yamaha dx7 basic fm synthesis (magazine article)

8/22/2019 Yamaha DX7 Basic FM Synthesis (Magazine Article)

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Basic FM Synthesis

on the

Yamaha DX7

by

Ma rk P hillips


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Introduction

This booklet wa s w rit ten t o help students t o learn the ba sics of linear FM s ynth esis and t o bett erunders ta nd th e Ya ma ha D X/TX series synt hesizers. It is not int ended to be a complete course of stu dy oneither FM syn th esis or the DX7. There are a lread y several very comprehensive books plus a fairlysubsta ntia l users' ma nua l tha t provide a mounta in of informa tion. The Complete DX7, by Howar d

Mass ey, for insta nce, ass umes no prior knowledge or experience in a nyth ing related t o synthesis. It is agood, fairly comprehensive "self-tea ch" met hod book for a ra nk beginner. As such, it is a lot to wa dethrough if you are not a beginner. This book is aimed a t t hose students w ho do ha ve some degree ofknowledge about convent ional ana log a nd subtra ct ive synthesis and assumes a t least a passinga cquainta nce with th e DX7 itself--such as can be acquired in a couple of hours spent w ith t he man ual a ndthe instrument . It is meant to be used with the ma nua l (an d/or an inst ructor), not a s a substit ute.

A significan t aspect of this instruction ma nua l is its use of OpCode's E ditor/Librar ian softw ar e for t heMa cintosh computer. With it, one ca n see a t once a ll of the dat a for a given voice. Screen-dumps from theprogra m, incorporated in the text , are sha ded to dra w a tt ention to the pertinent da ta . If a Ma cintosh andthis softwa re, and a ppropriat e MIDI int erfaces are ava ilable (an d if you first ma ster a couple of basicMa cintosh convent ions an d keep OpCode's user m a nua l near by for reference), this booklet w ill help youacquire some fluency with the program as you lear n a bout the principles underlying the D X7's method oft imbre production. It is q uite possible to lear n from these pages w ithout a Macintosh, by accessing the

tut orial voices directly from a R AM cart ridge wh ich conta ins th e voices a nd by performing t hese exercisesusing the buttons and LCD display of the DX7.

This instr uctional packa ge is still in its development a l sta ges. Your comment s, compliments, criticisms,an d encoura gements a re welcome.

Note:In voices where performa nce functions a re relat ively unimporta nt , th e box in the diagra m w ith " OK" writ tenin it will appear sha ded. For these voices, you need not w orry much about performance data . In voiceswh ere these functions are importa nt , th e "OK" box will be unshaded, indica ting tha t a significan t a spect ofth e demonstra tion tim bre w ill be affected by one of th e four controllers (genera lly th e Modulat ion Wheel orthe Foot Control.)

Special note to Macintosh users:

These tutorial voices were programmed as TX voices so that function data could be incorporated in them.B e sure to select " Yama ha TX" on the menu when you launch the program. B e sure also tha t th ere ar e

three menu items under the "Load/Send" menu tha t ha ve a beside th em: "S end on Select" (so w hen youpoint a nd click on a voice it w ill automa tically be sent t o the Edit B uffer of the D X7 so you can hear it),"S end P erf. to DX7" (to facilita te ha ndling voices tha t need changes in performa nce data in order to workproperly), and " DX7/DX1/DX5 Voices." B e sure tha t t he DX7 is set up to receive dat a fr om the Ma cintosh.This means that the DX7 must have its Internal Memory "Unprotected" and System Information must be"Availa ble". (P ress the brown FU NCTION button, then press button "8" repeatedly until the message SYSINFO U NAVAIL a ppear s, next press the "YE S" button.) B oth the DX7 an d the Macintosh must a lso agr eeon the MIDI chann el.

DX7 I I-FD Users:See Addendum a t the end of th is booklet .

1987 Mar k P hillips


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1: FM Demo 1-A

(E.G. Contr ol of T im bre)

General Description:This voice is designed to imitat e the fa miliar a na log synt hesis sound of slowly opening an d closing a low-pass filter . Since the DX-7 has no filters, this subtra ctive synth esis sound must be obta ined in acompletely different method: by linear frequency modulat ion (FM) using a dyna mic index of modula tion. Inother words, we will modulat e the car rier sine wa ve with a second sine wa ve that var ies in a mplitude overa given t ime.

As the am plitude of the modula tor increases, the sound gets br ighter(a na logous t o opening a filter).

As the amplitude of the modula tor decreases the sound gets darker(a na logous t o closing a filter).

Patch Information:Opera tor 1 modulated by Opera tor 2; both a t ma ximum output; both a t sa me frequency ra tio (i.e. bothproducing th e identica l frequencies when a ny given key is pressed); E.G . 2 cont rols tim bre cha nge.

Exercises:1. Experiment w ith va rious frequency ra tios for both t he opera tors, especially tha t of the modulat or

(Op. 2). B egin with va rious Coarse sett ings betw een .5 and 4 or 5. After you begin to understan dthe t imbra l cha nges tha t result , try w idening the range and incorporate also some cha nges in theFine sett ings.

2. Experiment with the Output Level of Op. 2 (sett ings from 60 - 99 will give audible results)

B a sic FM S ynt hesis -3-


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2: MW-Demo 1

(Mod Wheel Contr ol of Ti mbr e)

General description:This voice is a lso designed to imita te t he fa miliar an a log synt hesis sound of opening and closing a low-passfilter. The difference betw een this voice and t he previous one is tha t th e timbra l cha nges ar e nota utoma tic, but ar e controlled in rea l time by the performer using t he Modula tion Wheel. (Refer to th eprevious F M-Dem o 1A.)

As you rota te the Mod Wheel aw ay from you, the amplitude of the modula t or increases a nd thesound gets brighter (analogous to opening a low-pass filter).

