Dave Smith Instruments TETRA User Manual

Operation Manual

Tetra

Operation Manual

Version 1.3

September 2010

Dave Smith Instruments

1210 Cabrillo Hwy N

Half Moon Bay, CA 94019-1449

USA

©2010 Dave Smith Instruments

www.DaveSmithInstruments.com

Tested To Comply
With FCC Standards
FOR OFFICE USE

This device complies with Part 15 of the FCC Rules.
Operation is subject to the following two conditions:
(1) This device may not cause harmful interference and
(2) this device must accept any interference received,
including interference that may cause undesired
operation.

This Class B digital apparatus meets all requirements of
the Canadian Interference-Causing Equipment Regulations.

Cet appareil numerique de la classe B respecte toutes
les exigences du Reglement sur le materiel brouilleur du
Canada.

For Technical Support, email: [e-mail]

Contents

Quick Start................................................................................................. 1

Getting Connected ....................................................................................3

Front Panel Controls .................................................................................5

Basic Operation......................................................................................... 9

Global Parameters ..................................................................................13

Program Parameters...............................................................................17

Oscillator Parameters ..........................................................................17

Miscellaneous Oscillator Parameters .................................................. 18

Mixer Parameters ................................................................................19

Feedback Parameters ......................................................................... 19

Low-pass Filter Parameters................................................................. 19

VCA Parameters.................................................................................. 20

LFO Parameters .................................................................................. 21

Envelope 3 Parameters .......................................................................22

Modulation Parameters .......................................................................23

Unison Parameters..............................................................................24

Push It Switch Parameters .................................................................. 25

Keyboard Mode Parameters................................................................25

Clock Parameters ................................................................................ 26

Arpeggiator Parameters ......................................................................26

Sequencer Parameters........................................................................ 27

Name Parameter .................................................................................32

Combos ...................................................................................................33

Creating a Combo ...............................................................................33

Combos and Multi Mode...................................................................... 35

Using Poly Chain..................................................................................... 36

A Note About Poly Chain and the Mopho Desktop .............................36

Using USB............................................................................................... 39

Modulation Destinations..........................................................................41

Modulation Sources ................................................................................43

Parameter List.........................................................................................44

Support....................................................................................................45

MIDI Implementation ............................................................................... 47

MIDI Messages.................................................................................... 47

NRPN Messages ................................................................................. 50

Global Parameter Data........................................................................ 51

Program Parameter Data ....................................................................52

Combo Parameter Data....................................................................... 58

Sysex Messages .................................................................................62

Packed Data Format............................................................................ 67

Hidden Functions ....................................................................................68

Quick Start

Thanks for purchasing your Tetra synthesizer! Listen to the sounds, twiddle
some knobs, have some fun!

Please Register!

Please go to www.davesmithinstruments.com and register your synth. If you
purchased directly from us, there is no need to register — we already have your
contact information.

Powering Up

So, plug in the power supply, connect (in stereo!) to your mixer/sound system,
and start playing!

You can use the P

USH IT switch to trigger sounds without a keyboard. If you’re

using a MIDI keyboard, try applying keyboard pressure (aftertouch) and the
mod wheel. Many sounds are fairly simple at first, and then come alive when
you use the controllers. With other sounds, you may need to hold the notes a
while to let the sound unfold. Playing in different ways has a big effect on the
programs.

Selecting and Editing Programs, Combos, and Global Settings

Use S

ELECT or the increment and decrement (+ and -) switches to step through

the programs. Hold the switches down briefly to increment or decrement the
bank. There are 4 banks of 128 programs. Banks 1 and 2 are the Prophet ’08
factory programs.

If you want to edit a program, just turn any knob. The new value will be
displayed in the bottom line of the LCD (the top line displays the programmed
value for handy reference).

After turning knobs, just press the Mode (P

ROGRAM/COMBO/GLOBAL) switch to

exit Edit Mode and return to Program Mode, allowing you to change programs
again.

While in Program Mode, press the Mode switch again to change to Combo
Mode. Combos contain a combination of four different programs—one per
voice—that can be used to play polyphonically or in unison, or to play four
different sequences simultaneously.

Press and hold the Mode switch briefly to display the Global menu and change
higher level parameters such as MIDI channel number, Transpose/Detune, and
so on. The S

ELECT knob changes the displayed page and increment and

1

decrement change the values. These settings are remembered when the synth is
turned off.

