Tascam MMR-8 - Manual (Page 28)

28 TASCAM MMR-8 User’s Guide • Chapter 2 • Installation MMR-8
Audio Connections
All audio inputs and outputs (both analog and digital) connect to/from the MMR-8 using DB-25
connectors. The pin configuration used on the DB-25 analog audio connectors is identical to that used for
TASCAM DTRS format digital tape machines such as the DA-88. Two female DB-25 connectors are
used for the analog connections, one for input and one for output, as labeled on the MMR back panel. A
single female DB-25 carries all eight channels of AES/EBU digital input and output signals.
Analog In/Out Connections
All analog inputs and outputs use balanced signals designed to mate with standard 600-ohm devices using
+4 dBu levels. Internal trim pots are available to set the exact input levels, as required to match external
equipment, although the MMR-8 is factory set to a nominal +4 dBu in and out. The inputs can also be set
for a nominal -10 dBu level for unbalanced consumer and semi-pro equipment signal levels.
Analog audio processing is done on two separate 20-bit Analog to Digital and Digital to Analog converter
cards mounted within the MMR-8. These converters are mounted in a special shielded cage within the
MMR and are attached via ribbon cable to a card (labeled A I/O) plugged into one of the system ISA bus
slots on the PC motherboard. These A/D and D/A boards have their own power supply separate from the
main PC power supply. Maximum load is 12.28 vrms.
Digital In/Out Connections
A single female DB-25 connector is used to provide four stereo digital inputs and four stereo digital
outputs. TASCAM DA-88 analog I/O cables can be adapted for use as Digital I/O cables by using 4 XLR
gender adapters. Digital input 1 is the default reference track for the AES/EBU reference. This can be
changed to use digital input 3, 5, or 7 from one of the other three digital input pairs using Setup Menu 600
(Dig In Ref Track).
NOTE: The digital clock signals coming from any external device connected to the AES/EBU inputs will
force the MMR-8’s internal clock to try to lock to it when digital input is selected (Setup Menu 500). This
can cause playback and record problems if the clock source is not accurate. If this occurs set that track to
use the sample rate converter in Setup Menu 500 (Input Source).
Monitoring Connections
For monitoring at the MMR-8 there is a mono headphone jack on the front panel (compatible with stereo
headphones of either low or high impedance). For studio Cue or remote monitoring there is a rear panel
line level mono mini phone jack. It is an unbalanced output designed to be connected to external
amplification.
The front panel headphone monitor jack is controlled by the LEVEL control located next to the jack on
the front panel. Press the MON key and select the desired tracks using the Track Select keys to choose
which of the MMR-8 tracks will be summed to appear at the headphone jack output. The rear panel jack
is a pre-LEVEL control, so it is a fixed line level output (-10 dBu), and it always presents a summed
output of the audio channels selected using the MON function on the front panel.