Warm Audio EQP-WA User manual
EQP-WA
TUBE AMPLIFIED
PROGRAM EQUALIZER
Thank you!
Thank you for purchasing the Warm Audio EQP-WA
mono program equalizer. We feel this product oers
the best in in terms of the sound, function, and vibe of
classic premium equalizers from the classic analog era
of recording. We cut no corners when it comes to what
goes into our products, and the EQP-WA is no exception.
We’ve chosen the highest quality input and output
transformers, and inductors by Cinemag Transformers.
The EQP-WA features selected high quality vacuum tubes,
potentiometers, switches, and rugged construction. We
are confident you will love recording with the EQP-WA.
Bryce Young
CEO, Warm Audio
Round Rock, Texas USA
RegisteR youR eqp-wa
Before we begin, please
take the time to visit
www.warmaudio.com
to register your product.
To ensure you receive
proper and uninterrupted
warranty support for
your product, please
register your unit within
14 days from purchase.
1
WarranTy STaTemenT
Warm Audio warranties this product to be free from defect in materials and
workmanship for one year from date of purchase, for the original purchaser to
whom this equipment is registered. This warranty is non-transferrable.
This warranty is void in the event of damage incurred from unauthorized
service to this unit, or from electrical or mechanical modification to this
unit. This warranty does not cover damage resulting from abuse, accidental
damage, misuse, improper electrical conditions such as mis-wiring, incorrect
voltage or frequency, unstable power, disconnection from earth ground (for
products requiring a 3 pin, grounded power cable), or from exposure to hostile
environmental conditions such as moisture, humidity, smoke, fire, sand and other
debris, and extreme temperatures.
Warm Audio will, at it’s sole discretion, repair or replace this product in a
timely manner. This limited warranty extends only to products determined to be
defective and does not cover incidental costs such as equipment rental, loss of
revenue, etc. Please visit us at www.warmaudio.com for more information on your
warranty, or to request warranty service.
This warranty applies to products sold in the United States of America. For
warranty information in any other country, please refer to your local distributor for
Warm Audio. This warranty provides specific legal rights, which may vary from
state to state. Depending on the state in which you live, you may have rights in
addition to those covered in this statement. Please refer to your state laws or see
your local retailer for Warm Audio for more information.
non-WarranTy Service
If you have a defective unit that is outside of our warranty period or conditions; we
are still here for you and can get your unit working again for a modest service fee.
Please visit us at www.warmaudio.com to contact us about setting up a repair or
for more information.
With the proper care, your Warm Audio gear should last a lifetime and
provide a lifetime of enjoyment. We believe the best advertisement we can have
is a properly working unit being put to great use. Let’s work together to make it
happen.
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2
chapTer 1:
noW LeT’S GeT STarTed!
HARDWARE CONTROLS — FRONT PANEL
Bypass Switch: Located on the bottom left hand side of the faceplate is the
bypass toggle switch. This switch engages or disengages the equalizer sec-
tion of the EQP-WA. By design, it is not a true bypass; but merely takes the EQ
circuitry out of the audio path. More on this is discussed later in the manual.
Power Switch and indicator bulb: Located on the bottom right hand side
of the faceplate is the mains power toggle switch. This turns the unit
on, and power will be indicated by the adjacent power indicator bulb.
LOW FREQUENCY CONTROL
Boost and Cut - Low Frequency’ selector: this rotary switch selects a fre-
quency in the low to lower midrange bands for boost, cut, or even simulta-
neous boost and cut to create a desired texture eect to the selected band.
‘Boost’ (low frequency): this controls the amount of gain
applied to the band selected by the low frequency selector
with a range from zero (unity gain) to +12db.
‘Cut’ (low frequency): this controls the amount of attenuation
applied to the band selected by the low frequency selector,
with a range from zero (unity gain) to -18db.
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The Low Frequency Control Section.
HIGH FREQUENCY CONTROL
Bandwidth: this knob varies the width of the high frequency boost and cut controls
from a relatively sharp cue (aecting the least surrounding frequencies) to a
somewhat broader cue (aecting a larger area of bandwidth). A sharp cue is
considered useful for more surgical work, such as boosting or cutting a specific
overhead piece or octave of an instrument; while a broader cue is more natural
and musical, for gentler tone shaping of instruments or program material.
Boost knob: This knob controls the amount of boost applied by the
high frequency boost selector, from zero (unity gain) to +18db.
Boost High Frequency Selector: This rotary switch selects
the high frequency to be boosted by the boost knob.
Cut knob: This knob controls the amount of attenuation applied by
the high frequency cut selector, from zero (unity gain) to -14db.