Summary

You should be up and running now; for more operation information, read on. Or,
just look up specific parameters for detailed notes. Pages 41 through 43 contain
a handy reference for mod destinations and sources. At some point you should
read through the manual to discover all the little features that you might not
notice at first.

Don’t forget you get a free editor for Mac OS or Windows with your purchase.
Download it from www.soundtower.com/tetra.

I should mention that this manual does not include explanations of basic analog
synthesizer functions. It assumes you already know what an oscillator is, how a
low-pass filter affects the sound, what an ADSR envelope looks like, and so on.

Fortunately, these days it is quite easy to find such resources on the Internet. If
you want to learn the lingo and the basics, just try a search in Google (or the
search engine of your choice), something like “analog synthesizer tutorial.”
You’ll find plenty of good reading material.

Have fun!

Dave Smith

Special thanks to:

Tim Ande, Dave Polich, Ravi Sharma, James Terris, Stefan Trippler, and Jason
Ware for their voicing work. Thanks also to the authors of the Prophet ’08
programs, many of which are used in Tetra. Finally, the DSI Team: Chris
Hector, Andrew McGowan, Joanne McGowan, and Tracy Wadley.

2

Getting Connected

Tetra has several inputs and outputs on its back panel.

Power Input — Connect the power supply included with your Tetra. The power

supply comes with different AC adaptor prongs that allow it to work anywhere
in the world. If for whatever reason you need to use a different supply, it must
match the specifications printed on the front panel.

Note: The power supply label says “Evolver” on it; we use the same
supply for the mono Evolvers, Mophos, and the Prophets.

USB — Tetra transmits and receives MIDI data via this standard, Type B, USB

receptacle.

MIDI In — To receive MIDI data from another device, connect this to the other

device's MIDI Out.

MIDI Out — To send MIDI data to another device, connect this to the other

device's MIDI In. This output can also be configured as a MIDI Thru using the
MIDI Out Select parameter in the Global menu.

Poly Chain Out — Up to four Tetras can be chained for increased polyphony

and multiple Tetras can be poly chained with a Prophet ’08 or Mopho Keyboard.
For details, see Using Poly Chain on page 36.

Note: When Poly Chain is turned off in the Global menu, the Poly Chain
Out simply mirrors the MIDI Out and transmits the same data.

Audio Outputs — Tetra has four, unbalanced, ¼ inch outputs. 1/Left and

2/Right are the summed outputs of all four voices in Stereo or Mono mode and
are typically used for “normal” polyphonic or unison playing. They are also the
direct outputs of voices 1 and 2 in Quad mode. Outputs 3 and 4 are the direct
outputs of voices 3 and 4, respectively, and are always mono. The individual,
direct outputs are typically used in Multi Mode or Combo Mode, so that each
voice can be mixed and processed separately. For more about the Audio Out and
Multi Mode parameters, see Global Parameters on page 13.

Phones — A ¼ inch stereo headphone jack.

3

4

Front Panel Controls

Select — Use SELECT to change and scroll through programs and combos.

When ASSIGN PARAMS is on, SELECT changes the value of the current
parameter. Also used to select parameters in Global mode.

Mode (Program/Combo/Global) — Tetra has four modes of operation:

program, combo, global, and edit. Press the button to toggle between Program
and Combo Mode.

When in Program Mode, the display shows the name, number, and bank of the
current program. Editing any of the parameters puts Tetra into Edit Mode and
displays the last parameter edited and its stored and edited values. To return to
Program Mode, simply press the mode switch. See Program Parameters starting
on page 17 for more information.

In Combo Mode, the display shows the name and number of the current combo.
Editing any of the parameters puts Tetra into Edit Mode and displays the voice
(V1, V2, V3, or V4) being edited, the last parameter edited and its edited value.
To return to Combo Mode, simply press the mode switch. See Combos on page
33 for more information.

Global mode is accessed by briefly holding down the mode

button. The Global

menu is displayed. Use SELECT to scroll the Global menu and the increment and
decrement (+ and -) buttons to change the settings. To return to Program or
Combo Mode, simply press

the mode button. See Global Parameters on page 13

for more information.

5

Write — Use WRITE to save an edited program or combo to any of Tetra’s

memory locations. To execute the write operation, press the increment (+)
button.

To store a program or combo in a different location, press the W
change the destination using the S

ELECT knob before executing the write.

