207d
instruction Manual
Aphex Systems Ltd. Model 207D
Page 4
207d
2-ch tube mic preamp with adc
Page 5
Aphex Systems Ltd. Model 207D
POWER ON
When the unit is turned on, audio is not passed
through to the output for a few moments while the
tube warms up. During the warm-up time, the power
indicator is yellow. When the power indicator turns
green, the audio will pass through to the output. This
protects you from heavy turn-on thumps.
MICROPHONES
You can use any type of balanced, low impedance
microphone from dynamics to ribbons to condens-
ers. The 207D supplies a very clean and stable 48V
phantom voltage source suitable for even the most
expensive microphones. Phantom voltage is sepa-
rately selectable on or off for each channel at the
front panel.
OUTPUTS
The two outputs can be used at the same time. They
are not fully isolated from each other, however. To
unbalance the XLR output, simply use pin 2 (high)
and pin 1 (ground) leaving pin 3 either grounded or
floating. You may ground the ring of the phone jack,
as will happen when you plug in a mono style phone
plug. The XLR output will still remain balanced. The
output impedance of the XLR jack is low enough to
optimally drive loads of 600 ohms and higher. It is
designed to interface with fully professional balanced
gear. The phone jack output impedance is signifi-
cantly higher but meets the requirements for driving
typical semi-pro (“prosumer”) balanced and unbal-
1.0 Controls and Indicators with Quick Setup
anced equipment.
INSERT JACK
This allows you to insert any kind of line level equip-
ment into the signal path between the 207D’s front-
end preamps (mic and instrument) and tube output
stage. The operating level at this jack is in the vicinity
of IHF level (-10dBV). You should set up your inserted
outboard gear for -10dBV I/O sensitivity. All Aphex
processors can be readily set to operate at this level.
HEADROOM METER
As the level approaches 0dB, you run out of head-
room and the output will go into clipping unless
MicLim is turned on. There is a span of 27dB indi-
cated, so you can watch your signal level for safety
and convenience. When MicLim is on, the peak level
will be held to about 3dB under clip for over-level
inputs rising as much as 20dB beyond the normal
overload point.
INSTRUMENT INPUT
This input is available at the front panel through a
quarter inch phone jack. The input impedance is 1
megohms to match all coil type pickups and all pow-
ered pickups. Fully passive piezo pickups will work,
but may not deliver full tone. High impedance unbal-
anced microphones will usually work extremely well
with this input. When a plug is inserted, the mic
input is inoperative.
PAD
Inserts 20dB of loss
at mic and instru-
ment inputs, allow-
ing for excessively
high levels.
POLARITY
Inverts the relative
polarity (phase) of
the mic and instru-
ment inputs.
LOW CUT
Switches on the
70Hz Low Cut filter.
Affects mic and
instrument inputs.
PHANTOM
Switches the +48V
phantom power to
the microphone jack
on or off.
POWER INDICATOR
Aphex logo glows yellow when
power is first turned on. After a
minute of tube warm-up time, the
light turns green to indicate the
output is enabled.