Cut High Frequency Selector: This rotary switch selects the
high frequency to be attenuated by the cut knob.
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The High Frequency Control Section
To the left: Sharp cue, Bandwidth knob set to 0.
To the right: Broad cue, Bandwidth knob set to 10
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HARDWARE CONTROLS — REAR PANEL
POWER
The EQP-WA requires a 3-pin, grounded IEC cord, and should ship
with the power cord appropriate for the territory in which it is sold.
Voltage is selectable between 115v and 230v operation, from the
rear voltage selector switch. Power input is via a standard fused
IEC power receptacle with built in fuse access, chassis mounted on
the rear of the unit. Power is turned on and o via the toggle switch
labeled ‘ON/OFF’ on the right side of the unit’s front panel.
AUDIO CONNECTIONS
The EQP-WA has both XLR and ¼ inch TRS balanced inputs and
outputs, rear chassis-mounted, operating at line level. Unbalanced
connection is also possible via a ¼ inch TS cable. It is not advised to
connect both input connectors or both output connectors at once.
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The rear panel
6
chapTer 2:
TechnicaL SpecificaTionS
frequency response: 20hz - 50khz, +/-1db
insertion loss: none (vacuum tube makeup gain amplifier)
self noise: below -75db
input impedance: 600 ohms
output impedance capable of driving a 600 ohm load
tube compliment (1x) 12AX7, (1x) 12AU7 (graded for
low noise/low microphonics)
power selectable 115v 60hz/230v 50hz via standard
grounded 3 conductor IEC cable
fuse compliment 1amp, 250 volt, fast blow
input transformer balanced, pin 2/tip=positive, pin
3/ring=negative, pin 1/sleeve=ground
output transformer balanced, pin 2/tip=positive, pin
3/ring=negative, pin 1/sleeve=ground
low frequency boost 20, 30, 60, 100, 200, 400, and 800hz
by +12 db maximum
low frequency cut 20, 30, 60, 100, 200, 400, and 800hz
by -18 db maximum
high frequency boost 3, 4, 5, 8, 10, 12, and 16khz by +18 db maximum
high frequency cut 3, 4, 5, 10, and 20 khz by -14 db maximum
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chapTer 3:
a BiT of hiSTory
In the beginning...
Most early recording consoles had very primitive equalization capabilities,
often consisting of only two knobs. These consisted of either a simple ‘tone
control’ type shelving equalizer, or a ‘low’ and ‘hi’ control knob with a fixed
frequency center. One of the most significant advancements in early studio
recording came with the advent of dedicated equalizers. The invention of
dedicated equalizers inspired desk manufacturers to start putting more
comprehensive equalization into their desks. This addition, more than any
other, brought about what we would consider the modern recording desk.
Many of the earliest outboard equalizers were passive devices, operating
in a purely subtractive manner, requiring a preamplifier (either in the form
of outboard gear, or routed back into an unoccupied channel of the console).
Not only did the equalizer lose signal level by performing equalization; but
often caused ‘loading loss’ merely by being patched in, resulting in added
noise, hum or buzz, and loss of tone or high frequencies. By the time an
equalized signal was preamplified again and passed through additional
console circuitry, the signal to noise ratio was often worse o. This
made EQ dicult to use without negatively aecting the signal quality.
7
What followed next was the innovation that brought the use of EQ into the
mainstream, known as active equalization. ‘Active equalization’ allowed an EQ
to be patched into a mixing desk for the first time without the fear of ‘insertion
loss’, added noise, or loss of fidelity. Finally, EQ could be performed risk-free.
Most analog equalizers manufactured today use some form of solid state
electronics to apply their boosts or makeup gain. The earliest incarnations of
these equalizers, however, used vacuum tubes, along with large input and output
transformers, as required by most high voltage tube circuits. This type of design
imparts a ‘sweet’ character that many modern designs fail to reproduce. Though
many modern EQ’s have a generous amount of features, few oer the warmth
and richness, or the natural and forgiving qualities of the classic designs.
In the early days of recording, distance mic recording was more common
than close-mic technique. Large rooms tend to ‘even out’ a soundstage,
eliminating the need for much of the corrective EQ used in modern production.
As close mic recording became the the accepted norm for superior track
isolation, the need for equalization became much more apparent to recording
engineers. Early studios began to utilize what many termed the ‘Tamla/
Motown’ technique (named after the famous record label and studio), whereby
an instrument or voice is ‘manipulated’ to some degree via equalization
in order to sit well within the context of a mix. Today, this is a nearly
inseparable part of the art and science of modern music production.
