Eventide Harmonizer H910 User manual

Eventide
the next step
MODEL H9IO
HARMONIZED
INSTRUCTION MANUAL
EVENTIDE INC * ONE ALSAN WAY - LITTLE FERRY. NEW JERSEY 07643 *201 -64M200 710 991^6715
J

TABLE OF CONTENTS
Warranty
Warranty Registration Form
Table of Contents
OPERATING MANUAL
Introduction
Specifications
System Interconnection
Control and Indicator Description
Applications
Pseudo Stereo
Haas Effect Source Location
Hum Reduction
Vocal and Instrument "Doubling 1 1 10
Delayed Echo Feed 10
Sound Reinforcement 10
Reverb e r a tion 11
Pitch/Tempo Variation 11
Retuning Tracks H
Length Change H
Multiple Ratio Adjustments 11
Live Performance Use 11
Use of Feedback 12
Pitch Ratio Readouts for Musical Relationships 13
HK940 Keyboard for Eventide Harmonizer 14
Interconnection of keyboard and
up to three Harmonizers 15
TECHNICAL INFORMATION - SEE SEPARATE SECTION
EVENTIDE HARMONIZER model H910
ALL PATENT RIGHTS RESERVED
f H ARMONIZER* is a trademark of Eventide Cloekteorks Ijict,

Eventide s^sofafeooss
MODEL H910 HARMONIZEft®
INPUT CHARACTERISTICS
OUTPUT CHARACTERISTICS
DISTORTION
DYNAMIC RANGE
Impedance nominal IOk, balanced, maximum level +24dBm Level
for full dynamic range from -lOdBm to +24dBm.
Impedance nominal
greater at +18dBm.
150 ohms. Suitable for driving 600 ohms
With xfmr, 600 ohms balanced +2ZdBm.
or
than .2% at 1kHz, reference output level»
Greater than 90dB from clipping to noise floor.
PITCH VARIATION
One octave up, one octave down, continuously variable,
readout indicates precise ratio.
Digital
DELAY
FREQUENCY RESPONSE
SIZE
POWER REQUIREMENTS
REMOTE CONTROL
In pitch change mode: 0, 30, 60 milliseconds.
In delay only mode: 0 to 112.5ms in 7.5ms steps.
Delay only output: 0 to 02.5ms in 7,5ms steps.
At any delay, unity pitch ratio: 20Hz to 12kHz, +idB.
No degradation with increasing delay.
Requires 8.89 centimetres (3V') x 48,26cm (19”) panel space.
Extends 22.86cm (9 M ) behind panel.
115VAC, 50/60HZ +5% or 230VAC 5G/60Hz. Nominal power dissi¬
pation 25 watts.
The HK94Q keyboard is available to control the H910 Harmonizer.
This is a two-octave keyboard (C to C) and each key corre¬
sponds to its associated musical interval. With this unit,
one can play various harmonies in real time. If the keyboard
is ordered with polyphonic capability (option 06), it may be
used to control up to three H9l(Ts at a time to produce
four part harmony.
An input is provided to phase-lock the H91D Harmonizer to any
synthesizer. A 3-volt peak-to-peak signal Is required.
The pitch may be varied by a control voltage input in the
5 to 15 volt DC range (internally selected).
NOTE; Depending on the pitch ratio selected and the nature of the program material,
the H910 may produce "glitches 14 in the output during the pitch change operation. The
H910 has been designed to minimize this problem, especially with musically useful small
pitch changes. For critical applications requiring the maximum in "no-glitch" operation
specify Eventide's H949 Harmonizer.

Eventide m ° d e l h»io
the n harmonher
n?D ™ ^ D, f U S i° MRH0NIZER SPECIAL EFFECTS UNIT — THE H910 HARMONIZER IS
aud i o E f fects process i ng E C TIVE ‘ AND MULTIPURP0SE PACKAGE that revolutionized 5
E VENTlOE
c LOCk! Uucun k
NdiMiie
FEATURES OF THE H910 HARMONIZER
PITCH CHANGE -- One octave up, one down. The H910 preserves all harmonic
ratios and thus all musical values since it incorporates advanced circuitry
which actually transposes input signals. Any musical interval can be achieved
by the continuously variable pitch change control. The pitch ratio selected
is shown on the 3-digit LED readout. An optional keyboard allows for pitch
change to be produced in discrete musical steps.
DELAY AND REVERB -- The economical H910 Is a versatile digital delay line.
It can be used for "doubling" vocals, delay equalization in sound reinforce¬
ment, and for many special effects, including several types of reverb and
echo. Two outputs are available, each with a variable delay, which allow
for vocal multiplying, distributing speaker systems (especially useful for
PA work), and even more effects.
ANTI-FEEDBACK — Feedback caused by energy buildup due to room resonance is
decreased by shifting successive repetitions of the same signal away from the
resonant frequency. The H91Q incorporates a control which periodically shifts
the signal pitch up and down to accomplish this. Unlike heterodyne "frequency
shifters," no dissonances are introduced.
SPECIAL EFFECTS -- Simultaneous use of feedback, delay, and pitch change can be
used to create a variety of audio effects. Maximum delay and one interval of
pitch change combined with feedback generates a musical progression of a single
note. Pitch change and feedback with no delay gives an unusual robot or alien
speech effect. Short delay with feedback but no pitch change gives a hollow
flanging or tunneling effect; long delay generates a distinctive reverb.
EVENTIDE INC - ONE ALSAN WAY * UTTLE FERRY, NEW JERSEY 07643* 201 641-1200-TWX: 710 991-8715

