Aphex CHANNEL User manual

User Manual
P/N
Revision 1
Released 05/30/2011
Manufactured by
Aphex
11068 Randall St.
Sun Valley, CA 91352
USA
Master Preamp and Input Processor
Copyright 2011 Aphex All rights reserved.
.
Channel

Channel instructionManual
Page 2
Copyright 2011 by Aphex. All rights reserved. All Aphex products are trademarks or registered trademarks of Aphex. Other brand and
product names are trademarks or registered trademarks of their respective holders.
Safety Declarations
CAUTION: For protection against electric shock, do not remove the cover. No user serviceable parts inside.
WARNING: This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to
Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when
the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency
energy and, if not installed and used in accordance with the operating guide, may cause interference to radio communica-
tions. Operation of this equipment in a residential area is likely to cause interference in which case the user will be required
to correct the interference at his own expense.
The user is cautioned that changes and modifications made to the equipment without approval of the manufacturer could
void the user’s authority to operate this equipment.
It is suggested that the user use only shielded and grounded cables to ensure compliance with FCC Rules.
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Aphex Channel

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1.0 CONTROLS & INDICATORS PLUS QUICK SETUP........................................................................
2.0 INSTALLATION AND INTERFACING
2.1 Installation .........................................................................................................................
2.2 Rear Panel View ..................................................................................................................
2.3 AC Line Connection ............................................................................................................
2.4 Mic Input Connections .........................................................................................................
2.5 Insert Jacks...........................................................................................................................
2.6 Output Connections.............................................................................................................
2.7 Digital Audio Outputs .........................................................................................................
2.8 Word Clock .........................................................................................................................
2.8.1 INT/EXT...............................................................................................................
2.8.2 WC IN................................................................................................................
2.8.3 WC OUT.............................................................................................................
2.8.4 Local Clock Mastering.........................................................................................
2.9 Power Supply........................................................................................................................
2.9.1 Cough Switch ...................................................................................................................
3.0 USING THE Channel
3.1 Using the Mic Input..............................................................................................................
3.2 Using the Instrument Input ..................................................................................................
3.3 Using Phantom Power...........................................................................................................
3.4 Using the Polarity Switch..... ................................................................................................
3.5 Using the Pad.......................................................................................................................
3.6 Using the Low Cut................................................................................................................
3.7 Using the Phase Rotator........................................................................................................
3.8 Using the Compressor...........................................................................................................
3.9 Using the Logic Assisted Gate.............................................................................................
3.10 Using the De-esser..............................................................................................................
3.11 Using the Equalizer Block....................................................................................................
3.11.1 Big Bottom........................................................................................................
3.11.2 Parametric Equalizer..........................................................................................
3.11.3 Aural Exciter.....................................................................................................
3.12 Using the Level Control......................................................................................................
3.13 Clip Light...........................................................................................................................
4.0 WARRANTY AND SERVICE
4.1 Limited Warranty ................................................................................................................
4.2 Service Information .............................................................................................................
5.0 SPECIFICATIONS
5.1 General Specifications .........................................................................................................
5.2 Architectural Specifications .................................................................................................
5.3 Patent Notice ......................................................................................................................
Table of Contents
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Aphex Channel

Channel instructionManual
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POWER INDICATION
The Aphex logo above the power switch glows yellow during the
tube preamp’s warmup time and green when the unit is ready.
LOW NOISE MIC PRE
The Channel works with all professional microphones. The clean
and stable 48V phantom supply is suitable for even the most
expensive microphones. The 12dB/octave low cut filter starts at
70Hz to effectively reduce wind blast without diminishing voice
body. Included is a selectable phase rotator following the principles
of the Spectral Phase Refractor (SPR) circuit. The main bebefit of
the Phase Rotator is that by making certain voice waveforms more
symetrical, the compressors action becomes more efficient. This
allows for a more optimized output level.
COMPRESSOR
The Channel includes a special version of Aphex’s patented
Easyrider™ Compressor which has proven to be outstanding. It is
very simple to use with only two controls: Gain/Drive and Release.
To get deeper compression, turn up more Gain. To manage the
density and loudness, work with Release. Faster is louder and
denser. Slower is more natural and open. Note that turnring up
the Gain/Drive to get more compression alters the overall gain
structure through the device such that the output may need com-
pensating adjustment.
