Whirlwind PreePower 2 User manual

The Presspower 2 has two balanced inputs, each switch selectable for mic
or line level signals. In mic mode, a Bauer RE115Kepc mumetal shielded
transformer provides low distortion, impedance gain of 18 dB and high
common mode rejection. Faraday shields in the transformer and RF beads
used at the input XLR offer broadband RF rejection. Capacitors are also used
for AM band rejection. A phantom power switch applies DC power to both mic
inputs simultaneously. The value of the phantom voltage is dependent upon
the type of power source energizing the Presspower 2. In line input mode, the
mic preamplifier transformer is bypassed and an active balanced input is
employed. The line input is capable of receiving signals up to +23 dBm.
From each input circuit the signal is applied to a potentiometer circuit that
has an audio like taper, allowing fine tuning of the level from the 9 o’clock
through the 3 o’clock range. The 12 o’clock position yields unity gain in either
mic or line mode with approximately 6 dB of gain adjustment 90 degrees in
either direction. Below the 9 o’clock position, the potentiometer attenuates the
signal in larger increments and fully counter clockwise the attenuation is 65
dBm which will mute the input. Above the 3 o’clock position, gain increases
rapidly up to + 20 dBm with the control turned fully clockwise. After the gain
circuits, the signal passes through a switchable low cut filter. The filter has a 24
dBm per octave slope, down 3 dBm at 120 Hertz. This filter is recommended for
mic use as it eliminates low frequency handling and wind noise.
The inputs signals are then summed and applied to two separate output
busses, one for mic level outputs and one with an additional 20 dB of gain for
line level outputs. The line level feed also is applied to the headphone monitor
section and the LED level display. The mic and line level busses are routed to
the active jack boards via a balanced cable harness with plug terminations. The
Expander receptacle is also connected at this point in the circuit.
At each of the 16 outputs of the Presspower 2 or its expander module, the
mic/line switch selects the mic level or the line level signal buss and delivers it to
a buffer circuit which drives a whirlwind TRSP-1 balancing transformer. In mic
output mode a resistive H pad is switched into the circuit to attenuate the signal
by 20 dB. The H pad also provides a ground reference relative to pins 2 and 3 of
the XLR, but not connected to any other ground, which minimizes possible
ground loop problems. In line output mode, pin 1 of the output XLR is left
floating. A 3.5 mm mono jack is provided for each output.
The tone oscillator applies a 1 kHz sine wave to all outputs for level
calibration during setup. The tone level is +4 dBm or 0 VU in line mode and -43
dBm in mic mode.
The headphone driver circuitry provides monitoring of the Presspower 2
output. Each earpiece is powered by a separate amp circuit ensuring that
Tip/Sleeve headphone connectors (which short the ring) will not short out the
entire signal. The headphone amps are capable of driving 0 dB into 30 ohm
headphones, which can significantly reduce battery life. When only using
battery power, turn the headphone level full counter clockwise or unplug the
headphones to conserve the batteries. The taper of this level control is similar
to the control on the inputs.
A 20 segment LED level meter with a 3 dB per segment resolution provides a
wide range of display with 1 dB accuracy. Two switches are provided to help
maximize battery life when using 9 volt battery power. Under battery power only
select dot mode to calibrate levels and use the meter on/off switch to turn the
LED display off when not required. Use the bar mode when the Presspower 2 is
under AC power.
The Presspower 2 has a versatile unipolar power supply allowing the unit to
operate from 120 VAC 60 Hz, 230 VAC 50 Hz, 4 internal 9 volt batteries or any
battery or regulated DC source from 12 to 36 volts. Any combination of the
three types of power can be used simultaneously. The unit will automatically
select the highest voltage, providing fail safe backup and making it easier to
power in remote applications. Under AC power a toroid power transformer is
used internally for superior performance and a voltage switch on the back
panel selects 120 or 230 VAC. Nine volt batteries are mounted on the front
panel in convenient quick change holders. An external DC input (screw type)
on the back panel will accept 12 to 36 volts DC, from either batteries or a
regulated source. This allows use with camera belt packs, car batteries, etc. At
12 volts DC with a -40 dB mic input and 40 dB of gain, the Presspower 2 will
ouput up to +8 dBm in line mode.