3
SYSTEM INTERCONNECTION
HARMONIZER model H910
TERMINAL
NUMBER
FUNCTION
---'V
FUNCTION |
(option 03}
1
2
3
4
Remote Control Bias OUT
Remote Control Voltage IN
Remote Control Frequency IK
Remote Control GROUND
■
Remote Control Bias OUT '
Remote Control Voltage IN i
Remote Control Frequency IN
Remote Control GROUND
5
6
Optional Output OUT 150 ohm unbal.
Optional Output COMMON
Optional Output OUT 6D0 ohm +phase
Optional Output OUT 600 ohm -phase
7
Chess Is Ground
Chassis Ground
8
3
Main Output OUT 150 ohm unbal
Main Output COMMON
Main Output OUT 600 ohm +phase
Main Output OUT 600 ohm -phase
la
91
INPUT 10K +phase
INPUT 10K -phase
INPUT +phase
INPUT -phase ^
12
Chassis Ground
Chassis Ground
REAR VIEW OF TERMINAL STRIP ON
REAR PANEL OF HARMONIZER,
If the Harmonizer Is equipped
for use with the optional Key¬
board, additional connector(s)
will be provided. Refer to the
Instructions on pages 14 and 15,
INTERFACE MODES;
Voltage control of It Is possible to remotely control the Harmonlzer pitch
Pitch Ratio ratio by supplying a control voltage in the range from 0
to +15VDC. An Internal adjustment allows setting of the
control voltage full scale between +5VDC and +15V0C, making
it compatlble with various synthesizers. The control vol¬
tage should be applied between terminal strip pins 4 and
2 , with pin 2 being more positive. Care should be taken
to Insure that the control voltage is as pure and free of
i

4
Resistive control
of Pitch Ratio
Anomalous Readout
Indications
Control Voltage
Range Adj ust
Frequency Control
of Pitch Ratio
SIgnal Requ1 rement 5
ripple as possible to avoid
pitch shifted signal.
frequency modulation of the
TT ms 1 7.- V nl voits, current
limited by a I0K resistor, Is available at pin I of the ter-
mtnai strip. The equivalent input circuit at the control
voltage IN pin is a 10K resistor in series with an opera¬
tional amplifier non-Inverting input. Therefore, voltages
withm the range 0 to +15 will be feeding an essentially
open circuit. Exceeding +15 volts will cause current to
flow into the input* limited by the resistor* Greatly
exceeding +15 may damage the Input, and should be avoided.
A remote control may be provided simply by connecting a 10K
potentiometer between terminal strip Pins I and 4, and con¬
necting the wiper to Pin 2* The unit is factory set so that
this connection will provide a full range. Note that the
maximum Input voltage in this configuration Is 7*5 volts-
When operated in the Remote Control modes * a Harnxjnizer
containing a Pitch Ratio Readout may Indicate ratios above
2*00. However, the actual ratio will be limited to 2.00
regardless of the reading. Note that the Pitch Ratio
Readout continues to operate even in the DELAY ONLY mode.
This is of advantage because it permits one to set a pre*
cise ratio and then switch from normal to that ratio without
going into the PITCH CHANGE mode.
To adjust the external control voltage range, remove the Har-
monizer top cover and swing the top board up on its hinges*
The adjustment (labelled "CV ADJ") is a small trim resistor
located about 3 cm behind the KYBD/CV switches on the bottom
clrcuit board*
In addition to voltage control, the Harmonizer may be exter¬
nally varied In pitch ratio by applying an input frequency
from a signal generator, synthesizer, or other source* This
mode Is preferable to the Control Voltage mode for musical
applications as the input frequency is precisely related to
the pitch ratio. 1*e* If the Input frequency is increased by
one interval, the pitch ratio likewise increases by one inter¬
val .
The input frequency must be spectrally pure in that only the
fundamental and its harmonics may be present. The unit will
not accept signals with more than one fundamental frequency
present, and should not be driven by any source from which
a clean* constant level signal cannot be guaranteed. Function
generator/synthesizer waveforms such as sine, square, and tri¬
angle waves are all acceptable*
The input voltage should be at least Svolts peak to peak for
a sine wave, and at least 3 volts for a square wave. All
standard logic families meet these requirements.

