Peavey Automix2 User Manual

OPERATING GUIDE

8 Channel Automatic Mixer

AUTOMIX

2

™

2

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AUTOMIXª2

INTRODUCTION

Thank you for purchasing the Automixª2! The Architectural Acoustics Automixª2 is a high quality
automatic mixer with eight transformer balanced mic/line inputs. Each channel provides a gain
control, 48 Volt phantom power (mic inputs), low cut filter, activity/clipping LED, an Aux send control
and a choice between manual or automatic operation. Each channel also provides a defeatable
insert point, 5 Volt TTL status output and can be muted individually or multiple channels can be
muted simultaneously via an assignable mutebus. In addition, channels one and two provide an
adjustable priority control.

The master section provides a gain trim control, three 1/9 octave sweepable notch filters, a
downward expander, transformer balanced outputs (main and aux) and remote volume connections.
The Automixª2 has been designed to easily link multiple units together to form a single mixer with
many more inputs (16, 24, 32...). The Automix 2 is supplied with a see-through plexiglass security
panel to prevent changes to the installerÕs settings.

THEORY OF OPERATION
FRONT PANEL

FRONT P

ANEL FEATURES

1. CHANNEL LEVEL
Manual Mode: In the manual mode the channel level controls provide 6dB of gain and 50dB

of attenuation.

Auto Mode: In the auto mode the control still provides 50dB of attenuation, but the control
does not add gain to the overall system level. Instead, when the level is adjusted above Ò0Ó,
the other channels are attenuated to make the channel being adjusted sound louder in the
mix without adding to the system gain.

2. MASTER LEVEL

The master level controls the overall output level. The range is set for 10dB of gain above,
and 40dB of attenuation.

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ENGLISH

1 2

INTERNAL PANEL FEATURES

3. DIP SWITCHES

Each channel has four DIP switches that control the following functions.

A. MAN/AUTO

This switch determines whether the channel is operating in the automatic or manual
mode.

B. OFF/MBUS

This switch is used to connect the channel to the system mutebus. This allows multiple
inputs to be muted simultaneously under external control. See MUTEBUS, page 7.

C. LO CUT/FLAT

This switch selects the low cut filter. The low cut filter provides a low frequency rolloff
that will help minimize unwanted noise (handling of mics, bumping of table, etc...). The
rolloff starts at 100 Hz (-3dB) and is a 6dB per octave filter.

D. OFF/+48

When this switch is in the +48 position, +48 volts of phantom power is supplied to
the mic ± terminals. This provides power for condenser mics and should be
defeated when using dynamic microphones or unbalanced inputs.

4. AUX SEND CONTROL

Controls the level of the signal being sent to the AUX bus. The level being sent to the Aux
bus will also be affected if the gain control in that channel is changed.

5. GAIN TRIM

This control sets the input gain in each channel. The amount of gain is adjustable from
+25dB to +60dB. (Mic input.)

6. ACTIVITY/CLIPPING LED ACTIVITY

In the automatic mode the LED will glow green, indicating the channel that is predominant in
the mix (auto mode). If the channel is in the manual mode the LED will stay on if the front
panel level control is at or above the 12:00 position. The green LED is also an indication of
the status output state. If the LED is on, then the status output will be high (+5 Volts). If the
LED is off, then the status output will be low (0 Volts).

CLIPPING

The LED will turn red if the channel is within 1dB of clipping.

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3

12

4

10

INTERNAL PANEL

5

6

13 11

98

4

7. PRIORITY (CHANNEL 1 and 2 ONLY)

Turning the priority control clockwise allows one channel to override the others in the mix. It
does this by ÒtrickingÓthe gain computing circuits into thinking this channel is louder than the
others. Up to 9dB of priority is available.

8. AUX MASTER LEVEL CONTROL

This control sets the level of the signal being sent to the Aux Out. This level should be set
after the individual channel levels have been set.

9. DOWNWARD EXPANDER

The downward expander can be used to attenuate the system gain when all of the
input signals are low. This can be used to prevent background room noise from being
amplified.

SETTING THE DOWNWARD EXPANDER

Have someone speak into a microphone at the softest level you can expect to
encounter. Slowly turn the downward expander clockwise until the background noise
between words is attenuated. Be careful not to go too far. The more downward
expander that is used, the less ÒnaturalÓ sounding the system will become.
This method will give you a good starting point, but the best way to set the downward
expander is during an actual meeting or event. While doing this, the downward
expander can be adjusted for the best sound. If you have to deal with both loud and
quiet events, you will need to trade off between natural sounding ambient and back­ground noise.