LOGIC ASSISTED GATE™
Once triggered, even by a microscopic transient, the signal pro-
gresses fully through the attack, hold, and release sequence.
This virtually eliminates the chatter experienced with other gate
products. The attenuation depth and gating threshold are user
1.0 Controls and Indicators
adjustable to allow for varying requirements. The attack, hold,
and release timing are internally set to function optimally on voice
waveforms.
DE-ESSER
Using a split-band technique with Linkwitz-Riley crossovers, the
voice remains bright and sharp, never losing presence while de-
essing. The de-ess threshold control lets you chose the essing level
that you want.
EQUALIZATION BLOCK
A fully parametric equalizer band is provided along with the popu-
lar Aphex Big Bottom and Aural Exciter. These features increase
power, punch and intelligibility without adding noise or an increase
in output level. As a real plus, they are also very easy to adjust.
REAR INSERT JACK
Allows you to insert any kind of line level audio equipment into
the signal path between the Channel’s dynamics processing and
the equalizer section. The operating level at this jack is 0dBu. You
should set up your inserted outboard gear accordingly.
METERS
Meters are provided for peak output level (relevant to both analog
and digital headroom at 0dB = max before clip) and the com-
pressor’s gain reduction. The output level bar graph will move
upwards indicating level, and the gain reduction bar graph will
move downwards indicating gain reduction.
GAIN/DRIVE
Adjusts
preamp gain
and drive into
the compres-
sor.
Lo Cut
Switches on
the 70Hz Low
Cut filter.
Invert
Polarity
When
pressed,
inverts the
polarity
(phase) of the
mic input.
Phase Rota-
tor
Enables the
Spectral
Phase
Refractor
to improve
speech sym-
metry.
Compressor
Turns on the
Easyrider
compressor
circuit.
RELEASE
Controls the
density of
compres-
sion. Slow
for natural
leveling and
fast for more
loudness.
GATING
Shows when
the gate
is closed
or closing.
When the
light is off,
the gate is
fully open.
GATE THRESHOLD
When the sound is higher than this
level, the gate opens up instantly. No
“chattering” thanks to the patented
Logic Assisted Gate.
CLIP/MUTE
Flashes yellow when the
preamp is muted by the
cough switch. Flashes red
indicating clipping.
PAD
When pressed,
turns on the 20dB
input pad.
48V
When pressed,
turns on the
microphone phan-
tom 48V power
IINSTRU-
MENT INPUT
Allows con-
nection of
a guitar or
bass.
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Page 5
Quick Setup
Why You Shouldn’t Connect the Channel’s Output to a Mic Level Input.
The bottom line: you will get an unsatisfactory noise level. The Channel is designed to generate a line
level output from a mic level input. It optimizes the signal to noise ratio by giving you a strong signal far
above the preamplifier’s basic self noise level. This strong output signal can be up to 65dB higher than
the mic signal. It is perfect for a standard line input of a mixer or console but can overload a mic input. If
you have no other choice but to plug the Channel in to a mic input, turn that mic input’s gain all the way
down. If the signal still clips the input, try bringing down the Channel output level.
GATING
Shows when
the gate
is closed
or closing.
When the
light is off,
the gate is
fully open.
DEPTH
Lets you set how much attenuation the
gate will deliver. Use the lowest attenuation
that’s needed to reduce room wetness,
breath, or background noise. Usually 6 to
15dB is sufficient. Fully CCW is off.
BIG-BOTTOM
FREQ
Adjusts the
frequency
below which
enhancement
takes place.
PARAMETRIC EQ
Works like a standard parametric band
with tune, Q, and boost/cut controls.
AURAL EXCITER
FREQ
Adjusts frequency
above which
enhancement
takes place.
AURAL EXCITER
AMOUNT
Adjusts the
strength (boost) of
the Aural Exciter
effect.
BB/EQ/AX
ON
Switches the
BB/EQ/AX
on/off.
Provides full
true bypass
of the circuits
when off.
OUTPUT
Adjusts the
final pro-
cessed output
level as seen
on the VU
meter.
