LC-EQP Sound on Sound review
on test
Wes Audio LC EQP
Mono Valve Equaliser
Hugh Robjohns
W
es Audio are relative
newcomers to the pro-audio
market, joining a small throng
of interesting ‘boutique’ manufacturers
from Poland, alongside Bettermaker,
Looptrotter, IGS Audio and others. The
company’s first hardware product was
a tribute to the well-known Urei 1176 FET
compressor, in the form of an enhanced
version called the ß76 (or Beta 76,
reviewed in SOS January 2013). Radoslaw
Wesolowski, the man behind Wes
Audio, spent over a year developing the
second offering, which is a reworking of
a Pultec-style equaliser. This single-channel
LC EQP combines passive inductor,
capacitor and resistor-based EQ circuitry
with a twin-valve make-up gain stage and
also incorporates several new features and
enhancements over the Pultec EQP 1A
that clearly inspired it.
Inside & Out
This mono equaliser is housed in a 2U
rackmounting case (instead of the 3U
case of an original Pultec), with a 1.5mm
stainless-steel chassis and 4mm-thick
black-anodised aluminium front panel. The
chassis extends about 230mm behind the
rack ears and the unit weighs 7kg, thanks
in part to its Carnhill input and output
transformers. The lid is held on by six Torx
screws, so to replace the valves you’ll need
to have the right Torx screwdriver or bit.
140
Could this comparatively affordable passive
EQ with valve make-up gain actually be better
than the revered Pultec unit that inspired it?
The unit has a three-year warranty, which is
reassuring, and I gather that the company
is very responsive to its customers.
Easy-to-read white front-panel
legends detail each control’s settings,
and the controls are arranged in a layout
that broadly follows that of the classic
Pultec design. The same format of large
gain-adjusting potentiometers (scaled
from 0 -10 with half-position markers)
and smaller frequency-setting switches is
retained too. Paddle-style toggle switches
at each end of the panel implement a true
relay hard-bypass function, and turn the
unit on/off. Indicator LEDs are associated
with both switches.
The rear panel carries a pair of Neutrik
XLRs for the transformer-balanced,
line-level input and output, while an IEC
inlet with integral fuse holder accepts
mains power. The internal linear power
supply can be switched between 115 and
230 V AC supplies via a rear-panel switch.
Internal construction is very simple,
but nicely done. The mains inlet, voltage
selector and torroidal transformer are
contained behind a metal screen, with the
mains safety earth being taken directly
to the case. The only minor negative
observation I’d make here is the use of
green-coloured wiring connecting the live
June 2014 / w w w . s o u n d o n s o u n d . c o m
supply between the IEC socket, front-panel
mains on/off switch and transformer. It’s
not unsafe, just unusual and will cause any
servicing technicians to look twice!
A single, large circuit board dominates
the internal floor space, with clearly
Wes Audio LC EQP
£1320
pros
• Very nicely enhanced Pultec-style
progamme equaliser.
• Superb sound from its Carnhill
transformers and dual-triode valves.
• Good technical specifications and
build quality.
• Great price.
cons
• None really, but if pressed I’d offer the lack
of a gain trim control.
summary
This very nicely enhanced Pultec-style
programme equaliser offers separate
frequency controls for every section and
useful turnover frequency additions. Great
build quality, Carnhill transformers, twin
dual-triode valve gain stage with minimal
feedback, good technical performance, and
a lower cost than the nearest equivalent
mean there’s not really anything not to like!
divided zones for the regulated power
supply, amplifier stage, filters and output
electronics. Wima MKP4 metalised
polypropylene capacitors are used
throughout, and in the filter sections the
capacitor banks are arranged in elegant
groups according to their height and size!
A single multi-tap open-frame inductor is
employed in the HF boost filter section,
and relays provide the hard-bypass
function. A Carnhill input transformer
is mounted on the circuit board, while
a much larger output transformer is fixed
to the rear panel — both will be familiar to
Neve aficionados.
Passive equalisers can only attenuate
the signal, of course, and so some form of
amplifier is required to provide the boost
functionality on offer here. To that end
the LC EQP is equipped with a gain stage
built around two dual-triode valves: an
ECC82 (12AU7) from JJ Electronic, and
a 12AX7 (ECC83) from Electro-Harmonix.
Both the anode HT and heater power
rails for the valves are fully regulated
to ensure consistent performance, and
apparently there is no negative feedback
employed around the amplifiers in an
effort to minimise transient distortion. All
of the operational controls are wired to
a daughter PCB mounted behind the front
panel, and that is connected to the main
board via three ribbon cables.
The technical performance is good for
a valve device, with a maximum output
level of +22dBu at a total harmonic
distortion (THD) figure of around 0.8
percent, a signal-to-noise ratio of 90dB
(ref +4dBu), and a frequency response
extending between 5Hz and 65kHz
(-3dB points).
Operational Controls
All of the front-panel controls are logically
divided into four separate and completely
independent sections, each with its
own pair of gain and frequency selector
controls. On the left are the low-boost and
low-cut sections, with high boost and high
cut to the right. A bandwidth control in the
centre of the panel is associated with the
high-boost section.