5
I
Tuning
Input frequency for unity pitch ratio Is 4l86 Hz (c8), in¬
creasing or decreasing the Input frequency by up to one
octave produces a corresponding change In the pitch ratio*
wnen using the Harmonizer with a customer supplied keyboard
It may be necessary or desirable to tune the master oscillator
to match another musical source. This may be done by ear
b y,^ s t r u ment - For absolute accuracy, a frequency counter
should be attached to the TRIG point In the center of the
and the rnductor be adjusted for a frequency of
33.48B KHz. For relative accuracy (for instance, to compen¬
sate for improper tape speed or poorly tuned Instruments]
apply the *1)66 Hz C8 tone to the control frequency Input,
and adjust the inductor until the Harmonizer input signal
Is in tune with the other instruments or sources.
1
j
1
J
The inductor Is located underneath the top board. The tuning 1
adjustment may be made by inserting a plastic hex alignment 1
tool through the hole In the ground plane on the left side
of the top board. Be sure to use the proper tool-a screw¬
driver will crack the core and make it impossible to move. n!
Grounding As with any piece of audio equipment, good grounding practices
should be followed when connecting the Harmonizer. In the
balanced configuration (option 03), terminal strip pins 4, ;
7, and 12 are all grounded and there is a DC path connecting
these pins, tn the unbalanced configuration (standard) pins
6, 9i and 11 are also connected to the same DC ground.
Nonetheless*. the grounds should be connected insofar as possi¬
ble as described in the table. Thls will help prevent ground
loops and subtle troubles that can occur when equipment to
be interconnected is at differing ground potentials. ■
A sure sign of grounding problems is if an unexplained hum
or buzz is present even when the LINE switch of the Harmonizer
is in the OUT position. The LINE switch bypasses the unit
with a DC path, and is independent of whether power is applied. - J
While the Harmonizer is susceptible to certain faults and 1
component breakdown, It Is very unlikely that generating hum J
or buzz is among them. If the unit seems to be contributing
such a signal, and there is no evidence that the power supply "]
is faulty, check your grounding scheme first of all. Inciden¬
tally* this applies to almost all accessory equipment.
i
The Harmonizer is supplied with a three wire power cord and
International standard I EC connector. The ground pin connects ^
the chassis to the electrical ground system. The unit may
be operated on M5 (nominal) or 230 (nominal) VAC, 50-&0Hz. H
U
Power

CONTROL AND INDICATOR DESCRIPTJDN
6
LINE
INPUT LEVEL and
LIMIT INDICATOR
FEEDBACK
This control switches the Harmonlzer in and out of an
audio circuit- When the switch is in the OUT position,
the unit is completely bypassed by a DC path and power
need not be app lied.
This control varies theMevel of the audio input to the
Harmonlzer. it should be adjusted to take advantage of the
maximum dynamic range of the digitil and analog circuitry by
setting the control as far clockwise as possible before
excessive distortion becomes apparent on the output signal.
The LIMIT Indicator is used as an aid In setting the INPUT
LEVEL control. It is adjusted to give a brief flash each
time the maximum dynamic range is even momentarily exceeded.
Because the LIMIT indicator is peak responding, and because
of the characteristics of the internal signal processing
circuitry, It is desirable for the indicator to flash occa-
sionalltj during' normal operation. The amount of flashing
is strongly dependent upon the nature of the Input signal.
As an aid to the operator, a general guide is provided:
SIGNAL SOURCE
Integrated program (radio)
Integrated program (live)
Voice (tal king)
Piano
Guitar, acoustic
Guitar, fuzz
Synthesizer
Organ
Drums
LIMIT INDICATOR DUTY CYCLE
once per two seconds
once per second
once per two seconds
2-3 per second
2 per second
1 per second
infrequent
infrequent
once per beat
Remember, the above is a general guideline! The ear is the
best measuring instrument around, and the best setting Is
one at which the output level is maximum and distortion is
not yet evident.
The FEEDBACK control may be used to add reverb In controlled
amounts to the delayed output of the Harmonizer. The control
attenuates the signal coming from the main output and re¬
applies it to the input where It is mixed with the incoming
signal. (The signal Is Isolated internally so that no sig¬
nal is applied back to the input line). The reverb period
is controlled by the DELAY setting, the decay time is varied
by adjustment of the FEEDBACK control. Clockwise rotation
of the control increases reverb time, until the feedback
gain exceeds unity, at which time the system will begin to
oscillate. The control Is also operative in the PITCH
CHANGE mode, and may be used to create numerous extremely
unusual special effects.
MANUAL
The MANUAL control is operative in the PITCH CHANGE mode
only. It Is used to change the pitch ratio between the In-

