12-in-1. The most complete collection of classic equalizers ever in
one DirectX / VST PlugIn: ten serial plus two parallel. Precise emulation
of legendary analog equalizers, extended by progressive, new models:
standard / vintage / modern / experimental. A sonic paradise for every
recording and mixing engineer.
A few years ago we did not even think about spending our time to
develop perhaps the 157th parametric equalizer on the market. Why
one more? Is it possible to be noticed among all the other already
It was you, our customers using our LinearPhase PEQ Red and
Orange who asked Algorithmix to develop a classical recording/mixing
equalizer but with its unparalleled purity and transparency. The
biggest problem we had in the beginning was the equalizer style,
so we closely analyzed many of them. To satisfy our customers as
much as possible, we decided to implement not only one, but an entire
collection of traditional (minimal-phase) equalizers. Most of them
emulate analog archetypes; some are based on new ideas.
We hope you enjoy the dozen shades of Blue and find that favorite
sound you previously could get only from very expensive outboard
An engineer’s best friend
The equalizer is the oldest and the most popular sound processing
tool. From the earliest days, its main function has been to correct
or enhance sound by boosting or cutting certain frequency ranges.
Engineers have developed countless equalizers for over 50 years.
Some of them became legendary and were considered benchmarks--until
now. The most popular version in recording and post-production studios
is the parametric equalizer or PEQ. It offers maximal flexibility
due to direct access to all relevant filter parameters. Properly
used, the PEQ is a very powerful tool and the best friend of every
sound engineer in the battle for perfect sound. If misused, it can
be the greatest enemy of any recording.
The good, the bad and the ugly
In today’s era of digital audio workstations, hundreds of software
parametric equalizers are available. Many of them are intended to
be THE best sounding equalizer ever. The truth is that few of them
are recognized and adored by the experts. You may ask why one equalizer
sounds great while another does not. This question is almost as
old as the equalizer itself and still is not completely answered.
On the one hand there are some obvious rules which must be followed
when designing a good sounding PEQ, on the other hand some esoteric
claims driven by marketing departments or self-nominated audio evangelists,
that never have really been proven. Especially treasured analog
equalizers are considered by some people as being absolutely unique
and unmatched by any ‘dirty’ digital equalizer. The truth is that
with a properly designed, fully parametric analytic PEQ, every amplitude
and phase characteristic of any other equalizer setup can be recreated.
Of course, the contribution of distortions to the specific sound
of a particular analog equalizer caused by the respective electronics
has to be considered. If the distortions are ‘good’, they may make
certain applications sound better. Usually, however, ‘bad’ non linear
distortions and other deficiencies like limited dynamic range are
surely not responsible for a ‘magic’ sound. Therefore our policy
in PEQ design has always been to make the equalizer filters as precise
and clean as possible. For controlled generation of distortions
(if you really need any), we recommend using enhancers or any other
specialized processors with proper built-in anti-aliasing technology.
The Blue Alchemy
After Algorithmix unveiled its linear-phase equalizers, the best
mastering engineers certificated their unparalleled sound clarity
and transparency, declaring them to be the new benchmark worldwide.
At that time, our main intention was developing an equalizer for
critical mastering and re-mastering tasks that could significantly
boost or cut complex audio material without adding its own sound.
After passing this difficult exam, our customers started asking
us to develop a classic PEQ for recording and mixing, but with the
world-famous Algorithmix purity and transparency. We knew that there
has been no single particular PEQ style that could satisfy all the
different flavors and habits in the audio community. Our intensive
research and development efforts finally resulted in the Classic
PEQ Blue, a parametric equalizer with 12 different faces. It
contains the most complete collection of classic, vintage, modern
and experimental equalizers ever included in one PlugIn. We hope
that everybody will find his favorite PEQ characteristic depending
on preferences and given applications. To avoid any conflict with
trademark owners, we did not assign any real names to the PEQ types.
Instead, we gave them rather neutral names related to their technical
classification. You are invited to discover sound nuances and share
with us your associations with real brands and/or products.
