dbx 128 - How to Use the Peak Unlimiter;Peak Limiter; Quadraphonic Operation

How to Use the Peak Unlimiter/Peak Limiter
1. Set the 128’s front panel switches and controls as
shown.
THRESHOLD ODE.
szLon ©) © snove 1
DYNAMIC RANGE ENHANCER, ie
py be NOISE REDUCTION
Zo gt? SYSTEM
Pay
Levey Mare
Pouxm
re) ve * § ws
HBSS. | Bo,
8 aise
mo Bia ee ee oe
3 .
@o 1" “sOOe0eO
~ rom 5 S OG
Senaaite wane oe
sosigh,
Geet
wb
tenancts
Liwostrcoucnosl
oe
Lh
Ona Osordt
2. Adjust the COMPRESSION/EXPANSION control
to the desired expansion or compression ratio. For peak
unlimiting, set expansion between 1.4 and 1.6. For peak
limiting, set compression at a relatively high ratio (10.0 or
higher).
3. Adjust the LEVEL control so that the ABOVE
THRESHOLD indicator (red) illuminates only on musical
peaks. When peak limiting, compress only the highest
peaks of the program and the effect will be less noticeable.
Quad Operation
With two 128’s you can expand a quad recording or FM
broadcast and gain the same benefits you would in stereo
with a single 128. Connecting the two 128’s together at their
QUAD CONNECTORS allows the circuits of the two units
to “‘track’’ each other so that the ‘‘quad image” will not
shift unnaturally.
1. Set up the two 128’s ‘normally, using one for the front
two channels, and the other for the rear two channels.
2. Connect the QUAD CGNNECTORS of the two units
together with a spare patch cable, as per in Figure 13.
3. Simultaneously feed the front stereo signals to the
23
front 128 and the rear stereo signals to the rear 128. The
front panel mode switches and controls on both units should
be adjusted to exactly the same positions. Then adjust the
level match control only on the rear-channel 128 so that
both units “‘track’’ one another. That is, set the level match
control so that the red or amber L.E.D.’s on both 128's
flash on in almost perfect synchronization, and so that the
output levels from both 128’s are nearly identical. Once the
level match is set for proper tracking, do not readjust it.
To use the dbx I! tape noise reduction sections of the two
128’s for quad recordings, simply operate the two 128’s as °
if you were doing two separate stereo recordings. It is not
necessary to connect the two QUAD CONNECTORS to-
gether for quad tape noise reduction, but you can leave them
connected together if you intend to expand the program
before or after recording.
To expand a quad program before dbx II tape recording,
follow the instructions to the right for stereo expansion and
encoding. Adjust the two 128’s separately.
Fig. 13 — 4 Channel Operation with Two dbx 128’s