The LF boost and cut sections both
have gentle shelving responses and, as
with the Pultec design, combining the LF
boost and cut equalisers simultaneously
produces the famous ‘dip before lift’ EQ
w w w . s o u n d o n s o u n d . c o m / June 2014
141
on test
Wes Audio LC EQP
shape which is such an important element
in the characteristic Pultec sound. The gain
controls both provide up to 18dB of boost
or cut, as appropriate, and the equaliser
turnover frequency options are generously
expanded in comparison with the original
Pultec. Not only are there separate
frequency controls for the bass boost
and bass cut sections, but two additional
options have also been added (120 and
250 Hz) to supplement the standard 20,
30, 60 and 100 Hz turnovers.
The high-cut section again offers 18dB
of attenuation for its shelving response,
and some additional turnover options,
comprising 2, 4, 6, 12, 16, and 20 kHz.
As in the original Pultec, the HF boost
section provides a peaking or bell-shaped
response, with adjustable bandwidth.
Slightly more gain is provided here, with up
to 20dB on offer, and the counter-clockwise
(0) end of the bandwidth control provides
the narrowest bandwidth option, while the
clockwise end (10) provides the broadest —
although the bandwidth actually varies with
frequency, getting narrower with higher
centre frequency values. Supplementing
the original Pultec’s 3, 4, 5, 8, 10, 12 and
16 kHz positions, this Wes Audio design
extends the range at both ends and in
the middle, with new 1, 1.5, 2, 6, and
20 kHz positions.
In Use
Using the LC EQP is very straightforward
— easier and far more logical than
the classic Pultec EQP 1A, in fact.
Everything works exactly as it should,
and the expanded turnover frequency
settings make it very easy to achieve
the desired effect in a very short time.
142
Like the Pultec, this is most definitely
a ‘programme equaliser’ —
­ a device
for gentle and subtle sweetening and
enhancement of a sound source — rather
than being a surgically corrective tool.
It achieves that tonal shaping in a very
musically sympathetic way.
Although the ability to combine both
LF cut and boost simultaneously might
sound odd, it actually works remarkably
well, just as it does in the Pultec, because
the shapes of the curves are different
and the way they interact produces
a complementary EQ ‘change of direction’.
So if you want to boost the LF, the cut
control (set to the same frequency)
introduces a dip at the start of the shelf
which helps to minimise the mid-range
muddiness that might otherwise result. The
The EQ itself is a passive design, and the
make-up gain that this makes necessary is
provided by two dual-triode vacuum tubes, one
an ECC82/12AU7, the other an ECC83/12AX7.
outcome is low-end weight with mid-range
clarity, which is usually exactly what is
required, and not something that can be
achieved with a simple LF shelf equaliser
alone. One big advantage over the
original Pultec design is that the LC EQP
affords the option to set the boost and cut
sections to different frequencies, giving far
greater flexibility and the ability to tune the
dip more effectively. It works really well on
bass guitars, upright bass, kick drums and
pianos, helping to add weight and solidity
without losing definition, and in general
none of the gain controls ever need to
be raised higher than 4 or 5 on the scale.
Subtlety is the name of the game here.
The high-boost control is useful for
adding air or presence, and the adjustable
June 2014 / w w w . s o u n d o n s o u n d . c o m
Alternatives
There are countless Pultec equivalents on
the market, such as the Cartec EQP 1A,
Manley Enhanced Pultec EQ1PA Single,
Mercury EQP1, Pulse Techniques EQM 1A3
or 1S3, and Tubetech PE1C studio equalisers,
but all are more expensive than the Wes
Audio LC EQP. For stereo bus or mastering
applications the Retro Instruments 2A3
Program EQ and Manley Enhanced Pultec
EQP 1A Dual are strong contenders. The
nearest competitor in terms of price is
probably the Pultec clone offered by Polish
compatriots IGS Audio.
bandwidth helps to focus in on the specific
area that needs treatment. The additional
high-mid centre-frequency options cater
for situations where you want to push the
mid-range energy a little harder, but for me
the real strength of this EQ section lies at
the high end, where it adds sparkle and air
in a deliciously subtle way. Again, working
in concert with the high-cut section allows
useful tonal sculpting with great flexibility.
As always, being able to compare the
EQ changes against the source is vital to
check whether you have really improved
matters or just made it louder and brighter
— something which is so easily done! —
and the hard-bypass function is very handy
in that respect. However, there is currently
no option to trim the EQ output to allow
properly matched levels, which is a minor
frustration. I know that few equalisers
include this function, but it would be very
useful, it would further enhance the Pultec
concept, and there is certainly space
to add the extra control — perhaps
that’s something to consider for a future
update. A stereo unit with carefully
matched gain controls would also be
a worthy sibling, ideally suited for mix-bus
shaping and mastering applications.
Verdict
The LC EQP is a very nice product with
a well-executed enhancement of the
Pultec passive EQ concept, an elegant
minimal-feedback valve amplifier,
transformer-balanced I/O, and a very
good build quality. It also sounds fabulous
and is remarkably easy to use, and in all
of those respects I’d tentatively suggest
it offers valid improvements over the
original Pultec EQP 1A and easily justifies
the asking price.
££ £1320 including VAT.
TT Funky Junk +44 (0)20 7281 4478
EE [email protected]
WW www.proaudioeurope.com
WW www.wesaudio.com
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This article was originally published
in Sound On Sound magazine,
June 2014 edition
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