As you rotat e the Mod Wheel towa rds you, the am plitude of the modulat or decreases a nd the soundgets darker (analogous to closing a low-pass filter).

Note: If the Modulation Wheel does not cause the timbre to change in a manner similar to FM-Demo 1-A,see Additional Help on the adjacent page.

Exercises:Try d uplicatin g t he Mod Wheel's control of Op. 2 using a nother controller (i.e. the F oot P edal, or the AfterTouch. If you are using t he Macintosh, simply click on th e "E DIT" but ton, then select "S end Functions toDX-7" and " Edit Set t ings" under the "Funct ion" menu. You can then edit the set t ings with sta ndardMacintosh techniques. You must "E xit " (under the "F ile" menu) an d click on th e "E DI T" button or reselectth e same voice in order for your new Contr oller informa tion to be tr a nsferred. You can a lso chan ge thecontroller information by running through the nine steps listed in the Additional Help, but subst i tut ingthe buttons 21-24 or 29-32 for buttons 17-21 on the right side of DX-7.

-4- B a sic FM S ynthesis


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Additional Help for MW-Demo 1:

For original DX7:If you are using th e Macintosh librar ian program, you can select t he option " Send P erf. to DX7" under th e" Load /Send " menu, th en re-select th is voice.

If you a re still una ble to get t he Mod Wheel to respond, or if you are not using t he Ma cintosh, then y oushould perform the following steps. When you ha ve completed th ese, th e par a meters from your diagra mshould be in effect on the DX-7 (i.e. ma ximum Mod Wheel range, P itch and Amplitude "OFF ", E G B ias"ON").

1) P ress the brown " Function" butt on on the left side of the DX-72) P ress button "17" on the right side of DX-73) Sl ide the "Da t a En t ry " f ader down then push i t a l l the wa y up4) P ress button "18" on the right side of DX-75) P ress the "Da ta Entry-Off" but ton on the lef t side of the DX-76) P ress button "19" on the right side of DX-77) P ress the "Da ta Entry-OFF" but ton on the leftside of the DX-78) P ress button "20" on the right side of DX-79) P ress the "Da ta Entry-ON" but ton on the left side of the DX-7

Note:If y ou ar e using th e TX7, TX802, or t he D X7II -FD , th e function da ta (i.e. mod wh eel, foot cont roller, etc.) isstored separ at ely with each individual pat ch so there should not be any problems if you ar e using one ofthese newer synth esizers.



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3. FM Demo 1-B

(E.G. Cont r ol of T im bre using Velocit y)

General Description:This voice, too, is designed to imit a te th e sound of opening a nd closing a low-pa ss filter. The differencebetween this voice and previous ones is tha t w hile the t imbra l changes a re aut omatic a s in FM Demo 1-A,the a mount of modulat ion a chieved is dependent on how ha rd you play on the keyboar d.

The hard er you hit a key, the more it sounds like FM Demo 1-A.

The softer you hit a key, the less noticeable the modulation becomes.(It is possible to play softly enough to hear none at all.)

Patch Information:Nearly identical to FM Demo 1-A, except Op. 2 is velocity sensitive, meaning that the amplitude of themodulating signa l is dependent on how fast (how ha rd) you hit t he keyboar d.

Exercises:1. Experiment with various sett ings of velocity sensit ivity from 0 (no sensit ivity) to 7 (maximum

sensitivity)

2. Experiment wit h various sett ings of the Op. 2 EG Ra te 1. Macintosh users should experiment witha ll th ree meth ods of editing th e envelope: 1) dra gging 2) typing 3) mouse butt on w/a rrow



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4. FM Demo 1-C

(E.G. Contr ol of T im bre, wi th Rate Scali ng)

General Description:This is a nother voice designed to imita te th e sound of opening an d closing a low-pass filt er. In t his voicetimbra l cha nges aga in are a utomat ic an d the am ount of modulat ion is fixed, as in FM Demo 1-A. Thesignifican t difference is tha t speed of the " opening" a nd " closing" (i. e. the E G at ta ck and decay of Op. 2) isdependent on how high or low you play on the keyboard. The lower end of the keyboard w ill sound m orelike FM Demo 1-A. Ch a nge seems to occur more as a result of accelera ting t he given envelope (ra th er tha nfrom slowing it down.)

The higher you play , the faster the modula t ion sweep.

The lower you play , the slower the modula t ion sweep.

Patch Information:Nearly identical to FM Demo 1-A, except the EG of Op. 2 is subjected to "Rate Scaling"(i.e. set to "5")

Exercises:1. Experiment w ith va rious ra te scalings from 0 (no rate scaling) to 7 (ma ximum rat e scaling)

2. Experiment w ith control of Op. 2 EG Ra te 1 an d Rat e 2 as you did wit h the FM Demo 1-B . Notetha t if th ese rates a re too short the effects of rate scaling w ill be insignificant .



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5. FM Demo 1-D


General Description:This voice is also closely rela ted t o FM D emo 1-A. The ma in difference is in t he envelope sha pe of Op. 2,wh ich now ha s an at ta ck every bit a s fast as t he car rier (Op. 1). Thus the sound begins with index ofmodulation at ma ximum. You no longer hear t he "filter opening" a spect of the sound, only the closing. Asimilar effect m ay be achieved on a n a na log synt hesizer using an envelope genera tor (EG ) to control a low-pas s filter's cut-off frequency. (Of course th e slowly opening a nd closing [of] a low-pass filter in t heprevious ana log models for exa mples 1-A,-B , a nd-C could also ha ve been a ccomplished using a n E G --wit h aslow attack--to control the low-pass filter rather than the implied manipulation of the filters control dial.)

