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INSTALLATION
The UM-33 is designedto be rack mounted.
It
is suggested that it be placed in a rack with
th
e rear terminal strip
can be easily accessed. If
th
e LED VU meters are to be used in your application, the unit should be placed at a
height that makes viewing easy.
For the highest quality speakeraudio, we recommend connecting external speakers to the UM-33 Relatively high
efficiency bookshelf type speakerswould be appropriate. If you choose to use the internal speakers, the unit
should be placed in a rack th
at
has other equipment above and below it
to
provide proper baffling. The internal
speakers were designed to
pr
ovide a simple self contained method of monitoring audio sources
wh
ere quality
is
not critical.
CONNECTING INPUTS
Up
to
eight stereo sources can be connected to the UM-33. Connections are made to inputs 1 thru 8 as indicated
on the backpanel. Notethat each input has provision for balanced inpu
ts
and a shield connection. If unbalanced
sources areto be connected,
the'+'
input terminal should be used forthe audio input with the common and/or
shield connected to the '.· and 'G' terminals Input levels should be in the range of -1O
dB
to +8
dB
for prop
er
operation. Standard
pr
actice should be followedto prevent ground loops.
CONNECTING OUTPUTS
The UM-
33
has two
se
parate stereo outputs. The 'direct out' output is simplythe input switched directly to the
output through the
me
chanical contacts of the front panel switch.
The 'buffer out' output is audio that is isolated from the
inp
ut
by
bufferamplifiers. Its output impedance is 600
ohms and can be used in either a balanced
or
unbalanced configuration. Note that when using unbalanced
inputs, the outputswill be unbalanced. The circuit has been designed to provide unity gain between input and
output. Formost applications, the buffered output should be used.
INTERNAL/EXTERNAL SPEAKER CONNECTION:
To
use the internal speakers, it is necessary to putjumpers from EXT L
to
INT L and EXT R to INT R on the
te
rminal strip. The ground connections are internally connected. '
Whether the internal speakers are connected
or
not, the external speakers are connected to the EXT speaker
outputs. The external speakers should be rated at 8 ohms and should be relatively efficient. The UM-
33
will drive
external speakers at 2 watts
per
channel.
OPERATION
FRONT PANEL CONTROLS: (See Figure 1)
1. Internal speakers ... left and right.
2 SpeakerON/OFF switch. When in the
OFF
position, both internal and external speakers are off.
3. Headphone jack. Headphone audio is always present regardless of the position of the speakerON/OFF
switch.
4. LED UV meter.
5. •20
dB
LED VU meter calibration controls (see ADJUSTMENTS).
6. O
dB
LED VU met
er
calibration cont
ro
ls.
2
