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8/10/2019 Synthi Handbook
1/90
WRNN
The Synthi AKS
i s
an extremely
del i cate i nstrument
t has
an
enormous
amount of
ci rcui try n t for ts
si ze
and
t i s essenti al
that despi te ts portabi l i ty
t
i s
not thrown around
as
t may
recei ve
damage to
some of
the
very
del i cate ci rcui ts
The machi ne i s
natural l y guaranteed but
i t s
i mportant that i n
order to
comply
wth thi s
guarantee
that
t s
not
tampered
wth
i n any way
Some of
the screws
are
auto destructi ve
so
that i
they
are removed they
cannot
be
repl aced
Therefore great
care
must
be
taken i n
di s assembl i ng the
Synthi
8/10/2019 Synthi Handbook
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THE
SYNTH
EDUC TION L
H ND OOK
Peter
Grogono
PRL
1972
ELECTRONCMUSICSTUDOS
OF
MERC NINC
46
WST
STMHERSTM SS
TEL 413
256 8591
8/10/2019 Synthi Handbook
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l e ft - hand moni t or
speaker
w t h
muti ng
sw t c h
Two
vol tage controll ed audio
osci l l a tors w t h
rectangle, ramp,
and
sine
out put s and shape
control s,
coveri ng more t han
t he
enti re audi o range i n onp
sweep
fromover 5XHz
t o
as
l ow
as
1Hz
Volt age
controll ed
s low
oscil l ator
005-500Hz) f or
vol tage
central
and peri odi c
e ffects. two
i ndependent
out-
put s
rectangl e and ramp w th
vari abl e shape cont rol
.
tVhi te
noi se
generat or
w t h col our and
ampfi t nde cont rol
1N-l e f r l t e r s
f or wde
col our contro l on
each
output .
Steno
out put s
w t h
panni ng
control s
Half hi nges
on
l i d t o
enable
easy removal
Ent i re
keyhoard
l i f t s
out
f or
easy
playing
Automat i c
hal f t one
t hrough
one octave
tr ansposi ti on t ouch
pads
Cl ock ra te
cont rol f or
sequencer i ndi cated on
met er )
Stereo headphones j ack
Hi gh
l evel
out put s
AC/DCmeter f or
precise s igna l
and
cont rol
checks, and
sequencer
memory
i ndicati on
Scope
output
f or
waveformmoni t ori ng
Record/ Pl ay/ Hol d
sel ect
pads
2~
octave plasti c-coated
tuneable touch
keyhoard w t h
dynamc
cont rol
Total
versati l i ty
w th no
movi ng
parts
Fac i l i t i e s
socket
f or
si gnal
and
power connecti on
t o
keyboard
or
EMS
modul es
e . g
pi tch
f o
vol tage
convert er, random
vol tage generator)
DC
out put s f or vol tage
controll ing
external
equi pment
Stowage f or
pat ch pins
Prestopatch f or
i nstant
patchi ng
of
a
pre-
programmed
sound
can
be
made t o order)
Line l evel
i nputs
f or
signal s
or
cont rol
vol tages
e . g
tape
recorders, f oot
pedal,
et c
I nputs
f or a i r
or
cont act
mkes, gui tars,
et c
Random
vol tage key
AC
power
s ocket w t h
vol tage range
sw tch
and
i ndi cator
neon
I ndependent
t imn
control s
f or
r e a l
t i me
and
sequenced
vol tage
T56
hol e
pi n panel
For
patchi ng
any
comhi na
l i o n of
signal s
and
rol tages
Wth
pins
N - D Mult i f uncti on F I t e r /
Oscil l ator
w t h
vari abl e
r esponse
and
vol tage control l ed
f requency, givi ng sharp
resonant f i l t e r i n g
t o steep cut
l owpass
or
pure s ine
output
Transformerl ess high
rejecti on
I C
r ing
modul at or
For
very
dramat i c t one
tr ansformati on
or
octave spl i tt i ng
Three posit i on
swtch-
speaker on speaker
mute/
l ogger
from
exter nal
i nst r ument
Envel ope shaper
recycl e indicator
l amp
Trapezoi d output
DC
anal ogue
of
envel ops
shaper
f or
controll i ng
other circui ts
Envel ope
shaper
f or automat i c
or
manual t i me
cont rol
of
si gnals att ack,
on decay
and
off
t i mes al l
separatel y
adj ustahl e)
.
Reverberat i on
w t h
vol tage controll ed
dir ect/echo rat io
X-Y Joyst i ck
f or
si mul t aneous
cont r ol of
any
two
or
more
devices
.
J oysti ck vol tage range
control s
and sequencer
on/ of f sw t c h
Attack
but ton fo r preci se
manual i n i t i a t i o n
of
envel ope
cycl e Conveni entl y
placed
f ar
one
hand
operati on
w t h
j oysti ck
D gi ta l
sequencer and
cl oak
l ogic circuit ry
Up
t o
256
event s
controll ed
and
stored
6y
a complex
of i ntegrated
circui ts .
Envel ope shaper
tri gger mode
sel ector
f or
r e a l
t i me
or
sequencer
.
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THE SYNTH
EDUCATIONAL
HANDBOOK
Wee al so have Sound-houses,
where wee practi se and
demonstrate
al l Sounds, and thei r
Generati on
Wee have harmonies
whi ch you
have not,
of Quarter
Sounds,
and
l esser Sl i des of Sounds
Dverse
I nstruments
of Musick l i kewse
to
you
unknowne, some
sweeter
than
any you
have
Together wth Bel l s and R ngs
that
are dai nty and
sweet
Wee
represent Smal l Sounds
as
wel l
as
Great and Deepe
Likewei se
Great Sounds, Extenuate and
Sharpe
Wee
make di verse
Trembl i ngs
and Warbl i ngs of
Sounds,
whi ch i n
thei r
ori gi nal l e
are Enti re Wee represent
and imtate al l
Arti cul ate Sounds and Letters and the
Voi ces and Notes Beasts
and Bi rds
Wee
have
certai n Helps, whi ch
sett
to
the Eare doe
further the
Heari ng greatl y
Wee
al so
have Strange and
Arti f i ci al
Echos s, Refl ecti ng
the Voi ce
many
times, and
as
i t were Tossi ng
i t
And
some that gi ve
back
the
voi ce l owder
than i t cam some
Shri l l er,
some
Deeper
Yea some
renderi ng
the
Voi ce,
Dfferi ng
i n
the l etters
or
Arti cul ate
Sound,
from
that they receyve,
wee
have
al so means to convey Sounds i n Trunks
and Pipes,
i n
strange
Lines,
and Dstances
.Roger Bacon The New
Atl anti s
1624
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SYNTH EDUCATIONAL
HANDBOOK
CONTENTS
I ntroducti on
Usi ng
your
SYNTH
I I Simpl e Properti es
of
oun s
I I I Techni ques
of
El ectroni c Musi c
6
IV
The Keyboard and Sequencer 45
V Equipment for El ectroni c Music 54
VI Prestopatches
6
VI I
Care
and Maintenance 7
Gossary
75
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Li st
of
Experi ments
Loudness Percepti on
4
Envel opes
14
3 Frequency
Percepti on
7
4 Timbre Percepti on 18
5 Frequency
Anal ysi s
21
6
Noise
3
7
Fi l tered Noise
23
8
Trapezoid
Vol tage
27
9
Vol tage Control
29
1
Chi mes
35
11
Reverberati on 41
12
Usi ng the Keyboard 48
13 Usi ng
the Sequencer
52
14
Usi ng the Keyboard and Sequencer
together 53
15 Echo wth Tape recorder 56
16 I nput Devi ces 57
17 Battl e Prestopatch 65
18 Keyboard Prestopatch 65
19 Gui tar Prestopatch 69
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Li st
of Dagram
I The SYNTH AKS
f ronti spi ece
I I
Tabl e of Sound I ntensi ti es
3
I I 2
Tabl e of Envel ope Shaper Ti mngs
5
I I 3
Envel ope Shaper Waveform
6
I I 4 Si ne
Osci l l ator Shape Control
9
I I 5
Square Osi l l ator Shape Control
9
I I 6 Ramp
Osci l l ator Shape
Control
9
I I 7
Si mpl e WaveformSpectra
9
I I 8
Coloured Noi se Spectra
24
I I 9
Fi l tered Noise Spectra
24
I I I Panni ng wth the Envelope Shaper 33
I I I 2 Ri ng modul ator Spectra 33
I I I 3 Reverberati on
i n
a room
38
I I I 4 Reverberati on Uni t
38
I I I 5 Bl ock Dagramof SYNTH Output Ampl i f i ers
44
I V
Bl ock Dagramof Keyboard and Sequencer 46
V SYNTH connected to a Stereo Ampl i f i er 58
V 2 SYNTH connected to a Stereo
Tape recorder
58
V 3 SYNTH i n a Si mpl e Studi o 6
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I NTRODUCTION
Primari l y, thi s book
i s i ntended
to showyou how
to
use your
SYNTH
AKS
A though i t
i s
not
comprehensi ve
text-book, i t
may al so
tel l
you
something
about
the
way
i n
which sounds are made or
al tered
The SYNTH AKS i s a Synthesi zer,
whi chmeans that
i t
i s
used to bui l d up or
synthesi ze,
sounds frombasi c tones I t
di ffers from
other
musi cal
i nstruments i n that i t
has
no
characteri sti c
sound
of
i ts
own, and i n order to
use
i t you
have
to
know
something
about
the
nature of
sounds
so you can
bui l d
your
own
creati vel y
For
thi s reason, we
do not apol ogi se
for wi ti ng a
book
whi ch i s
educati onal
i n
tone
We
hope
that
thi s
book
wl l be
used
i n
school s
which
have
a SYNTH AKS, and
we al so hope
i t wl l be
used
by
others,
i n every f ield, to
faml i ari se
themel ves wth what a sound i s before
they
become
confused
by
mul ti tude of el ectroni c devi ces
I n
the fi rst chapter, USINGYOUR SYNTH , we expl ai n how
the SYNTH
i s
set
up
and
what
the
control s
do Unl ess you have
experi ence
of
el ectroni c
equi pment,