8
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chapTer 4:
WaxinG phiLoSophicaL
WHEN TO EQ?
This is a question that deserves thought. In some cases, EQ can be intuitive.
One of the simplest examples of corrective EQ would be in treating the
human voice; adding top end to a vocal that needs articulation, or adding
bottom end to a vocal that appears thin. In all cases, one should listen
thoughtfully and let the material tell you what it needs. Ultimately, one
should EQ when a signal requires help to fit naturally and compliment a mix.
Most musicians and artists would say they want their voice or instrument
to sound as natural as possible; however, there are many acoustic factors
which can aect one’s perception of how an event sounds. What most
artists and engineers desire is for an instrument to sound natural or, in
an idealized way, closer to the artist’s intention. Most artists expect their
recorded material to perform well in the context of a mix without covering
other performers or getting covered up. Using an outboard equalizer should
typically be viewed as much of a way to make corrective changes as it is to
make creative changes. The reason for this is that microphone placement,
room acoustics, the settings of the instrument or amp, and a whole host
of other variables are always applying their own unique type of EQ to a
signal, some of which may be outside of your control and undesirable.
As a general rule, one should do most EQ after applying compression;
though there are exceptions, such as taming a problem frequency in
advance of a compressor to allow the compressor to respond more
naturally. In this situation, one might consider subtractive EQ prior to
compression, and additive EQ post-compression. The most notable
exception to this rule is in stereo mastering, where EQ should precede
final compression and limiting, to prevent any chance of peak overages.
TIPS ON USING YOUR EQP-WA
The EQP-WA is a program equalizer by design, which means, though quite
capable on individual instruments, it especially shines on complex, full
bandwidth material; i.e. complete mixes or instrument groups. It is especially
good with providing a final tone balance and adjusting the relationship of the
midrange to the low and high frequency bands in finished material. As with
all equalization, listen for what the source material calls for, and reference
back to the original (unaltered) source often to maintain perspective.
9
THE ‘BOOST AND CUT’ TRICK
Another phenomenon well known with this classic type of design is the ability to
apply both boost and cut to a specific frequency at the same time. The resulting
eect is hardly the type of simple cancellation one might expect. The cue shape
of the boost and cut functions vary slightly, as do their gain potential; so even
matching boost and cut levels by ear can produce a result quite dierent from
when boost and cut are returned to zero. Some have described this eect as
a gentle scooping of the area around the target frequency, with an emphasis
added closer to the center frequency itself. Others describe it as a phase shift
type of eect for the target frequency. The result, by any name, is hardly subtle;
and can be used to create emphasis or texture to a specified frequency.
USING THE EQP-WA IN BYPASS MODE
When in bypass mode, the audio signal is still routed through the Cinemag
input transformer, dual vacuum tube stage line amplifier, and Cinemag output
transformer; and the EQP-WA will output at approximately unity gain relative
to the input level (or within close margin, due to small variations in output
gain from individual vacuum tubes). This design allows the user to take
advantage of an old ‘engineering trick’ known to many successful producers
and recordists, whereby one uses a piece of gear with large transformers and
high voltage tube stages as a ‘pass-through’ device or ‘tube buer’ following
a mic preamp, console send, or other piece of hardware, adding subtle sheen,
richness, thickness, and harmonic content to an audio signal. This technique
can also be used on program material (complete mixes or subgroups).
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chapTer 5:
hookup diaGramS
11
In this example, a microphone is feeding into a preampflier, which feeds in to
the EQP-WA via a balanced XLR patch cable, which feeds in the LINE LEVEL
input of your recording interface/recorder.
Note: it is important to use a line level input on your recording
device as opposed to a microphone or instrument level input.
Preamplifier
EQP-WA
Recording interface
12
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In this example, the EQP-WA is being routed as an insert into a recording device.
This is useful for using the EQP-WA as an “analog plug-in” or insert for mix-down.
The recording device is feeding the EQP-WA with a balanced 1/4” cable via a line
output. Then, the recording device is capturing the EQP-WA via a LINE LEVEL input.
EQP-WA
Recording interface
chapTer 6:
recaLL SheeTS
Session:______________ Track:_____________________ Notes:___________________________________________
Date:_________________ Instrument:________________ Notes:___________________________________________
Session:______________ Track:_____________________ Notes:___________________________________________
Date:_________________ Instrument:________________ Notes:___________________________________________
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Session:______________ Track:_____________________ Notes:___________________________________________
Date:_________________ Instrument:________________ Notes:___________________________________________
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©2015 Warm Audio LLC
Round Rock, Texas USA | www.warmaudio.com
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