Line Level
Processor,
i.e.,
Compressor, EQ
+4dBu
Balanced
XLR
Output
Rear Panel Analog Connections
-10dBV/
+4dBu
switchable
TRS Output
BALANCED
TRS
Rear Panel Digital Connections
AES/EBU
OUTPUT
Digital 110
Ohm cables
only. (Do not
use regular
audio cables.)
S/PDIF &
OPTICAL
OUTPUTS
All outputs are
active at the
same time.
WORD CLOCK
BNC input and output jacks.
OUTPUT CONTROL
Once all processing and equal-
ization is set where you want
it, the output level may need to
be adjusted. Do not let the peak
level frequently exceed -6dBFS.
This will make sure the digital
output carries well through sub-
sequent mixing and processing.
When using the analog output,
adjust the level to produce the
desired average output level
(0VU) as seen on the outboard
equipment’s meters.
DIGITAL AUDIO
The Channel supplies industry standard stereo
AES/EBU, S/PDIF, and TOSLINK digital audio
outputs. The single mic channel appears
on both stereo channels as a mono signal.
Sample rate and word clock options are all
available at the front panel. The word clock
selection LEDs will flash when no clock signal
is present and light solid when locked.
MIC INPUT
Works with all standard
microphones, phantom
powered or passive.
Phantom power acti-
vated from front panel.
COUGH SWITCH
Allows you to
silently mute the
output on the
fly using a hand-
held, desktop, or
floor switch.
BIG-BOTTOM
AMOUNT
Adjusts the
strength
(boost) of the
Big Bottom
effect.
DE-ESS
THRESHOLD
Lets you set
the level
where you
want your
esses to level
off.
DE-ESSING
Shows when
the the de-
esser is work-
ing. When
the light is
on, sibilance
is being
controlled.
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Page 6
2.0 Installation & Interfacing
2.4 MIC INPUT CONNECTION
The microphone input connector is located on the
rear panel. It is the standard XLR-3F type. Use only
properly wired balanced mic cables.
CAUTION: Some ribbon mics will be damaged by
phantom power. Some ribbon mics require phan-
tom power and some just ignore it. Please consult
your manual before connecting a ribbon mic to
the Channel.
CAUTION: Beware that 48 volt PHANTOM POWER
may be applied to the microphone input, creat-
ing a potential shock hazard. Standard practice
dictates shutting off the phantom power before
plugging or unplugging microphones. Wait at
least 10 seconds for the voltage to fall sufficiently.
This is not only for safety, but for protection of
sensitive microphones against power inrush.
2.5 INSERT JACKS
The Channel allows you to insert additional signal
processing between the Channel’s dynamics process-
ing and the equalizer block. Both Send and Return
jacks are balanced and run at 0dBu. This is a perfect
place to insert an external reverb unit or profanity
delay, but you have the option to put anything there
that you wish as long as it returns a nominal level.
Direct feed-through occurs with the normalling con-
tacts of the jacks. If you plug into either the SEND
or RETURN jack, the internal path is interrupted. You
need to be sure you have a viable send-return circuit
externally or there will be no audio output from the
Channel.
There is no insert bypass switch. Once plugged in, the
insert is always inserted. If you can’t get any output
from the Channel, make sure the inserted gear is
operating.
2.1 INSTALLATION
The Channel occupies a single rack space (45mm or 1-3/4 inches) of a standard EIA equipment rack.
When rack mounting, use appropriate cushioned rack screws. Never restrict air flow through the device’s vents.
When installing the units into a rack, distribute the units evenly. Otherwise, hazardous conditions may be cre-
ated by an uneven weight distribution. Connect the unit only to a properly rated supply circuit. Reliable earthing
(grounding) of rack mounted equipment should be maintained. Try not to position the Channel directly above
devices that generate excessive heat such as power amplifiers (unless adequately ventilated) or near equipment
with heavy transformer hum fields.
2.2 REAR PANEL VIEW
2.3 AC LINE CONNECTION
Use only a power cord that carries approvals for use in your location. The Channel’s internal power supply is
designed to operate from all nominal power sources from 100 to 240 volts a.c. at 50/60Hz without requiring
the user to change any settings. In case of failure, do not attempt to change the internal fuse because it will
never blow unless the power supply fails catasrophically. The power supply will need to be serviced by a com-
petent service technician in such a case.
