Acoustic Image Coda EX Owner's Manual - Page 4

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optimized to get the best sound from piezo pickups. The XLR input is a

low impedance balanced input with sufficient gain to allow

microphones to be plugged into it. There is a switchable 10 dB pad to

attenuate the mic level when it is too "hot." Phantom power is available

through the connector for powering a mic or outboard preamp and can

be activated using the push button switch located next to the

connector. To avoid an audible "pop", set the input level control all the

way off when switching on the phantom power. An LED indicates

when phantom power is on. In the two channel versions, each channel

is identical and can be blended to mix two instruments, 2 microphones

or a mic and an instrument thereby performing much like a small PA

system.

Controls

The preamp has the following controls in each channel: input level,

bass, mid, treble and effects level. In addition, there is a variable

frequency low cut filter and a phase reverse switch and a master level

control that affects both channels.

Level

The input level controls the level of the signal at the input stage of the

preamp. The master volume controls the level of the signal at the

output of the preamp (at the input of the power amp). Set the master

control at "12 o'clock" and the input level at zero. The input level

should then be used to control the overall output of the unit. The two

controls are provided to allow independent control of "house" volume

and "stage" volume when the unit is used as a stage monitor with a

connection to a house PA. See the discussion under "Direct Out"

below.

The maximum volume at which the system will play is limited by the

capability of the speaker system. A 10-inch driver in a small cabinet

has a limitation in how loudly it will play. The 2x10 configuration of the

Te n 2 w i l l p l a y l o u d e r b u t i t s t i l l w o n ' t p l a y a t

"rock" levels. If more volume is needed, use an extension cabinet

(Coda EX, Corus EX or Ten2 EX) or take a feed from the Direct Out

jack to a PA system or another amplifier.

Tone

Each tone control has a center detent at the flat position. Experiment

with settings to achieve the frequency balance that sounds best to

you. In general, small values of boost and cut are best. The amp is

designed with flat frequency response so only minor corrections

should be required to compensate for room effects or "peaky" pickups

in order to maintain the balanced response desired for acoustic

instrument amplification. To minimize electronic noise, avoid

operating all controls simultaneously at their maximum settings.

The bass control is a shelving-type that affects frequencies below 250

Hz and with a maximum boost/cut of 15 dB. The mid control affects

frequencies between 300 Hz and 2000 Hz and has a maximum

boost/cut of 15 dB. The treble control is also a shelving-type that

affects frequencies above 1000 Hz with a maximum boost/cut of 15

dB.

Low Cut Filter/Phase Reverse

The amps have a low cut filter and phase reverse switch in each

channel. The low cut filter is a variable frequency type that inserts a 12

dB per octave rolloff at frequencies between 30 and 400 Hz,

depending on the position of the control. Approximate frequency

settings are noted on the frequency control. Note that the first half of

the control's rotation affects frequencies from 30 to 60 Hz, the last half

of the rotation affects frequencies between 70 and 400 Hz. This is

done so that there is plenty of control in the critical low frequency

range. The low cut filter is used to reduce the bass output in cases

where room location or instrument/pickup combination results in

"boomy" sound. Press the on/off switch to turn on the filter circuit. Start

with the frequency control fully counterclockwise and gradually turn it

clockwise until the desired effect is achieved. Experiment with the

position of the control to give you the sound you like best.

The phase reverse switch is used to reduce feedback and to control

phase interactions between the two channels. If you are using two

pickups or a mic and a pickup, you will find the phase reverse switch to

come in handy. Mic feedback can be reduced by reversing the phase

of the signal. Phase related interactions between a mic and a pickup

or two pickups can be cleared up by reversing the phase of one of the

channels. You should experiment with the phase reverse switch to see

if the effect is one that you like.

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 return input can also be used as an auxiliary input for connecting

other line level signals such as a CD player.