Audio Precision APx1701 Series, Installation Instructions Manual, Page: 34 / 44

Chapter : User’s Guide
16 APx1701 Transducer Test Interface: User’s Guide
DUT connections (microphone
inputs)
The APx1701 is designed to easily interface with common
measurement microphones, and with common professional
recording and sound reinforcement microphones.
Unbalanced Microphone Inputs
Most measurement microphones have an unbalanced audio
output, typically provided on a BNC connector. The BNC
Unbalanced Microphone Inputs are designed to connect to
such microphones.
Pre-polarized measurement microphones typically use the
+24 V CCP (constant current power) system, which can be
provided by the APx1701. See Microphone Powering on
page 22.
TEDS data can be read from TEDS-enabled microphones
connected to an APx1701 unbalanced microphone input.
See TEDS data on page 22.
If the microphone requires a proprietary power supply (typi-
cal of measurement microphones that require a polarizing
voltage) connect the audio output from the power supply to
an unbalanced microphone input, using high-quality
shielded microphone cable.
Balanced Microphone Inputs
Most professional recording and sound reinforcement
microphones have a balanced audio output, typically pro-
vided on an XLR connector. The XLR Balanced Micro-
phone Inputs are designed to interface directly with
professional recording or sound reinforcement micro-
phones.
Solid-state condenser microphones typically use the +48 V
phantom power system, which can be provided by the
APx1701. See Microphone Powering on page 22.
Unpowered professional microphones, such as dynamic or
ribbon microphones, can be connected to the balanced
inputs and operated with the phantom power off.
If the microphone requires a proprietary power supply (typi-
cal of tube/valve microphones) connect the audio output
from the power supply to a balanced microphone input,
using high-quality shielded balanced microphone cable.
Testing with the APx1701
The APx1701 Transducer Test Interface is intended for use
with an APx500 Series analyzer and APx500 measurement
software. We will look at some typical test cases, beginning
on page 17.
System connections
In all cases shown, the APx1701 must be connected to the
APx500 analysis system, including the PC running the mea-
surement software and the analyzer instrument hardware.
The connection to the PC is accomplished by a USB 2.0
connection between the PC and the APx1701.
The audio connections between the analyzer and the
APx1701 are accomplished using one or two unbalanced
shielded BNC-to-BNC cables, and one, two or three bal-
anced shielded XLR-to-XLR cables. Typically, one or two
analyzer unbalanced analog outputs are connected to the
APx1701 amplifier inputs, and one or two of the APx1701
microphone outputs (pass thru) are connected to the ana-
lyzer balanced analog inputs. For impedance tests, the