you wl l probabl y not
understandmuch
of
thi s
chapter, but you
wl l fi nd
l ater on
when you
have
l earnt bi t more about
the
SYNTH,
that
i t i s
useful chapter for reference
I n the other
chapters,
there
are
secti ons of
expl anati on
and
experiments
The experiments
are
wi tten i n i tal i cs for
cl ari ty) The
experiments
are
ot
i ntended to be complete
rather
they are
start i ng
poi nts
for the
much more detai l ed
experiments which
we
expect you
to
do
We want
you
to thi nk
of the SYNTH
as
a
ki nd
of
constructi onal set,
wth whi ch
you
can bui l d
your
own sounds The
patches
we
provi de
are
not
complex,
because
we
want to i l l ustrate howthe
SYNTH
works,
but when you
have
understood
an
i dea
or techni que,
you shoul d
try
to
i ncorporate
i t i nto
your
own patches
8/10/2019 Synthi Handbook
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Many of
the
experiments n
thi s book
are
mre
i nteresti ng
i f you can connect
your
SYNTH
to
an Osci l l oscope n
osci l l oscope i s an
el ectroni c
i nstrument whi ch shows the
vol tage i n
ci rcui t
vi sual l y
on
smal l screen rather
l i ke
tel evi si on
screen We do
not menti on osci l l oscopes much
because most SYNTH
owners do not possess one
i f
you do have
access to
an
osci l l oscope you wl l f i nd
i t
very hel pful i n
understanding how the SYNTH works
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CHAPTER USING YOUR SYNTH
Thi s
chapter descri bes the use
of
the SYNTH, and
al so
descri bes the devices
i t
contai ns
I t
shoul d be
read
through
fi rst
of
al l i t may
seem
rather abstract i ni ti al l y and
then
shoul d be used
for
reference
l ater,
when you
are
doing
the
experiments for the SYNTH Before doi ng any
of
the experiments,
make sure you have read
the next
secti on,
Connecti ng the SYNTH
Unl i ke mst
of
the el ectroni c devi ces we are accustomed
to whi ch perform
one functi on onl y
radi o
and tel evi si on
recei vers
for
example ,
or
a
fewfuncti ons
a
radi ogramcan pl ay
records and recei ve
radi o programmes ,
the SYNTH
has
very
many
functi ons
The
SYNTH contai ns
a number
of
separate ci rcui ts
whi ch
are connected
by
the
user
; the
knobs on
the
f ront
control
the ci rcui ts and the
patchboard
the
bl ack square
i n the
l ower
centre connects
them I f the SYNTH l ooks
compl i cated
to you,
remember
that
i t
uses onl y simpl e devi ces, and that complex
sounds ari se
f romthe use
of
several devi ces together
Connecti ng
the SYNTH
Power Suppl y
Before i t can be used at al l ,
the
SYNTH
must
be connected
to
the
mai ns
European mdel s
are adj usted for
200-250VAC and
North Ameri can mdel s
for 100-130VAC
I f
for any
reason
the
setti ng
i s
i ncorrect
i t
shoul d
be
al tered, using the sl i de-swtch
on
the f ront panel before connecti ng the SYNTH The SYNTH
uses
a
transformer
desi gned
for
50-60Hz
AC and must never be
connected to a
DC suppl y
Connect
the SYNTH
to
the
mains suppl y
wth the l ead
provi ded
The earthi ng
ground
connecti on green/yel l ow
i s not
essenti al
and
may
be
l ef t
unconnected i f
two-pi n sockets
onl y
are
avai l abl e
Turn
the
POWER swtch on and check
that the
mai ns
i ndi cator
l i ght
gl ows red
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Si gnal and
Control Connecti on
Other
el ectroni c equi pment
i s
connected to the SYNTH
by
the
j acks at
the top
of
the
panel
The
SYNTH can
be
used
as
an
enti rel y sel f -contai ned
i nstrument, but
i ts
resources can
be
expl oi ted
more ful l y
when
other equi pment i s
used wth
i t
I n parti cul ar, the bui l t-i n
l oudspeakers
are very smal l and,
al though they are adequate
for
moni tori ng
purposes,
an external
ampl i f i er and
l oudspeaker
systemshoul d be
used for
anythi ng
but
personal
experiments
J ack pl ugs
are
always
connected
as
fol l ows
Earth
ground) goes
to
the
body
or
shaf t when screened
cabl e
i s
used,
thi s w l l
be
the outer screeni ng)
The l i ve connecti on
goes to
the top
of
the pl ug
The headphone
j ack
must be used wth
a stereo pl ug,
whi ch has an addi ti onal
ri ng
on
i t
for
the
second
l i ve
l ead
I t
i s
best
to
sol der al l wres, but
i f
you cannot solder
obtai n
some j ack
pl ugs I grani c type) wth
screw
termnal s
The
functi ons
and
speci f i cati ons
of the
J acks
on
the
SYNTH
are
expl ai ned
here
Stereo Phones Stereo three wre) j ack gi vi ng a two
channel signal sui tabl e
for
poweri ng a
pai r
of stereo
headphones
Level 1 V p-p
max
i nt o
5
ohms
Scope A mono Output two wre) connected to the
Meter C rcui t
I t i s
sui tabl e for an
osci l l oscope
di spl ay,
and
i s
sometimes
connected
to
the SYNTH i nputs
as
part
of
a
patch
Level Devi ce dependent 5V p p
may
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Si gnal Outputs These outputs are sui tabl e for
power
ampl i f i er or stereo
tape recorder
Level 2V p p max i nto 600
ohm
Control Outputs These outputs shoul d be
used when the
SYNTH
i s
requi red
to
provi de
DC
control
vol tage to another
synthesi zer
or
vol tage
control l ed ci rcui t
They
are
connected
to
the Output Channel
rows
on
the Patchboard
Level t5VDC max
i nto
1OKohm
Keyboard
Thi s
socket i s desi gned to connect the
SYNTH
to
SYNTH
or
S
keyboard
and
other
SYNTH modul es and shoul d not
be
used for any other purpose
Si gnal
or
Control I nput J acks connected
to
the I nput Ampl i f i ers
of
the SYNTH An external source
wth
l i ne
output such
as
pre ampl i f i er
or
tape
recorder
shoul d be connected here
Sensi ti vi ty
.5VACp p
2.5VDC
i nto
50Kohm for
vol tage control
Mcrophone I nput
These i nputs are
sui tabl e for
most form
of l owl evel
si gnal as
produced by ai r
mcrophones
contact mcrophones and
gui tars
Sensi ti vi ty 5mVAC i nto 600 ohm
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. The
Devices
The SYNTH has
a
number
of
devi ces, each
wth i ts own
control s
on
the f ront panel The bri ef speci f i cati ons bel ow
are i ntended for reference, and
do
not descri be the uses
of
the
devi ce
Control refers
to
the functi on
of
the devi ce,
i f
any,
whi ch can
be
vol tage-control l ed Matri x gi ves the i denti f i cati on
by
di gi ts and l etters
of
the rows and col umns on the Patchboard
al l ocated
to
the devi ce
Osci l l ator
1
Audi o frequency osci l l ator wth
sine
and
ramp waveform
Manual
control s for
f requency, shape
of si ne
output
minl y
even harmni cs may
be
added , l evel of
sine output, l evel
of
ramp output The
outputs are mxed
at
the Patchboard
Range 1Hz 10KHz
on
di al
output si ne 2Vp-p
ramp 2Vp-p
Control f requency 0. 32 V/octave
Matri x
3
I
Osci l l ator
Audi o frequency osci l l ator
wth rectangul ar
and tri angul ar waveform
Manual control
for f requency, shape, l evel s Outputs are
mxed
at
the patchboard
Range 1Hz 10KHz on di al
Output
square p-p
tri angl e
1-5Vp-p symmtri cal posi ti on
ramp
3V
p-p
extrem
posi ti on
Control
f requency
0
. 32 V/octave
Matri x
4 J
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osci l l ator 3 : Audi o and
subsoni c
osci l l ator
wth
rectangul ar and tri angul ar waveform
Manual
control s for
frequency, shape
and
l evel s Thi s osci l l ator may
be
run
at
very l ow frequenci es for control
appl i cati ons
Range: 0. 02X2 500Hz
on
di al
square 4V p-p
tri angl e
3V
p-p symmetri cal posi ti on
ramp 6V
p-p
extreme
posi ti on
Control s frequency
0 . 26 V/octave
Matri x
5 6
K
Noi se Generator
Whi te and col oured noi se source
Manual
control
of
l evel and col our
Output 3Vp-p
F i l ter/osci l l ator
: Amul ti -purpose fi l ter, resonator
and
osci l l ator,
wth adj ustabl e
bandwdth Q
and frequency
Manual control of
frequency, mode
and output
l evel
Range
5Hz -
10KHz on
di al
Cut-of f Rate
18db/octave max
20max
Control frequency
0
. 2 V/octave
Matri x
10, H
N
Rng, -Modul ator : An advanced design wth
hi gh
i nput
rej ecti on Manual control of output
l evel
I nput
Level
1 . 5V
p-p
max
Output 6V p-pmax
Rej ecti on
-50db
at
1 . 5V
i nput
Matri x
13 E
F
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Envel ope Shaper A programmed vari abl e-gai n
ampl i fi er for
envel ope control
Manual control s
for
attack, on,
decay and off times, si gnal
output l evel and
control
output ( trapezoi d )