Patch Information:Nearly identical t o FM Demo 1-A (i.e. Op. 1 modulat ed by Op. 2; both at ma ximum output; both a t sa mefrequency ratio, etc.), except that EG rate 1 of Op. 2 is set at maximum speed (i.e. 99).


(Op. 2) as in FM Demo 1-A.




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6. FM Demo 1-E

Veloci ty Cont r ol of Carr ier (i.e. Ampl i tude)

General Description:This voice is closely rela ted t o FM Demo 1-D. The only difference is th a t n ow th e voice responds t o keyvelocity. The ha rder (fa ster) the key is stru ck, th e louder th e sound a nd vice versa .

Patch Information:Nearly identical to FM Demo 1-D, except that now the carrier (Op. 1) is set at maximum velocitysensit ivity.

Exercises:1. Experiment w ith va rious sett ings of velocity sensit ivity for Op. 2 an d

Op. 1, both t ogether a nd independently

2. Exper iment w ith the Output Level of Op. 2



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7. FM Demo 1-F


General Description:This voice is also closely rela ted t o FM D emo 1-D. The ma in difference is in t he envelope sha pe of Op. 2,wh ich now h as a perceptibly slower at ta ck. The sound may also be perceived as a sped-up version of FMDemo 1-A. A simila r effect w ould be a chieved on an a na log synt hesizer using a n envelope genera tor (EG ) tocont rol a low-pa ss filter's cut-off frequency. (P robably in combinat ion with some filter regenerat ion toemphasize the t imbra l extremes of the sound.)

Patch Information:Nearly identical t o FM Demo 1-D, except t ha t E G ra te 1 of Op. 2 is slower


(Op. 2)--as in FM Demo 1-A.




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8. FM Demo 1-G

(slower car r i er E .G. w i th faster m odul ator E .G. affects timbre changes, too)

General Description:This voice, too, is closely rela ted t o FM D emo 1-D. The ma in difference is in t he envelope sha pe of Op. 1,wh ich now ha s a perceptibly slower att ack. A similar effect might be achieved on an an alog synthesizerusing a n envelope genera tor (EG ) to cont rol the cent er frequency of a ban d-pas s filter. This effect, a chieved

wit h great ease an d flexibility on the DX7 compar ed to many older ana log synth esizers, is the bas is for awide var iety of sounds from the factory preset Was p Sting to various simulated bowed string a tt acks.

Patch Information:Nearly identical t o FM Demo 1-D, except t ha t E G ra te 1 of Op. 1 is slower



2. Experiment wit h th e Output Level of Op. 2 (sett ings from 70 - 99 will give audible results)

3. Experiment w ith va rious degrees of rate scaling (RSc) for Op. 1

B a sic FM S ynt hesis -1 1-


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9. FM Demo 2-A


General Description:While this voice may initially appear to be a duplicate of FM Demo 1-A, when later characteristics of thesound are heard (i.e. when a key is held down for a while, or upon release of the key if it 's not held downlong), it is clea r tha t th ere a re significa nt differences. They result prima rily from the fact th a t th e envelopefor th e modulat ing Op. 2 is inverted--meaning t ha t t he beginning a nd ending a re at ma ximum a mplitude,wh ile the internal a mplitude is much lower. Fa irly slow internal ra tes allow th e changes betw een thea mplitude levels to be quite a pparent.

Patch Information:B as ic tw o operat or pat ch (i.e. Op. 1 modulat ed by Op. 2; both a t ma ximum output; both at sa mefrequency ratio, etc.), but Op. 2 has an inverted envelope.

Exercises:1. Experiment w ith var ious sett ings for the envelope of Op. 2. Adjust both th e EG R at es and Levels.

Try to get r id of the "r elease sound" by decreasing EG Ra te 4 on Op. 2. Use a ll three methods ofedit ing the envelope: 1) dragging 2) typing 3) mouse but ton w/arrow

2. Experiment wit h t he Output Level of Op. 2 (sett ings from 60 - 99 should give audible results)



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10. FM Demo 2-B


General Description:This voice is derived from FM D emo 2-A. It ha s a s imila r invert ed envelope for Op. 2, but the sus ta in levelis kept low. Thus it is indis ting uisha ble from FM D emo 1-D, w ith it s right -side-up envelope, unt il a key isreleased. The "m etallic" sound of the release is the cha ra cterist ic sound and one of the prima ry uses forinvert ed envelopes. The var ious DX7 ha rpsichord presets all use some version of this device.

Patch Information:Nearly identical t o FM Demo 2-A, except tha t Op. 2 has a low sus ta in sett ing



2. Experiment wit h t he Output Level of Op. 2 (sett ings from 60 - 99 will give audible results).

3. Experiment w ith va rious degrees of rate scaling (RSc) for Op. 2.



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11. Pitch EG Demo 1

General Description:This voice is designed to demonstr a te obvious (a nd dra ma tic) use of the P itch EG . The DX-7 has only oneenvelope for pitch control. I t affects a ll operat ors simultaneously, whether t hey be carriers or modulat ors.There is no wa y to isolate th e effects of the pitch envelope on a ny given operat or, nor is th ere any wa y toha ve more tha n one pitch envelope per voice.

Patch Information:Op. 2 modulat es Op. 1 (both at full output) with a slowly ascending a nd descending Pit ch EG controllingboth simulta neously. A Level sett ing of 50 indicat es normal pitch; numbers above 50 indicat e a h igherpitch; numbers below 50 indica te a lower pitch. The am plitude EG for Op. 2 (th e modulat or) is set wit hrelatively slow r at es so tha t chan ges in t imbre accompan y changes in pitch.

Exercises:1. Try adjust ing the shape of the Pitch EG by drast ica l ly changing the first two ra tes. I f you are using

the Macintosh, simply "dra g" th e appropriate corners of the graphic display of the EG . (You mayneed to "point a nd click" the mouse on one of the num erical sett ings of the pitch EG to bring thegraphic EG into the edit ing window.)