PROPER MICROPHONE CABLE WIRING
Female XLR Male XLR
AUTIONC
48V
Aphex Channel

Channel instructionManual
Page 7
Installation & Interfacing
2.6 OUTPUT CONNECTORS
There are two output connectors located on the
rear panel: one 1/4” TRS phone type and one XLR-
3M type. They can be used at the same time to feed
separate equipment.
The output level at the XLR is +4dBu impedance
balanced, while the TRS balanced/unbalanced jack
is switchable between -10dBV (consumer level) and
+4dBU (professional level).
If you intend to make an unbalanced output from
the XLR jack, simply take “hot” from pin 2 and
use pin 1 for ground. Leave pin 3 unconnected or
grounded. Never ground pin 2.
2.7 DIGITAL AUDIO OUTPUTS
The processed mic signal is converted to digital in
both channels at equal level as a mono signal. There
is no provision to externally drive one of the A/D Con-
verter inputs.
2.8 WORD CLOCK
2.8.1 Clock Select
Synchronization is selected by the Clock Select button
on the front panel. Sample rates of 44.1, 48, 88.2 or
96kHz are supported.
2.8.2 WC IN
This BNC jack is provided to receive your master clock
source. It will accept industry standard Word Clock,
from less than 1 to over 5Vp-p pulse amplitude. It
does not accept AES/EBU or Superclock.
2.8.3 WC OUT
The Channel provides a very accurate internal word
clock generator. When using the Channel as a clock
master, the word clock signal is sent from the BNC
word clock output. Note that the Channel does not
support word clock THRU. External clock signals
received at the BNC input are not routed to the BNC
output. A word clock distribution device should be
used in systems with multiple digital devices.
2.9 POWER SUPPLY
The Channel is internally powered from a standard
IEC power receptacle on the rear panel. Be sure you
use a power cord that is approved for use in your
jurisdiction.
Soft-start, overload foldback limiting, and accros-the-
line voltage spike protection is incorporated to protect
the power supply from damage that might be caused
by component failure or power line disturbances. If
the internal fuse blows out, a catastrophic failure has
occurred and simply replacing the fuse will not fix the
problem. Due to the extensive protective measures
used, it is highly unlikely a catastrophic power supply
failure will ever occur. However, if it does, you should
contact the factory or a competent service technician
to affect repairs. There are no user serviceable parts
inside.
100 to 240V~, 50 to 60Hz
ACCEPTABLE POWER RANGE
2.9.1 Cough Switch
Voice artists/actors often find it necessary to clear the
throat, sip a beverage, or cough during narration.
Thus, a convenient mute and unmute jack is provided.
Any standard momentary or latching foot pedal or
switch wired to a mono phone plug will work. Usu-
ally, a desktop box mounted silent pushbutton is pre-
ferred, as it can be accessed most readily.
XLR: AES/EBU 110Ω@ 5Vp-p
RCA: S/PDIF 75Ω@ 1Vp-p
OPTICAL: Toslink S/PDIF encoded for optical fiber.
DIGITAL OUTPUT DEFINITIONS
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Channel instructionManual
Page 8
3.1 USING THE MICROPHONE INPUT
The Channel is perfect for all types of microphones,
either powered or not. We encourage you to try every
mic you own with the Channel.
Many features of the Channel are standard with all
professional preamps - polarity - pad - etc. Some
features are unique and we hope you will fully exploit
them.
3.2 USING THE INSTRUMENT INPUT
The Channel can also be used as a high quality direct
box. When an instrument cable is plugged in to the
Instrument input on the front panel, the rear panel
XLR input is bypassed. This allows the user to keep a
microphone connected to the rear panel and simply
insert an instrument cable in to the front panel instru-
ment input when D.I. functions are required. You will
be able to acheive proper input levels no matter what
kind of pickups are used. Single coil passive pickups
will work just as well as active humbuckers.
3.3 USING PHANTOM POWER
Active microphones that take power through the stan-
dard mic cable fall into a class called “phantom pow-
ered” mics. The power is called “phantom” because it
rides the mic cable invisibly, without interfering with
the audio signal carried on the same wires.