l evel
There
i s
al so a recycl e
( attack )
button by
the
J oysti ck
Timng Attack
2m
I s
on
0
2
. 5s
Decay 3m
15s
Of l Om
5s
+
off posi ti on to
i nhi bi t recycl i ng
Si gnal
Output 5V
p-pmax
Control
Output
Control
Ma
trix
t3VDC
Decay
time 0
V/octave
11, 12,
D L
Reverberati on
Uni t
doubl e
spri ng device
wth
del ays of
25m
and 30m
Due
to the smal l cabi net of the
SYNTH,
acousti c feedback can occur when
the i nternal l oudspeakers are used and
thi s
shoul d be avoided as far as possi bl e
Manual
control s
for mx and l evel
Fl ax Reverb
Time
2s
Output 5V p-pmax
Control Reverberati on
time
-2V for 0 +2V for
100
mx
Matri x
14,
G
J oysti ck
Two manual control vol tages are provi ded
by movi ng the
j oysti ck
up or down or
from
side
to
side
Manual range control s
are
provided
Output
2
x
1
. 5VDC
Matri x 15,
16
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Meter Mul ti -purpose meter for moni tori ng
checki hg and cuei ng Swtch for sel ecti ng
SIGNAL
or
CONTROL modes
I nput t1VDC i n Control Voltage mode
4Vp-p i n Si gnal Level mode
I nput Ampl i f i ers Si gnal s and control s may
be
i nput
to
the
SYNTH
at
l i ne
or
mcrophone l evel Manual
control of
sensi ti vi ty
Sensi ti vi ty
2
x 2
. 5VAC si n l
2
x
2
.5VDC control
2 x 5mVACmcrophone
Matri x
8 9
Output
Ampl i f i ers
Two
output channel s
wth manual
control
of
l evel f i l teri ng and panni ng I nternal
moni tori ng
speakers
wth muti ng swtch
Outputs
2
x 2V
p-p
i nto
600 ohm
si gnal
panned
2
x 10V
p-p
i nto 50
ohm signal unpanned
2
x 5VDC i nto IOKohm
unpanned
Control l evel 15dbl y average
Matri x
2 A
C
O P
Si gnal Tri gger
A si gnal sent
to
Channel 2 can
be
used
to
tri gger
the Envel ope Shaper
i f
the Channel
2
muti ng swtch i s
set
to
the md-posi ti on
Tri gger
Keyboard
30 Touch Contacts provi di ng
pi tch and
Dynamc Output
Sequencer
wth 256 event
storage and
touch
control s
for
Record
Pl ay i nstant Transposi ti on and random
note generati on
Matri x
8 9 6
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Patchi ng
1
The devi ces
i n
the SYNTH are not
connected
i nternal l y
Before the SYNTH wl l make any sound at al l
i t
must
be
programmed
by putt i ng
pi ns i nto
the
Patchboard Each
pin
connects the
output of
one
devi ce to
the i nput
of
another
Suppose
you want to
connect the output
of
the Noi se Generator
to
the
i nput of
the Fi l ter, for exampl e Look
down
the l abel s
at
the l eft
hand
side
of
the Patchboard
and you
wl l
see
that
row 7
i s
l abel l ed
noise Now
l ook
Patchboard
to
fi l ter
at
the top
of
a pi n at
the i ntersecti on of the 7th
connect the two devi ces as
requi red
si gnal
travel l i ng
froml eft
to
ri ght
i t
.meets
the pin,
and then travel l i ng up to the top of the
Patchboard
al ong
the 8th
col umn
al ong
the
top of
the
the 8th
col umn
putti ng
rowand 8th col umnwl l
I t
hel ps to imagine the
al ong the 7th rowunti l
Latef i n
thi s
book, patches wl l be descri bed
by
a
l etter
A P and a
number 1 16
These refer to the col umn and row
respecti vel y
and for conveni ence they are i nscri bed
on
the
ri ght
and bottomsides of
the Patchboard
The pi n used i n
the exampl e
above
Noi se
to
Fi l ter) was H7
The 30-way socket i n the spare pi n
reposi tory
at
the
bottom
of
the panel i s connected to
each
rowand
each
col umn
of
the Patchboard
I t i s used for Prestopatches
whi ch set
up any combinati on
of
pins
immedi ately
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CHAPTER SIMPLE
PROPERTIES
OF
SOUNDS
We are very accustomed to heari ng sounds
Ani mls bi rds
people machi nery and natural events
make sounds
People i n
parti cul ar make compl ex sounds
to
communicate
wth each other
and go to great
l engths
to
make i nstruments whi ch produce the
organi sed sounds cal l ed musi c
Anythi ng that makes
a
soundwe
wl l cal l a source of sound
What
do sources
of
sound have i n common? The answer
i s
si mpl y
that they
move There are many di f ferent ki nds
of move
ment and
they
gi ve
ri se
to
many di f ferent kinds
of sound
Some
movements are obvi ous a
rock fal l i ng
or waves on
the
beach
But
many
sounds are caused by
ti ny
vi brati ons whi ch
are not
vi si bl e to the unai ded
eye
such
as
the
vi brati ons of a
ti ny
bel l
when
i t
i s
ri ngi ng
The reason that
we hear sounds
i s
that the movement
of
the sound sources makes the surroundi ng
ai r
move
and i t i s
the ai r movement that our ears dgtect
I nside each
ear there
i s
a
sml l
mechani sm
whi ch
converts
vi brati ons
of the ai r i nto
vi brati ons
of
a nervous membrane and
then i nto el ectri cal
vi brati ons
whi ch
are
i nterpreted by
the
brai n
Duri ng
the l ast
hundred
years men have
developed thei r
own art i f i ci al ways of
turni ng
sound
vi brati ons i nto el ectri cal
vi brati ons and
vi ce
versa
t
was
by
doi ng
thi s
that they
were
abl e
to
send sounds over l ong di stances
by
using tel ephones and
radi os and
to
store them
i n
permanent form
on
phonograph
records and recordi ng tapes A mcrophone
i s a devi ce whi ch
turns sounds i nto el ectr i cal si gnal s and
a
l oudspeaker turns
el ectri cal si gnal s back i nto sounds
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Loudness
Usi ng a l ogari thmc scal e, whi ch means
that
we
measure
reasonabl e The rati o
uni t
we use
i s
named after A exander
Graham
Bel l
the Bel
i s
a l arge uni t,
so i n
practi ce
we
use
12
Loudness
i s probabl y
the
most
obvious
qual i ty
of a sound
The vi brati ons
i n
the ai r
cause
changes
of
pressure,
and
i t
i s
these
changes
which move
our
eardrum
A
l oud
sound for
i nstance,
a r i f le shot
as heard
by
the marksman)
produces more
than
a hundred
ml l i on
times as much pressure on the eardrum
than
a qui et sound whi ch you can onl y
j ust
hear I t i s
astoni shi ng
that the ear can
accommodate thi s
enormous range
of
sound
l evel s imagi ne a weighi ng machine
that
coul d weigh
fl eas as
accuratel y
as el ephants
We
coul d
use a uni t of pressure
to
measure
l oudness,
but
there
are two good reasons
for
not
doi ng
so
One
i s
the
i nconveni ence of usi ng numbers whi ch vary over such a wde
range
100,000,000
: 1 and the other
i s
that
i t
does not agree
wth our own
i dea
of l oudness
Most peopl e,
i f
asked, woul d
not guess
than
an orchestra pl ayi ng l oudl y produces
a thousand
times as much sound as the same orchestra pl ayi ng softl y, and
a ml l i on times as much sound
as
a qui et conversati on
rati os of sound power, we
f i nd that
the numbers are muchmore,
one-tenth
of a
Bel ,
whi ch
i s
cal l ed
a
deci bel and
i s
abbreviated
db Si nce the l ogari thmto, the
base
10 of
i s
0 . 301, when we
doubl e
the
sound power we add 0 . 301 Bel s, or approximately 3db
Siml arl y, taking away 3db often cal l ed a 3db l oss) means
hal vi ng the power You
can
easi l y see that gai ns
or
l osses
of
20db or 30db
represent l arge
mul ti pl es
of
smal l fracti ons
of
the ori gi nal si gnal
W
use Odb as a reference point, sometimes
gi vi ng
i t
a defi ni te val ue and sometimes merely using
i t as
a
compari son For
i nstance,
we
mght say
that
mezzo-forte
m
i n
musi c
i s a
normal dynamc,
and
cal l
i t
Odb Then mght
be -3db and f
- +- 3db
I n
the Tabl e,
Fi g. I I -1, we
have
def i ned
Odb
to be
the
l evel of
the
qui etest sound
that
can
be
heard,
so
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that a sound
at
-3db
or any negati ve
val ue
woul d be
i naudi bl e but we coul d have
started anywhere wthout
affecti ng the accuracy of the
scal e
Qui etest sound
0 db
Gentl e rustl e of l eaves
10
db
Whisper at 4
feet
20
Qui et bedroom
35 db
Conversati on
at
12
feet
50 db
Busy off i ce
wth
typewi ters
65 db
A armcl ock at feet
80 db
Heavy di esel l orry at
20 feet 90 db
Very
noi sy factory 100 db
J et ai rcraft taki ng off
at 75
feet 140
db
Noon rocket
taki ng
off
at 1000
feet
200
db
Fi g
. I I -
Tabl e of sound
l evel s
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Experiment
1
Turn
the SYNTH on
and connect
i t
(i f possi bl e)
to power
ampl i f i ers
Connect
Osci l l ator 1 to
output
Channel 1 by
putti ng
a
pi n
at A3
(I f you
don t
understand
thi s, re-read
the
secti on on
patchi ng
i n Chapter I
.