2. Make adjustment in the Level sett ings for the Pitch EG . B egin simply by altering the non-50

sett ings. Next sta rt alt ering the levels set at 50. Fina lly, try to make the Pit ch EG changedirections more tha n tw o times by alt erna ting levels (i.e. high-low-high-low, etc.)



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12: Pitch EG Demo 2

General Description:This is an other voice with dr a ma tic use of the pitch envelope. A sine wa ve moves from a very high pitch tonorma l pitch (50) in one smooth descent.

Patch Information:Op. 1 is the only operator used so the P itch EG operat es only on it . Note that in order for the P itch EG tosta rt w ay above norma l, Level 4 needs to be up very high. This is the only w ay to have the sound beginhigh sud denly. In other w ords the sound begins wh ere it left off on Level 4 and t hen proceeds to Level 1 a tRa te 1. If you ar e using the Macintosh, note also tha t you can n ot "dra g" t he far left box of the EG graphic.You must "d rag" the Level 4 box, then t he left box will move to wha tever value you set for Level 4.

Exercises:1. Try adjust ing the shape of the Pitch EG by signif icant ly a l ter ing Rate 1 and the Level 4. I f you are

using the Ma cintosh, simply drag t he appropriat e corners of the graphic display of the EG . (Youma y need to point a nd click the m ouse on one of the numerical sett ings of the pitch EG to bring thegraphic EG into the edit ing window.)

2. Increase the Output Level for Op. 2 and make adjustments in it s a mplitude EG so tha t the t imbreof the voice cha nges over time as w ell as its pitch. Try to coordina te the tw o different t ypes of

envelopes to achieve an in terestin g effect.



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13: TM Demo

(LFO Contr ol of T im bre)

General Description:This voice is designed to imitat e the subtr active synt hesis sound a chieved by filter modulation or t imbra lmodula tion (TM). The FM equiva lent of this sound is ar rived at using a low frequency oscillat or (LFO) tocontrol the a mplitude of the modulat ing operat or. As w e have seen before, cha nges in the a mplitude of themodulating operat or result in changes in the overall t imbre. In th is exam ple, the cha nges in amplitude arecontrolled by an LFO.

Patch Information:LFO controls amplitude modulation of Op. 2, which in turn provides for frequency modulation of Op. 1(both a t full output). Op. 2 response to LF O is effected by the Amplitud e setting of the Mod Sens itivit yparameter (set to a maximum of 3 in this case--labelled AM on the Macintosh).

Exercises:1. Experiment w ith changes in the Amplitude Modulat ion Sensit ivity (sett ings ra nge from 0-3). Note

the blip in the sound caused by imposing a limit (settings 1-2) on the range of amplitude variance--the result is a virtua l "clipping" of the tr ian gle wa veform of the LFO.

2. With t he AM sensit ivity set on 3, experiment w ith cha nges in the Output Level of Op. 2 (from ca.40-99). Next try va rying t he output in conjunction wit h chang es in the AM sensitivity .

3. Exper iment w ith var ious wa veforms for the LFO

4. Experiment w ith changes in the frequency (Speed) of the LFO.



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14: TM Demo-MW

(Mod Wheel determ in es depth of L FO cont rol of t im bre)

General Description:This voice is also designed to imitate the subtractive synthesis sound achieved by timbral modulation (TM).In t his case, the am ount of TM can be a ltered in real t ime. Specifically, th e overall am plitude of Op. 2, aswell as the operator's responsiveness to the LFO amplitude modulation, is controlled by the Mod Wheel.

Patch Information:Similar to the previous TM Demo except that the Mod Wheel is set to have maximum control (setting "15")over Amplitud e (" On" ) a nd E G B ia s (" On" ). Only Op. 2 is set to respond to either (by virtue of its AM/"3"sett ing). Amplitude " On" results in th e Mod Wheel controlling the degree of low-frequency AM of Op. 2; E GB ias " On" r esults in th e Mod Wheel controlling all th e levels of am plitude EG for Op. 2. (With t he ModWheel rotat ed all the wa y forwar d the stored EG values for Op. 2 ar e functional. As the wh eel is rota tedforwa rd, a ll the levels a re reduced proportionally unt il they reach " 0.")

Exercises: (a ll exercises should in corporat e rota tions of t he Mod Wheel)

1. Experiment w ith chan ges in the Mod Wheel Range. (rotat e Mod Wheel)

2. Sw itch EG B ias to "Off " (rota te MW). Note that the TM sound st i l l fades in and out as you rota teth e MW, but t ha t t he ba sic reference timbre is very brigh t--th e result of havin g th e full output of Op.2 modulat ing Op. 1 until the LFO is brought int o play by th e MW.

3. Experiment w ith changes in LFO frequency (Speed) an d wa veform.



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15: TM-Organ

General Description:This voice is designed to show how the basic concept of timbre modulation can be used as part of a morecomplex, musica lly interesting sound. It is included here mainly t o show wh at this discussion of simple FMsynt hesis might lead t o once th ese concepts a re ma stered. Though this voice is proba bly more complextha n a beginning syn thesist m ight be expected to invent, most of the individual components of the soundconst ruction hav e a lrea dy been discussed. Wha t ma kes this voice complex (a nd musica lly sat isfying) is theinteraction of several individually simple components.