7
ANTI-FEEDBACK
f
DELAY ONLY and
LED INDICATOR
ADD 1 L DELAY
SWITCH GROUP
PITCH CONTROL SELECT
SWITCH GROUP, LED
INDICATOR
put and the output. When centered* the ratio 1$ unity* When
fully clockwise, the ratio Is 2, and the output pitch it
increased by one octave* When fully counter-clockwise, the
ratio is .5, and the output pitch Is decreased by one octave.
Intermediate settings produce fractional octave ratios, and
the control is "bandspread" around unity to make small ratio
adjustments easier*
This control Is operative In the PITCH CHANGE mode only,
when the A-F button In the PITCH CONTROL SELECT group Is
depressed* Increasing clockwise rotation of the ANTI-FEED¬
BACK control progressively adds a smalt up and down frequency
shift to the output signal, which serves to decrease the
effect of room resonance peaks on the signal which ultimately
re-arrives at the microphone* Because the effect becomes
more audible as the control Is advanced, the optimum setting
Is a compromise between adequate feedback reduction and
audience and/or performer disturbance.
This switch determines the mode of operation of the Harmon¬
izes* When It is depressed, the pitch change capability of
the unit Is defeated, and the Harmonlzer acts strictly as a
digital delay line. In this mode, the LED INDICATOR Timed-
lately adjacent to the switch becomes Illuminated, and the
legends beneath the ADD'L DELAY switch group become relevant.
When the DELAY ONLY switch is in the out position, the LED
INDICATOR adjacent to the PITCH CONTROL SELECT switch group
becomes illuminated, and the two right hand buttons In the
ADD'L DELAY group are the only ones activated* In this case,
the legends above the switches are relevant.
This switch group controls the delay of the main output. In
the DELAY ONLY mode, the delay Is the sum of the delays of
the Individual switches depressed, as read out on the bottom
of the switch group* Maximum delay is 7*5-H5+J0+60 millisec¬
onds {H2*5ms), and any intermediate setting can be achieved
in /.5ms steps* In the PITCH CHANGE mode, the additional
delay Is the sum of the delays of the two right hand switches
depressed. Maximum additional delay Is 3{H30ms. Note that
In the PITCH CHANGE mode, the delay Is continuously varying
over an approximate 30ms range, and so a precise delay is not
achievable*
When the PITCH CONTROL mode Is activated, the LED INDICATOR
Immediately to the left of the PITCH CONTROL SELECT switch
group becomes illuminated, and the four switches assume con¬
trol of the pitch change function.
MANual: This switch delegates control of the pitch ratio to
the MANUAL control, as described above.
A-F: Depressing the Anti-Feedback switch delegates control
to the ANTI-FEEDBACK control as described above*
KYBO: Allows operating the Harmonlzer by an external key¬
board. This keyboard may be either EVENTIDE option
l
a
n
■ l

8
POWER AND LEO
INDICATOR
OPTIONAL EQUIPMENT:
PITCH RATIO READOUT
05 single voice or 06 polyphonic phase-locked key¬
board, or a synthesizer or other oscillator which
provides sIgnaIs In the same frequency range, For
level and frequency requirements, refer to the
Interfacing section of this manual,
An external variable voltage variable from 0 to
7*5V may be used to control the pitch ratio. The
precise range may be internally adjusted to make
the Harmonizer compatible with various synthesizers.
For requirements and adjustment information, refer
to the Interfacing section of this manual.
Depressing this switch applies AC power to the Harmonizer.
The LED 1 NOICATOR becomes i11umjnated indicating that the
unit is operational.
If your Harmonizer is not equipped with the PITCH RATIO
READOUT or a second output, the front panel locations reser¬
ved for them will be covered with a plate.
An LED readout gives the numerical pitch ratio of the Har¬
monizer, As this is a true digital readout, it is not sub¬
ject to ml sea1 1 b r a11on and may be used as a precise referenee *
When using the Harmonizer in conjunction with a tape player
for tempo regulation, the oscillator controlling the tape
speed should be set to the reciprocal of the readout multi¬
plied by the base frequency (such as 60Hz). example: The
PITCH RATIO READOUT shows 1,30 (which corresponds to an
Increase of about 5 musical intervals). To find the osc¬
illator frequency to reduce this to normal pitch, assuming
a 60Hz synchronous motor, multiply hOHzXl/ 1.3Q = j +6 ■ 1 5Hz,
A similar procedure may be used to calculate time speed up
or slow down. Assume you have a 65 second tape which you
want to run in 60 seconds.
I: Find the speed ratio desired: 65/60-1.0S3
2; Find the requlred osci1 lator frequency: 1.083x60Hz=65Hz,
3: Find the pitch ratio required to reduce the pitch to
normal: reciprocal of speed ratlo=t/l,083= ■ 9 2 3 -
Note that settings past the second decimal place are not
too important in non-musical applications, or even in musical
applications in which the entire program is being pitch or
tempo adjusted,
For musical applicat ions, our optional keyboard will .allow
setting to precise Intervals automatical 1y. These same
intervals can be set using the readout, and referring to a
page of this manual reprinted from our 17 ^ 5 H manual* which
contains a chart showing PITCH RATIO READOUTS FOR VARIOUS
MUSICAL RELATIONSHIPS.
This switch group controls the delay of the second output.
It is operative regardless of the setting of the DELAY ONLY
switch. The total delay is the sum of the buttons depressed.
OUTPUT 2

9
applications
The preceding
gnd its interconnect
will discuss a few of the uses to
distinct functions: DELAY and PITCH
L sections detail the .operation of the Harmonizer
with other components of the system. This section
which It may be put. The Harmonizer performs two
aM^n^J 0 8 ' a r 9<! e f e n t b0th m0des are ""^pendent, and one should not fee) that
all applications must make use of all features* For ' tnat
cost effective digital delay line for
circumstances Is the ideal purchase even If the PITCH CHANGE
on
nstance, the Harmoni zer is a
Urge group of applications* and in some
capabi11ty is never used
PSEUDO STEREO
HAAS EFFECT
SOURCE LOCATION
HUM REDUCTION BY
C0M8 FILTERING
SHORT DELAY, PITCH CHANGE UNUSED
Connect the Harmonlzer to a program source, and add Its
output to its input through operational amplifiers Set
the unit for 7.5ms delay, If J op amps are used> as
shown below, there will be a broad range of frequencies
over which there will be addition in one channel and can-
Right
cell ation in the other,
interleaved comb filters
filter width being about
the source wilt appear to
output. The circuit introduces no
the two signals added together recreate the original Input
and cancel the delayed signal* yet the illusion of stereo
very convincing*
The outputs will appear as two
in the frequency domain, with the
As the input frequency shifts
vary from the "left" to the "right"
compatibility problems as
j s
7 , 5 ms, and perhaps as much as 15ms of delay can be added to
one side of one or more instruments in a stereo or quad
mixdown to aid the illusion of source placement. The ear
tends to localize a source as coming from the direction
of first incidence* even if the signal coming from another
direction is somewhat louder. This may be used to advantage
In "delay panning" in situations where the signal must be
present in all speakers* such as in a three-channel motion 1
picture sound track. As the Harmonizer is much less expensive :J
than the typical DDL* it is economical to tie up a channel of
delay for such uses.
By setting the Harmonizer at 15ms and subtracting the output — 1
from the input in an operational amplifier, cancellations are
produced at every 66*67 Hz. By following the TUNING Instruc¬
tions given earlier. It should be possible to increase the
delay to precisely 16.666ms, which will produce nulls at 60,120,
I 8 OH 2 , etc* (If the tuning range is too small, a very small ps
capacitor may be added in parallel to the coll* 5 p f should be M
enough.)