Set
the
FREQUENCY
control
of
Osci l l ator
1
to
7
the
SHAPE
control
to
5 and
the LEVEL
control s
to
8 (sine)
and 0
(ramp)
Set
OUTPUT LEVEL
1 to 7
(or
to
a conveni ent
l i steni ng
l evel ) and
check
that
OUTPUT
FILTER
1
i s
set
to
5
(central l y)
By al teri ng
the LEVEL
control ,
observe that
the sound can
bemade i naudi bl e
or (i f
suf f i ci ent
ampl i f i cati on i s
avai l abl e)
pai nful l y
l oud
By
al teri ng the
FREQUENCY
control note
that
the
l evel at which
the sound
becomes i naudi bl e
depends on
the
f requency
As wel l
as
bei ng
l oud
or
soft,
sounds
can
be
l ong or
short
Some
sounds are
conti nuous
thei r l oudness i s
the
same
al l the
and
stop
they are
cal l ed
transi ent
i n
which
they
start and
stop
i s very
i s
made up
almost
enti rel y
of
transi ent
time
other
sounds
start
sounds,
and the
exact way
important
i nmusi c,
which
sounds
Expe
riment
2
0
14
Connect
Osci l l ator
1 through the
Envel ope
Shaper
to
Output
Channel
1 The
i nput to
the Envel ope
Shaper i s
col umn D
and
i ts output
( env
si gnal )
i s row
12,
so
the
pi ns requi red
are
at D3 and
A12
Make
sure that
the
Osci l l ator
and
Output Control s
are
set
to
gi ve
an audi bl e
signal ,
and
turn
the
Envel ope
Shaper
SIGNAL OUTPUT
control to
8
Set the
timng control s
of
the
Envel ope
Shaper
(l abel l ed
ATTACK,
ON DECAY,
OFF) accordi ng
to
the
tabl e, Fi g
I I -2,
and
l i sten to
the di f ferent
envel opes
Graphs
of the
si gnal l evel
against
time
are
shown
i n Fi g
I I -3
I n
case
a the
si gnal
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15
reaches i ts maxi muml evel i nstantaneousl y, stays there duri ng
the
ON ti me, and fal l s
i nstantaneousl y
to
zero
where i t remains
duri ng the OFF
ti me
I n b , the si gnal di es away sl owy
decays ,
and i n c i t rises sl owy attacks as wel l
c has no ON
ti me
because
the note
starts
decayi ng
as soon
as
the
attack i s compl eted ON
ti me
woul d be shown as a
f l at
top on
the
wave
form I n d
the
OFF
ti me
has
been
set
to
be
i nfi ni te,
but
the
Envel ope
Shaper can be reacti vated by
pressi ng the ATTACK button whi ch starts a newcycl e The red
l i ght on the front panel l i ghts up duri ng the ATTACK and ON
parts
of
the cycl e
Experi ment
wth the ti mng
control s your-
sel f,
tryi ng perhaps
to
i mtate vari ous i nstruments A ter
the frequency the osci l l ator and l i sten
to
the di fferent
aural effect of the same envel ope at di fferent pi tches
Add a pi n at B11 and set the Meter swtch
to
CONTROL
VOLTAGE The output at row11 i s not a si gnal but
a control
vol tage
of
whi ch more l ater)
-
and
i n
thi s
case i t i s
the
vol tage
used
to
control the signal output l evel
of
the Envel ope
Shaper The Meter shoul d
move
i n ti me
wth the Attack/Decay
cycl e - i f
i t
doesn t,
turn
up the
TRAPEZODLEVEL control
Fi g I I -3 shows
the
way
i n
whi ch
the
l oudness
of
the
sound
comng fromthe Envel ope Shaper changes wth ti me, and
i t
al so
represents the vol tage comng fromthe Trapezoi d, whi ch expl ai ns
i ts name
Fi g I I -2 Envel ope Shaper ti mng control setti ngs
for
Ex eri ment 2
Setti ng
: a b c d
ATTACK
0 0 4 4
ON 3
3
2
2
DECAY: 0 7 7 7
OFF: 5 0 0 10
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db
0
-20
-40
-60
ON OFF ON OFF
v
Fi g
I I -3
The Envel ope
Shap
er
V
+2
0
_2
16
d) I nfi ni te
OFF time, cycl e restarted by Attack Button
The
graphs show
time
hori zontal l y and output signal l evel
vert i cal l y
The l eft hand scal e
i s
db O
db is
maximum l oudness and
the
ri ght
hand scal e i s
the trapezoi d vol tage Fi g I I -2 shows the control
setti ngs
requi red to
produce
the
envel opes shown
0 1 2
time
3
a) I nstantaneous Attack and Decay
db
I I
~ON DECAY OFF :ON `
I
.DECAY V
0
f
+2
-201 I \
i
-40
-60
-2
0 1 2 time 3
b) I nstantaneous Attack,
Stow
Decay
I I I I I
ATT, ON ;DECAY OFF
i ATT I ;DECAY I V
0 I
+2
-20
I
I
0
-40
I
v I
i
-60
-2
0 1 2 time 3
c) Fast
Attack
and Sl awDecay
db
I
ATT
~ ON ;DECAY
OFF ~ ATT ~ V
0
~ I
+2
-20
I I v
Attack I 0
-40
I
i v
6
0
1
2
time
3
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7
FreAen
Y
The
second obvi ous qual i ty
of
a sound
i s
i ts f requency
Thi s
i s
bothmore complex and i n many ways more important
than
l oudness
More
compl ex because
most
sounds
have
more than
one
f requency, and more important because we i denti fy sounds more
by
thei r f requency structure than
by
thei r l oudness
Frequency
i s
the rate
of
vi brati on
of
the sound
source, masured i n
(after
Heinri ch
Hertz, the
radi o
pi oneer),
whi ch mans cycl es
per
second,
and
i s
usual l y abbrevi ated
to Hz
You
do not
have
to say Hertz per
second any
more
than
you
say
knots per
hour
when
tal ki ng
about
a
shi p s speed
The
per
second and
per
hour are part of the
def i ni ti on
We
hear
di f ferent
f requenci es
rather as we
hear
di f ferent
l oudnesses, wth
a
l ogari thmc
l aw When the f requency of a
sound i s
doubl ed,
we
hear
i t an
octave hi gher
800Hz i s
an
octave
hi gher
than
400Hz and two
octaves hi gher
than
200Hz
We can
hear
sounds
over
almost
ten
octaves, f rom20Hz
to 20000Hz,
and the ear
i s
most
sensi ti ve
at
4000Hz
As
we get
ol der, our
abi l i ty
to
hear
very
hi gh
sounds dimni shes
and
onl y young
peopl e
can hear
sounds above 20000Hz
Experimnt
3
Use the sam
experimntal set-up as in Experimnt
Set
the SHAPE
control
to
5
Adj ust
the
LEVEL
control for
control At
very
al together
or
i t
heard as separate
per second) and at
very hi gh f requencies
i t becoms
very
thi n
and
then
di sappears I t may be
impossi bl e
to
make
the
f requency
hi gh
enough usi ng the
di al
al one
J oysti ck
to
extend the f requency
range
as
fol l ows
put
a pi n
RAMP
LEVEL
control
to
zero,
and
the
SI NE
a fai r ly
l oud
si gnal , andmove the
FREQUENCY
l owf requenci es the sound
wl l
di sappear
may
turn i nto
a seri es
of
cl i cks whi ch are
sounds
when they
are sl ower
than
about 20
I f thi s
i s so
use the
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at 116 and set
the
VERTICAL RANGE control to
10, then
mve
the J oysti ck
up and
down
to
control
the
frequency .