Patch Information:The "TM" aspect of the sound is caused by LFO amplitude modulation of Op. 2 (which modulates Op. 1).Op. 2 is set for maximum sensit ivity t o th e LFO modulat ion (see AM/" 3" sett ing). This is simila r to theprevious tw o exam ples. One small but significant difference in the LFO modulat ion is tha t LFO " Syn c" isturned off in this exam ple. This means t ha t t he patt ern of LFO modulation occurs independent ofkeyboar d depressions. The keyboa rd does not t r igger the LFO t o begin a new cycle, wh ich mea ns t ha t ea chnote played is likely to occur durin g a different pa rt of the cont inuously ongoing LF O cycle. Sin ce th e LFO iscontrolling timbre, each note is likely to have a slightly different timbre depending on where in the LFOcycle the key is depressed. U sing a m odera tely gentle touch, tap out a r hythm ic pat tern on any one note onthe lower half of the keyboard. If you look at t he para meters for Operators 3-6, you will note tha t t hey allha ve some degree of Velocity Sens itivity progra mm ed into them. The modulat ors, which w e've seen contr ol

t imbre, ha ve higher sensit ivity sett ings so the ha rder/fast er a key is depressed the bright er the t imbre.Including this touch sensitive portion of the voice allows the keyboard player instant control of the timbreth a t w ill over-ride the LFO control of the timbr e. This gives the player a grea t dea l of expressive flexibility.When you are playing easy un accented lines an d chords the LFO a utomat ically provides subtle changes intimbre (similar to a " Wah -Wah " pedal). When you want to call a t t ention to a note by giving it a brightertimbre simply accent the note. Try a rt iculating a rhyth mic pat tern on one note in the middle or upperregister, but t his tim e use occasiona l accent s. The last t ouches ad ded to the voice a re Level Sca ling on Op.2 and R a te Sca ling (" RS c") on Op. 3. The Level Scaling of Op. 2 causes t he "TM" effect to be empha sized inth e lower regist er and de-empha sized in the upper register. The Ra te Sca ling of Op. 3 causes tim bra ldifferences in the lower register between accented and unaccented notes to be less pronounced than in theupper register. Experiment w ith va rious degrees of accents in different registers on the keyboa rd an d listenfor this subtle d ifference in effect.



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16: "Wah" Organ

General Description:This voice is very sim ilar to th e previous TM-Orga n. The only difference is th a t t he a spect of tim bre contr olpreviously a ccomplished a utomat ica lly by the LFO is now effected by using t he Foot C ontroller . P laysevera l notes on t he keyboar d in va rious registers w hile moving the foot pedal up a nd down an d listen tothe effect on th e t imbre. Note that the t imbre is st ill touch-sensit ive in th e same general w ay as the TM-Orga n voice.

Note: If you ha ve trouble getting a proper response from the Foot Contr oller, follow t he instr uctions underthe heading Additional Help for MW-Demo, but substitute buttons 21-24 for buttons 17-20respectively. Also Ma ke sure tha t t he foot controller peda l is connected to th e ja ck on th e back ofth e DX7 labeled controller NOT th e one labeled volume



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17: LF Carri 1

General Description:This voice introduces the concept of using an operator as a sine wave LFO by assigning it a very low fixedfrequency. U sed as a modula tor, this low, fixed-frequency operat or could provide an alt erna tive type ofvibra to control. In t his voice, however, th e low-frequency operat or functions a s a ca rrier, causing cyclicchanges in t imbre.

Patch Information:Op. 1 is set t o a frequency of 1H z, the lowest possible fixed-frequency on the D X7. (The fact t ha t t he DX7does not a llow it s operat ors to be fine-tuned betw een 1 and 0 Hertz is a design flaw t ha t ha s disa ppointedma ny synth esists.) Op. 2 tra cks the keyboar d and modulat es Op. 1 at full output.

Exercises:1. Experiment with Op. 2 Output Level. Try sett ings between 50 an d 99.

2. Experiment w ith the Mod Wheel. Note tha t its effects are simply added onto the low-frequencyeffects alrea dy present.

3. With Op. 2 at wha tever Output Level you find pleasing, experiment with Op. 1 frequency cha nges.To do this, press the OPERATOR SELECT button on the left side of the DX7 repeatedly until the

displa y read s, "OP 1" in the upper right corner. Then press the E DI T/COMP ARE on th e left side ofDX7, follow ed by butt on "19" (FR EQU EN CY/FI NE ) on th e right . List en to th e frequency chan gesas you hold down a chord w hile you slowly slide the dat a entry fa der up and down. This is one ofthe few insta nces where dat a cha nges are heard w hile a key is depressed. (The other butt onscontrolling oscillator frequency and t he buttons for LFO Wave a nd S peed a lso respond t his w ay.)Usu ally th e sound is not updat ed until you press another key down.

4. Return Op. 2 to Output Level 99 and progra m a Level Scaling on it . To do this in an ea sy ma nner,press button "25" (DEP TH) once or t wice until the lower left corner has an "R " in it , t hen slide thedat a ent ry fader a round until the number in the lower right corner is between 25 and 40. If you areusing the Ma cintosh you can do th is even more simply by pointing a nd clicking on the " 0" t o the rightof th e A-1 beneat h Op. 2 a nd simply ty ping in a num ber betw een 25 a nd 40. The default set ting onLevel Scaling is a nega tive linear curve wit h a brea k point of A-1 (th e lowest A on a pia no) w hich isoff the D X7 keyboard . B y programming a negative linear curve to the right of that Low-A, you've

constructed a sound with a brighter t imbre on the lower end of the keyboar d.

18: LF Carri 2

General Description/Patch Information:This voice simply expan ds on th e concepts of th e previous voice. The sett ings for Op. 1 and Op. 2 a reidentical in both voices. In t his voice Op. 3 and Op. 4 ar e added, wit h sett ings t ha t nea rly duplica te Op. 1a nd Op. 2. The only difference is tha t th e Op. 3 ha s a different F ixed-Freq uency settin g.

Exercises:

1. Hold one note down a nd listen to the complex beat ing patt ern tha t results from the intera ction of theslightly out-of-tune LF Operators. P lay several notes one at a t ime and h old them down. Noticetha t beat ing pat terns are not in sync with each other , so tha t each note swells a nd fadesindependently of the rest.

