Front Panel
12
Digital Controls
(14) Power -
Turns the 4-710d power on or off. When powered on, the front panel meters light up.
(15) Bit Depth –
This switch determines the bit depth, or resolution, of the digital output signal for all
eight A/D channels. In the up position, the digital output word length is 24 bits; in the down position,
the digital output word length is 16 bits.
The actual A/D conversion of the 4-710d is always performed at a 24-bit word length. When the switch
is set to 16-bit mode, the 24-bit signal is triangular dithered to 16 bits.
(16) Limit 1-8 –
This switch activates the built-in analog limiter for all eight inputs prior to A/D
conversion. The limiter is global for all eight inputs; it cannot be individually enabled per channel
(unlike the mic pre compressors on channels 1-4).
The limiter threshold is 17dBu (= -3dBFS) and the ratio is effectively infinite. The attack time is 0.075
ms and the release time is 100 ms. Although the limiter will help prevent “digital overs” (A/D clipping)
during conversion, it is not a “brick wall” limiter. It is still possible to clip the A/D input, especially
with very hot signal levels and/or signals with fast transient peaks.
(17) Sample Rate -
This knob defines the internal sample rate of the A/D converter or selects external
clocking. The following sample rates are supported (kHz): 44.1, 48, 88.2, 96, 176.4, and 192.
When Sample Rate is set to W/C (external word clock) the 4-710d is a word clock slave and the
incoming clock rate at the rear panel’s BNC Word Clock In connector
(
#2 on page 14)
is used to
determine the sample rate for A/D conversion.
(
For more details, please see the “Digital Clocking Primer” section on page 23
)
The 4-710d should be powered off when it is not being used for extended periods of time.
