Furman VU-40 Instruction Sheet

FURMAN SOUND, INC.
30 RICH STREET
GREENBRAE, CALIFORNIA 94904
PHONE: (41s) 927-1225
FAX: (415) 927-4548
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Congratulations on your purchase of a Furman Sound Model
VU-40 Stereo System Monitor. The VU-40 is a convenient rack-
mount dual channel level monitor for use in sound reinforcement,
concert sound, recording studio monitoring, or in any application
where a quick visual check of system performance is desirable.
VU-40 Features
O Two independent metering channels
O
On/off transient muting function protects speakers
O Familiar VU meter scales
O
Greenl/ellodRed LED color coding
O Peak or Average response switch
O
Line Level/Power Out switch for each channel
O
Line Level may be set to -10, 0, or +4 dBu
O Sixteen Power Out choices from 20 to 1260 Watts
O Ground lift, on/off switches
Operation
Front Panel
The VU-40 is comprised of two 20 LED bar-graph meters, cali-
brated in dB like standard VU meters. They may be set with the
pushbutton switch on the left side of the front panel to read either
Peak (button in) or Average (button out) response. The two me-
ter scales above the LED's are used for Average, while the two
scales below are for Peak. Because audio signals are AC (alter-
nating current), their actual voltage level varies from millisecond
to millisecond. "Average" refers to the average magnitude during
a time span of about 1/4 second. To approximate the action of a
traditional electromechanical VU meter, choose the Average set-
ting. Average also gives a good indication of the perceived loud-
ness of the signal. The Peak setting indicates the highest point of
the waveform, regardless of the average. Therefore, the Peak
position will always result in higher readings, but it will give a truer
indication of how close the signal is to clipping.
Rear Panel
The Input Select switches on the rear-panel select either Line
(line level) or Amplifier (power output), allowing you to monitor ei-
ther the inputs or outputs, respectively, of a power amp. Since
each channel may be switched independently, another possibility
is to use one VU-40 channelfor input and the other for output. Of
4-9532
course, the Line setting may be used to monitor any line level sig-
nal, even if no power amp is involved. For Line, the
"zero" meter
positions may be set to either -10, 0, or +4 dBu with the Line Input
slide switch. This switch controls both the left and right channels
(assuming both are set to the Line position with their Input Select
switches). For line level metering, refer to the white scales on the
front panel, which are calibrated in decibels. The choice of -10, 0,
or +4 depends on the nominal line level of the other equipment in
your system, especially the mixer and tape recorder. lf in doubt,
consult the manuals for that equipment.
When either or both of the Input Select switches are set to
Amplifier, the VU-40 is ready to monitor the output(s) of a power
amp. The blue scales, calibrated in percent of full power, are
used. There are 16 power output choices from 20 to 630 watts for
8 ohm loads, or f rom 40 to
'1260 watts tor 4 ohm loads. Check
the maximum power output for your amplifier and the rated impe-
dance of your speakers to determine which range to use. The ex-
act wattage corresponding to 100 percent is determined by the
settings of the four Amplifier Power switches, according to the fol-
lowing table. The switches are shown as seen at the rear panel,
from left (closest to Power Amp binding posts) to right.
In adjusting system levels, the VU-40's meters serve as a
guide to avoid overdriving the power amplifier, which can result in
Amplifier Power Switches
When switches are set as follows:
The 100o/o reading in watts i,
Left
down down
down
up down down
down up down
up up down
down down up
up down up
down up up
up up up
down down down
up down down
down up
down
up up down
down down up
up down up
down up up
up up up
R i g h t S o h m s 4 o h m s
down 20 40
down 25 50
down 32 64
down 40 80
down 50
100
down 63 126
down
80 160
down 100 200
up 125 250
up
160 32O
up 20O 400
up 250 500
up
320
640
up 400 800
up 500 1000
up 630 1260
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