2. Make minor cha nges in Fine Frequency sett ings for Op. 1 & 3. (repeat 1)



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19: LF Carri 3

General Description:This voice is designed t o expand still furt her on th e bas ic concept of low - frequency car riers. In t his voicea nother pair of operators with an L F carrier is added.

Patch Information:

The sett ings for Op. 1, Op. 2, Op. 3, and Op. 4 a re identica l to LF Ca rri 2. Now, Op. 5 a nd Op. 6 a reincluded, with sett ings tha t nea rly duplicate those of the oth er pa irs. The fixed-frequency value for the LFOp. 5 is the only difference. In order for Op. 5 to function as a carr ier, algorithm 5 is used for the first tim ein these studies.

Exercises:1. Hold one note down a nd listen to the complex beat ing patt ern tha t results from the intera ction of the

slightly out-of-tune LF Operators. P lay several notes one at a t ime and h old them down. Noticethat beating patterns are not in sync with each other, so that each note swells and fadesindependent of th e rest .

2. Make minor cha nges in Fine Frequency sett ings for Op. 1 & 3. (repeat 1)



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20: Addsynth 1

General Description:This voice is const ructed using a ddit ive synth esis. With only six sine wa ves to sum , the DX7 is not apowerful tool for th is method of sound constru ction. B ut it does provide the bas ics for using it a lone or incombinat ion w ith FM synth esis. Algorithm 32, with a ll six operat ors functioning as carriers, allowsma ximum add itive synthesis power a nd flexibility .

Patch Information:In Algorithm 32, all six operat ors are used as carriers. The Output Level for each is set a t t he ma ximum(" 99" ). Freq uency Ra tios ar e set to the as cending wh ole int egers 1, 2, 3, 4, 5, 6, producing th e first sixha rmonics. All other settings , including envelopes, a re left at th e Voice Init ializa tion default va lues. (Nowyou know basically how cheap organs get t heir sound!)

Exercises:1. Isolate the sound of each operat or by turning off all but one of them at a t ime. Use the OPE RATOR

ON/OFF sw itches on th e DX7 (butt ons "1-6") or, w ith t he Ma cintosh, use t he mouse to click in t hebox with the " X" in it (next to t he big operator numbers).

2. Exper iment w ith the Output Levels for a l l the operators.

3. Exper iment w ith the Coarse Frequency Rat ios of a l l the operators, making sure tha t you set them allto different in tegers.

4. Experiment w ith the Fine Frequency Ra tios of all the operators. The sounds you are most likely toconstruct t his wa y will be examples of non-ha rmonic ad dit ive synthesis.



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21: Addsynth 2

General Description:This voice is similar t o the previous Addsynt h 1. In fa ct , the steady -sta te sound of a n ote that ha s beenheld down 3 or 4 seconds is absolutely ident ical. The only differences occur at th e beginnin g of th e sound.The envelope generators are designed so as to bring in each harmonic of the sound separately.

Patch Information:Identical to Addsynt h 1 except for EG sett ings. Ops. 2-6 all have a ra ther slow EG Ra te 1 (ra nging from 7to 23) w hich is combined wit h a L evel 1 sett ing th a t is too low to be a udible. This combina tion serves todelay th e the audible "a t ta ck" w hich is provided by a moderat e EG Ra te 2 ( ca. 50) in combina tion with ama ximum Level 2 sett ing.

Exercises:1. Try a ltering the order of har monic entra nces by adjusting EG Ra te 1 on Ops. 2-6. If you "get lost "

an d w an t t o get ba ck to the original sound t o try a gain, or before going on to Exercise 2, simply recalla fresh copy of the voice to the Edit B uffer. (Select "C ompare" u nder the Ed it menu for Macintosh orCARTRID G E button followed by butt on "21" on DX7)

2. Exper iment w ith the Coarse Frequency Rat ios of a l l the operators, making sure tha t you set them allto different in tegers.

3. Exper iment w ith the Fine Frequency Ra t ios of a l l the operat ors.



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22: Addsynth 3

General Description:This voice is similar t o the previous Addsynth 2, but t his t ime th e entran ces of the various ha rmonics ha vea stronger, more bell-like at ta ck and a re higher pitched tha n before. The sound also dies a wa y moreslowly.

Patch Information:EG settings similar to Addsynth 2 (Ops. 2-6: Level 1 is ca. 50, Rate 1 ranges from 6 to 23), but now Rate 2is above 90 (bell-like a tt a ck) a nd a ll operat ors hav e a Ra te 4 of 30 (slow decay). Freq uency Ra tios ra ngefrom 3 to 8.

Exercises:1. Try adjusting a ll the EG Ra te 4 sett ings to cause the ha rmonics to decay a t different ra tes, becoming

inaudible in the same order as their at tacks.

2. Assign the same Ra te Scaling value to each operator so tha t t ime-delays for entra nces of theha rmonics vary a ccording to the highness or lown ess of the key depressed. Try severa l different"a cross-the-boar d" values.



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23: Addsynth 4

General Description:This voice is derived from Addsynt h 1 an d sha res an identical st eady-sta te sound wit h it . The onlydifference is that the harmonics smoothly, but quickly fade in one by one over a short span of time (ca. 1sec.). Notice th a t th is effect is very simila r to the sound of a low-pa ss filter cont rolled by an E G , which intur n w e've seen to be similar in effect to the linear FM s ounds intr oduced a t t he begining of this book. (i.e.U sing an a mplitude EG to control a sinewa ve which then modulates a sinewa ve car rier .) So we now ha ve 2utt erly different w ay s of approximat ing tha t common subtra ctive synth esis sound on the DX7.