The power on/off switch turns both the AC and the internal 9 volt battery
power on and off. The external DC input on the back panel is unswitched. The
AC LED illuminates when AC power is present and is switched on. The DC
power LED functions as a battery check LED for the 9 volt batteries and
illuminates when 12 VDC or more is present at the external DC power input.
With no external DC, the DC LED will light when the batteries are good and the
power switch is on. When the total series voltage drops below 27 volts the DC
LED goes out and all four batteries should be changed.
THEORY OF OPERATION

CONTROLS AND FUNCTIONS
1BATTERY HOLDERS contain the four 9 volt batteries in drawer style
holders. Alkaline batteries are recommended.
2POWER SWITCH turns both the AC and internal 9 volt battery power on and
off. It does not effect the rear panel DC input.
3AC POWER LED illuminates with AC power present and switched on.
4DC POWER LED illuminates when the 9 volt batteries are good and the
power switch is on, or when 12 volts DC (minimum) is present at the external
DC power input connector.
5HEADPHONE LEVEL CONTROL adjusts the volume at the headphone
jack through a range of -60 to +20 dBm. Under battery power, turn the level off
when not using the phones to prolong battery life.
6HEADPHONE JACK is 1/4“ TRS for connecting stereo headphones but will
also work with mono earpieces.
7METER ON/OFF SWITCH turns the LED display on and off when not
required which will conserve the 9 volt batteries.
8METER BAR/DOT MODE SWITCH selects bar or dot display mode so that
either all LEDs below the actual level are on, or a single LED is on at the actual
level. Use the dot mode with 9 volt battery power.
920 SEGMENT LED METER with 3 dB per segment resolution provides a
wide range display with 1 dB accuracy.
10PHANTOM POWER SWITCH applies phantom power to both mic inputs.
Voltage is 48 VDC (AC Operation), 36 VDC (9 volt internal battery operation) or
the value of the external DC power supply.
11 TONE SWITCH applies a 1 kHz sine wave to all outputs for level
calibration during setup. The tone level is +4 dBm or 0 VU in line mode and -43
dBm in mic mode.
12 INPUT LEVEL CONTROL varies the amount of signal delivered to the
outputs. The 12 o’clock (U) position yields unity gain in either mic or line mode
with approximately 6 dB of gain adjustment 90 degrees in either direction.
Large increments of adjustment occur at both ends of pot rotation with a total
range of -60 to +20 dBm.
13 LOW CUT SWITCH activates a filter with a 24 dBm per octave slope,
down 3 dBm at 120 Hertz. This filter is recommended for mic use as it
eliminates low frequency handling and wind noise.
14 INPUT MIC/LINE SWITCH selects the appropriate circuit for the applied
signal. The mic circuit is transformer balanced with a maximum input level of -5
dBm. The line circuit is actively balanced with a maximum input level of +23
dBm.
15INPUT XLR female connector is RF filtered with pin 2 positive.
16 OUTPUT 3.5 MM JACK is wired positive signal to tip and negative to ring.
Do not use this and the XLR output simultaneously.
17 OUTPUT XLR male connectors are transformer isolated and ground lifted
from each other, pin 2 is positive.
18 OUTPUT MIC/LINE SWITCH selects the signal level at each output. Mic
level is 43 dBm below line level.
FRONT PANEL
12-36
VOLTS
DC
GND
AUDIO
SHIELD
TO EARTH
LIFT
VOLTAGE
OUTPUT
EXPANDER
EXTERNAL
POWER
INPUT
19 20 21 22 23
19 OUTPUT EXPANDER PLUG for connection of the Press 2XP 16 channel
expander module. The unit is connected through a 6 pin right angle
switchcraft R6M.
20 EXTERNAL DC INPUT PLUG allows attachment of batteries or regulated
DC supplies from 12 to 36 VDC to power the unit.
21EARTH LIFT SWITCH disconnects the AC chassis ground from the audio
common and is sometimes useful in reducing hum.
22UNIVERSAL AC INLET for attachment of the AC cord.
