OUTPUT (BALANCED) Jacks
The Tip/Ring/Sleeve phone jack and XLR-type jack are wired in parallel; either OUTPUT will send
an audio signal to a load. The phone jack accepts a standard TRS 1/4” phone plug for a
balanced output load, or a 2-circuit (Tip/Sleeve) 1/4” phone plug for an unbalanced load. The
XLR-type jack is wired pin 2 HOT(+), pin 3 COLD (-) and pin 1 GROUND. For proper unbalanced
operation, the unused pin (either pin 2 or 3) must be grounded. Nominal output signal level is
+4dBu or -10dBV into 600
Ω
, and typical maximum output level is +20dBu into 600
Ω
(+20dBm).
NOTE:
A given pair of channel output jacks (e.g., Channel 1 XLR OUTPUT and Channel 1
1/4” OUTPUT) are internally connected (TIP = Pin 2, RING = Pin 3, SLEEVE = Pin 1) and
can simultaneously deliver the same signal to two separate loads, but if one of the jacks
is unbalanced, then the other jack will be unbalanced. For example, if a 1/4” OUTPUT jack
is used with a mono cable, and is therefore unbalanced, the XLR OUTPUT jack will also be
unbalanced (Pin 3 shorted to ground). If using both outputs of a given pair simultaneously,
the total parallel load on the output should be 600
Ω
minimum.
SIDECHAIN INSERT Jack
This jack accepts a standard TRS 1/4” phone plug and provides a connection to the 166xs
detector path. The RING acts as a Send, carrying a buffered version of the signal present at
the 166xs INPUT jack, at an impedance of 2k . The TIP acts as a Return for equipment to feed
the 166xs detector circuitry, such as an equalizer for de-essing or frequency-sensitive gating/
compression. You can also drive the 166xs SIDECHAIN INSERT with the output of most
equipment, by using a 1/4” mono phone plug. Input impedance is greater than 10k
Ω
.
NOTE:
When a cable is plugged into this jack, it automatically breaks the connection from
the INPUT jack to the 166xs detection circuitry.
NOTE:
The
Operating Notes
section of this manual contains several applications for using
the sidechain circuit.
2.2 Front Panel Connections
EXPANDER/GATE Section
Expander/Gate THRESHOLD Control and LEDs (BELOW/ABOVE):
Adjusting this control sets the level at which the gate will open and allow the signal at the
input to pass through to the output. Turning the knob fully counterclockwise (to OFF) allows
the gate to pass signals unattenuated, effectively bypassing the gate. Turning the knob fully
clockwise causes the gate to attenuate input signals below +15dBu. The two Expander/Gate
LEDs indicate the relationship of the input signal level to the threshold setting. The red LED
lights when the signal is BELOW threshold, the green LED lights when the signal is ABOVE
threshold.
NOTE:
The 166xs expander/gate attack rate (which controls how fast the signal is restored
after being attenuated) is internally set to be very fast - fast enough to allow all of the
transient at the beginning of a note, vocal or spoken word to come through.
Section 2
Getting Started
5
dbx 166xs
