|
 Measuring
the listening space of your audio or home theater system is a sure way to know
if you're getting the most out of your system. Taking those measurements can be
a difficult and time consuming task and equipment needed to take such measurements
can be quite costly, especially for those wanting to make one-time readings on
their listening space. Simple level meters do not give users enough information
about the frequency peaks and nulls that exist in practically all environments.
A company called Phonic, known in the professional audio community, has introduced
the PAA2 Personal Audio Assistant, a reasonably priced real-time audio spectrum
analyzer that is loaded with useful features. The PAA2 is an accurate 31-band
real-time analyzer capable of measuring frequencies from 21Hz to 20kHz. This handheld
unit operates on four "AA" batteries and its lightweight design makes
it simple to use. The 160x160 backlit LCD display with adjustable contrast gives
the user plenty of useful feedback on the audio being measured. The built-in calibrated
microphone can handle sound pressure levels from 30dB to 130dB. The unit also
includes line inputs to measure directly from a source. The heart of the PAA2
is built around a Texas Instrument's TMS320VC5402A fixed point Digital Signal
Processor (DSP) for very fast performance.
Controls
and I/O
The PAA2 is a compact design that requires the user to push and
unlock the microphone as it spins around from its seated position. Four buttons
on the front panel are used for Power/Backlight, Right/Down, Left/Up and Enter.
The user interface takes some getting used to, but in a short time we were operating
the unit efficiently. A more desirable alternative is to use the Jog control,
located on the left side of the unit. The operator can move quickly through the
menu and submenu items and select by simply pushing on the wheel. The opposite
side of the unit has a connector for the 6VDC power adapter and another connector
for an RS232 interface that can communicate with a PC.  Both
male and female XLR connectors are on the bottom of the unit. The male XLR outputs
one of three signals for testing. Pink Noise or a 1kHz tone can be sent to a connected
component. The unit also uses this connection to output the Polarity pulse
for checking the system's wiring for proper polarity. The female XLR is used to
measure line-level signals in dBu, dBV or AC or to check the phase of the input
signal that is sent from the output connector when testing cables.
The
back of the PAA2 has a Power Lock switch that is used to prevent the unit
from being accidentally turned on. Since power is a simple button push on the
front user panel, this switch helps prevent inadvertent battery drain. Also located
on the back of the unit is the contrast control for the LCD display. The four
"AA" batteries are also located here with a cover that slides on and
off. There is also a standard threaded mount for a tripod to help hold the unit
in position during measurements. Operation
The PAA2 can perform full acoustical analysis using its real-time spectrum analyzer.
Thirty-one, one-third octave bands are displayed on the screen real-time with
selectable response times (35ms, 125ms, 250ms and 1 second) and weighting options
(Flat, A and C). The operator needs to select the SPL (Speaker Pressure Level)
range (30-90 dBSPL, 50-110 dBSPL, 70-130 dBSPL) for the test being run. The user
can select any of the center frequencies and display the level that was measured
with the numbers displayed above the real-time graph. The peak level can also
be displayed for reference. There are a total of sixteen memory locations for
storing data. The measured spectrum data can be stored to any one of ten memory
locations. Averaged data from any or all of the ten memory locations can be stored
to the remaining six memory locations. The
SPL mode can either measure sound from the calibrated microphone or from the line
input. The weighting, response time, SPL range and peak level is also selectable
in this mode. In addition, a bar graph exists along with the numeric readout of
the SPL reading. The
EQ Setting mode is designed to help provide information of the acoustics of the
room you are monitoring. Using the CD provided with the unit, pink noise is played
back through the system and sampled by the PAA2. Multiple samples can be stored
into memory, which the user can select to average. The averaged results can be
stored to one of six unique memory locations. This data taken by the PAA2 will
then calculate the amount of equalization that is required at each of the center
frequencies. The
polarity test is designed to check either system polarity or cabling. System polarity
is tested by sending out a pulse to the system electronics and measuring the sonic
wave produced by the loudspeaker. If the system hears the pulse in-phase then
a "+" is displayed on the screen. If it's out-of-phase then a "-"
is displayed. A "?" will be displayed if the analyzer cannot determine
the polarity. This same test can be run on a cable connected between the two XLR
connectors.  Software
A serial interface cable is provided to allow the PAA2 to work with the application
software provided. The software actually worked fine on our older Sony Vaio laptop
running Windows ME. The serial link was surprisingly fast in the real-time mode
with third octave bars updating at a reasonable rate. The memory locations took
tens of seconds to load, but it wasn't unbearable for a serial link. The software
allows the user to save or load data to/from the PAA2 using the hard drive. The
software can also command the backlight on or off and the software display matches
the PAA2 display.
Battery
life on the PAA2 is rather short, so it might be a good idea to use rechargeable
batteries. We tried a set of 1800mAH batteries during our testing and they work
great. Our rechargeable batteries lasted about two to three hours while the alkaline
batteries lasted a little longer. Conclusion
There is finally a middle ground between the inexpensive Radio Shack SPL meter
and the professional audio spectrum analyzers used by sound professionals. The
Phonic PAA2 certainly comes closer to satisfying the professional while still
keeping the test equipment investment amazing low. Considering the cost of the
PAA2, it did very well in our tests and was really quite simple to use. Although
the product is geared for sound professionals, many consumers will want this for
setting up their audio and home theater systems. The full spectrum analyzer is
a powerful tool and will satisfy those interested in getting their room acoustics
in order. Subwoofer placement can be especially difficult and the PAA2 can help
verify what you are hearing. Based on its performance
and price, we can easily recommend the PAA2 to anyone willing to take the time
to analyze and adjust their listening room. -
Kevin Nakano | 
