User Manual

The whirlwind PA-1 is a high quality, portable stereo headphone
amplifier designed to deliver superior sonic accuracy in any audio
monitoring application. High output level combined with very low
distortion make the PA-1 suitable for critically listening to all
professional audio sources in any environment. The PA-1 accepts
both balanced and unbalanced stereo line level signals through
paralleled XLR and 1/4” TRS inputs. A switch changes the input
configuration from separate balanced stereo inputs to unbalanced
TRS (ring-right/tip-left) for sources such as headphone jack outputs.
Power is supplied by two nine volt batteries that load into easy access
drawers or an external AC supply which is included.
MPLIFICATION SYSTEMPERSONAL A
LEFT
INPUT MODE
R=PIN 3=
RIGHT
1/8” MINI
HEADPHONE
1/4” TRS
PAN
STEREO/
MONO
STEREO
LEVEL
CONTROL
20 dB PAD SWITCH
UNBAL STEREO
T=PIN 2=L
R=PIN 3=R
ALL JACKS
PARALLEL
BALANCED L/R
T=PIN 2=+
The PA-1 accepts line level inputs and will monitor both separate
balanced left and right feeds and unbalanced stereo signals on a
single connector. Each channel has a female XLR and a 1/4” TRS jack
that are parallel wired with pin 2 wired to tip, pin 3 wired to ring and pin
1 connected to shield. This feature allows for loop through operation
with commonly available adapter cables. The input mode select switch
changes the input wiring from balanced left and right to unbalanced
stereo. The XLR and 1/4” jacks are all paralleled together in
unbalanced stereo mode. After the input hardware the audio can be
attenuated by 20 dB by applying the pad. Signals are then routed to
balanced buffers and the stereo gain circuit. Volume is controlled by a
dual gang potentiometer, which provides a gain range of -60 to +15
dBm of gain. The volume control has an audio type taper from the 9
o’clock to 3 o’clock positions with larger amounts of gain and cut at
the extremes (above 3 o’clock and below 9 o’clock). The stereo signals
then go through a standard audio taper pan potentiometer, for
balancing the signal in the two earpieces. The stereo/mono switch,
when in mono, allows the PA-1 to be used as a two mix monitor. In
mono mode, the pan pot serves as a mix control adjusting the blend of
the two input sources in both ears. The output drivers of the PA-1 are
capable of delivering high sound pressure levels with low impedance
headphones. Turn the volume control down before putting on
headphones to prevent accidental ear damage. Both 1/4” and 1/8”
jacks are available on the PA-1 for use with all types of headphones.
The PA-1 is powered by 2 nine volt batteries or the supplied PS-24 wall
power supply. When using the PS-24, the batteries are automatically
disconnected.
CIRCUIT DESCRIPTION
This product is guaranteed to be free from defects in materials and
workmanship to the original purchaser for a period of (2) years from
the date of purchase. Should service be required, return the unit
postage prepaid along with the original sales receipt to:
whirlwind
Attention - Repair
99 Ling Road
Rochester, New York 14612
The warranty on this product shall not apply to defects or damage
resulting from abuse, abnormal use or from repairs or modifications
performed by anyone other than whirlwind. If it is determined a
manufacturing defect has occurred, whirlwind will repair or replace the
unit at our option and pay the postage back to you.
THIS UNIT IS CAPABLE OF DELIVERING
HIGH SOUND PRESSURE LEVELS.
PERMANENT HEARING LOSS CAN RESULT
FROM EXPOSURE TO VERY LOUD SIGNALS.
MAKE SURE TO TURN THE VOLUME DOWN
BEFORE CONNECTING HEADPHONES.
WARNING
WARRANTY
®