dbx 122 - Page 25

1. For overdubbing, connect your system as shown in
Figure 16.
2. Set the 124’s front pane! switches as shown below:
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3. The decoded signal from the 124’s Channel 2 & 4
PLAY OUTPUT jacks feeds two of the inputs on the mixer.
Use any quality commercial, line-level mixer.
4. The voice signal (signal to be added) feeds a third
mixer input. Since microphone signals are generally low
level, the microphone must be preamplified by a good
quality mic preamp, which may already be built-in to the
mixer, tf it is commercial type. Inexpensive, battery-
powered mic preamps are available from many electronics
stores and hi-fi dealers.
5. The mixer output feeds the 124’s Channel 1 & 3
RECORD INPUTS. To balance the original and added
signals as your record the tape, use the mixer’s volume
controls and monitor the balance at the mixer’s headphone
output or at your tape recorder headphone output. If
necessary, add an additional headphone amplifier, as shown.
6. The encoded output from dbx channels 1 & 3 feed
the remaining two tracks of the 4-channel tape machine,
or to feed the second stereo tape machine.
It’s possible to perform multi-channel sound-on-sound
mixes with the 124 and an inexpensive passive mixer if the
material to be processed is re-recorded one channel at a
time. Connect the 124 in a similar manner to that shown
in Figure 17, using the passive mixer shown, constructed
in a metal box.
PASSIVE MIXER
TAPE B
4.7K
(or additional
channel in 2
OUT
machine A) 4
4.7K
Fig. 17 — Mixing Two dbx-Encoded Channels to One Track
while Maintaining dbx Encoding (for sound-on-sound)
Signals are first decoded, then mixed together and re-
encoded. A passive mixer may be built using two 4.7k-ohm
resistors, as shown. DO NOT mix signals unless they are first
decoded; mixing encoded signals will cause inaccurate
decoding later.