Patch Information:Identical t o Addsynt h 1, except EG Ra te 1 sett ings for Ops. 1-6 descend by a factor of 10 as the ha rmonicra tio ascends by wh ole integers.

Exercises:1. Assign the same Ra te Scaling value to each operator so tha t t ime-delays for entra nces of the

ha rmonics vary a ccording to the highness or lown ess of the key depressed. Try severa l different"a cross-the-boar d" values.

2. Try a djusting the E G for Ops. 2-6 to give the illusion of closing a low-pass filter . Hint: P ut a l l Level3 and Level 4 sett ings for Ops. 2-6 to "0" th en a djust the Ra te 2 sett ings so they read something

like 20, 25, 30, 35, 40.



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24: Addsynth 5

General Description:This voice, too, is derived from Addsynth 1 and s ha res an identical stea dy-sta te sound with it . I t a lsosha res wit h Addsynt h 4 the concept of ha rmonics fadin g in one by one over a period of time. The differencesthis t ime are tha t t he har monics enter in opposite order, from high t o low, and ta ke longer to enter. This isof course similar to opening up a high-pas s filter.

Patch Information:Identical t o Addsynt h 1, except E G Ra te 1 sett ings for Ops. 1-6 ascend from 15 to 70 as t he ha rmonic ratioa scends by wh ole integers.

Exercises:1. Assign the same Ra te Scaling value to each operator so tha t t ime-delays for entra nces of the

ha rmonics vary a ccording to the highness or lown ess of the key depressed. Try severa l different"a cross-the-boar d" values.

2. Try a djusting t he EG for Ops. 2-6 to give the illusion of sweeping the cent er-frequency of a ban d-pas sfilter from high to low. Hint : P ut a ll Level 3 and Level 4 sett ings for Ops. 2-6 to "0" t hen adjust theRate 2 settings so they read something like 30, 35, 40, 45, 50.



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Expressive Pitch Bend with Timbre Variation

On many acoustic instruments, expressive pitch bending also results in changes timbre (or tone color).Often (as in a sa xophone or ha rmonica, for example) it is a ma tt er of losing some of th e origina l brillian ce oredginess of the sound a s the pitch is bent downw ar d. This effect can be achieved on a synt hesizer wit h adedicat ed pitch wheel, such a s t he DX series of keyboar ds, only by incorpora ting simult an eous a nd pa ra lleluse of an other controller . I experimented with the P itch Wheel in var ious combinat ions w ith th e Brea thController , Foot P edal a nd After Touch, but wa s not q uite sa tisfied. The results w ere often interesting, but

not very na tura l-sounding, because even a fter much pra ctice it w as st ill difficult t o achieve the necessarydegree of physical coordina tion. Though it first seemed the lea st likely prospect (my left ha nd w a s alrea dybusy w ith th e Pit ch Wheel at the t ime, r ight?), I ha ve sett led on th e Mod Wheel as the easiest , surest w ayto coordina te cha nges of timbre with pitch bend. Achieving th e best results wit h this effect requirescult ivat ing a tw o-fingered, dual-wh eel technique with y our left ha nd a nd a lit t le minor reprogram ming ofth e patches you wa nt t o use. The dua l-w heel techniq ue involves using th e index finger on the Mod Wheela nd t he middle finger on the P itch Wheel, each doing exa ctly the sa me thing a t t he sam e time. Thereprogra mming is necessary so tha t th e t imbre will be "n ormalized" wh en the Mod Wheel is half wa y up. Ita lso compensat es for the reduced sweep of the Mod Wheel from t he ha lf-wa y point down t o minimum--which coincides with the most frequently used pitch bend range ( i.e. from middle, or "0" on down) forinstrum ents such as ha rmonica an d sa xophone. To reprogram a pa tch for use with t his technique, simplyfollow these steps.

1. Choose an existing patch or t imbre and determine which operators are car riers and which aremodifiers. For our tutoria l exam ple let's use the original DX7 fact ory ACC ORD ION preset. It usesalgorithm 4, which means that operators #1 and #4 are both carriers and operators #2, #3, #5, and#6 a re all modifiers. (I know t he accordion is not noted for its expressive pitch bends, but by t hetime were through it ' ll ma ke a da ndy ha rmonica pa tch.)

2. Determine which modulat ing operators feed directly into a carrier and progra m them for am plitudemodulation sensit ivity. (On the DX7, enter the edit mode and press button 16; on the DX7II , enterth e edit mode, press butt on 11, and move the cursor over to the "Ams" column. Then select th especific operat ors you wish t o program.) In t he ACC ORDI ON preset , opera tors #2 an d #5 are themodifiers which feed directly into the car riers. P rogram t hese modulat ors so they each ha ve anam plitude modulat ion sensit ivity sett ing of "2."

3. Now, program the Mod Wheel so that i t wil l control only E.G . B ias w ith ma ximum ra nge sensit ivity .This ma y requ ire removing pitch modulat ion (vibra to) or am plitude modula tion (tremolo) from ModWheel control. (On th e DX7, while in th e function mode, butt ons 17, 18, 19, an d 20 w ill allow you toprogram this: Range should be "99", Pitch and Amplitude should be "OFF" while E.G. Bias shouldbe "ON." On the DX7II , enter th e edit m ode an d press button 25 repeat edly until " Modulat ionwh eel" appears in the upper left of the edit window: P mod should be "0," Amod should be "0," an dEG bia s should be " 99." ) If you wa nt t o be able to control vibra to/tr emolo effects, t oo, as I us ua lly do,then I'd recommend program ming After Touch t o contr ol these.

At t his point , push th e Mod Wheel all t he wa y up a nd listen to th e sound of the pat ch you a reworking with. It should sound the sam e as it did before you sta rted. When you return the modwh eel to "0" you should get a m uch darker sound.