10
VOCAL AND INSTRUMENT
"DOUBLING"
DELAYED ECHO FEED
SOUND REINFORCEMENT
At delays between 15 and 60 milliseconds (typically 22 to
45ms) adding the delayed signal to the original, either
directiy, or to a different panning position creates the
Illusion of more than one singer or player. Doing so
tends to "fatten" the signal, and is an excellent method
of adding iushness to string and horn sections. Using
the optional output produces a further multiplying effect.
A typical application would be to feed a small string sec¬
tion in the center of the mix, and the same signal delayed,
say,37-5 milliseconds on the left, and the same signal delay¬
ed this tl me by 60 milliseconds on the right. The correct
delay setting is largely a matter of taste* Instruments with
sharp transients such as guitars will typically require shorter
delays, vocals medium delays, and strings and horns longer
deI ays,
Natural room echo is characterized by a short delay before
the original return from the first reflective surface. By
interposing the Harmonizer between the signal and the chamber
input, one can to a degree simulate rooms of various sizes
by delaying the onset of the echo. Typical pre-echo delays
vary from 30 to 100ms,
LONGER DELAYS, PITCH CHANGE UNUSED
A common problem in sound reinforcement is caused by the slow
propagation velocity of sound in air. Assuming a room or
auditorium 100 feet long with a lecturer or singer at one
end, how does one get the sound to the other end without echoes?
For good coverage, speakers could be placed, say, at 40 feet
and 70 feet from the end, but a listener near the end of the roorr
would hear sound from the nearest speaker first, followed by
sound from the middle speaker, followed finally by the voice
of the lecturer. For proper perspective, it is highly desir¬
able to hear the direct sound first, followed by the reinforced
sound. The traditional solution has been to avoid distributed
systems in favor of loudspeakers slightly behind the stage.
This solution works, but requires more level than is strictly
necessary, and gives progressively poorer quality as the dimen¬
sions of the room emphasize length over height. In low rooms
with balconies (such as many churches), the distributed approach
must be employed for intelligible results.
By using a two-output Harmonizer, one can feed the distributed
speakers with signals delayed according to their distance from
the microphone, thus eliminating the precedence reversal
effect. The delays should be adjusted to the setting which
makes the sound appear to emanate from the front of the room,
(This Is a practical application of the Haas effect, mentioned
earlier In this section).

REVERBERATION
PITCH/TEHPO
VARIATION
GETTING TRACKS
BACK IN TUNE
SPEEDING UP/
SLOWING DOWN
COMMERCIALS
FAST REACTION
LIVE PERFORMANCE
The Harmonizer employs a FEEDBACK control, which applies
varying amounts of the main output bac£ to the Input, Turning
this control clockwise while the unit is In DELAY creates
FFFnnir* U , a t ! ? n i°° P ’ Wh ° Se decay tirne depends upon the
FEEDBACK amplitude and the length of delay engaged. Various
types of reverb and echo can be simulated by adjusting these
two parameters. Additional realism can be Injected with a
dual output unit by adding another feedback pot from the
second output to the input, thus giving two independent
time constants*
PITCH CHANGE
The Harmon Izer is capable of changing pitch by up to a full
octave in either direction while preserving musical values
The CONTROL AND INDICATOR DESCRIPTION section describes the
modes and methods by which this may be accomplished.
When mixing a multitrack master, someone may notice that an
instrument 1s out of tune, (Don't ask why it wasn't noticed -s
earlier). It may be Impractical or impossible to recall the
musician. By playing that track through the harmonizer, It
1s possible to restore it to the pitch of the rest of the
t racks,
There are numerous occasions when radio stations must vary
the length of recorded material. An editorial may have to
be fit Into a time slot, a conmercial may be 63 seconds long, J
etc. Using the Harmonizer In conjunction with a tape recorder
speed control or VSO allows one to correct length without
changing the pitch of the recorded material.
In certain c i resistances, particularly in film work, it is
necessary to make rapid changes In pitch* from one controlled
value to another. The voltage control mode may be used In
conjunction with an easily built accessory to effect this.
The accessory consists of a rotary switch (or any other conven- j
lent switching arrangement) and several variable resistors. J
These resistors may be sequentially switched across the control
terminals on the rear panel, and the Harmonizer will immediately
assume the pitch ratio to which they were set earlier. A j
similar set of resistors can be concurrently switched In the
tape speed control, so that pitch and tempo may be simultaneously
and independently varied.
i
The optional keyboard available for the Harmonizer allows one
to M p l a y" the pitch ratio so that any musical Interval between
the original Input and the pitch-changed output may be Instan¬
taneously achieved. If purchased in its polyphonic configur¬
ation, the keyboard may control three Harmonlzers at once,
allowing multipart harmony. Note that If this feature Is to

