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Operation
Power
CAUTION: TO REDUCE THE
AC Input
RISK OF ELECTRIC SHOCK
DO NOT REMOVE COVER.
115/230 VAC
NO USER SERVICABLE PARTS
INSIDE. REFER SERVICING
50/60 Hz
TO QUALIFIED PERSONNEL
250 Watts
CAUTION: TO REDUCE
RISK OF FIRE, REPLACE
FUSE WITH SAME TYPE
3A-250V SLO BLO FUSE
Power Switch
Clarus Rear Panel (the Focus and Clarus SL rear panels are similar).
Plug the detachable AC power cord into the receptacle on the back of the amp
and into a wall receptacle. A power switch next to the AC connector turns
on power to the pre- and power amps, illuminating a "power on" indicator on
the front panel of the amp. A 3-amp slo-blo fuse (Clarus models) or 6.3 amp
fast blo fuse is mounted on the back panel. To replace this, remove the AC
cord and twist out the fuse holder. A spare fuse is included with this manual.
AIl amps will work with either 115 volt, 60 Hz AC or 230 volt, 50 Hz AC power.
A switch located on the rear panel selects the appropriate voltage. Note that
the correct AC power cord must be used for connection to the appropriate wall
plug. If you do not have the right cord, you can buy one from an electronics
or computer store. Be sure the switch is in the correct position for the intended
application. Operation at 230 volts with the switch in the 115 volt
position will damage the unit.
Preamp
Refer to the signal flow diagram (shown for the Clarus/Focus 2R--the other
models have the same signal flow for the features equipped) and the control
panel drawings for more information.
Inputs
The Clarus and Focus models both have an instrument channel with high (10
megohm) and low impedance (1 megohm) inputs, accessible using standard
1/4-inch plugs. The option is given in order to get the best sound from piezo
pickups. Both inputs have the same gain through the amp. Which impedance
is most appropriate for your particular instrument depends on pickup design.
To decide, listen to the bass/treble balance as you change inputs. Typically,
terminating in the higher impedance will raise the relative level of the bass
frequencies. Magnetic pickups normally sound best with the low impedance
input. Don't be afraid to experiment to find the best sound for your
ears. There are no set rules as to which input is best to use.
If your preamp has two channels, the microphone channel is accessed using
a standard XLR connector. 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 mic input level control all the way off when switching on the phantom
power.
2
Fuse
Voltage Switch
Speaker Output 2 min
115/230 V
The two instrument inputs are separately buffered. This allows you to plug two
instruments into your amp and play them separately or together. This feature
is useful when you are doubling on two instruments with different impedance
requirements (for example, electric and acoustic guitar or bass). Plug the
acoustic into the high Z input and the electric in to the low Z input. You can then
play each instrument as needed without having to plug and unplug instruments.
With the two-channel models, the mic and instrument channels can be blended
to mix a mic and pickup for best sound from one instrument or to mix vocals
with an instrument. An adaptor can be used to convert the XLR to a 1/4 inch
input if a second instrument channel is desired. However, when using an
adaptor, the resulting input impedance is fairly low which limits the use of the
channel to magnetic pickups. Using a piezo pickup with such a low impedance
will likely result in poor sound quality.
Controls
The preamp has the following controls in each channel: input level, bass, mid,
treble, brite and effects level. In addition, there is a variable frequency,
selectable notch/high pass filter and a master level control. Note that the Clarus
SL amps do not have the effects level control or the filter capability.
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.
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
Hzwith 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.
3
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