Experimnt
4
Use
the
sam
experimnt
set-up as Experimnt 2
that
the sound
gets buzzier
i n qual i ty By mvi ng the
Most sounds contai n not
one frequency
but
several ,
and
we tal k
about frequency comonents
Wth
the SHAPE control at 5 the sound from
Osci l l ator
8
i s almst
pure Turn the
SHAPE
control
ei ther
way
and note
FREQUENCY
control try
to di scover
whether
your
range heari ng
i s al tered by
the
change
i n
tone
Move the pi n
to
B2 and l i sten
to
the di fferent qual i ti es of square and ram waveform,
adj usti ng the SHAPE control and both LEVEL control s of
Osci l l ator
2
The buzzi er qual i ty
of
the sound
i n
thi s
experimnt
i s
due
to
the presence
of
extra frequencies
The pure sound
i s a
vi brati on
at
a certai n frequency, f
say,
and the SHAPE
control
i ntroduces other frequenci es
at
2f, 3f, 4f, etc
Provi ded
that
the new frequenci es are siml e ml ti pl es twce,
three
tims,
four
tims,
etc .
of
the ori gi nal frequency, we
hear onl y
a singl e
note
wth a characteri sti c
tone
The i ni ti al
frequency f i s cal l ed the fundamntal and the other
frequenci es
are
cal l ed harmni cs or overtones
The
tone
of
the
note
i s
techni cal l y cal l ed
i ts
ti mre
In the
experimnt
above, you
shoul d
have
found that you coul d hear the Osci l l ator
at
l ower
frequency setti ngs when
the
SHAPE
control was
mved, since al though
the fundamntal
becam
i naudi bl e l ess than 20Hz) the overtones
coul d sti l l be heard
We wl l now
descri be two
ways i n whi ch
a
sound can be
represented on a
graph Fi rstl y, we
can drawthe
sound as i t
appears
on
an
osci l l oscope
screen
What
we
are
doi ng
here i s
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V
+2
0
-2
V
+2
0
V
+2
0
19
a b
c
Fi g
I I -4
Effect of SH
APE
Control on
Si ne Wave
n n
a b
c
Fi a I I -5 Effect
SHAPE Control on Souare
Wave
Fi g I I -6 Effect SHAPE Control on Tri angul ar Wave
ti me
ti me
I n Fi gs I I -4, I I -5 and I I -6,
a
corresponds
to a
SHAPE
setti ng
of
1, b
to
a
SHAPE
setti ng
of
5,
and
c
to
a SHAPE setti ng
9
freq
octaves
a
si ne wave
freq
octaves
bJ
ramp
wave
Fi g I I -7 Spectra thr
ee
waveform
freq octaves
c
square
wave
0
0 0
-10 -10
-10
-20
-20 -20
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pl otti ng
a
vari abl e whi ch
changes wth time
i t
does
not
matter
much,
whether we pl ot ai r-pressure, movement of
the ear-drum
posi ti on
of
the di aphragm
of
a mcrophone
or
the vol tage whi ch
the
mcrophone produces, because they al l l ook the
same
The
vol tage
i s
most
conveni ent,
because
the
osci l l oscope
i s
an
i nstrument designed especi al l y
to
pl ot a changing
vol tage
Fi gs I I - 4
to
11-6 show the waveform that
we
have
heard so
far as they woul d
appear on an
osci l l oscope
screen
These
drawngs
cl ari fy the meani ng
of
the
l i t t le
squi ggl es that you
can see
on
the
f ront panel of
the SYNTH
by
the
Osci l l ator
control s, and
al so expl ai n
the
names
square and ramp
whi ch
we have gi ven
to
the waveform
By
l i steni ng to the sounds
and
l ooking
at
the
graphs
you
wl l
l earn to associate a sound
wth i ts
waveform note that
the waveform wth the sharpest
corners
have
the hardest sounds I f you have access to an
osci l l oscope,
connect i t to
the
SYNTH output or SCOPE
j ack
and
experiment wth the SHAPE control s whi l e watchi ng and l i steni ng
The
other way i n whi ch a sound i s represented on a graph
i s
sl i ghtl y
more di f f i cul t to understand, but
i t i s
often
more
useful
Hori zontal l y
we
use
a
f requency
scal e
and
verti cal l y
we
use
an
ampl i tude
scal e
Si nce thi s ki nd
of graph
has no
time
axi s,
i t
does
not represent the
way a
sound
change s,
but
onl y an
i nstantaneous
si tuati on For reasons whi ch you wl l
nowunderstand,
both
scal es in this graph are
l ogari thmc
i n
fact, i t i s
conveni ent
to use octaves for
the
f requency scal e
and decibel s for the ampl i tude scale The resul ti ng graph i s
cal l ed the spectrumof the sound, and you wl l see
that
the
spectrum
of
a sound
i s
analogous,
to
the spectrum
of l i ght,
since
we
see
di f ferent
f requencies
of
l i ght
as
di f ferent
col ours
Nowwe wl l
l ook
at the spectra of
some of
the sounds
we
have
been l i steni ng
see Fig
I I -7
a shows the
spectrumof a pure sound whi ch has exactl y one f requency
component,
represented
i n
the
graph
as
a
singl e l i ne at
that
f requency we
have
chosen 160Hz) b shows
the
spectrumof a
ramp waveform
at
the same fundamental f requency
(160Hz) but
2
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1
now
there are overtones at
the
frequencies
of the harmoni cs
320Hz, 480Hz, etc The harmoni cs
are equal l y spaced
i n
f requency each bei ng 160Hz
hi gher than the l ast but appear
unequal on the l ogari thmc scal e
of
the spectrum They al so
sound
unequal musi cal l y
the
i nterval s
between
harmoni cs
are
an
octave, a fi fth, a fourth, a thi rd and
so
on,
and thi s
j usti f i es our use
of
a l ogari thmc
scal e
c
shows
the
wave-
form
of
a square wave whi ch
has
odd harmoni cs
onl y 3x160=480Hz,
5x160=800Hz,
7x160=l 20Hz, etc Thi s
i s a property of
al l
symmetri cal
waveform
There
i s an
i nstrument
whi ch di spl ays the spectrumof
a sound
di rectl y,
rather as an
osci l l oscope
di spl ays
the
wave-
form but
i t i s
compl i cated
and expensi ve
However,
the
SYNTHI
can be used to
demonstrate the frequency structure
of a sound
acousti cal l y
A fi l ter i s a devi ce
whi ch al l ows
some
thi ngs
to
pass
through i t but bl ocks others
An oi l fi l ter
i s
a
wre
mesh
whi ch al l ows
oi l
to
pass
through i t but stops di rt, and
a
food strai ner
al l ows water
and
di rt
to pass through i t but
stops vegetabl es
In
sound
experi ments,
a fi l ter i s used
to
sel ect
or
rej ect certai n frequency
components of the sound
Acousti c fi l ters
can be made, but nowadays i t i s more
conveni ent
to
fi l ter
an
el ectri cal
si gnal and l i sten to the resul t
wth a
l oudspeaker
Experi ment 5
Connect the Fi l ter to Output Channel
wth a pi n
at
C o
The Fi l ter shoul d be set
to gi ve
the
hi ghest possi bl e sel ecti vi ty
wthout . resonati ng
as fol l ows
turn
the RESPONSE control
to
about 5 and the LEVEL
al l the
way f rom
to
RESPONSE
up a bi t and
the
Fi l ter resonates
makes
a pure
sound
i ts
own there i s
no i nput si gnal
yet
over a smal l f requency
range, and
then turn
the RESPONSE
down
a bi t The
Fi l ter i s
now
i n bandpass
mode,
control to 10 Turn the FREQUENCY
control
10 i f there
i s
no sound
at