The industry standard phantom power source is posi-
tive 48 volts d.c. supplied to pins 2 and 3 through
precision low noise 6.81KΩ resistors. You may note
from spec sheets that many mics rated for phantom
power actually run at something less than 48 volts.
Don’t let these specifications confuse you. They all
run perfectly well off the standard 48V phantom
power source.
Plugging and Unplugging a microphone when phan-
tom power is switched on can sometimes be dan-
gerous. Some microphones can be damaged by
power inrush. Good practice calls for switching off
the phantom power before changing or inserting a
microphone. Wait long enough to hear the mic go
silent before unplugging.
3.0 Using the Channel
FRONT PANEL VIEW
You should be aware of the shock hazard with the
phantom power system. Long, open mic cables that
are disconnected from the preamp while phantom is
on can hold a d.c. charge for long periods of time,
sometimes days, weeks or months. They will act as
a storage capacitor and you can get shocked most
rudely by holding the XLR plug and touching the
pins inside. Also beware of microphone patch bays
that may carry phantom voltage. Don’t hold the
patch cord by the metal parts, only the plastic shell.
CAUTION: Some ribbon mics will be damaged by
phantom power. Some ribbon mics require phan-
tom power and some just ignore it. Please consult
your manual before connecting a ribbon mic to
the Channel.
3.4 USING THE POLARITY SWITCH
There will be times when you need to reverse the
polarity (phase) of a mic signal. Vocalists monitor-
ing themselves on headphones will hear a different
sound when the phase is reversed. The reversed phase
may sound fuller and more truthful or hollow and
far away. That is because there is a cancellation of
frequencies within the ear when the external sound
from the headphone mixes with the sound directly
conducted to the ear. “Flipping the phase” can make
the problem either more or less noticeable.
Another time when phase reversing can be helpful is
when using multiple microphones on the same
source. For exapmple, using two microphones on a
guitar speaker cabinet. You may get a “nasal” or
hollow effect when both mics are on. Changing the
polarity of one mic will often clear up the problem.
It is always worth the time to experiment with mic
polarity.
Aphex Channel

Page 9
Figure 4-2 Phase Cancellation Effect
Distance
to Mic2
Distance
to Mic1
Sound
Cancelled
=
3.5 USING THE PAD
An input pad is nothing more than a resistive
attenuator that drops the level coming from the
input. Its purpose is to give you a way of prevent-
ing overload of the preamp when incoming signals
become excessive.
In the Channel, we provided a pad of 20dB. That
means when the pad is on, the net gain of the
preamp is 20dB lower. There are times that the input
may be overloaded even with the GAIN control set all
the way down. For example, a bass player with active
pickups and an agressive playing style might peak the
instrument input. Or a microphone on a kick drum
or snare drum could do it. Engage the pad and 20dB
of headroom will be provided allowing you to better
control the input signal.
3.6 USING LOW CUT
In the rearl world, mics pick up all sorts of unwanted
low frequencies such as handling noise, wind rumble,
or lectern thumps. We designed into the Channel a
very effective way of cutting out these low frequen-
cies. Switching on the LOW CUT FILTER rolls off all fre-
quencies below 70Hz at 12dB per octave but places
a slight compensation around 120Hz to improve the
low end phase distortion and perception of remain-
ing bass.
Figure 3-6 LO CUT
3.7 USING THE PHASE ROTATOR
The Channel’s phase rotator is designed to help
reduce high assymmetric peaks that often occur with
audio waves. By reducing the amplitude of assym-
metric peaks, and making the wave more symmetri-
cal, the voice can ride louder through compressors
and limiters. This is accomplished by displacing the
time relationship of even harmonics to their funda-
mentals. Thus, it is called a “Phase Rotator”.
Some words of advice: When doing voice work while
wearing headphones, the Phase Rotator will affect
how you hear yourself even though it is not affecting
the actual sound of your voice. That’s because the
body-conducted sound mixes with the sound from
the “headphones”. When the two sounds are out of
phase, there will be partial to full cancellation at vari-
ous frequencies. Just as you experience the effect of
switching polarity, turning on the phase rotator will
have a pronounced effect. You should evaluate the
phase rotator by auditioning recorded tracks made
with and without the rotator effect.
It should also be noted that the effecs of the Phase
Rotator are program dependant and results should
be evaluated with any new signal.
