User's Guide MADI Bridge © RME
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10.2 MADI Bridge Technology
A MADI patchbay basically can be realized in two ways: using a complete signal regeneration
(including reclocking), or by a buffered distribution of the un-processed input signal.
Complete Signal Regeneration: This method requires a complete MADI receiver per input,
and a complete MADI transmitter per output. The signal must be processed and reclocked. The
costs are extreme, as the special MADI chip (required 8 times!) is already very expensive. Addi-
tionally another very powerful FPGA is necessary. Operation gets cumbersome, as the unit has
to provide full clock support and control. The advantage is that the MADI signal at the output is
completely independent from the quality of the input signal, as it is fully newly generated.
Buffered Distribution: This method uses a sensitive receiver to amplify the input signal to a
standard level, then puts out this signal with an active driver stage. The signal is not processed
nor reclocked. The different combinations (routings) of the input and output signals as well as
the MIDI control can be performed by a fast FPGA. The component costs are dramatically lower
compared to the Signal Regeneration method. The operation is very easy, as the current clock
situation is completely ignored. The disadvantage is that the quality of the output signal de-
pends on that of the input signal, as the signal is passed on nearly unchanged. Additionally the
maximum coaxial cable length is reduced, as a signal to/from the MADI Bridge travels double
the distance.
RME's MADI Bridge uses adapted termination and a special equalizing, to reach higher cable
lengths despite its simpler design. The MADI Bridge can even serve as cable buffer for the lim-
ited outputs of some manufacturers (90 meter coaxial instead of 30 meter...).
Real world tests with MADI devices of various manufacturers confirmed the outstanding per-
formance of the MADI Bridge. There exists only one exception: The output signal of the Sony
3348 (digital tape machine of the first MADI generation) becomes unreadable when passed
through the MADI Bridge. Fortunately this problem was easy to be fixed. The inputs 5 and 6 of
the MADI Bridge can be made compatible to the 3348 by internal jumpers.
10.3 Setting Inputs 5/6 into Compatibility Mode (Sony 3348)
The changes described below must be performed by trained technicians only, following the
usual safety instructions and regulations. Risk of electric shock by high voltage inside the
unit!
1. Disconnect the power cord and all other cables from the MADI Bridge.
2. Remove the rack ears using a screwdriver (Phillips 1, two screws per ear).
3. Remove the screws of the cover (7 screws).
4. Slide the cover to the back and remove it.
5. Jumper JP1 and JP2 are placed near the BNC jacks of input 5 and 6. The jumper position is
printed to the left on the PCB. The factory default is the setting 'Standard'. Changing the jump-
ers to the other position activates the Sony 3348 mode.
6. Put the cover back on and slide it into the front panel's frame, so that all 7 screws can be re-
fit and tightened.
7. Mount the rack ears.
8. Connect power and other cables.
(42 pages)
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