23 VOLTAGE SELECT SWITCH allows use with 120 VAC 60 Hz or 230 VAC
50 Hz.
REAR
PANEL
1 2 3 4 5 6
DC
ON
BAR
DOT
PH POWER
TONE +4dB
-36 dB +21 dB0-15
LINE LEVEL 0 VU
PHONES
VOLUME
OUTPUTS
INPUT INPUT
0
1
2
3
456
7
9
10
8
ON
ACTIVE PRESS FEED BOX
LOW
LINE
CUT
MIC
LOW
CUT
LINE
MIC
WARNING: USE ONLY ONE CONNECTOR PER CHANNEL
0dB = -43dB MIC LEVEL OUT
AC
0
1
2
3
46
7
9
10
8
U
0
1
2
3
46
7
9
10
8
METER
VOLUME VOLUME
U
POWER
1-16
12
U.S.Audio
2
7
8
16 17 18
9
10
11 12
13
14 15
PRESSPOWER 2 EXPANDER MODULE
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
LINE
MIC
17 18 19 20 21 22 23 24
26 27 28 29 30 31 32
25
PRESSPOWER
EXPANDER
MODULE
OUTPUTS 17-32
U.S.Audio
2
LINE
MIC
LINE
MIC
910
LINE
MIC
LINE
MIC
11 12
LINE
MIC
LINE
MIC
13 14
LINE
MIC
LINE
MIC
15 16
LINE
MIC
LINE
MIC
12
LINE
MIC
LINE
MIC
34
LINE
MIC
LINE
MIC
56
LINE
MIC
LINE
MIC
78
WARNING: USE ONLY ONE CONNECTOR PER CHANNEL
0dB = -43dB MIC LEVEL OUT
WARNING: USE ONLY ONE
CONNECTOR PER CHANNEL
www.whirlwindusa.com
MADE IN USA BY U.S. AUDIO
A DIVISION OF WHIRLWIND
99 LING ROAD
ROCHESTER, NY 14612
WARNING
CAUTION
ATTENTION
120 VAC at 60Hz
230 VAC at 50 Hz
31 WATTS MAX

SPECIFICATIONS
Frequency Response
Input Impedance
Mic mode
Line mode
Maximum Input Level
Mic mode
Line mode
Output Impedance
Mic mode
Line mode
Maximum Output Level
Mic mode
Line mode
T.H.D.
Phase Shift
Intermodulation Distortion
Range of Level Pot
CMR of Mic Input at 60 Hz
CMR of Line Input at 60 Hz
Range of Headphone Volume Control
Isolation between Mic Outputs
Isolation between Line Outputs
Power draw
AC mode
Battery mode
(All measurements using Mic input driving all outputs)
On with no Led Meter no Headphones
On with Led Meter in Dot mode no Headphones
On with no Led Meter and 30 ohm Headphones
On with Led Meter in Dot mode and 30 ohm Headphones
Size (in Case)
Weight
Rack Unit with no Case
Rack Unit with Case
Shipping Weight Unit in Case
SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE
-.5 dBm 20 Hz to -2 dBm at 16 kHz
1.5 k ohms
200 k ohms
-5 dBm mic mode
+23 dBm line mode
150 ohms
150 ohms
-5 dBm into 2 k ohms
+23 dBm into 2 k ohms
.075% at 1 kHz at unity gain mic mode
-6 degrees at 1 kHz unity gain
.04% at unity gain mic mode
-60 to +20 dBm
>75 dBm at 60 Hz
>50 dBm
-60 to +20 dBm
>95 dBm
>60 dBm
31 watts maximum
mA DC battery life
40 15 hours
73 9 hours
60 10 hours
94 5 hours
20 X 9.5 X 8.5 inches
12 lbs
17 lbs
20 lbs
99 Ling Road
Rochester, NY 14612
Phone [phone] . Fax [phone]
Email: [email protected]
http://www.whirlwindusa.com
U.S.Audio
Thank you for selecting the U.S. Audio Presspower 2 audio
press feed distribution box. The Presspower 2 delivers
broadcast quality audio from 16 mic or line level transformer
isolated outputs. Features include a 20 segment led VU display
for quick visual level setting, a headphone monitoring section, a
tone oscillator for level calibration and a fail safe AC/DC battery
power supply for uninterrupted operation and portable use.
There are two balanced mic or line level inputs and an optional
expander unit, the Presspower 2 Expander is available with 16
additional mic or line level outputs. The Presspower 2 is a four
rack space unit and comes with a padded nylon carrying case for
portability.
INTRODUCTION
2
U.S. Audio has made every effort to ensure that your
equipment is received in the same perfect condition it was in
when it left the factory. Please inspect your product for any signs
of damage during shipping and report them to your dealer so
that a claim can be presented to the shipper. We recommend
that you save your packaging material for use in the unlikely
event that you need to return your equipment for service.
UNPACKING