3.8 USING THE COMPRESSOR
The Channel’s compressor is probably the simplest
one to use that you will ever see. Nevertheless, it
is more sophisticated than compressors with many
more controls. The Easyrider compression automati-
cally adapts to audio waves in a manner that greatly
reduces any pumping effect while it tightens the
average level very flatteringly.
There is only one obvious control: RELEASE. How-
ever, the mic pre’s GAIN control doubles as the com-
pression drive adjustment. To get more compression
depth, run up more gain. The RELEASE control allows
you to chose the aggressiveness of the compression.
For thick and loud, go faster. For more natural and
“open”, go slower.
The gain reduction is displayed on the Channel’s 10
segment bargraph meter. You may need to boost the
output level to compensate for the gain reduction of
the signal.
Aphex Channel

Channel instructionManual
Page 10
Using the Channel
3.9 USING THE LOGIC ASSISTED GATE
If you’ve worked with gates before, you probably
know how frustrating they can be. Finding the
threshold and attack setting that doesn’t clip the first
sound and still reliably gates out the noise is usu-
ally difficult. Aphex’s Logic Assisted Gate solves all
that for you very simply. The Channel’s gate trigger
is absolutely positive because it’s independent from
the energy content of the sound peak. The slightest
tickling of the threshold by the soundwave triggers
a chain reaction that forces the gate’s attack-hold-
release sequences to perform completely and repeat-
ably. That makes finding the right threshold fast and
easy. All you need to set are the threshold and depth
of gating.
If you want complete silence between phrases, then
use the maximum depth. However, if you simply
want to bring down ambience pickup as with mul-
tiple open mics in a room, then use minimal depth.
When the gate is closed or closing (blocking), the LED
indicator is lit. When it is open (passing audio), the
LED is dark.
3.10 USING THE DE-ESSER
Certain mics are too harsh in the upper range and
some sounds tend to whistle or splatter. Conventional
de-essers simply detect the presence of any frequency
above a certain tuning point and duck the whole
signal accordingly. The Channel’s de-esser is differ-
ent. It uses split band techniques to attenuate only
the sibilance, while leaving the body of the sound
alone.
Operation of the de-esser is simple. Just set the
threshold to the point where you want the esses to
limit out. Reducing the threshold setting brings down
the level of the esses dynamically. In other words, it’s
like an automatic downward shelving equalizer. It
stays flat until the ess level gets too high and then
introduces the shelf at the level needed to limit the
sound to the threshold level. When there is de-
essing, the LED is lit.
3.11 USING THE TONE ENHANCEMENT BLOCK
Once the signal passes through the compressor, gate
and de-esser, it encounters the Big Bottom low fre-
quency enhancer, parametric peak/dip section, and
the Aural Exciter top end enhancer. The whole block
is bypassable with the BB/EQ/AX on/off pushbutton.
3.11.1 Big Bottom
Some signals have no low bottom end. In such cases,
the Big Bottom won’t synthesize a new low end for
you and it should not be used. However, voices that
contain a deep chest resonance can be augmented
by the Big Bottom.
Start by turning up the BB Amount to 12:00. Then
adjust the BB FREQ to find a frequency that lifts the
bottom. Last, reduce the BB Amount until just the
right touch of bass enhancement is felt.
3.11.2 Parametric Equalizer
This is a familiar and conventional EQ section. You
can adjust the boost/cut, frequency selection and Q.
3.11.3 Aural Exciter
Clarity, presence, and loudness can all be enhanced
by the Aural Exciter.
Start with the AX Ampount at 12:00. Next, sweep
the FREQ to find the best tonal balance. Presence is
best augmented with lower settingss. Air is added
with higher settings. Finally, readjust the AX Amount
for the right amount of brilliance. Be conservative.
Use the BB/EQ/AX on/off switch to compare the origi-
nal signal to the enhanced signal.
3.12 USING THE OUTPUT LEVEL CONTROL
Once all the processing is set, the output level may
need to be adjusted. Change the OUTPUT control
to obtain peaks that don’t go above -6dBFS on the
output meter. Check the input meter of the device the
Channels output is plugged in to. If the input device
is cliping, first turn the input devices gain control
down. If the input is still cliping, bring the OUTPUT
level of the Channel down to compensate. Be sure
that the operation level of each device is set properly
at either -10dBV or +4dBu.