RITE button and

Note: You can also change program banks by holding the increment (+)
and decrement (-) buttons, but be careful! If you hit the increment button
quickly, it saves the program wherever you are at that point. If you want
to change banks, just be sure to hold the button until you see the bank
change.

To cancel a write, press W

RITE, decrement (-), or the mode button. WRITE is

also used to execute certain operations in the Global menu.

Volume — The master volume control for all of Tetra’s audio outputs and the

headphone output.

Increment/Decrement — The increment and decrement (+ and -) controls are

used to step through programs in Program Mode, combos in Combo Mode, to
change values in the Global menu, and to confirm or cancel various operations.
In Edit Mode they increase/decrease the parameter value. They are also used to
select Tetra’s four program banks. Hold increment briefly to switch to the next
highest bank; hold decrement to switch to the next lowest bank.

Assignable Parameters 1-4 — Any of Tetra’s program parameters can be

edited from the front panel using the ASSIGNABLE PARAMETERS controls and the
assignments for the controls are saved per program, to best suit that program. In
other words, the assignments for the controls can be completely different from
one program to another.

In Combo Mode, each of the four controls is routed to the respective voice. That
is, parameter 1 controls an assigned parameter for voice 1, parameter 2 controls
voice 2, etc.

See also Edit B/Combo below for more information.

Assign Parameters — When the ASSIGN PARAMETERS LED is lit, turn any of

the ASSIGNABLE PARAMETERS controls to select from the list of program
parameters. Press A

SSIGN PARAMETERS again (turn the LED off) to use the

ASSIGNABLE PARAMETERS controls to edit the selected parameters. For a
description of the parameters, see Program Parameters beginning on page 17.
For a list of the parameters, see page 44.

6

Alternately, with ASSIGN PARAMETERS on, choose a parameter to edit with any
of the A
using S

Edit B/Combo — This button behaves differently depending upon the current

SSIGNABLE PARAMETERS controls, and change the parameter’s value

ELECT or the increment (+) or decrement (-) buttons.

mode. In Program Mode, it switches between program layers. Each program has
two layers, A and B. Each layer can be a complete, separate patch. The layers
are used in conjunction with the KeyMode parameter for creating stacked or
split programs. When E

DIT B/COMBO is active, the front panel controls the B

layer.

Note: The A

In Combo Mode, E
Press E

DIT B/COMBO once to edit voice 1 parameters. Press the button

SSIGNABLE PARAMETERS are the same for both layers.

DIT B/COMBO is used to access various combo parameters.

repeatedly to cycle through the voices and exit Edit Mode. See Combos on page
33 for more information.

Note: In Combo Mode or when Multi Mode is turned on in the Global
menu, a program’s B layer is ignored.

Pitch — Controls the base frequency of the oscillators. The relative interval

between the two oscillators is in each voice is maintained, even when the
extremes are reached.

Cutoff — Controls the filter cutoff.

Resonance — Controls filter resonance.

Note: The filter will only self oscillate when in 4-pole mode. See Low­pass Filter Parameters on page 19 for more information.

Attack — Simultaneously adjusts the attack portion of all envelope generators:

filter, amplifier, and Envelope 3.

Decay/Release — Simultaneously adjusts the decay and release portions of all

envelope generators: filter, amplifier, and Envelope 3.

Push It! — The PUSH IT button is a manual trigger to play Tetra. In Program

Mode, it can trigger a specific note (at a specific velocity) or a gated sequence,
latch notes or sequences on and off, and manually step through a sequence. For
more information, see Program Parameters, beginning on page 17.

In Combo Mode, the P

USH IT button cycles through the voices for polyphonic

combos and plays all voices simultaneously when unison is on. See Combos on
page 33 for more information.

7

Basic Operation

Tetra has multiple personalities. It is a four-voice, analog poly synth, a sort of
“mini Prophet.” But the voice architecture is based on Mopho, so it has a couple
of sonic tricks up its sleeve—specifically sub-octave generators and feedback—
that are absent from the Prophet. Tetra is also a four-part, multitimbral synth
with separate outputs, essentially four Mophos in one very compact box. And
it’s a voice expander for other Tetras or for a Prophet ’08. (Program banks 1 and
2 are the Prophet ’08 factory programs.)

In designing Tetra, the goal was to make a great sounding synth that was also
affordable. Toward that end, we wanted to give players enough control over
parameters to make it useful for performance, so we came up with a
combination of “hard-wired” commonly used controls and user-assignable
controls. Any of Tetra’s parameters can be edited in real time from the front
panel controls. But we also recognize that may not be the quickest or easiest
way to program sounds from scratch. A free editor for Mac OS and Windows
gives you easy access to all of Tetra’s program parameters. Download it here:
www.soundtower.com/tetra. Also, an advanced version of the editor with more
features can be purchased from our Web site.

Note: The Prophet ’08’s controls map directly to Tetra’s, so if you have a
Prophet ’08, you can use it as a MIDI control surface for Tetra.

Programs

When Tetra first powers up, it is in Program Mode. The top line of the LCD
shows the Program (1…128) and Bank (1…4) number of the currently selected
program, and the bottom line shows the 16-character name of the program.
S

ELECT changes the program. The program can also be changed by pressing the

increment (+) or decrement (-) switches. To increment to the next bank, hold the
increment switch briefly; to decrement to the previous bank, hold the decrement
switch.

To edit a program, simply turn any knob. The A

SSIGNABLE PARAMETERS knobs

have been preset to useful parameters for the factory programs. To change a
knob’s assignment, press A

SSIGN PARAMETERS to light the LED. Turning any of

the ASSIGNABLE PARAMETERS knobs now will scroll through the list of available
parameters. Choose one or more parameters to edit and then press A

SSIGN

PARAMETERS again to exit the assignment mode (ASSIGN PARAMETERS LED
should now be off). Alternately, turn ASSIGN PARAMETERS on, use any of the
A

SSIGNABLE PARAMETERS knobs to choose a parameter, and change the value

with SELECT or the increment (+) and decrement (-) buttons. See Program
Parameters on page 17 for a detailed list of all parameters and their functions.
After editing parameters, press the Mode (P

ROGRAM/COMBO/GLOBAL) switch to

exit Edit Mode and return to Program Mode.

9

Combos

When in Program Mode, press the Mode switch to enter Combo Mode. Combos
are combinations of four programs, one for each voice. In Combo Mode, use
S

ELECT and increment/decrement to change combos. Each of the ASSIGNABLE

PARAMETERS knobs controls a parameter for its respective voice: knob 1 for
voice 1, knob 2 for voice 2, and so on. And the bottom row of knobs affects all
voices and programs in the combo. For more about combos, see Combos on
page 33.

Saving a Program or Combo

To save a program or combo, press W

RITE. To store in a different location, use

SELECT to choose the target destination, and hold the increment or decrement
switch to choose a different bank (programs only; there is only one bank of
combos). Press increment (+) to complete the write operation or decrement (-) to
cancel (or press W

RITE again).

Voice Architecture and Feedback

As you can see from the illustration on the following page, the left Audio Output
goes through a programmable-gain pre-amp (controlled by the Feedback Gain
parameter), then through a VCA for feedback volume control, and then to the
filter input. Turning up the Feedback Volume will cause varying amounts of the
audio output to be mixed back in pre-filter, individually per voice. For most
purposes, small amounts of feedback are most useful and the resulting effect is
similar to an overdrive distortion. Higher levels of feedback can get very
squirrelly and rude (which may be exactly the effect you’re looking for).

F

EEDBACK GAIN also affects the level of the feedback signal, so you’ll typically

want to start with FEEDBACK GAIN turned down.

Several of the factory programs already have some level of feedback
programmed in, as often indicated by the letters “FB” following the name. To
hear the effect of Feedback Volume and Feedback Gain, call up one of those
programs and vary those parameters.

Further Reading

For information about using Tetra multitimbrally, see “Multi Mode” and “Audio
Out” in Global Parameters on page 13.

For information about using Tetra as a voice expander with a Prophet ’08 or
another Tetra, or using Mopho as an additional voice for Tetra, see Using Poly
Chain on page 36.

10

11

Global Parameters

Tetra’s Global parameters affect all programs globally. Examples include MIDI
channel and fine tune. To edit the Global parameters, hold down the Mode
switch (Program/Combo/Global) until the G
knob changes the global parameter and the increment and decrement buttons
change the value.

Transpose: -12…+12 — Master Transpose control, 0 is centered. Steps in

semitones.

Fine Tune: -50…+50 — Master Fine Tune control; 0 centered. Steps in cents (50

cents = 1/2 semitone).

MIDI Channel: ALL, 1…16 — Selects which MIDI channel to send and receive

data, 1 to 16. All receives on all 16 channels.

Clock: see table — Selects the MIDI clock status.

Display MIDI Clock Setting

Internal

V1 Master

MIDI Out

MIDI In

Midi In/Out

MIDI Parameter Send: NRPN, CC, Off — Changes to the values of Tetra’s front

MIDI clock is neither sent nor received

Voice 1 provides the master clock for all 4
voices when in Combo mode.

MIDI clock is sent

MIDI clock is received

MIDI clock is received and transmitted

panel controls are transmitted via MIDI as Non-registered Parameter Number
(NRPN) controllers or as Continuous Controllers (CC). Transmission of
parameters can also be turned off. See MIDI Implementation on page 45 for
details.

LOBAL LED lights. The SELECT

Note: NRPNs are the preferred method of parameter transmission, since
they cover the complete range of all parameters, while CCs only handle
the main parameters.

MIDI Parameter Receive: All, NRPN, CC, Off — Sets the method by which Tetra

receives parameter changes via MIDI. As with transmission, NRPNs are the
preferred method, though some controllers may only be able to send CCs.

MIDI Control: Off, On — When On, the synth will respond to MIDI controllers,

including Pitch Wheel, Mod Wheel, Pedal, Breath, Volume, and Expression.

13

MIDI SysEx: Off, On — When On, the synth will respond to received MIDI

SysEx messages, and will transmit them, when prompted, to the MIDI Out. See
Sysex Messages on page 62 for details.

MIDI Out Select: Out, Thru — MIDI Out can be switched to MIDI Thru to

daisychain multiple MIDI devices.

Poly Chain: Off, Out 1, Out 4, Out 8, Out 12, In End, InOut4, InOut8 —

Using
Poly Chain, up to four Tetras can be chained together for increased polyphony.
One or two Tetras can also be chained with a Prophet ’08 for twelve- or sixteen­note polyphony. And a Tetra and Mopho can be chained for five-note
polyphony. For a more complete description of Poly Chain and how to use it,
see Using Poly Chain on page 36.

Multi Mode: Off, On — Multi Mode enables Tetra to respond to four separate

MIDI channels for multitimbral playback. With Multi Mode on, voice one
responds to the base MIDI channel and the other three voices respond to the next
three consecutive channels. For example, if Tetra’s base channel setting is 3,
voice one responds to MIDI channel 3, voice two to MIDI channel 4, and so on.

Note: For all four voices to play in Multi Mode, the base channel must
be 13 or lower.

Local Control: Off, On — When on (the default), the front panel controls

directly affect Tetra. When off, the controls are transmitted via MIDI but do not
directly affect the “local” device (that is, Tetra). This is primarily useful for
avoiding MIDI data loops that can occur with some external sequencers.

Mode Lock: Off, Prog, Combo — Prevents Tetra from being switched from

Program mode to Combo mode or vice versa. This prevents the loss of unsaved
edits caused by unintentional mode changes.

Audio Out: Stereo, Mono, Quad, Q LR34 — Tetra has four audio outputs:

1/Left, 2/Right, 3, and 4. Stereo operation is the default. When set to Stereo, a
stereo mix of all voices is available via the Left and Right outputs.

Note: Outputs 3 and 4 are always direct outputs for voices 3 and 4 and
are mono, regardless of the Audio Out mode. Inserting a plug into output
3 or 4 does not remove that voice from the mix outputs when in Stereo or
Mono mode.

When set to Mono, this parameter defeats all pan settings and modulation,
effectively making each of the Left and Right outputs a mono output.

Quad directs each of the four voices to its respective, mono output.

14

Note: Outputs 3 and 4 are noticeably louder than the other two outputs.
This is normal. Outputs 3 and 4 are always monophonic and, therefore,
do not require as much headroom as the mix outputs, which have to
accommodate up to four voices at one time without distorting. The higher
level provides optimum signal-to-noise ratio. Compensate for differences
in level with a mixer.

Choosing “Q LR34” is similar to Quad, but voices 1 and 2 retain whatever
panning effects are present in the assigned programs and the stereo outputs of
those voices are present at both the Left and Right outputs.

PotMode: Relative, Passthru, Jump –Tetra’s Cutoff, Resonance, and Volume

controls are potentiometers or “pots.” There are three pot modes to determine
how the synth reacts when the programmable parameters—Cutoff and
Resonance—are edited. (Master volume is not programmable, so these modes
don’t apply.)

When set to Relative, changes are relative to the stored setting. In Relative
mode, the full value range is not available until either the minimum or maximum
value and the respective lower or upper limit of the pot’s travel is reached.

For example, the Resonance parameter has a value range of 0 to 127. Let’s say
the physical position of the Resonance pot is the equivalent of a value of 100. If
you switch to a program that has a stored Resonance setting of 63 and turn the
pot all the way up, it will only go to 90. To get to the maximum value of 127,
you first have to turn down until the value is at the other extreme and the pot is
at the limit of its travel (in this case, 0 and fully counter-clockwise,
respectively).

In Passthru mode, turning the pot has no effect until after the edited value equals
the preset value (that is, until the edited value “passes through” the stored
value).

Jump mode uses an absolute value based upon the position of the pot when
edited: turn a pot and the value jumps immediately from the stored value to the
edited value.

Balance V 1 - 4: -14…+14 — Adjusts the left/right balance of each voice by

approximately +/- 4 dB.

Basic Patch — Press the WRITE button to load a basic patch into the edit buffer.

(The patch will not actually be written to the current program location unless
intentionally written to memory in Program Mode using the W

RITE button.)

15

Reset Globals — Tetra does not have a full hardware reset, but select this

parameter and press W

RITE to reset the global parameters to their factory

defaults.

MIDI SysEx Dump: see table — Allows dumping of programs and combos in

SysEx format via MIDI.

Display Data to be dumped to SysEx

Current Program

Current Prog Bank

All Progrm Banks

Current Combo

Combo Bank
All Progs Combos
Current Prog P08

CurrentProgMopho

Program Bank P08

Prog Bank Mopho

Dump current program

Dump all 128 programs in current bank

Dump all programs in all 4 banks

Dump current combo

Dump all combos

Dump all program banks and combos

Dump current program in Prophet ’08 format

Dump current program in Mopho format

Dump current bank in Prophet ’08 format

Dump current bank in Mopho format

Press the WRITE switch to start transmission. This feature is handy for saving
Programs on a computer in SysEx format, or for sending them to another Tetra
via a direct MIDI connection. The dumps include Program and Bank numbers,
so when received, the programs will be stored in the same location.

Programs can also be exported in Mopho and Prophet ’08 formats.
Features/parameters not available on those instruments are stripped out. For
example, Mopho does not support layers, so only layer A is exported. The
Prophet ’08 does not have feedback or sub-octave generators.

Program Copy Utility — Enables layer A or layer B of a program to be copied

to layer A or B of the same or a different program. The top line displays the
current bank and program. Use increment (+) or decrement (-) to choose the
layer to be copied. Then use S

ELECT to select the destination bank, program, and

layer and increment/decrement to change the values.

16

Program Parameters

All Program parameters can be edited using any of ASSIGNABLE PARAMETERS
controls. To assign a parameter to a control, press the A
button to light the LED, and then turn any of the knobs (1 through 4) to select a
parameter. A full list of the parameters can be found on page 44. The selected
parameter and value appear in the LCD display. The top line of the LCD
displays the programmed value for reference; the bottom line displays the edited
value.

SSIGN PARAMETERS

To then change the value of the parameter you selected, hit the A

SSIGN

PARAMETERS button again, and the same knob will now change the value. You
can also use the increment and decrement switches to adjust parameter values.

Note: Once you are done editing a program, before you save it, you
should consider what parameters you want to access when playing the
new program. Generally, when making a program, we try to assign each
of the 4 knobs to a different parameter that makes sense for that
particular program, providing extra live control.

Though it is certainly possible to perform detailed program generation and
editing using these controls, it is usually much faster to use the free editor
available for Mac OS or Windows. The minimal front panel of the Tetra is
designed for fast, real-time changes in live performance.

Following are descriptions of each Tetra Program parameter.

Oscillator Parameters

Tetra has two analog oscillators per voice. The basic controls for each oscillator
are the same.

Note: There are additional modulation controls that can affect the pitch
of Oscillators 1 and 2. These are covered in other sections of the
Parameter definitions.

Osc Freq: C 0…C 10 — Sets the base oscillator frequency over a 10 octave

range, from 8 Hz to 8KHz, stepping in semitones. C3 is middle C, the first
octave is 0 (C0, C#0, etc.), the second octave is 1 (C1, C#1, etc.), and so on.

Fine Freq: -50…+50 — Fine Tune control; 0 centered. Steps in cents (50 cents =

1/2 semitone).

Shape: see table — Selects the oscillator waveshape as follows:

17