12
FEEDBACK
nm” f n J d t Sm9er dUn " 9 3 Hve Performance, some
provision should be made to eliminate the Harmonizer output
from the monitor mix, as the acoustical feedback to the
perfonner tends to create some confusion about what note is
actually being sung* This tends to throw him off pitch, at
A unique effect can be achieved by employing feedback
while the Harmonizer Is changing pitch. Three controls
effect: The WANUAL * ADD F L DELAY, and FEEDBACK all chang
the character and extravagance of the weirdness caused*
have
e
What happens? Each time a signal goes around the loop, its
pitch is Increased or decreased according to the setting of
the MANUAL control. If the ratio is small, many repetitions
can occur before the original signal is out of the frequency
band avallable if for Instance the ratio is set at one inter¬
val (about 1*0b), putting a tone into the input generates an
equally tempered scale which is output sequentially. The time
between the notes is determined by the delay setting, and the
amplitude between successive notes is determined by the feed¬
back amptitude,
Additional interest is added by the fact that as a consequence
of the pitch change, the delay is contInuously changing over
a 30ms range. If the ADD'L DELAY is set at 0 and the feedback
is turned up, an extremely "hollow" variable reverb is set up
when the pitch ratio is near unity, and as the ratio is varied,
a literally indescribable effect is created. Wait until the
next generation of monster pictures comes out— we bet that
a Harmonizer will be used to audioize the BEH^s.

13
PITCH RATIO READOUTS
FOR VARIOUS MUSICAL RELATIONSHIPS
The figures in this table are accurate to four decimal places.
For use with the 17*5M Delay Line with Pitch Change Module ‘
For use with the Model H910 Harmoniaer, round off the fi
tgnore the last
gure to two decimal
digit.
places.
-3/4
- 1 / 2 -1/4
NOTE
RELATIONSHIP
NOTE
+ 1/4
mm
) , 0 000
1*0145
1,0749 mum
1.0595
E^E
1 1225
1.1388
1,1892
1,2065
1.2599
1.2782
E^E
1.33*8
1.35*3
1,4142 1,4348
E^B
1.11983 1.5201
E9
1.587*
1.6105
-9
+9
1,6818
1.7063
-10
+10
1.7818
1,8077
-11
+n
1,8877
t.3152
OCTAVE-
2,0000
n
*9576
■ 9039
*8531
.8052
.7601
* 7174
,6771
■ 6391
.6033
,5694
,5374
■ 5073
■ 9715
-9170
■ 8655
.8170
,7711
-7278
.6870
.6484
*6120
-5777
■ 5453
■ 5147
■ 9857
■ 9303
■ 8781
.8288
■ 7823
7384
■ 6570
6579
.6209
5861
5532
5221
1,0000
*9439
*8909
.8409
*7937
■ 7432
■ 7071
,6674
*6300
*5946
,5612
♦ 5297
,5000
1,0293
1.0905
1.1554
1.2241
1.2968
1-3740
1*4557
1.5422
1.6339
K7311
1 , 8 340
1*9431
I.0443
).1064
1,1722
1.2419
1*3157
1.3939
1.4768
I.5646
1.6577
1.7563
1.8607
1*9713
PITCH CHANGE:
The Eventide Harmoni 2 e r and 1745M Delay Line with Pitch Change Module may be used
to generate musical harmonies by reference to the above table. Because a digital
compression or stretching process is used, all harmonic relatlonships are preserved,
unlike the disharmony produced by heterodyne-type 'frequency shifters'.
For example* suppose two frequencies, originally In a musical relationship, are
shifted up by 100 Hz* Although the absolute difference between the signals remains
constant, the musical interval between them decreases. However* if the two
frequencies are jnuJtipiied by any constant, as in the Harmonlzer and Pitch Change
Module, the interval remains constant, even though the absolute difference will
change.
TEMPO REGULATION:
The internal oscillator of the 1745M provides an output frequency which may be
used to control the speed of a tape recorder* The H91Q Harmonlzer does not have
this facMity.

