Page 48
MICROPHONE PREAMPLIFIER
Page 49
Instruction Manual
APPENDIX F
NOTE ON CONVERTING TO A
MATCHED LINE:
because of the
1788A’s automatic input level adap-
tation, you can convert a brute forced
clock source into a workable matched
line by inserting an in-line 75
Ω
, 10dB
pad
at the sending end of the
cable
, and then installing a 75
Ω
ter-
mination adapter at the receiving end.
This may reduce or eliminate jitter
problems when the word clock distri-
bution cable is of appreciable length.
Typical 75Ω Attenuator
Figure 5
End-of-Line Termination
the last unit in line, the best option for terminating the line
as shown in figure 5.
Clocking The 1788A With Brute Force
Not knowing what the 1788A’s word clock input may be
driven by, we made it automatically accept the brute force
voltage levels.
When accepting brute force clock, do not install
a termination adapter - it would be of no benefit.
When the driving source is not matched to the line
impedance, then adding a load impedance will not
improve the transmission characteristics.
Maximum Brute Force cable length depends on several fac-
tors, but you probably shouldn’t attempt distances greater
than 4 feet.
WORD
CLOCK
OPTICAL
AES/EBU OUTPUT
TDIF
ADAT
IN
OUT
UTIL
1 2 3 4
ON
Tee
75
Ω
Terminator
Last Unit In Line
Terminator Can
Go Here Instead
