Compr essor – Joemeek three Q Desktop Channel User Manual
Page 5
9
Compression
Ratio
What??
OK,
it’
s
simpler
than
it
sounds.
If
the
input
gets
10dB
louder
but
the
output
only
increases
by
5dB
then
the
compression
ratio
is
“2
to
1”.
If
the
input
goes
up
10dB
but
the
output
only
goes
up
1dB,
then
the
compression
ratio
is
“10
to
1”.
In
a
theoretically
ideal
compressor
,
this
ratio
is
the
same
for
any
size
of
signal
above
the
threshold
but
for
that
to
be
true,
the
gain
cell
and
its
control
circuitry
must
be
perfectly
linear
over
a
very
wide
range.
In
practice
only
compressors
based
on
VCAs
and
digital
potentiometers
are
likely
to
behave
in
this
way
.
Some
compressors
have
a
control
to
set
the
ratio
anywhere
between
1:1
(ie:
no
compression),
and
20:1
(which
would
be
regarded
as
a
“brick
wall
limiter”).
In
the
threeQ
the
“Slope”
or
“Compression
Ratio”
is
fixed
at
5:1.
This
is
a
good
compromise
between
being
gentle
enough
for
vocals
and
hard
enough
for
drums
and
guitars.
However
that’
s
not
all
there
is
to
it.
V
ariable
Ratio
In
the
Joemeek
optical
compressor
the
compression
‘threshold’
is
not
clearly
defined
and
the
compression
ratio
varies
with
the
amount
of
com
-
pression
applied.
For
signals
only
just
exceeding
threshold,
the
ratio
is
little
more
than
1:1.
As
the
compressor
is
driven
harder
,
the
ratio
rises
to
5:1,
at
least
up
to
a
point.
It
is
a
feature
of
the
Joemeek
compressor
that
the
com
-
pression
ratio
actually
reduces
again
during
large
transients
and,
adjusted
correctly
,
this
helps
to
retain
brightness
that
is
often
lost
with
other
types
of
compressor
.
This
is
why
vintage
compressors
often
sound
more
lively
than
their
modern
counterparts.
Controls
‘COMPRESS’
sets
the
level
of
signal
(the
“Threshold”)
above
which
the
signal
starts
to
be
compressed.
T
urning
the
COMPRESS
control
clockwise
lowers
the
compression
threshold,
and
drives
the
compressor
harder
.
‘A
TT
ACK’
sets
how
quickly
the
compressor
reacts
to
peaks
above
threshold.
T
urn
this
control
anti-clockwise
for
a
quick
response.
Slower
(clockwise)
allows
the
fast
leading
edge
of
percussive
sounds
to
pass
uncompressed
for
a
moment,
before
the
compressor
reacts
to
control
the
gain.
This
example
of
“changing
the
envelope”
of
a
sound
exag
-
gerates
the
percussive
nature
of
drums
and
other
instruments.
Faster
attack
times
(anti-clockwise)
are
used
where
the
compression
needs
to
be
less
obvious.
For
vocals
the
Attack
needs
to
be
around
1msec
for
a
natural
sounding
result.
‘RELEASE’
sets
how
long
the
compressor
goes
on
squashing
the
sound
for
,
once
the
signal
has
dropped
below
threshold.
If
it
stopped
instantly
there
would
be
very
noticeable
modulation
or
“pumping”
of
the
sound.
So
we
want
it
to
stop
compressing
less
abruptly
and
that
is
what
the
Release
control
is
for
. Generally
, the
longer
the
Release
time,
the
less
obvious
is
the
compression.
Of
course
some
“pumping”
might
actually
be
desirable
as
a
special
ef
fect
and
that
is
another
way
in
which
the
envelope
of
a
sound
can
be
modified.
The
threeQ
Release
is
variable
from
100mS
up
to
3
seconds
giving
a
wide
variety
of
ef
fects.
How
the
compressor
behaves
actually
changes
with
programme
con
-
tent
and
volume.
So
experiment
with
the
controls
with
dif
ferent
kinds
of
material
to
discover
the
range
and
depth
of
ef
fects
that
can
be
achieved.
The
“COMP”
in/out
switch
allows
comparison
between
com
-
pressed
and
uncompressed
sound
(green
LED
lights
when
active).
The
Compressor
is
after
the
Preamplifier
and
the
Insert
Point,
and
before
the
Meequalizer
.
8
Compr
essor
The
hardest
device
to
understand,
yet
one
of
the
most
useful,
the
PhotoOptical
Compressor
is
what
gives
Joemeek
products
their
unique
character
.