al l , turn the
sweep
the
FREQUENCY agai n Do
thi s
unti l
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whi ch i s to say
that
i t
wl l onl y
l et through a narrow
band
of frequenci es
The
frequency at
the
centre of
the band
i s
control l ed
by
the
FREQUEN Y
control
22
Now
put vari ous
sounds
i nto
the
Fi l ter and
sweep
the
FREQUEN Y
control from0 to 10 to fi nd thei r frequency
components
Use as l owa sett i ng for
the
source devi ce as
possi bl e because
the
Fi l ter
i s
most sel ecti ve
when
i ts i nput
si gnal i s sml l
A pi n
at H3
enabl es you
to
anal yse a si ne-
wave (whi ch shoul d have no harmonics wth the SH PE control
at
5 or ramp, and movi ng
i t to
H4 enabl es you
to
anal yse a square
wave or ramp,
or
combi nati on of the two
A though the audi bl e
resul ts are not
qui te
as
clear
as
the
graphs,
the
harmonic
structure shoul d be apparent
You can
conti nue
the
experiment
wth
external sources,
usi ng the I nput Ampl i f i ers and a pi n
at
H8
Much of the ori gi nal research i nto the frequency compon-
ents of sounds was carri ed out
i n
the ni neteenth century by
Helmhol tz
He
di d not have the advantages
of
modern el ectroni c
equi pment, and
he
made acousti c fi l ters whi ch serve the sam
purpose as
the SYNTHI Fi l ter
i n
the experiment above, usi ng
the
actual sounds rather
than
thei r
el ectri cal equi val ents
H s
fi l ters, nowcal l ed Helmhol tz
resonators,
were
desi gned
for
maximum
sel ecti vi ty, but almost
any container
wth one or
two
hol es i n i t
functi ons
as a fi l ter as you
can
veri fy by
speaki ng i nto a
ti n can or al ong
a tube
A most al l
musi cal
i nst ruments
use resonators
i n
fact, wthout them they woul d
be almost
i naudi bl e
The
body
of a vi ol i n i s a resonator, as
i s the
gourd
on an
I ndi an si tar
The
tympanum
(kettl edrum i s
a resonator Unl i ke an acousti c resonator, whi ch works at
one
frequency onl y,
the
SYNTHI Fi l ter s frequency can be
adj usted
over
the
whol e
audi bl e
range
An
important advantage
of
the
sound
. spectrum
graph
over
the waveform
graph i s
i ts abi l i ty
to show
the
characteri sti cs
of noi se
Noi se
i s a
col l oqui al termused for
any sound whi ch
i s not
del i beratel y organi sed
for
a
purpose, as
speech and musi c
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23
are But i t
al so
has a techni cal sensewhi ch we wl l defi ne
here noi se i s a sound composed of al l
frequenci es
we
al so
make a di sti ncti on between whi te noi se whi ch contai ns al l
frequenci es
equal l y, and col oured noi se whi ch contai ns more
sound
at
some
frequenci es
than
others
As
wth
spectrum,
the words are chosen by anal ogy wth l i ght
a
mxture
of
l i ght of al l frequenci es col ours)
i s
whi te Noi se
i s
caused
i n
nature by many randomevents, and
i s
di fferent
from
pi tched
sounds whi ch are produced by steady vi brati ons
of
stri ngs,
membranes etc
The
sea,
wnd,
and
di stant
traff i c are examples
of noi se
sources
The waveformof
noi se,
vi ewed on an
osci l l oscope, vari es constantl y, and i s not at al l l i ke the
steady pattern of a note The most characteri sti c feature
of
noi se
i s i ts
spectrumsi nce
thi s
shows the average energy
l evel s at di fferent frequenci es
Experiment
6
Connect
the
Noi se Generator of
the
SYNTH to output
Channel 1
wth
a
pi n at A7
Adj ust the Noi se
LEVEL control
so
you
can hear the
noi se Wth
the
COLOUR control
central ,
the noi se i s whi te
make sure you have OUTPUT FILTERChannel 1 set to
;
turni ng
the COLOUR control to the l eft
emphasi ses l owfrequenci es,
and
turni ng
i t to
the
ri ght emphasi ses hi gh frequenci es
See Fi g
I I -8
Note: the Noise Generator requi res 10-30 seconds
to
warm
up
after
the
SYNTH
has been
swtched
on
Experiment 7
Adj ust the Fi l ter to gi ve a narrowpassband as
i n
Experiment
4 Connect the Noi se Generator through the Fi l ter
to
Output Channel 1 H7 A10)
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freq
ctaves)
freq
ctaves) freq ctaves)
a
O OUR
at
0
b O OUR at
5
c O OUR at 10
Fi g I I -8 Effect
of
COLOUR
Control
on
Nois
e
Generator
db
24
Fi g I I -9 Effect of RESPONSE Co
nt
rol on F
i l 1,~rlOsc ZZctor
db
db
db
0
0 0
-10
10 -10
-20
-20 -20
0
0 0
-10 -10
-10
1
-20 -20
-201
freq ctaves)
r-
freq
ctaves)
freq
1
ctaves)
a
RESPONSE at
0
b RESPONSE
at
S
c RESPONSE
at
10
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A band
of
noi se can nowbe sel ected by movi ng the
FREQUENCY control of the Fi l ter
The wdth of the band can be
al tered by movi ng
the RESPONSE control but
remember
that
above
certai n setti ng of RESPONSE the Fi l ter
wl l
resonate
generati ng an
addi ti onal
pure note
i n the
mddl e of
the
band
of noi se See Fig I I - 9
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CHAPTER I I I TECHNQUES
OF
ELECTRONCMUSIC
I n
thi s Chapter
we
w l l l ook
at
the ori gi ns and hi story
of
El ectroni c Musi c, and the techni cal devel opments
that l ead
to
the SYNTH, and then showhow these pri nci pl es are
i ncorporated i nto the SYNTH
El ectroni c
Musi c i s almost as ol d as
el ectroni cs
wthi n
fewyears of the i nventi on of the radi o val ve, Dr Theremn
was
experimenti ng
wth an
i nstrument
pl ayed by performer
who moved
hi s
hands around
two aeri al s, and
M Martenot was
bui l di ng
earl y
versi ons
of
keyboard i nstrument
cal l ed
the
Ondes
Martenot Both
i nstruments are
bui l t i n modi f i ed form
and
used
today
The
i nventi on
whi ch
had the most profound
ef fect on
el ectroni c
musi c was
the
tape-recorder
A though
phonograph
records had
been
i n exi stence for
l ong
time, and
some
the pi oneers of
el ectroni c
musi c had made
consi derabl e
use of them a more
f l exi bl e
medi umwas needed
Wth
tape, i t
became possi bl e to edi t,
mx, superimpose
and
perform
other
i mportant processes
very
much
more easi l y
than
w th di scs
The probl emnowbecame one
of
control wel l -equi pped
studi o
of
the ni neteen-f i f ti es and there
were
very few mght
have
an
assortment
of
osci l l ators and f i l ters, but very
l imted techniques for performng on
them
A composi ti on
woul d be real i sed very l abori ously by recordi ng the requi red
sounds, of ten one note
at
time, and edi ti ng the resul ti ng
tapes
unti l
the
composi ti on
was compl ete
The next step was
to
make more devices
to
control the
exi sti ng
ones
The f l exi bi l i ty
of
modern studi o s determned
l ess by
the sound-producing devi ces themel ves than by the
control l i ng equi pment The SYNTH
