19
Basic operation
- Select the In section on the Main page by pressing the
BLOCK keys.
- Press the PARAMETER keys to move the cursor.
- Use the ADJUST wheel to change values.
- Use the MENU keys to switch between In page 1 and In page 2.
The In block settings are Global parameters.
Global Parameters are not affected by preset or setup changes.
Analog I/O levels are scaled in the analog domain and controlled
from the Ref. Levels page using the analog levels In Level
parameter. This is where you establish a basic relationship on
both Outputs and Inputs between analog level and digital full
scale. Also Inputs and Outputs may be offset individually on this
page. The settings are part of the Setup parameters.
Input page 1
Input
Select Input type.
Options are Analog, AES/EBU or S/PDIF
When a digital Input is used, the transmitting device and the
DBMAX need to run at the same Clock Rate, or Sample Rate
Conversion (SRC) has to be used.
If the SRC is off, you have to put either the DBMAX in External
Clock mode, or the transmitting device has to get a clock from
the same source as the DBMAX.
To test the digital connection, try listening for a minute or so to a
sine tone at say -18dBFS generated by the transmitting device.
If you hear no distortion or glitches, you’ve probably got it right.
Sample Rate Conversion
Sample Rate Conversion may be applied to the AES/EBU or
S/PDIF Input. The Input Sample Rate may be asynchronous.
The Output of the Sample Rate converter is locked to the system
Clock source.
Internal references at 44.1 or 48kHz or an external Word Clock
signal may be used to drive the Sample Rate Converter and thus
the rest of the system. Even though the Sample Rate Converter of
the DBMAX has a wide dynamic range and low distortion
(-106dBFS), synchronous data transfers are complete and should
be used if possible.
It is not possible to loop through Channel Status or User Bits on
the AES/EBU interface, when the SRC is inactive.
MAIN PAGE
Input
Clock - Output Sample Rate
Select Master Clock:
44.1kHz/48kHz/DI/Sync
(44.1 and 48kHz are internally generated).
The Output Sample Rate (= system rate) of the DBMAX is
always set in the Clock box of the In page no 1.
Normally 48kHz is used for production in PAL and SECAM
countries. 32 or 48kHz are normally used for transmission.
44.1kHz is used for regular audio CDs.
Sample Rate LED’s
When a digital Input is used, and the signal is recognized, one of
the three yellow RATE LEDs light up. If no signal is present, and
you’ve selected a digital Input or Insert, all three LED’s will
blink.
Note: Blinking LEDs indicate a lock error condition.
The Outputs of the DBMAX will be muted and the digital audio
Inputs and the BNC wordclock Input may be used as a
synchronization source for the analog Inputs (AES 11).
When using Ext. wordclock, from the BNC connector, select Sync.
Note: When changing the Input to digital, the Sample Rate
parameter automatically defaults to DI.
Delay - Master Input Delay
This Delay parameter enables you to delay the entire signal
through the DBMAX. The delay can be set in various Frame
Rates or in milliseconds.
The Delay through the unit is made up by
(values given @ 48kHz sampling):
- AD Converter Delay 0.8ms
- DA Converter Delay 0.57ms
- Processing Delay 0.54ms
- Look Ahead Delay typical 2-3ms
- User additional Delay 0-400ms
On the Input Page, the delay value is shown in total, but
excluding the delay from the AD and DA converters.
To obtain the best sound quality through the multi-band
compression stage a delay value between 1 and 10ms is preferable.
A typical value for transmission would be 2-3ms.
A typical value for production would be 2-10ms.
If you add additional delay (e.g. link compensation), maximum
Look-ahead delay is automatically given.
