This week I installed the TMC-1-Penta with a Dolby RMU, although there were one or two problems the system worked correctly. I will be modifying the TMC-1 software to provide more elegant solutions to the problems found. My to-do list has become bigger!
The last problem was interesting, as you can see from the signal flow diagram below there is a 10dB loss in the signal passing through the RMU to allow headroom for the speaker equaliser. This causes a problem when switching from 7.1.4 from the RMU to 7.1 or 5.1 from Protools.
7.1.4 and 7.1/5.1 Signal Flow (Click on image to enlarge)
10 dB of gain is added to the RMU return to make up for the 10dB attenuation through the RMU. The TMC-1 originally configured the Penta 720 with unity gain for 85 dB spl, to ensure that the speaker outputs do not clip a 10dB loss is inserted in the NTP Penta Output, This will also allow for internal summing and where digital outputs are used external equalisers.