uses
the powerful techni que
of
vol tage control ,
and
al so an
enti rel y
newand
sophi sti cated
method of sequenci ng, or
pl ayi ng
number of notes i n
successi on
wthout i nterventi on f romthe pl ayer The most advanced modern
studi os use a di gi tal computer, whi ch may
be
regarded
i n
thi s
appl i cati on
as
very advanced sequencer
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2
7
Vol tage Control
So far,
wth one excepti on,
the signal s whi ch we
have
used i n
the SYNTH
have
been
anal ogous to sounds
; that
i s,
the
si gnal coul d be taken to an Output Ampl i f i er at any stage i n
the
process
and
be
heard The
excepti on
was at
the
end of
Experi ment 2 when
we
watched the
Meter move i n
ti me
wth
the
Attack/Decay
cycle
wth the
pi n at
Bl l
we
can read the vol tage,
but i f we move i t to
A l , connecti ng Trapezoi d
to Output Channel
there i s no sound
Thi s
i s
not because the
si gnal i s of
a
di f ferent
ki nd,
but because i ts f requency
i s
too l ow
to be
heard A though such signal s are no use for maki ng sounds,
they may be very useful for
control l i ng
other devi ces,
and they
are
cal l ed control vol tages
for thi s
reason
Experi ment 8
Connect
Osci l l ator
to
the
Fi l ter
H3),
the
Fi l ter
to
the Envel ope Shaper
D10), and the
Envel ope Shaper
to
Output
Channel
A12)
Use the Meter to di spl ay
the Trapezoi d vol tage
B l )
and
adj ust
the
Envel ope Shaper ti mng
control s
for
a
medi umcycle
about 2
seconds
l ong Turn the TRAPEZOD LEVEL
control up so
that the
Meter sweeps across most the scal e
the Meter swtch shoul d be
set
to CONTROL
VOLTAGE) Nowuse
the Trapezoi d vol tage to affect three di f ferent vari abl es of
the sound
Use the
Trapezoid to control the
f requency
the
Osci l l ator wth
a
pi n at
111
The
pi tch swoops i n
ti me
wth
the
Attack/Decay cycle
The
FREQUENCY
control
the Osci l l ator
sti l l
has
an
effect,
but
now
i t
onl y
al ters the average
frequency
2 The Trapezoi d
wl l
control the f i l tering i f
the
pi n i s
moved to
N l Once again,
i t i s
the f requency
of fi l ter-
i ng whi ch i s
control l ed
and
thi s
can be
very
useful i n
i nstrumental si mul ati on
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28
The
Trapezoi d
can be
used to
control
the Output l evel
Si nce
the
Envel ope
Shaper i s al ready control l i ng
the
Output l evel
Channel 1 put a pi n at
C10,
which takes
the
Fi l ter output
to
Channel 2 bypassi ng the
Envel ope
Shaper
Put another pi n at
Pl l ,
and
Channel
2
l evel
i s
now
control l i ng
of
phase
versa
control s,
fromone
side to
the
other
I t
may be necessary
to
set the
TRAPEZOD
LEVEL
control
to
8 or 9
to
achi eve
thi s
effect
See
Fig. I I I - 1
wl l
f l uctuate
because the Trapezoi d
i ts l evel Note
that
the
two channel s are out
when one
i s
l oud,
the other is soft, and
vi ce
i n fact,
wth sui tabl e adj ustment of
the timng
i t i s possi bl e
to
make the sound appear
tomove
I n
som
el ectroni c
musi c system,
great
care
i s taken
to
di sti ngui sh si gnal s
and control s
I n
the SYNTH there i s
no
such
di sti ncti on,
and the
resul t
i s
a consi derabl e
economy
i n
wri ng and number
of devi ces Any
vol tage may be used
ei ther
to
produce
a sound or to
control a devi ce Al l we
can say i s
that
vol tages
wth
very
l ow
often
subsoni c) frequenci es
wl l
more often
be
used
for control ,
and vol tages
of
higher
audibl e)
frequenci es
wl l
normal l y
be
used
as sounds
i f
you
l ook
at
the top
of
the
Patchboard,
you wl l see
that
the i nputs are
di vi ded i nto two secti ons
Signal I nputs
and
So
far
we
have
used
the
Si gnal
I nputs mostl y,
and
we
wl l
now l ook at
the Control I nputs
i n
more detai l ; we
wl l refer
to
a Control I nput
by
the l etter i n the
correspondi ng
at
the bottom
of
the Patchboard,
I J
etc The Control I nputs
do not
provide
any new functi ons,
but
they
do
enabl e
the
manual
control s
to
be al tered
automati cal l y
They
do
not overri de the
Manual
Control s,
but add
thei r
own
effect to
them
Control
I nputs
I
J
K Vol tages
i n
these
col umns control the
frequenci es
of
the
three
osci l l ators
The range-of
vol tage control
i s
greater than
that
provided by
the
knob
osci l l ators
and 2 have the
sam
sensi ti vi ty,
so
they
can
be
set
to
a
gi ven
i nterval , say
a
fi fth apart, and
that i nterval
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29
L
M
N
O P
Experiment 9
wl l be mai ntai ned
as
the frequencies are changed
by
the same vol tage There are no forbi dden combi nati ons
on the SYNTH -
an
Osci l l ator can control i ts own
frequency, or the osci l l ators can be connected i n a
ri ng, control l i ng one another
Thi s col umn control s
the
decay time of
the
Envel ope
Shaper ; +2V l engthens the l ongest decay time
(knob
set
to
10 by about 50
to
25 seconds
Thi s col umn control s the proporti on of reverberated
si gnal mxed wth di rect si gnal when the Reverberati on
Uni t i s
used
I t can be
swtched
on and
off rapi dl y,
permtti ng
unusual
effects
Thi s col umn control s the frequency of the Fi l ter
As
wth the Osci l l ators, the effecti ve frequency range
of
the Fi l ter i s i ncreased
by
vol tage control
These two col umns control the signal l evel
of
Output
Channel s and Wen
they
are
i n
use
i t
wl l often
be
necessary
to
adj ust
the
OUTPUT
LEVEL control s
to
bal ance the channel s correctl y
I n thi s experiment
we
gi ve a si mpl e example of the use of
each vol tage control i nput I t
i s
a useful exercise to bui l d
more el aborate patches fromthem tryi ng
to
di scover more i nter
esti ng sounds
W
do not gi ve control sett i ngs
i n
detai l , but
l eave i t to
you
to
di scover useful
combi nati ons of
control s
a Patch
A12,
D3,
14
Osci l l ator 2
i s
used
to
control
the frequency
of
Osci l l ator
A good
vi brato
i s
obtai ned
wth
Osci l l ator
2
control s at
3, 5, 0, 1
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SYNTH Dopesheet
EMS London Lt d
Descri pti on :
External Connect i ons
Nam :
EXPERMENT
9 c
Sheet
Patch
Start
End
:
Notes
: S
0
FI LTEROSC
OF
~606- 71
I l k
0
RNGMOD
OSCILLATOR
0
ENVELOPE SHAPER
0 0 0 0 0
OSCI LLATOR
2
External
Patch
SIGNALS
CONTROLS
REVERBERATION
0
J
O
C
C
E
>
ow
V
>
co -
~~
J
o
00
o
E
C
a E
CD
-
0
CU
w- N
r
Ed Ek
OSCI LLATOR3
chan
1
I NPUT
LEVEL
out
2
2
0
N
:
0
osc
1
3
0 0
66-
osc
2 4
osc
ru
.
5
NOSE
GENERATOR
FI LTER
3
N
OUTPUT
noi se
6
RANGE
i nputs
_
0 0
0
i l t e r
10
tr apezoi d
11
- - - -
env si gnal
12
CHANNL1
OUTPUT CHANNEL 2
r i n g md .
