Aphex 1788A Premium Eight Chan Mic Pre - Manual (Page 23)

Page 22
MICROPHONE PREAMPLIFIER
Page 23
Instruction Manual
5. USING THE DIGITAL MODULE
5. USING THE DIGITAL MODULE
When you have the 1788A’s digital audio option installed, you have a very versatile digital
front end for any digital recorder, mixer, or DAW. The mic preamp and A/D Converters are
perfectly matched for headroom and low noise. There are only two areas you need to deal
with in using the digital module:
1. Synchronization (internal or external)
2. Sending digital audio data to other equipment
5.1 SYNCHRONIZATION
The 1788A can run on selectable internal crystal oscillators at 32Khz. 44.1KHz, 48Khz,
and 96KHz. When running from externally supplied sync, it can lock up on any frequency
between 32KHz and 96KHz.
NOTE: Beware that you will run into problems trying to use TDIF and ADAT Optical
outputs with any external clock sampling above 48KHz.
External Sync
The 1788A can take three types of external sync. All are received at the BNC Word Clock
IN jack.
1. Word Clock
2. Superclock (256 times sampling frequency)
3. AES/EBU Signal
Dip Switch Settings
Sync is detected according to the setting of three dip switches as illustrated below.
Switch 1: Determines if Word Clock at the sampling frequency or Superclock at 256X the
sampling frequency is accepted.
Switch 2: Determines if incoming Word Clock is expected to be shifted by 90 degrees. It’s
part of the Tascam TDIF specifications, but not all TDIF interfaces conform. Most seem to
produce standard in-phase Word Clocks. Try this switch if you have a DA-88 that won’t
recognize digital audio from the 1788A.
Switch 3: Determines if the source of switch 1 or AES/EBU input is accepted.
Switch 4: Word Clock output impedance; 10 ohms or 75 ohms. Allows either brute force
or impedance matched transmisison.
Refer to inset or Appendix F.
1 2 3 4
ON
Super Clock
Word Clock
1 2 3 4
ON
Phase 90
Phase 0
1 2 3 4
ON
AES3 In
Word Clock In
1 2 3 4
ON
Out 75 Ω
Out 10 Ω
Default Settings
1 2 3 4
ON