Synthi Handbook

of 90

Embed Size (px)

Transcript of Synthi Handbook

  • 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

    2/90

    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

    3/90

    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

    .

  • 8/10/2019 Synthi Handbook

    4/90

  • 8/10/2019 Synthi Handbook

    5/90

    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

  • 8/10/2019 Synthi Handbook

    6/90

    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

  • 8/10/2019 Synthi Handbook

    7/90

    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

  • 8/10/2019 Synthi Handbook

    8/90

    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

  • 8/10/2019 Synthi Handbook

    9/90

    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

    10/90

    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

  • 8/10/2019 Synthi Handbook

    11/90

    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

  • 8/10/2019 Synthi Handbook

    12/90

    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

  • 8/10/2019 Synthi Handbook

    13/90

    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

  • 8/10/2019 Synthi Handbook

    14/90

    . 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

  • 8/10/2019 Synthi Handbook

    15/90

    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

  • 8/10/2019 Synthi Handbook

    16/90

    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

  • 8/10/2019 Synthi Handbook

    17/90

    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

  • 8/10/2019 Synthi Handbook

    18/90

    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

  • 8/10/2019 Synthi Handbook

    19/90

    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

  • 8/10/2019 Synthi Handbook

    20/90

    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

  • 8/10/2019 Synthi Handbook

    21/90

    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

  • 8/10/2019 Synthi Handbook

    22/90

    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

  • 8/10/2019 Synthi Handbook

    23/90

    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

  • 8/10/2019 Synthi Handbook

    24/90

    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

  • 8/10/2019 Synthi Handbook

    25/90

    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

  • 8/10/2019 Synthi Handbook

    26/90

    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

  • 8/10/2019 Synthi Handbook

    27/90

    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

  • 8/10/2019 Synthi Handbook

    28/90

    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

  • 8/10/2019 Synthi Handbook

    29/90

    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

  • 8/10/2019 Synthi Handbook

    30/90

    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

  • 8/10/2019 Synthi Handbook

    31/90

    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)

  • 8/10/2019 Synthi Handbook

    32/90

    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

  • 8/10/2019 Synthi Handbook

    33/90

    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

  • 8/10/2019 Synthi Handbook

    34/90

    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

  • 8/10/2019 Synthi Handbook

    35/90

    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

  • 8/10/2019 Synthi Handbook

    36/90

    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

  • 8/10/2019 Synthi Handbook

    37/90

    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

  • 8/10/2019 Synthi Handbook

    38/90

    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

  • 8/10/2019 Synthi Handbook

    39/90

    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_

  • 8/10/2019 Synthi Handbook

    40/90

    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,

  • 8/10/2019 Synthi Handbook

    41/90

    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

  • 8/10/2019 Synthi Handbook

    42/90

    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

  • 8/10/2019 Synthi Handbook

    43/90

    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

  • 8/10/2019 Synthi Handbook

    44/90

    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

  • 8/10/2019 Synthi Handbook

    45/90

    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

  • 8/10/2019 Synthi Handbook

    46/90

    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

  • 8/10/2019 Synthi Handbook

    47/90

    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