13
reverb
14
s t i c k`
-
15
I
16
A
CD
E F
GH
J KLMNO
P
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3 1
b Patch
A12,
D4,
J 7, J l l
Osci l l ator 2 i s control l ed
by
Noi se
and
Trapezoi d
The
Noi se LEVEL
control
can
be
adj usted
to gi ve an almost pure tone or a
wde
range,of
col oured noi se
c
Patch A13, E5, F3, I 5,
X15,
K16
Thi s
i s a more
compl i cated patch
than we
have used before, and
i t i s
i l l ustrated
on
a Dopesheet
Osci l l ator 3 i s control l ed
by
the J oysti ck, and
i s ri ng-modul ated wth Osci l l ator
1
to produce
pl ucked
sounds The other
J oysti ck output
control s
the
frequency
o
Osci l l ator 1 X15
so
both
the
repeti ti on rate and
the
pi tch of the notes can be
al tered i n
performance The
J oysti ck gi ves good
manual
control
of
any
two parameters of the sound, and
a
use
can be
found for i t i n practi cal l y every patch
d
Patch
A12,
D7, L6 Set the Envel ope Shaper control s
to 0, 5, 0,
0,
10 and
the
Noise COLOUR to 5 and LEVEL
to 10 Osci l l ator 3
ini ti al l y
t 5, 6, 0, 6
control s
the
Decay
time
and hence
the
cycl e durati on of the
Envel ope Shaper
e Patch
A14, E5, F3,
G13, M5
Osci l l ator 1 5, 5, 8, 0
Osci l l ator 3 5, 5, 5, 0
Ri ng-modul ator 10
Reverberati on
7,
10
Correctl y
set up,
thi s
patch can produce a sound
resembl i ng
a short
rol l
on a pi tched drum Wthout
the pi n
at M5, whi ch i s control l i ng the reverberati on
mx,
i t i s merely a bl ur
Thi s
patch i l l ustrates
the
val ue
o control l ed reverberati on
f
The
patch i s shown on
the
Dopesheet
I t
i l l ustrates
another way of maki ng a
dul l
sound
from
an
unmodi fi ed
Osci l l ator i nto an i nteresti ng
musi cal timbre,
i n
thi s
case by control l i ng
the
Fi l ter
frequency
wth
Osci l l ator
3 and
the Trapezoid_
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33
g Patch A3,
C12, D3, 011
Thi s
patch moves
the sound i n
thi s
exampl e i t i s Osci l l ator 1,
but
i t coul d be
any
sound
from
one
channel
to
the
other
I t
depends on
the
fact
that
the Trapezoi d
output i s
i nverted,
so
that the Channel
control l ed by
the Trapezoi d
i s
l oud when the
output
the
Envel ope Shaper i s
l oud, and vi ce versa
Modul ati on
When a si gnal i s
modi f i ed
i n
some
way by
another si gnal ,
we
say
that
the
fi rst i s modul ated by
the
second
The most
common form of
modulati on
i n
conventi onal
musi c
are
smal l
f l uctuati ons i n
the ampl i tude
or
frequency
of
a note Both
kinds
of
f l uctuati on
general l y
have a
f requency of
5 -
1OHz
and a
proporti on
of 2 - 5 I t i s conveni ent to
di sti ngui sh
between ampl i tude modul ati on by
cal l i ng the fi rst tremol o and
the second vi brato Unfortunatel y, thi s conventi on i s not
always adhered to for
example, vi ol i ni sts
tal k
about vi brato
f requency
modul ati on produced by al teri ng
the
l ength of
the
stri ng wth one f i nger , f i ngered tremol o same but wth two
fi ngers ,
and bowed
tremol o
ampl i tude
modul ati on produced
by bowng
Experiment 9 a
showed howvi brato i s
obtai ned
wth the SYNTH, usi ng
Osci l l ator
2 to modul ate Osci l l ator 1
Thi s
can be made
i nto
a demonstrati on of
tremol o
by moving
the pi n at 14 to 04, so
that
Osci l l ator
2
i s
control l i ng the
l evel of Output Channel 1
The mathemati cs of
ampl i tude
modul ati on i s
not hard
i f
you know some
tri gonometry
Suppose we
have a pure sine
A, wth ampl i tude a and f requency f , so
that
A =a .si n
2r r f t
Then
suppose that the ampl i tude
i s
di sturbed by a smal l
si gnal
B =b
.si n
2Trgt
tone,
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db
0
-20
-40
-60
V
+2
0
-2
db
-20
-40
-60
a Envel ope Shape Output Level
b
Envelope
Shaper
Trapezoi d
Vol tage
Fi g I I I -1 Panni ng wth the Envel ope Shaper
and Trapezoi d
Vol tage
freq octaves
a Spectrumof C
261Hz
time
c Output Level of Ampl i f i er control l ed by Trapezoi d
time
time
Fig I I I - 2 Spectra of C, and thei r R ng Modul ati on products
33 . 1
freq octaves
c Spectrumof
ri ng-modul ati on
o
f
C and
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so
that
the apmi tude modul ated
si gnal ,
A1
i s gi ven by
Al
=
{a
b sin
2Trgt
}
sin 2T r f t
= a.s in
2T r f t
b sin 2Trgt sin 2T r f t
= a.s in
2T r f t
~b
. cos
r
f - g
t
}
+
~b. cos
r
f +g
t
}
I n
most cases of ampl i tude
modul ati on,
b
i s
l ess
than a and g
i s
l ess
than f
I f thi s
i s
so,
we
can
anal yse the modul ated
si gnal A1
i n
the
fol l owng way:
a. si n 2Tr f t
i s
the
ori gi nal si gnal
~b
. cos{2Tr f -g t}
i s a smal l er si gnal b
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3
5
That i s, the resul t
i s a
sound
wth two frequency components
of equal ampl i tudes and
frequenci es
whi ch are
the sum
f+g
and
di fference f-g of the ori gi nal
frequenci es
I f we put n
a more compl ex sounds wth
more than one frequency
component,
al l the frequency components
of each
sound
wl l i nteract i n
thi s way and
many new
frequenci es
wl l be produced Fi g. I I I - 2
shows the
spectra of two
sounds
each wth two
overtones,
the
fundamentals bei ng at mddl e C and
at
E
a
thi rd
above
Fi g
. I I I -2 c
shows the spectrum
of
the
resul t of ri ng-
modul ati ng
these
two sounds, and
i t
has
ei ghteen di f ferent
frequency components
The
resul t
of
ri ng-modul ati on
i s
sometimes
harsh
because
many of the new
frequenci es are not rel ated simpl y to each
other
However, i nstruments such as
bel l s
and
chi mes
have
resonances
whi ch al so are not rel ated i n
a
musi cal way, and
the ri ng-modul ator can be used to si mulate
them
al though i t
i s usual l y
stil l
necessary to
fi l ter
out some of the new
sounds whi ch
i t i ntroduces
Ex eriment 10
The
patch and
control setti ngs for thi s experi ment are
shown
i n
the
Dopesheet
The Keyboard i s used to
provi de
a
pi tch vol tage at I nput Channel and I nput Ampl i f i er LEVEL
shoul d be adj usted accordi ngl y The tuni ng of Osci l l ators
and
2
i s cri ti cal si nce very smal l changes i n thei r
rel ati ve
pi tches wl l produce
sounds
wdel y varyi ng
ti mbre
The
sound
can be
made
to
gi ve deep bel l sounds or l i ghter
chi me
sounds
by adj usti ng the Fi l ter FREQUENCY
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SYNTH Dopesheat
E.MS. London Lt d .
Descr i pti on :
Exter nal Connect i ons
Nam
EXPERMENT 10
Sheet
Patch
Start
FI LTERI OS RNGMOD
End
Notes
g
_
Go
OSC LLATOR 1
ENVELOPE SHAPER
rj _
7N
60
Z
~ 9
OSCLLATOR
2
-
External
Patch
SIGNALS
CONTROLS
REVERBERATION
~
I
a
~ I
5 6 p
o
>
j
a
;
` ~
Q
a~
OZ
a
r
p
E N
d
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37
Reverberati on
When a source i n a l arge
roomor
hal l
stops produci ng
sound, the sound we hear does not cease abruptl y, but conti nues
to echo round
the
room
for
a
short
time
Thi s i s
cal l ed
reverberati on
I n
assessi ng
the
reverberati on time
of a
parti cul ar
room we make a
l oud
abrupt
sound,
and measure
the
time
taken
for
i t to decay to one-ml l i onth of
i ts
ori gi nal
i ntensi ty
The
time depends
on f requency,
so
themeasuri ng
device must use
a
burst of whi te noi se
sometimes
a pi stol
shot
or a
sound
wth
many f requency components
A cl assroomhas a reverberati on
time
of at most 1 second
a l onger time woul d make speech hard to understand A smal l
hal l
for chamber musi c has a reverberati on
time
of 09
to
1 7
seconds,
and
a
l arge
hal l for
orchestral musi c may be
f rom
1 5
to
2
seconds Cathedral s
and
l arge churches
have l ong
reverberati on times -
as
much
as
8 seconds and are sui tabl e
onl y
for choral
and
organmusi c wi tten for them
El ectroni c musi c i s i n some
ways l i ke
i nstrumental musi c
recorded i n a, room
wth
no reverberati on at
al l I t
may be
i nteresti ng musical l y but i t i s dul l and l i fel ess to l i sten to
Having constructed
el ectroni c
analogues
of
acousti c osci l l ators
and
f i l ters
and
so
on,
to compl ete
the
pi cture
we
ought
to
simul ate reverberati on But there
i s
a di f f i cul ty because
reverberati on i nvol ves
l ong
del ays, whi ch are di f f i cul t
to
produce wth purel y el ectroni c techni ques There are vari ous
ways
of
getti ng round
thi s
probl em The
best
i s
to use a
soundproof
roomwth
a
l oudspeaker and
a
mcrophone i nsi de
i t
the l oudspeaker makes noi ses, and themcrophone detects the
noi ses
di rectl y,
and
al so the
reverberati on f romthe wal l s of
the room A good al ternati ve i s
to
use a l arge
steel pl ate
wth transducers
on
i t one
transducer
i s
siml ar to a
l oud-
speaker but i t makes the pl ate move rather than the ai r around
i t, and the other
corresponds to
themcrophone but
i t i s
desi gned to pi ck up vi brati ons
of
the pl ate The pri nci pl e
i s
that echoes
f romthe
edges of
the
pl ate
are
siml ar i n
nature
to echoes i n a
room
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i nput
ampl i fi er
i
I I I Reverberati on
i n a
Hal l
Fi g
II I 4 Spri ng
Reverberati on Uni t
l evel control
8
output
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39
Unfortunatel y, we coul d not bui l d ei ther
a roomor a
l arge
steel pl ate i nto your
SYNTH,
but we di d
manage to fi t
i n two smal l spri ngs, and these
provi de an effecti ve imtati on
of
reverberati on
i n
a smal l space
Once
again, two trans-
ducers
are
used and
signal s
are
sent
al ong
the
spri ngs
by the
fi rst and col l ected at the other
end by the second
Two
spri ngs are used rather
than
one
to
simul ate the
complex
mul ti pl e
echo
nature of l i ve reverberati on
the
del ays
are
sl i ghtl y di fferent
so
that
the
echoes do not
rei nforce one
another
I n
the SYNTH , the