3.13 CLIP/MUTE LIGHT
If the LED is flashing RED, then the internal operat-
ing level is too hot. This can only occur if the insert
return signal is too hot or if the parametric equalizer
is boosted way too much. This same LED will also
flash yellow while the Channel is in the MUTED state
activated by the COUGH SWITCH (rear panel jack).
Aphex Channel

Channel instructionManual
Page 11
4.2 SERVICE INFORMATION
If it becomes necessary to return this unit for repair, you must first contact Aphex Systems, Ltd. for a Return
Authorization (RMA number), which will need to be included with your shipment for proper identification. If
available, repack this unit in its original carton and packing material. Otherwise, pack the equipment in a strong
carton containing at least 2 inches of padding on all sides. Be sure the unit cannot shift around inside the
carton. Include a letter explaining the symptoms and/or defect(s). Be sure to reference the RMA number in your
letter and mark the RMA number on the outside of the carton. If you believe the problem should be covered
under the terms of the warranty, you must also include proof of purchase. Insure your shipment and send it
to:
Aphex
11068 Randall Street
Sun Valley, CA. 91352
PH: [phone] FAX: [phone]
4.0 Warranty & Service
5.1 Limited Warranty
PERIOD
One year from date of original purchase.
SCOPE
All defects in materials and workmanship.
The following are not covered:
Voltage conversions
Units on which the serial number has been defaced, modified or removed.
Damage or deterioration resulting from: Installation and/or removal of the unit; Accident, misuse, neglect,
unauthorized product modification; Failure to follow instructions in the Owner’s Manual, User Guide or other
official Aphex documentation; Repair or attempted repair by anyone not authorized by Aphex; Shipping damage
– claims must be presented to the shipper
WHO IS PROTECTED
This warranty will be enforceable by the original purchaser and by any subsequent owner during the warranty
period, so long as a copy of the original Bill of Sale is submitted whenever warranty service is required.
WHAT APHEX WILL PAY FOR
All labor and material expenses for covered items. Aphex will pay all return shipping charges if the repairs are
covered by the warranty.
LIMITATION OF WARRANTY
No warranty is made, either expressed or implied, as to the merchantability and fitness for any particular pur-
pose. Any and all warranties are limited to the duration of the warrant stated above.
EXCLUSION OF CERTAIN DAMAGES
Aphex liability for any defective unit is limited to the repair or replacement of said unit, out our option, and shall
not include damages of any kind, whether incidental, consequential, or otherwise. Some states do not allow
limitations on how long an implied warranty lasts and/or do not allow the exclusion or limitation of incidental or
consequential damages, so the above limitations and exclusions may not apply to you. This warranty gives you
specific rights which vary from state to state.
Aphex Channel

Page 12
OUTPUT
Connector:
Type:
Output Z Balanced:
Output Z Unbalanced:
Nominal Level
Maximum Output Level (MOL):
5.1 GENERAL SPECIFICATIONS
XLR-3M and TRS 1/4” phone jack
XLR is Impedance Balanced (may be used unbalanced); TRS is unbalanced.
XLR: 66Ω
XLR: 33Ω − TRS: 600Ω
XLR: +4dBu; TRS: -10dBV
XLR: +25dBu Unloaded; TRS: +11dBV
5.0 Specifications
All specifications are subject to change without notice.
MIC INPUT Connector:
Type:
Input Z:
Instrument Connector:
Instrument Input Z:
Type:
Maximum Input Level (MIL):
CMRR:
Nominal Preamp Gain:
Phantom Power:
Pad:
EIN:
XLR-3F
Transformerless, NPN active balanced, tube second stage
2KΩ nominal
1/4” TS
10MΩ nominal
Transformerless, NPN active balanced, tube second stage
0dBu
Greater than 70dB @ 60Hz
20 to 65dB
+48VDC
20dB
-127dBu (Input Shorted)
COMPRESSOR
Attack/Release:
Ratio:
Threshold:
Knee:
Program dependent, user variable release baseline.
4:1
Fixed
Medium Hard
INSERT
Connector Type Send:
Connector Type Return:
Nominal Operating Level:
Point of Insertion:
1/4” TRS Phone Jack, Balanced
1/4” TRS Phone Jack, Balanced
0dBu
Between dynamics processing and equalizers.