l4
HK940 KEYBOARD FOR EVENTIDE HARMON1ZER
MODEL H910 AND MODEL H949
n two vers ions -
option 05 ,
The two octave phase locked keyboard is available
“e I T hr« , H ™ Harm ° ni ^ r ’ and ° Pt,0n ° 6 ' P°’^nic, for control!
polyphonic h Ha ™ f "*ers. The mono keyboard pannot be 'upgraded’ to
i ng
The keyboard controls the pitch ratio of the Harmonizer(s)
steps. Middle C on the keyboard is KQO
(unison). Playing the E above middle C
E flat will give a
m
nor third, and so on.
n discrete
on the readout - a one-to-one
will give a harmony of a major
musical
pitch ratio
third, playing
When the polyphonic keyboard is
key pressed controls Harmonizer
controls Harmonizer #2 t and the third
second) controls Harmonizer #3,
will change the pitch of that Harmonizer only.
being used to control three Harmonizers, the first
#1, the second key pressed (while holding the first)
key pressed (while still holding the first and
Releasing any of these keys and pressing another
The keyboard GLIDE pot affects Harmonizer #1 only. The pitch change action ranges
from instantaneous to a gentle slide. There is a LOCH switch for each Harmonizer,
which holds the Harmonizer at the last note pressed. In non-LOCK mode the
Harmonjzer(s) will return to middle C in the absence of any key depression.
No music is generated in the keyboard. Your music, passing through the Harmonizer,
is pitch changed on Instruction from the keyboard. The keyboard/Harmonizer
combination can be used as a musical Instrument if the Harmonizer Input is supplied
with middle C (approximately 2b0 cycles) of the waveform or timbre you require.
The keyboard is basically an electronic cltick, with some sequencing and timing
circuitry. The keyboard is slaved to the Harmonizer clock (Harmonizer #1 for the
poly keyboard) for perfect unison at middle C, Keyboard keys select appropriate
timing pulses, which command the desired pitch change in the Harmonizer.
Use of the HK^O Keyboard with Model Harmonizer (AVERSE THIS MOD IF T CAT r ON Tp USE
—---~ £ - A H9^3 keyboard with the h?io)
The H9kg Harmonizer can lower the pitch of an input signal by two octaves. The
keyboard does not control this lower octave.
Tor use with the H949 Harmonizer, the keyboard requires the following modification.
With keys towards you, loosen the left wooden side enough to allow removal of the top
cover. Underneath is the underside of the circuit board. Add a 100 pF DM 15 capacitor,
as shown. Replace the top cover, and tighten the left side.
On the HA931 analog
board, make the cut
as shown:
Oyoopoooooo
our UEie.
NOTE: If the keyboard was supplied for use with a
949 Harmonizer, the modification has been done already.

15
jN TERCONNECTJOH OF HK940 KEYBOARD W I T H EVEKTIDE HARMONIZER MODELS H910 & H^q
K with mono keyboard, and Harmonizer *T with poly keyboard, should
be equipped with a keyboard socket on the Harmonizer rear panel*
If no socket Is supplied, hsk your dealer to provide one.
NOTE: every HW is fitted with a socket already.
If the socket is supplied but not installed, proceed as follows:
I. screw socket Into rear panel of Harmonizer (remove
blanking plate),
li* connector H3 together (observe polarity).
Ill* remove shorting connector from M4, KEEP IT SAFELY! It will
be needed If you ever require to use the Harmonizer with a
synthesizer keyboard or similar*
■ v* plug connector H4 together (observe polarity).
c) Connect keyboard cable to socket on Harmonizer rear panel.
d) H910: Press KBD switch on Harmonizer front panel*
H94f): Select KEYBOARD control mode on Harmonizer front panel*
2* Harmonizer §2 or #3 with poly keyboard
a) For H910 Harmon Izers only:
If Harmonizer has a keyboard socket* this must be disconnected
from H3 and M4, and shorting plug replaced on M4 (observe polarity).
I* If you have lost the shorting plug, the two pins to be
shorted together are (counting the pin nearest the front
panel as #1) pin tfZ and pin # 3 .
b)
c)
A cable which is phone plug to two lug connectors is supplied*
Connect phone plug to jack H2 or H3 on keyboard rear panel*
H910: Connect red lug to terminal 3 of harmonizer (see page 3
of manual: terminal 3 Is Remote Control Frequency IN).
Connect black lug to terminal 4 of Harmonizer (Remote
Control GROUND).
H94f): Connect red lug to terminal 9 of Harmonizer (External
Control FROM KYBD),
Connect black tug to terminal 10 of Harmonizer (External
Control GROUND)*
H310: Press KBO switch on Harmonizer front panel.
H949: Select KEYBOARD control mode on Harmonizer front panel*

