activates DS or QS mode. This way, AD-conversion and digital outputs are configured to oper-
ate in the frequency ranges Single Speed, Double Speed or Quad Speed.