GATE
Attack:
Hold/Release:
Threshold:
Depth:
0.1 millisecond
300 milliseconds/400 milliseconds
Variable -50 to +20dB
Variable, 1 to 58dB
DE-ESSER
Attack:
Release:
Threshold:
Raio:
Active Band:
0.1 millisecond
100 milliseconds
Variable -20 to +20dB
5:1
4.KHz to 20KHz Linkwitz-Riley 24dB/octave crossover
BIG BOTTOM
Frequency Tune:
MIx:
50Hz to 280Hz
OFF to +12dB
PARAMETRIC EQ
Frequency Tune:
Peak/Dip:
Q Range:
240Hz to 8KHz
+/- 12dB
0.5 to 5
AURAL EXCITER
Frequency Tune:
Mix:
500Hz to 5KHz
OFF to +12dB
ANALOG AUDIO
THD:
IMD:
Freq Resp (FLAT):
<.01% @ +4dBu Out
<.01% @ +4dBu Out
18Hz to 24KHz +/- 1dB
DIGITAL AUDIO
Internal Sample Rates:
External Sample Rates:
Resolution:
Word Clock Input:
Word Clock Output:
Dynamic Range:
Noise Dither:
Level Equivalency:
44.1KHz, 48KHz, 88.2KHz, 96KHz
Automatically syncs to any word clock between 32KHz and 96KHz
24 Bits
BNC Jack, High Z, Captures <1Vp-p to 5Vp-p
BNC Jack, 75 Ohms, 5Vp-p
Digital dynamic range greater than analog front end.
Dithered by analog preamp noise floor. Equivalent to 16-bit digital audio dither.
-20dBFS Digital = +4dBu Analog
OTHER SPECS
Power requirements:
Power Consumption (maximum):
Dimensions:
Depth Behind Front Panel:
Net Weight:
Shipping Weight:
Tube Type:
85 to 260V~, 50-60Hz
12 Watts
19” W x 1.75” H x 8.25” overall depth (482.6mm W x 445mm H x 209.6mm overall depth)
7.5” (190.5mm)
Rack-mounted: 6lbs. (2.73kg)
9lbs. (4.1kg)
12AT7/ECC81 Dual Triode
Aphex Channel

Channel instructionManual
Page 13
Specifications
5.2 ARCHITECTURAL SPECIFICATIONS
Basic Description
A single channel processor comprising an instrument input, transformerless tube-type microphone preamp, a
dynamics processing section and a tone controlling section, in that order. An insertion path shall be provided
between the dynamics procesisng section and the tone controlling section.
The microphone preamp shall comprise the following selectable functions: 1.) +48VDC Phantom Power; 2.)
Polarity Reversal; 3.) Selectable 20dB Pad; 4.) Selectable 70Hz 12dB/Octave Low Cut Filter; 5.) Continuous Gain
Control; 6.) Phase Rotator.
The dynamics processing section shall comprise an adaptive dynamic range compressor, a logic assisted noise
gate, and a split-band de-esser.
The tone control section shall comprise a Big-Bottom bass enhancer, an Aural Exciter treble enhancer, and a
single band parametric equalizer.
Physical Properties
The device shall be packaged in an all metal chassis measuring 19” (482.23mm) wide, 1.75” (44.42mm) high,
with an overall depth of 8.25” (210mm). Depth behind the front panel shall be approximately 7” (178mm).
The device shall have a net weight of approximately 6lbs. (2.73kg) and is capable of mounting in a standard
electronic equipment rack.
Power
The unit shall have a self contained power supply operating from the ac line. Primary voltage, connectorization
and agency listings shall be appropriate to meet local requirements.
Aphex Channel

Channel instructionManual
Page 14
This product is protected under one or more of the following Aphex patents.
4,578,648
4,633,501
4,843,626
4,939,471
5,115,471
5,155,769
5,334,947
5,359,665
5,422,602
5,424,488
5,450,034
5,463,695
5,483,600
5,485,077
5,612,612
5,737,432
5,848,167
5,896,458
5,898,395
5,930,374
6,266,423
Patent Notice
Aphex Channel