Acoustic Image Contra R 411 BA Owner's Manual - Page 5

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with a maximum boost/cut of 15 dB. The brite control affects frequencies

between 6,000 and 16,000 Hz and provides a maximum boost/cut of 15 dB.

Notch/High Pass Filter

The notch/high pass filter is a fixed amplitude, variable frequency type that

inserts either an 18 dB cut or a 12 dB per octave rolloff at frequencies between

30 and 700 Hz , depending on the position of the control. The notch filter is used

to remove a given feedback frequency to reduce feeback "howl". The high

pass filter is used to reduce the bass output in cases where room location or

instrument/pickup combination results in "boomy" sound. To use either, push

the on/off switch to turn on the filter circuit then select the filter type using the

notch/high pass switch. Start with the control fully counterclockwise and

gradually turn it clockwise until the desired effect is achieved, then experiment

with the position of the control to give you the sound you like best. The New

Yorker combo does not have the filter capability.

Effects Loop

Acoustic Image preamps have output ("Send") and input ("Return") capability

in each channel to allow you to use effects boxes. The send output is affected

by the input volume and tone controls and can also be used as a preamp output

for driving other power amplifiers. The Return input can be used to directly

connect an external preamp to the unit's power amp. The effects level control

in each channel controls the volume of the returned ("wet") signal relative to

the original ("dry") signal. Because the effects loop is a parallel type, plugging

something into the send output does not interrupt the signal path. So, a tuner

can be plugged into the send output without affecting the signal going through

the amp. When the effects loops are not used, the level controls should be set

at zero. The New Yorker does not have the effects level control.

Direct Out

An XLR jack is provided for a Direct Out connection that allows the system's

output to be fed to mixing boards of house PA systems or recording studios.

As a result, the instrument amplified by the unit can be recorded or further

amplified by the house PA system. In the Coda combos, the Direct Out signal

is the combined output of the mic and instrument channels and it is affected

by the input level and tone controls of each channel (post EQ). Any reverb

selected signal is also present in the direct out signal.

A ground lift switch is available to "lift" the ground from the output of the direct

out--reducing noise should a ground loop create hum when the unit is

connected to a mixing board. The New Yorker does not have the ground lift

switch.

Reverb (Contra R and Coda R only)

Our high-quality digital reverb units offer 8 program selections: 2 "Hall"

(Concert Hall and Arena), 3 "Room" (Club, Chamber and Garage), 2 "Plate"

reverb simulations (Plate and Vocal), and 1 "Spring" reverb simulation. With

the Coda R, there are also switches to select which channel (mic or instrument)

has reverb added. If both switches are closed, the selected reverb setting

appears in both channels. A level control affects the level of the reverb signal

that is mixed with the "dry" signal to control the overall effect of the reverb.

You should experiment with both the reverb program selection and the level

control to find the sound that you prefer. When reverb is not used, the switches

for both channels should be off and the level control should be turned fully

counterclockwise.

External Speaker Jack

An extension speaker (ideally, the Contra EX) can be connected to the amp

to increase its output level, using the jack provided on your amp's rear panel.

Speakers are connected via Neutrik Speakon connectors ("twist lock" type).

These connectors are used because of their low contact resistance and non-

shorting operation. The output of each Speakon connector is wired to pole "1".

Make sure the cables you use to connect an external speaker are similarly

wired. Cables with Speakon connectors are available from Acoustic Image

if you are unable obtain them from your local music store. A 16-inch speaker

cable that connects the amp output to the speaker is supplied with the unit.

Spares are available from Acoustic Image.

The power amplifier is capable of driving speaker loads as low as 2 ohms. Use

a high quality speaker system in order to get the maximum performance from

the amp. The Acoustic Image Contra EX is an excellent choice.

The power amp is short circuit protected. If a short is connected to one of the

speaker jacks, the output signal will be interrupted until the short is removed.

If there is an intermittent short, the output will be interrupted for about one

second each time the short appears. However, the nature of a switching

amplifier makes it difficult to protect against shorts in all circumstances. To

be on the safe side, you should shut off the power to the amp before

connecting or disconnecting speakers from the unit.

Speaker Placement (Combos or Contra EX)

The omnidirectional low frequency output of the Coda, Contra, New Yorker

or Contra EX makes speaker placement relatively noncritical. You will easily

be heard all over the bandstand no matter where one or more are located.

However, best results are obtained when the cabinet is placed on the floor.

Putting the unit on a shelf or stand will reduce bass frequencies. There may

be circumstances where this is desirable. Again, feel free to experiment to find

the sound that is best for you.

Sound Lifter

In some settings, such as a hollow stage or small, "boomy" room, your amp

or enclosure will produce too much bass. One way to cut unwanted bass

output is to use the "Sound Lifter" peg to lift the front of the cabinet, reducing

the coupling to the floor. To do this, remove the lifter peg from the storage clip

on the bottom of the cabinet and screw it into the recessed nut on the bottom