Its
job
is
to
make
quiet
sounds
louder
and
loud
sounds
quieter
,
or
in
other
words
to
reduce
the
dynamic
range
of
the
programme
material.
It’
s
a
bit
like
manually
riding
the
volume
control,
except
the
compressor
does
it
automatically
,
responding
far
quicker
and
more
accurately
than
you
ever
could
by
hand.
The
compressor
is
applied
in
several
ways:
1.
Make
Sounds
Stand
Out
Because
compressors
make
loud
sounds
quieter
, you
can
boost
the
volume
of
the
quiet
bits
without
the
loud
bits
getting
even
louder
.
That
means
you
can
raise
the
average
level
of
an
instrument
or
vocal
in
the
mix,
which
has
the
ef
fect
of
lifting
it
and
bringing
it
forwards.
This
can
actually
improve
vocals
for
example,
bringing
them
out
in
front
of
a
mix,
making
them
sound
denser
,
more
even,
and
more
confident!
2.
Crank
Up
The
V
olume
Raising
the
average
volume
of
whole
mixes
means
they
can
be
heard
in
noisy
environments,
such
as
vehicles
and
factories.
Boosting
the
average
level
is
what
makes
radio
stations
sound
LOUD
and
the
same
technique
is
used
on
TV
commercials
too,
which
is
why
they
always
seem
annoyingly
louder
than
the
movie
you
were
trying
to
watch!
3.
Protection
Fast
response
times
are
generally
used
to
control
brief
transients.
In
other
words
if
an
occasional
peak
sticks
its
head
above
a
maximum
permitted
level,
the
compressor
clobbers
it;
this
is
known
as
limiting
and
a
compressor
designed
solely
for
this
purpose
is
known
as
a
Limiter
. Limiters
are
primarily
used
to
protect
recorders
and
monitor
systems
from
overload,
radio
trans
-
mitters
from
overmodulation,
etc.
The
Joemeek
compressor
is
not
primarily
intended
for
this
purpose
as
the
Attack
is
not
really
fast
enough
to
satisfy
radio
station
requirements,
although
it
is
generally
good
enough
to
pro
-
tect
recorders
and
monitors,
where
the
ef
fect
of
transients
is
less
criti
-
cal.
Normally
you
should
not
hear
a
limiter
operating
but
if
it
is
driven
hard
constantly
,
it
can
render
a
mix
somewhat
flat
and
lifeless.
4.
Accommodation
The
dynamic
range
of
the
human
ear
is
phenomenal,
extending
from
the
threshold of
hearing (eg:
a
pin dropping onto
soft
carpet)
to
thresh
-
old
of
pain
(eg:
standing
next
to
a
jet
aircraft)
-
some
120dBA
in
all.
By
contrast,
vinyl,
cassette
tape
and
radio
broadcasts
all
have
a
dynamic
range
of
about
half
that.
Since
the
advent
of
the
CD,
the
dynamic
range
of
the
medium
is
far
less
of
an
issue
and
compressors
are
used
more
to
give
a
certain
“feel”
to
a
production.
AM
and
FM
radio
however
, is
still
very
much
compressed
to
fit
its
restricted
dynamic
range.
5.
Modification
A
compressor
can
change
the
dynamics,
or
“envelope”
of
the
track
and
it
is
here
that
the
Joemeek
Compressor
excels!
Types
of
Compressor
Most
compressors
work
in
essentially
the
same
way:
a
volume-con
-
trolling
element
or
“gain
cell”
is
inserted
into
the
audio
signal
path.
The
level
of
the
signal
at
any
given
moment
is
measured
and
that
information
is
used
to
control
the
gain
cell.
So
if
the
signal
gets
bigger
,
the
volume
is
turned
down.
V
arious
types
of
gain
cell
in
common
use
include
FET
s,
valves
(tubes),
light-dependent-resistors
(photoelectric),
digital
potentiometers
and
voltage-controlled-amplifiers,
better
known
as
VCAs.
The
threeQ
Compressor
is
a
unique
recreation
of
the
sort
of
photo
-
electric
compressor
used
by
record
producer
Joe
Meek
in
the
1960’
s.
U
si
n
g
m
o
d
e
rn
co
m
p
o
n
e
n
ts
fo
r
co
n
si
st
e
n
cy
a
n
d
re
lia
b
ili
ty
,
it
n
o
n
e
th
e
le
ss
reproduces
faithfully
the
same
punchy
sound
that
was
so
characteristic
of
the
pop
records
of
that
time.
three q manual.indd
3/9/04, 4:19 PM
10-11