use the “PREAMP OUT” of your guitar amp (if so equipped), or the output of some other
device that is designed to accept low-level instrument inputs (including various foot pedal
effects, acoustic pickup preamps, and some rack mount audio products). Such sources can be
balanced or unbalanced - this is no problem for the 166xs.
Microphones, bass guitars, and electric-acoustic instruments, also typically have low-level
outputs. With most setups they require signal boost to drive the 166xs INPUT. For example,
when recording voice directly to a portable tape deck, a mic preamp placed between the mic
and the 166xs (which is then fed to one of the recorder’s inputs) can boost the signal
for the 166xs as well as provide a high level signal to the tape deck. Keyboards, samplers,
drum machines and sound modules typically produce a line-level signal and can be connected
directly from the instrument’s output to the 166xs INPUT.
NOTE:
DO NOT CONNECT the 166xs input to the speaker output of an instrument or power
amplifier. Severe damage to system components may result.
Patch Bay
In the studio, the 166xs may be connected to a patch bay (such as a dbx PB-48) to allow
it to be used anywhere in the studio system. If your studio is not fully balanced, you must
ground the unused balanced output conductor: XLR pin (either pin 2 or 3) or the ring of a
1/4” stereo phone jack. Note that grounding pin 2 of the XLR jack reverses the phase
through the 166xs.
Sound Reinforcement
To compress a live mix or to protect loudspeakers, connect the 166xs between the source
(mixing board or distribution amp) and the power amp(s). If multi-way loudspeakers with
low-level electronic crossovers are used, the 166xs(s) should go after the crossover(s). For a
stereo system, you can separately stereo couple the two high band crossovers, low band
crossovers, etc. If limitations require that you use a single 166xs channel before a crossover,
adding an equalizer to the sidechain may provide some additional protection to your high
frequency components (see “Speaker Protection,” page 17).
3.3 Installation Considerations
Input/Output Cable Configurations
Hookups and Cabling
The 166xs is a balanced (differential) unit designed for n4dBu or -10dBV levels;
inputs and outputs are 1/4” tip/ring/sleeve (TRS) phone jacks and XLR-type jacks. The 166xs
can be used with either balanced or unbalanced sources and outputs can be used with either
balanced or unbalanced loads, provided you use proper cabling.
A balanced line is defined as two-conductor shielded cable with the two center conductors
carrying the same signal but of opposite polarity with respect to ground. An unbalanced line
is generally a single-conductor shielded cable with the center conductor carrying the signal
and the shield at ground potential.
Section 3
Making Connections
12
dbx 166xs