10. MASTER GAIN TRIM

This control sets the maximum overall system gain and should be set with the front panel
master gain set to the full clockwise position, all channels at unity, and external power amps
turned up and locked at operational settings. When trimmed to a safe margin below feedback,
no combination of user controls can cause feedback. This trim provides up to 25dB of
attenuation of the system gain.

11. NOTCH FILTER LEVEL CONTROL

The notch filter level control adjusts the amount of cut at the frequency selected by the
corresponding frequency control (12). It is adjustable from 0dB to 15dB of cut.

12. NOTCH FILTER FREQUENCY CONTROL

The notch filter frequency control is used to select the center frequency of the notch filter. The
bottom filter has a range of 40Hz to 925Hz. The middle filter has a range of 260Hz to
6kHz. The upper filter has a range of 500Hz to 12kHz.

13. POWER LED

Indicates that AC mains power power is connected and power switch is in the ÒONÓ position.

5

BACK PANEL FEATURES

14. MIC INPUTS

For use with low impedance microphones or low level sources. This is a transformer balanced
input with an impedance of 2,000½. Input sensitivity for nominal output is -56dBu to -19dBu.

LINE INPUTS

These allow line level inputs to be used. This is a transformer balanced input through a 30dB
resistive pad. Input impedance is >20k½.

15. INSERT IN/OUT

This is a signal loop that allows an external device such as an EQ to be inserted into the
signal path of individual channels (refer to diagram below).

16. INSERT BYPASS SWITCH

When no signal processor is being used or bypassing the signal processor is desired, this
switch should be in the ÒinÓ position. If a signal processor is being used, then this switch
should be in the ÒoutÓ position.

17. DIRECT OUTPUTS

Each channel has direct output terminals that can be used for recording or anytime the out­put of an individual channel is required. This signal is independent of ÒAutomixÓ gain manipu­lation. The nominal output level is 2.21dBu (1 Volt).

6

24

25

2223

18 19

20 21

14

17

16

15

IN

+ - G

Insert In/Out

CEQ 280a

OUT

G - +

MUTE

Channels can be muted individually by shorting this terminal to ground. It provides
approximately 45dB of attenuation.

STATUS OUTPUT

The status output is a DC logic output that is high (+5 Volts) when the channel is active and
low (0Volts) when the channel is not active. This DC voltage can be used to key video
cameras or trigger key lights on active microphones.

NOTE: Each channel can source a maximum of 10 mA.

18. MAIN OUT

The main output is a 600½, transformer balanced output that can be used to feed an external
power amplifier. It is at this point the automatically mixed or the manually mixed output is
accessed. The nominal output is 2.21 dBu (1 volt).

19. AUX OUT

The aux output is a 600½, transformer balanced output that can be used as an additional
non-automixed output. The nominal output is 2.21 dBu (1 volt).

20. REMOTE VOLUME

The master level of the mixer can be controlled remotely with a simple connection on the
back of the unit. A 10k pot will provide approximately 0 to 25dB of attenuation. A 100k pot will
provide 0 to 45dB of attenuation. If desired, a control voltage can be inserted to command 0
to 70dB of attenuation. The internal gain trim must be set full clockwise to achieve the
maximum attenuation range of the remote volume (refer to diagram below).

NOTE: THE CONTROL VOLTAGE SHOULD NEVER EXCEED 13 VOLTS DC.

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Mute with

External Switch

Remote Volume

Mute Bus

21. MUTEBUS

The mutebus is a control port that when shorted to ground will mute all channels that are
assigned to the mutebus approximately 45dB. The channels to be muted must be assigned
to the mutebus using the internal switch marked OFF/MBUS. See INTERNAL PANEL
FEATURES, page 4 and diagram page 7.

22. LINK PORT

To increase the number of inputs available, multiple Automixers can be linked together.
Linking automixers is a very simple process. It can be done with a small flat-head screwdriver
and a short length of four conductor shielded wire. The following diagram and procedures will
ensure proper linking.

1. Make a linking cable.

2. Connect the mixers according to the diagram above.

3. Select the mixer to be used as the master and place its link switch in the
ÒmasterÓ position.

4. All other mixers in the system should have their link switches in the ÒslaveÓ
position.

You now have a 16 (or more) channel automatic mixer. The master controls of the unit
chosen as ÒmasterÓ should be used to control the system.