4. Next, place the Mod Wheel exactly in t he middle of its r an ge (so its finger groove lines up w ith t hepitch w heel finger g roove).

5. If you are modifying the ACC ORDION pat ch, adjust the opera tor outputs a s follows: Opera tor #2goes from "79" t o "81" ; Opera tor #5 goes from "70" t o " 75." (On the D X7, in th e edit mode, pressbutt on 27. On the DX7II , enter the edit mode and press button 10 once or twice until you read">Level" in t he edit w indow.) This is done so tha t w hen the tw o wh eels are used together w ithnotches a ligned, the pat ch will have its original t imbre w hen the pitch wheel is at "0."

If you are using a different sta rt ing pa tch, simply go to the modulating operat ors on w hich you set upMod Wheel control a nd begin nudging t heir output values upwa rd w hile testing the a udio results byplayin g on th e keyboard . Keep experimenting unt il the voice sounds more or less the wa y itoriginally did. Hint : tw eak each output level a lit t le before going too far w ith one operat or.



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Now you can use your index and middle fingers t ogether to control pitch bend and t imbre simulta neously bymoving the two wheels together. Using pitch bends in the minus ra nge with pa ra llel movements of the ModWheel will vary t he pat ch's t imbre betw een its original sound a nd one severa l sha des dar ker in directcorrela tion to the am ount of pitch bend. With only a couple of pra ctice sessions I thin k you will find tha tmoving the tw o fingers in ta ndem becomes second na ture a nd only slightly more physically dema nding th anw orking only th e pitch bend wh eel. The resulting sound, however, is much more interest ing a nd expressivetha n mere pitch bend!

Extra s. I f ind tha t a pitch bend ran ge of "1 or 2" (ha lf or w hole step) works best to give nat ura l soundingbends wh ile st ill creating effective t imbre changes w hen the t wo w heels a re used together. Also for thispar ticula r pat ch, I set up After Touch to activa te a somewh a t exaggera ted tr emolo/vibra to effect using ara th er fast LFO speed settin g (ca. 45). On a D X7, set a comforta ble After Touch ra nge for your playin gstyle an d simply turn on the Pitch Mod and Amplitude Mod options. On a D X7II , where it's possible toma ke such dist inctions, I might use about t wice as m uch amplitude modulat ion or tremolo (ca."60") aspitch modulat ion or vibrat o (ca."30"). Other suggested modificat ions for this par ticular pa tch below:

A. G et rid of the very slow "beat s" creat ed by the extreme detuning of operators #2 a nd #3. (Adjustdetuning va lues of "+ 0" for opera tors #2 an d #3. Or you might desire to leave in a subtle detuningeffect by sett ing operat or #3 to ca. "+ 3" instea d of "0.")

B. Raise the sustain levels of the modifying operators (especially #5 and #6) so that the Mod Wheel can

exercise stronger control over the tim bre of long-held notes. (Once the E.G .'s reach t he low er susta inlevels on a long-held note, you can not ra ise the output a bove those levels wit h t he Mod Wheel.)



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Addendum/Update for Basic FM Synthesis booklet

Though the demos in this booklet were written for the original DX7, the concepts behind these demosounds are applica ble to any Ya ma ha FM synt hesizer. All of the actua l pat ches in the booklet arecompletely compatible with any 6-operator FM synthesizer such as the TX7, DX7II ,TX802, SY 77 (wh icha re all ava ilable in both st udios at O.U.). In fa ct since many of the demos use only tw o sine waveoperators, they can be duplicated on 4-operator synthesizer such as the TX81Z and the V50 which are also

available to students a t O.U.

Yamaha DX7 I I-FDSince the DX7 II -FD ha s th e benefit of a disk drive w hich allows you to load the sounds directly int o thesynth esizer, w ithout a computer or other softw ar e, you ma y w an t t o begin your explora tion of these demoson this synt hesizer.

Steps for exploring Basic FM Synthesis on the Yamaha DX7 I I-FD:

1. P ush the but ton labeled EDIT to the lef t o f the display screen.

2. P ush the but ton #14 under the UTILITY menu (you mayneed to push it repeat edly) until t he topline read s: >Mast er tun ing Memory P rotect >INT >CRT

3. Use the CURSOR but tons a t the f a r upper lef t of the DX7II to move the cursor to th e ar row (>) in frontof INT (wh ich sta nds for Interna l)

4. P ush the 1/OFF but ton to turn the internal memory protect o f f.

5. Inser t the disk conta ining the demos into the dr ive a t t he far le ft corner of the DX7II . (It m ay be therealrea dy, so you ma y wish to jump to the next step.)

6. P ush the but ton #16 under the DIS K menu (you ma y need to push it repeat edly) unt i l the top l ineread sa ys: DI SK INT >DI R >SAVE etc.

7. P ush the CU RSOR butt ons to move the cursor to the arr ow (>) in front of DI R (wh ich sta nds forDir ectory) and push t he + 1/Yes butt on

8. P ress the 1/OFF a nd/or the + 1/Yes buttons until you see the file nam e fm-demos on t hebottom line.

9. P ress the r ight arrow cursor tw o t imes so tha t the cursor is a t the arrow (>) in front of Load thenpress th e + 1/Yes tw o times.

10. P ress the SING LE but ton (which should have a red light above it . HOWEVERIf the red l ightabove the P ERFORMANCE but ton is on then press tha t but ton f irst , then th e SING LE but ton.

11. Now you will be a ble to simple press the butt on corresponding t o th e specific demo you wish t oexamin e. (B e sure tha t th ere is no red light a bove th e 132 butt on or you w ill be selecting pa tches3364 inst ead of 132. If th e red light is on simply push th e button a nd it w ill go off.)


yamaha dx7 basic fm synthesis (magazine article)

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