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Adjusting ”Off” Attenuation

In instances when the number of microphones in use is high, it may be necessary to increase the
amount of “off ” attenuation per microphone to keep the total ambient noise level low. There are
“off ” attenuation adjustments inside the unit. To adjust the “off ” attenuation of channel 1,
unplug the unit, remove the top cover and locate the trimpot designated on the circuit board by
“VR102” (Figs. 3 and 4). It is factory set at approximately 8 dB, the attenuation at the middle of
the control’s rotation. When the control is turned fully counter-clockwise, “off ” attenuation is
approximately 20 dB. Conversely, when the adjustment is turned fully clockwise, “off ” attenua-
tion is approximately 6 dB. VR202, VR302 and VR402 control “off ” attenuation for channels 2, 3
and 4 respectively.

Figure 3. Internal view of mixer.

Figure 4. Detail of internal controls.

Don't Touch !

Rear Panel

Output Level LED Meter

The Output Level LED meter is factory set 
to indicate RMS output. Should peak output
indication be desired, simply unplug the unit,
remove the top cover and change the setting
of the switch designated on the circuit board
by “S602” (Figs. 3 and 4). “Zero” (0) level is
factory-calibrated at +4 dBm into 600 ohms.

8

MIC

LINE

PEAK

RMS

OUTPUT

  ATT

METER RESPONSE

S501

LINE

MIC

INPUT

  A

TT

S

401

LINE

MIC

INPUT

  A

TT

S

301

ON

OFF

PHANT

OM

S

402

S602

-10dB

0dB

PAD

S

403

-10dB

0dB

PAD

S

303

-10dB

0dB

PAD

S

203

-10dB

0dB

-6dB

-20dB

PAD

S103

VR102

ON

OFF

PHANT

OM

S

302

LINE

MIC

INPUT

  A

TT

S

201

LINE

MIC

INPUT

  A

TT

S101

ON

OFF

PHANT

OM

S

202

ON

OFF

PHANT

OM

S102

GATE ATT

-6dB

-20dB

VR202

GATE ATT

-6dB

-20dB

VR302

GATE ATT

-6dB

-20dB

VR402

GATE ATT

Summary of Contents for AT-MX341b SmartMixer

Page 1: ...Microphone Mixer Installation and Operation Lockout Manual Priority Pre select 1 2 3 4 20 10 6 3 0 3 6 Output Level Master Threshold Master Level Gain 1 Gain 2 Gain 3 Gain 4 Power AUTOMATIC MICROPHONE MIXER AT MX341b Selected Channel ...

Page 2: ... 1 This device may not cause harmful interference and 2 this device must accept any interference received including interference that may cause undesired operation Caution for FCC You are cautioned that any changes or modifications not expressly approved in this manual could void your authority to operate this equipment Note This equipment has been tested and found to comply with the limits for a ...

Page 3: ...o are carried between mixers by the link cable The result is that all microphones on a multi mixer system can be controlled by one micro phone connected to any mixer Since all of the mixers are independently powered there is no practical limit to the number of SmartMixers that can be daisy chained Features To custom tailor conferencing needs the mode of each microphone channel can be independently...

Page 4: ...n assigns the respective channel priority over the other channels A priority channel can not be locked out by other channels Any combination of priority non priority selections is allowed 7 Master Level control Normal setting is fully clockwise full output If reducing the mixer s output is necessary carefully turn the control counter clockwise as needed with a small screwdriver Once set as desired...

Page 5: ...tput Can be changed to mic level output via internal switch see page 7 XLRM type connector 5 Inputs Balanced microphone inputs for low impedance dynamic or condenser mics Can be changed to line level inputs via internal switches see page 7 XLRF type connectors Figure 2 Rear panel 5 Link In Link Out Output Input 3 Input 2 Input 1 12V AC 15 18V DC Control Voltage Out 1 GND 2 3 4 Input 4 Lockout Manu...

Page 6: ...shold control fully counterclockwise In this mode the unit will behave like a conventional four channel microphone mixer all automatic functions are bypassed 12 The Master Level recessed control on the front panel may be adjusted with a small screwdriver if necessary This control is at the last stage in the mixer and does not affect microphone gain threshold setting or meter indication Priority Mi...

Page 7: ...stances higher output microphones are used for close talking it may be necessary to reduce the preamplifier gain This can be done by changing switch settings inside the unit With the unit unplugged remove the two screws on each side of the unit and remove the top cover Locate the internal switches designated on the circuit board by S103 S203 S303 and S403 Figs 3 and 4 page 8 Changing the settings ...

Page 8: ...B VR202 VR302 and VR402 control off attenuation for channels 2 3 and 4 respectively Figure 3 Internal view of mixer Figure 4 Detail of internal controls Don t Touch Rear Panel Output Level LED Meter The Output Level LED meter is factory set to indicate RMS output Should peak output indication be desired simply unplug the unit remove the top cover and change the setting of the switch designated on ...

Page 9: ...Out goes high 4 VDC This signal can be used to light indicator lamps switch speaker zones on and off select video cameras etc The control voltage should not be connected directly to an inductive load such as a relay coil as dam age to the mixer may result Several interface circuit possibilities are shown in Figure 5 Figure 5 Control interface examples 9 ...

Page 10: ... to the unit When using more than one SmartMixer in a system it may be advantageous to mount two mixers in a 1U rack space This can be accomplished using the two short rack ears and an optional joining plate Model AT8628 which allows two units to be con nected side by side in a single rack space Security Caps For permanent installations where microphone selections positions and acoustic conditions...

Page 11: ... DC either polarity 300 mA Operating Temperature 32 to 104 0 to 40 C Dimensions 8 25 210 mm W x 9 38 238 mm D x 1 75 44 mm H including feet knobs and connectors Weight 3 1 lbs 1 4 kg Included Accessories AC adapter AT8325 1 0 Link Cable Optional Accessory AT8628 Double Rackmount Joining Plate In the interest of standards development A T U S offers full details on its test methods to other industry...

Page 12: ...P52324 2011 ...

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