H9I0 Harmonizer - Technical Manual
T1
PERFORMANCE ASSURANCE
This section is provided to enable the user to determine whether the Harmoniier
desrrthB The ieft colgmn provides instructions, and the right column
describes the indications obtained when the instructions are followed If the
*** n0t , ? S described > refer the troubleshooting suggestions immed¬
iately following. If no abnormal indications are obtained, the Ha?moniter is
runctionmg properly.
STEP ACTION
1 Observe serial plate to deter¬
mine line voltage* Push in
DELAY ONLY and LINE swltches.
Push in POWER switch.
2 Apply a +*tdbm, I kHz low dis¬
tortion sine wave to rear pan¬
el audio input. Rotate LEVEL
control to maximum, FEEDBACK
to minimum, set DELAY to zero.
3 Connect a distortion meter to
the output terminal and de¬
crease the LEVEL control set¬
ting until the output level
is about +Adbm.
Set the DELAY to 7*5ms.
5 Set DELAY of first output
to maximum, and FEEDBACK
to center.
INDICATION
Power on, line in, and delay only LED's should
become Illuminated* If the Harmonizer is pro¬
vided with a digital readout, all three numer¬
als will light-
A clipped sine wave should appear at the audio
output termtna1{s). The LtMlT LED should be¬
come MI urnirated *
Observe that the LIMIT LED has gone off* The
distortion meter should read lower than .3%.
If a second output is installed, measure Its
distortion. It should be lower than ,3%, and
within .]% of that of the first output.
There should be no change in distortion reading.
Listen to see If any periodic noise has been
added to the signal.
Key the audio tone and confirm that a reverb¬
like decay Is present when the signal Is off.
& Set DELAY to zero, pi ace unit Pitch change LED shou1d become Ilium!nated. Va ry
in PITCH CHANGE mode, and se1 - the MANUAL control over its full range. The read-
ect MANual control. out should vary between *5 and 2.00, and a smooth
pitch change effect should be evident*
7 Select Anti^Feedback mode on
PITCH CONTROL SELECT group.
Observe narrow frequency modulation of the input
signal. Depth of modulation should increase with
clockwise rotation of ANT I-FEEDBACK control.
B Select keyboard mode* Apply
a 3volt rms signal in the 2*1
to 8.A kHz range to the KB In¬
put term1nal*
Varying the oscillator frequency from 2,3kHz
to B.AkHz should result in pitch ratios from
*5 to 2.0* This may be verified by the readout
if one is installed.
9 Connect a 10K linear variable Rotating this control from one extreme to the
resistor from REMOTE + to RE- other should result in the pitch ratio varying
MOTE GND on the rear panel. from to 2.0.
The wiper goes to C*V*
10 Return the LINE swith to the
OUT posT tion snd remove powe r.
Confirm that there is still an output signal.

T2
Successful completion of the above tests Is sufficient to allow one to
the Harmomzer Is operating properly.
infer that
TROUBLESHOOTING
Jf trouble was encountered during the above procedure,
(below) referred to the step number (above).
refer to the possible cause
TROUBLE
JN STEP
l I
2
3
4
5
6
POSSIBLE CAUSES
If no serial plate, inform factory imnediatelyI
supply voltages. Check internal fuse.
Check Individ ua1 power
If lamp works but no output Is present, check digital and analog output
circuitry-: output is present and clipped but lamp doesn't work, check
digital limit circuitry and lamp driver transistor. If lamp doesn't work
and output is not present, check input analog and A/0 circuitry. Make
sure all connectors and cards are properly and firmly Inserted.
Determine whether distortion is digital or analog in nature by observing
the output signal. If digital problem, check for defective memory or
conversion circuitry. If analog problem, refer to alignment procedure.
Check digital to analog converter circuitry and delay setting circuitry.
Check 6pin ttolex connectors to front panel.
If digital distortion results, check memory addressing logic circuitry.
Jf no output Is present, check phase-locked loop operation. If the pitch
ratio is not variable over the full range, refer to the phase-locked
loop alignment procedure.
7 , 8 , 9
Check phase-locked loop alignment procedure.
10 Check LINE switch and associated circuitry.
ALIGNMENT
The harmonizer is aligned at the factory, and the alignment is sufficiently stable
so that periodic adjustment should not be required. However, It may be desired to
realign the unit, either for reassurance or because some component or assembly has
been charged. Performing the analog adjustments will require a low distortion sig¬
nal generator amd a distortion meter. The digital adjustments will require an os¬
cilloscope with a calibrated time base.
HA920 ANALOG BOARD ALIGNMENT
COMPRESSOR
1: Refer to drawings for control locations on Compressor module.

2; Set Harmonizer controls for zero delay In the DELAY ONLY mode. Set
input level control to HAXimum.
3: Apply a ikHz signal at sufficient level to cause the LIMIT indicator
to become illuminated.
4: Observe signal at T.P. 3 on the top board (KD9IQ). Adjust the offset
trimpot for symmetrical clipping.
5: Attach distortion meter input to pin 12 of the Compressor module.
6: Set input signal level to +4dbm. Adjust the Compressor level control
so that the LIMIT LED just turns on.
7: Reduce the input level to -lOdbm. Adjust the HF Dist. control for a
null in distortion.
8: Reduce input frequency to 100Hz, Adjust the LF Dist. control for a
null In distortion.
IMPORTANT NOTE: Both of the above control adjustments can vary the
output signal level in addition to nulling the distortion. Be sure
that a true distortion null is obtained.
9: Repeat steps 6,7, and 8 if significant adjustment was made in any of
those steps.
EXPANDER
1: Set Harmonlzer controls for zero delay in the DELAY ONLY mode.
2: Apply a 1kHz signal and adjust the LEVEL control so that the LIMIT
LED is just on the threshold of Illumination.
3* Adjust the Expander Level control until the level at the output ter-
mlnal is 16 volts peak-to-peak,
A: Adjust the HF Dist. control to obtain a distortion null. If a spectrum
analyzer is available, null the second harmonic.
5: Reduce the input frequency to 100Hz. Adjust the LF Dist. control for
a nul1 1n dis tort ion.
6: Repeat steps and 8 if a significant adjustment was made in any
of those steps.
INPUT FILTER
Apply a iKHz signal and adjust the LEVEL control until the output level is
-Adbm. Change the Input frequency to 12kHz and adjust the HF Trim pot until
the output level Is -Adbm. Check the frequency response to confirm that it
is within specifIcation: it may be necessary to readjust the trim pot very
slightly to lower a high frequency peak near 12kHz.