Aphex J PRE 500 - Manual (Page 4)

Page 6 Page 7
The J PRE 500 mic pre is inspired by the Aphex flagship 1788A
preamp. They both use the same Jensen JT11K8 nickel input Trans-
former. Both preamps also feature the Aphex patented Mic Lim
limiter which limits before the preamp. Unlike the 1788A, the J
PRE 500 also features a Jensen JT-11DL nickel output transformer
for output balancing. This provides the cleanest possible balanced
output signal.
2.0 INTRODUCTION
3.4 -26dB PAD
When the input signal is clipping the preamp
with the input trim control turned all the way
down, the -26dB pad can be engaged to pro-
vide more headroom.
3.5 PHASE
The Phase button will invert the input signal
180 degrees. Using two microphones on
the same source can cause phase problems.
Reversing the phase of one of the microphone
signals will often clear up the issue.
3.6 75Hz HIGH PASS FILTER
Engaging the 75Hz HPF will roll off all the
freqencies below 75Hz at 18dB/octave. It’s
a good idea to use the HPF when recording
voices or instruments that don’t have much
low frequency content. Only capturing the
relevant frequencies will provide a cleaner mix
later on.
3.7 48V PHANTOM POWER
Condenser microphones require power to function. Sometimes a
microphone will use internal batteries, but usually the required power
is provided by the mic pre. Turning on the Phantom Power will send
power through the cable to power the microphone. Be carefull
though, as ribon microphones and some older dynamic microphones
can be damaged or destroyed by phantom power.
3.0 CONTROLS & INDICATORS
3.1 TRIM CONTROL
The Trim control boosts the input signal from
+26dB to +65dB.
3.2 INPUT METER
This 20 segment input meter provides visual
confirmation of the input signal level. The top
three LEDs of the meter are red. When the
input signal reaches the top red LED, the input
signal wil clip.
3.3 OUTPUT LEVEL SWITCH
The output level can be set to +16dB, +20dB
and +24dB. You will need to know the maxi-
mum input level of the next device in the audio
chain to set this properly. Most professional
audio devices can handle a +24db input signal
without issue.
However, some inexpensive computer audio
interfaces have a maximum input level of less
than +16dB. Most also offer a -20dB pad to
address these kind of issues.