The most comprehensive collection of classic equalizers ever
Every PEQ type has 10 bands with five freely assignable parametric
filter types including bell, low-shelf, high-shelf, low-cut, and
high-cut. The most significant filters determining the equalizer
name are bells. Set up to a certain Q, different bell filters change
their bandwidth in a specific way depending on the boost or cut
amount . To allow practical comparison between different equalizer
types in the Classic PEQ Blue, the bells in all PEQs have
been normalized to 6 dB boost, i.e., a separate bell looks identical
for 6 dB boost and the same Q, independent of chosen PEQ type.
The Classic Symmetrical is the most popular bell shape used
in many mixers and outboard equalizers. It is almost constant-Q.
The three Proportional PEQs emulate bell characteristics
which change their bandwidth proportionally to boost or cut. It
is said that they behave more musically when used for recording
and mixing; one does not need to correct Q after every amplitude
correction. Furthermore, there are three other constant-Q equalizers
with characteristics mostly used by some American brands. Algorithmix
also offers two proprietary constant-Q characteristics. The first
one, Constant-Q Ideal, is a perfect version of the Classic
Symmetrical equalizer, having exactly the same bandwidth at
any amplitude within Q definition range (i.e., measured 3 dB below
maximum amplitude at and above + 6 dB boost). Such PEQs are impossible
to implement in the analog domain. Similar curiosum is the Constant-Q
New following a new interesting Q definition. It preserves exactly
the same bandwidth at the half of the maximum amplitude; this for
all adjustable amplitude values (including, unlike the classical
Q definition, the range below 6 dB boost). Due to its amplitude/bandwidth
dependency in terms of classical Q definition, this new kind of
constant-Q PEQ could also be added to the proportional group.
Finally we emulated two vintage parallel equalizers. Unlike the
serial parametric equalizer (almost all parametric PEQs are currently
serial), parallel connected filters combine differently. They also
behave differently in terms of phase. Their special problem with
some interactive influences between bands is fully accepted due
to compensation by a pleasant sound character. The Parallel LC
emulates old parallel passive PEQ circuitry built with inductors
and capacitors. The Parallel FF-FB emulates the feed-forward/feed-back
structures still very popular in low-noise analog graphic equalizers.
While the feed-forward path is trivial to implement, the feedback
path is impossible to implement in traditional digital signal processing,
because of the so-called delay-free feedback loops. In Classic
PEQ Blue, we apply a very elaborate technique for true emulation
of delay-free feedbacks for the first time to a commercial product.
The result is a characteristic sound and perfectly complementary
filters for boost and cut.
Shelf and Cut Filter Library
In Classic PEQ Blue, not only are various bell filters used
but also different kinds of shelving filters. Nine of the serial
equalizers use a new shelving filter generation characterized by
cut-off frequency defined in the middle of the transition part.
We found these filter definitions more intuitive than the classical
‘– 3 dB below maximum’. The old definition is only used in the Classic
Asymmetrical type to conform to its original predecessor. All 2nd
order shelving filters have a Q adjustment to emulate vintage characteristics
with their specific bumps at higher slopes. Also, the parallel equalizers
are equipped with respective shelving filters shapes being typical
for the old parallel PEQs and interacting with other bands as did
their analog predecessors.
Every complex PEQ is equipped with cut filters. In Classic PEQ
Blue, each of the 12 equalizers can assign 1st and 2nd order
cut filters. The 2nd order filters have a Q adjustment to create
so-called resonant filters characteristics and very steep brickwall
filters after cascading more of them (Butterworth, Bessel, Elliptic).
The best of the analog and digital worlds
Classic PEQ Blue
is a creative equalizing tool combining the
best of both the analog and digital worlds. We modeled the most legendary
analog equalizers including two parallel ones and added a few experimental
characteristics only possible in digital domain. To avoid bell filter
asymmetry at high frequencies, typical for many digital equalizers,
we have applied reference-quality upsampling techniques, automatically
switchable if the sampling frequency of the input signal is 44.1 or
48 kHz. By using proprietary filter algorithms, we have achieved a huge
dynamic range, as well as extremely low noise and distortion level and
thus unparalleled sound purity--impossible with any analog circuitry.
The whole equalizer collection works with sample rates up to 384 kHz
and therefore is perfectly suitable for DSD post-processing. Several
instances can be opened simultaneously. Complete setups can be easily
exchanged between them. The true frequency response display is zoomable
and in the DirectX version the whole PlugIn can be enlarged to the full