23. LINK SWITCH

The link switch is used to place the unit in the master or slave mode of operation. A stand­alone unit should always be in the master mode. See Link Port (#22).

24. POWER SWITCH

Switch to ÒIÓ position to turn on.

25. IEC INLET (AC)

With the Power Switch in the off (O) position, plug the power cord into this connector prior to plug­ging into your AC power source. Always ensure proper

AC voltage and grounding practices

are utilized (proper voltage is labeled under inlet).
NOTE: FOR UK ONLY

As the colors of the wires in the mains lead of this apparatus may not correspond with the colored
markings identifying the terminals in your plug, proceed as follows: (1) The wire which is colored
green and yellow must be connected to the terminal which is marked by the letter E or by the earth
symbol or colored green or green and yellow. (2) The wire which is colored blue must be connected
to the terminal which is marked with the letter N or the color black. (3) The wire which is
colored brown must be connected to the terminal which is marked with the letter L or color red.

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Link Port

AUTOMIXª2 SPECIFICATIONS

Nominal Out = 2.21 dBu = 1 Volt

Input Specifications:

Function Input z Input Gains Input Levels Bal./ Connector

(ohms) Setting (to bal. outputs) Unbal.

Min Min* Nominal** Max

Microphone 2k Max Gain -64dBu -43dBu -2dBu Bal. Mic In (+)
(150 ohms) (60dB) (0.5mV) (5.5mV) (615mV) Mic In (-)

Ground

Line >20k Max Gain -35dBu -14dBu +27dBu Bal. Line In (+)
(10K ohms) (30dB) 13.7mV (155mV) (17.4V) Line In (-)

Ground

* Minimum input level (Sensitivity) is the smallest signal that will produce nominal output (2.21dBu) with channel and

master controls set for maximum gain.

** Nominal settings are defined s all control set at 0 dB (or 50% rotation for rotary pots.

EIN: -122dBu (Max gain, terminated 150 Ohms)
Phantom Power: +48 Volts at Mic ± terminated
Priority (Channels 1 and 2): 0dB to 9dB
Low Cut Filter: -3dB at 100Hz (6dB per octave)
Common Mode: >65dB at 20Hz Ñ 20kHz
Rejection Ratio: >85dB @ 1kHz

Output Specifications:

Minimum Output Levels Bal./ Connector

Function Load Z Unbal. Main Out (=)

(Ohms) Nominal Max

Main Out 600 +2.21dBu +20dBu +16dBm Bal. Main Out (+)

(1V) (7.75V) (6.44V) Main Out (-)

(Hi Z load) (600½ load) Ground

Aux Out 600 +2.21dBu +20dBu +16dBm Bal. Aux Out (+)

(1V) (Hi Z load) (600½ load) Aux Out (-)

Ground

Distortion:

Mic Input to Main Output: <0.2% at nominal (20Hz to 20kHz)

Frequency Response:

Mic Input Main Output: 20Hz to 20kHz +0/-1 dB at nominal
Mic Input to Aux Output: 20Hz to 20kHz +0/-1 dB at nominal

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(Hum and noise measurements: 22 Hz to 22 kHz BW)

GENERAL SPECS:

Remote volume range: 0dB to 70dB of attenuation

Off channel attenuation: 0dB to 70dB

Mute: Channel is attenuated 45dB when Mute to ground

connection is made.

MuteBus: Multiple channels can be attenuation 45dB when MuteBus

to ground connection is made.

Status output: Status is high (5V) when channel is active. It is low (0V)

when channel is not active.

Power consumption: AC 120 Volts, 60Hz, Domestic

AC 230 Volts, 50/60 Hz Export
15 watts

Weight: 11 pounds

Dimensions: Width: 19 inches

Depth: 9 1/4 inches
Height: 3 1/2 inches

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Output Residual Noise S/N Ratio Test Conditions

Ref: 0 dBu Ref: 2:21 dBu

Main Out -85dBu 87dB All controls down

-84dBu 86dB One channel nominal,
Master level nominal

-85dBu 87dB All controls down

Aux Out

-80dBu 82dB One channel send
nominal,Monitor master
nominal

AUTOMIXª2 SPECIFICATIONS

Hum and Noise: