Audio Precision APx Audio Analyzers
by Frank Wells, 01.04.2010
In general, sophisticated test instruments
once had a single main function
per device until the development of computer-
driven, multi-function test gear.
Graphically, the somewhat utilitarian GUI
interfaces for devices like Audio
Precision's System One/Two/2500/2700
test sets were designed for functionality,
control and operator feedback — enormous
configurability with the potential
for a cluttered appearance. As geeks, control
and information were the goals of
those of us using such devices.
A potentially cluttered screen was certainly
not more of an issue than having
five or six different hardware test instruments
all stacked up, each with their own
displays and controls and operating
schemes. The software interface for the
APx500 series brings a significant
change in operational paradigm. Now, a
moderately technically inclined individual
can perform a sophisticated panel of
tests with a few mouse clicks. In practice,
for comparative bench testing and manufacturing
quality control, the APx
approach is very practical and elegant.
For the novice, the steps necessary to
customize a test for a particular device
are simple — the user is walked through
the steps necessary to establish deviceto-
test set connections, test elements
and parameters settings — straight-forward
and elegant. The onscreen interface
is visually appealing and uncluttered,
showing just what you might need to see
at a given point in time and including aesthetically
pleasing elements like interconnection
illustrations and graphical knobs.
Reports produced (and saved as pdfs)
giving the results of a test sequence offer
quick pass/fail assessment as well as
sweep plots and a log of test configuration
and test data. Test elements can be added
or subtracted quickly with a mouse click
or three. The main display of the APx software
also includes a quick view panel for
level bargraphs, a soft oscilloscope display,
reading bargraphs, etc. With a click,
these panels are blown up for closer
scrutiny.
In short, the APx measurement software
is fast, effective, and full-featured.
It's easy to use for a novice without at all
being tedious for a power user. But, the
software is nothing without hardware,
and the APx series offers a new physical
platform as well. The APx comes in 2-, 4-,
8-, and 16- channel versions (I spent time
with the APx585 8-channel version), and
the series shines in its interface capability.
There's the usual balanced analog (on
DB25 connectors for multichannel),
unbalanced analog and, optionally,
AES3/SPDIF/TOSLink digital I/O (192 kHz
sampling capable). Option modules also
allow APx hardware to interface at the
component level with multichannel signal
generation and test in a range of chip
level formats such as I2S. Along with support
for the scientific programming environment,
LavVIEW, and Dolby and DTS
compliance testing, the APx is the only
direct HDMI audio analyzer available.
You can read all about the testing capability
and specs for the APx series online,
and even download the software (PC
only) and check it out in demo mode,
sans hardware. The full range of traditional
audio tests including an effective battery
of "chirp"-based (fast sweep to allow
distortion measurement) acoustic transducer
testing is included. A new option,
announced at AES and not available for
my tests, offers an amazing 1 MHz-wide
FFT analysis, taking the test band into
the realm of digital clocks and other
potential nasty influences.
The SYS-2722 test set still leads AP's
products in low-level and low-distortion
performance, but the APx series is no
slouch, (the APx525 delivers -105 dB or
better THD + N residual and -110 dB with
the AG52 high-performance analog option
installed) technically outperforming most
(AP says all) of the competition, with interface
options applauded by designers and
manufacturers. The measurement and
control software is as innovative as it is
easy to use. And, it's more affordable than
the 2700 series (contact AP for pricing).
The stuff geek dreams are made of.
Contact: Audio Precision | www.ap.com
Frank Wells is the editorial director of Pro Audio Review.