XO Wave is now discontinued
as we prepare to bring you the next generation
Digital Audio Workstation called
This site remains available for anyone who
purchased XO Wave in the past.
However, please keep in mind that as discontinued software:
- This site may not contain up-to-date information.
- Technical support is discontinued, though we will do our best to continue to provide
email support, especially to anyone who purchased recently.
XO Wave: Using EQ
XO Wave has two basic EQ effects: a simple Butterworth Filter, and a
Multi-band Parametric EQ, which offers several pre-configured
arrangements of multiple Butterworth filters. We'll start with
the standalone Butterworth Filter, and then review the
multi-band options. You may also want to read
How to use EQ for some pointers
on using EQ in your mix.
Butterworth filters are essentially the same filters found on most analog and digital equalizers.
The basic operation and sound of these filters should be
familiar to anyone who has used an equalizer.
XO Wave's EQ comes in several flavors (subtypes): High
Cut (also called a "low pass filter", and labelled
H-Cut inside XO Wave), Low Cut
(also called a "high pass filter", and labelled
L-Cut inside XO Wave), Band
Pass (B-Pass), Band
Boost/Cut (B/C, the default
Butterworth Filter), Low Shelf
(L-Shelf), and High Shelf
(H-Shelf). You will probably find yourself
using different types of filter at different times, so we'll
describe them all, along with possible uses for each. We'll save
Band Pass and Band Stop for
the end because they tend to be used least often in audio
The Butterworth Filter allows you to change the filter subtype with a
pop-up menu at any time.
High and Low Cut filters
As their name implies, the Low Cut and High
Cut filters eliminate frequencies at the extremes. The
Low Cut filter, for example, eliminates low
frequencies, while leaving high frequencies mostly unchanged.
This is extremely useful for eliminating rumbling sounds from a
track. It can also be used as a more noticeable effect, such as
thinning out a lead instrument so it cuts through a mix
The High Cut filter, though it's typically less used
than the Low Cut filter, can be used for
reducing high frequency noise, such as is found on bass and kick
drum tracks. It can also be used to soften a harsh-sounding
track such as an overly distorted guitar track.
High Cut and Low Cut filters offer
only one control: frequency. This is the "knee" point past which
most sounds are eliminated. For example, a Low
Cut filter with the frequency set to 200 Hz will
eliminate most sounds below 200 Hz and leave sounds above 200 Hz
more or less untouched. Similarly, a
filter with the same frequency setting will reduce most sounds
above 200 Hz and keep most sounds below 200 Hz.
High and Low Shelf filters
High and Low Shelf filters are useful for increasing
or reducing a broad range of either high or low frequencies.
Shelving filters are useful when the overall balance of high and
low frequencies is off. For example, if the bass is a little
weak, you could use a Low Shelf to bring it up
a bit. Similarly, if a mix seems a little dark, you might be
able to use a High Shelf to add a little high
frequency. If the mix is, instead, a little harsh, you can use a
High Shelf to reduce the high frequencies
without completely eliminating some frequencies, as would happen
with a High Cut.
High Shelf and Low Shelf filters
have two controls: frequency and level. The frequency control,
like the frequency control of the high and Low
Cut filters, controls which frequencies will be altered
by the filter. The level control adjusts how much of the
selected frequencies will be added or taken away. For example,
if you have a Low Shelf filter with the
frequency set at 1,000 Hz (1 kHz), and the level set at -5 dB,
all sounds below 1,000 Hz will be reduced by approximately 5 dB,
and other frequencies will remain unaffected.
The Boost/Cut filter is probably the one you will
use most often. It allows you to pick out a range, or band, of
frequencies and increase or decrease the sounds inside that
range. This is extremely useful for a wide range of
applications. For example, you can add mid and high frequencies
to a track to help it stand out in the mix better, or you can
reduce a certain frequency that is conflicting with another
instrument which is also strong in that range. It is also useful
if, for example, a particular instrument has an unpleasant
quality that falls in a particular frequency range. For example,
if a particular vocal track sounds very nasal, you can use a
Boost/Cut filter to reduce the offending
frequencies (probably somewhere between 400 Hz and 2,000
The Boost/Cut filter has three controls: frequency,
Q (Sharpness), and level. The frequency control adjusts the
center of the range of frequencies which will be boosted
(increased) or cut (reduced). Q controls the range of
frequencies that will be boosted or cut. The higher the Q, the
narrower the range of effected frequencies. Level controls how
much of the given range of frequencies should be added or
For example, a frequency setting of 500 Hz, a Q of 1.3, and a level
of 7dB, will increase a fairly broad range of frequencies around
500 Hz by 7 dB.
Band Pass and Band Stop
You probably won't find too much use for the Band
Pass and Band Stop filters, but
sometimes they can be very useful. A Band Stop
filter is like an extreme version of a band cut filter -- it
eliminates a range of frequencies almost entirely. A
Band Pass filter is the opposite: it allows
only a small range of frequencies to pass through.
Band Pass filters, though seldom used, can be useful
for special effects or for training your ear as to what certain
frequencies sound like. One special effect can be created by
using a low Q and a frequency roughly in 1000 Hz range, which
makes the track sound like it's coming over a telephone line.
Using a higher Q allows you to isolate certain frequencies,
which can produce a "ringing" effect.
A Band Stop filter can be used for eliminating
specific frequencies. This might be used for eliminating narrow
band noise, such as 60/50 Hz electrical noise or noise from
machinery. When eliminating electrical noise, it's important to
recognize that a significant amount of the noise may be at
harmonics, which are whole-number multiples of the fundamental
(or main) frequency. For example, the US uses 60 Hz power but it
is not uncommon to have a substantial amount of noise at 120 Hz
or even 180 Hz or 240 Hz.
The Multi-band Parametric EQ is essentially nothing more than several
Butterworth filters put together. When creating this effect, you
will be asked for the EQ type, which lets you select how many
"bands" you want, where one band is equivalent to one
Butterworth Filter. In the case of some EQ types, you will have
the option of having the lowest frequency filter be either a low
cut filter or a Boost/Cut filter. While you can
change the exact filter types and center frequencies later, it
is a good idea to start with the filter as close to what you
need as possible. Most engineers find that with a parametric EQ,
they seldom need more than 5 bands, and 3 is often fine, so if
you are unsure how many bands to use, start with between 3 and
5. Note that you cannot add or take away bands later, but just
about everything else can be changed.
The main window of the parametric EQ shows you the level controls for
each Boost/Cut filter and the frequency control
for each High or Low Cut
filter. For more fine-grained control of each filter, you can
either use the tabs at the top to switch to the band you want.
If you want to see all the controls at once, you can click the
"All-In-One View" button.