GS Music e7 User manual

USER MANUAL

INDEX
Introduction...............................................................................................................................................................2
Safety instructions.................................................................................................................................................2
Inside the box..........................................................................................................................................................2
Setup and connections...................................................................................................................................2
Overview and features....................................................................................................................................3
Front panel................................................................................................................................................4
Raer panel.................................................................................................................................................5
Signal path................................................................................................................................................................6
Basic operation......................................................................................................................................................6
Components and Controls............................................................................................................................6
Oscillators (VCOs)..............................................................................................................................7
Mixer................................................................................................................................................................8
Filter (VCF)..................................................................................................................................................9
Amplifier (VCA).......................................................................................................................................10
Envelope Generators (EGs).........................................................................................................12
Low-frequency Oscillators (LFOs)..........................................................................................14
Chorus..........................................................................................................................................................15
Delay..............................................................................................................................................................16
Portamento / Polyphony modes................................................................................................16
Global configuration........................................................................................................................................17
Panel Mode..............................................................................................................................................................19
Preset Mode.............................................................................................................................................................19
Multitimbral Mode.................................................................................................................................................21
Control Voltage (CV) ......................................................................................................................................25
Specs..............................................................................................................................................................................26
Support.........................................................................................................................................................................27
Warranty.......................................................................................................................................................................27

CREDiTS AND ACKNOWLEDGMENTS
Ernesto Romeo (Klauss/La Siesta Del Fauno, musician-synthist-producer): sound design;
Tomas Rodriguez (Sound Engineer): sound design, user manual; Romina Fontana a.k.a
Romiko Tchan: user manual, woodworking, assembly, graphic design and sound design;
Elena Epuin: assembly, quality control, design; Guido Salaya: electronic, mechanical and
sound design, programming and verification.
Special thanks to:
Sean McKee (Emmy-nominated composer, multi-instrumentalist and producer),
Jordan Rudess, Pat Scandalis, Daniel Lamela. Thank you very much for trusting GS Music.
We hope you enjoy the beautiful e7. We feel great joy and excitement to have created
the e7 synthesizer, the first polyphonic and multitimbral analog synthesizer made in
Argentina. Elena Epuin Guido Salaya Buenos Aires, Argentina, 2022
Elena Epuin
Guido Salaya
Buenos Aires, Argentina, 2022

SETUP AND CONNECTIONS
INSIDE THE BOX
With our greatest gratitude, from GS Music we thank you and congratulate you
for purchasing our new e7 polyphonic synthesizer. This instrument is the result of
years of research and development dedicated to bring you the first polyphonic
analog synthesizer created in Argentina.
The e7 will give you the chance to explore endless sonic possibilities that will
hopefully inspire you to create and enjoy. You will also be able to store more than
600 presets and thus generate your own sound bank.
We imagine that you are excited to start experimenting with the sounds that the
e7 has to offer. We encourage you to take the time to read this manual and get
an in-depth understanding of what you can do with this synthesizer.
PLEASE READ BEFORE USING THIS PRODUCT
When using the e7, these basic precautions must be followed:
- Read the manual carefully before operating this product.
- Do not use the e7 near water or heat sources.
- Connect the e7 to the power supply included in the box or one with the
same specs.
- Unplug the equipment if it will not be used for an extended period of time.
- In the event of equipment failure, do not open the equipment or attempt
to repair it yourself. Contact GS Music Technical Service.
Inside the box you will find the following items:
- GS Music e7 polyphonic analog synthesizer
- A DC 12V 3A power supply
- A user’s manual
Beside from what is included in the box, you may need the following:
SAFETY INSTRUCTIONS
INTRODUCTION
2
We encourage you to read the entire manual in order to learn more about the instrument and for a
better understanding of what you can do with the e7.
Be careful when unpacking and transporting this instrument.
Be sure to save the box and all packing material in case you need to ship it for any reason.

- A MIDI cable (DIN-5)
- A MIDI controller or keyboard
- A USB cable to connect the unit to a computer (USB MIDI)
- A TS or TRS ¼'' audio cable and an amplifier or a pair of headphones.
Connect the power supply included in the box to the DC 12 V connector at the
back of the unit. This power supply will work properly as long as it is connected to
a voltage of 100 to 240 V AC, 50 to 60 Hz.
Connect the MIDI cable between the MIDI OUT port of your MIDI controller or
keyboard and the MIDI IN port of the e7. The e7 is set up to receive MIDI
messages on channel 1 by default. If you wish to use a computer to send MIDI
information to it, plug one end of a USB cable into the USB port at the rear panel
of the unit and the other into your computer. Additionally, you can control the
synthesizer via CV.
Finally, connect the e7 to an amplifier or mixer using a TS or TRS ¼'' cable or a
pair of headphones.
Basic connections.
The e7 is an analog subtractive synthesizer with up to seven voices of polyphony.
In addition, it offers the possibility of distributing the seven voices in four different
Parts, thus achieving a multitimbral synthesizer. All settings can be stored in more
than 600 presets.
OVERViEW AND FEATURES
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USB
MiDi OUT
TO OTHER DEVICES
TO OTHER DEVICES
POWER SUPPLY AC 220
DC 12V
MiDi THRU
MiDi OUT
MiDi iN
USB
AUDiO OUTPUT

The audio generation as well as the signal path is 100% analog. This synthesizer
features two ultra-stable analog VCOs per voice, a white noise generator and
an external audio input. The control signals are digitally generated, including
three low-frequency oscillators (LFOs) and two ADSR-type envelope generators
(EGs) per voice. In addition, it incorporates an effects processor with Chorus and
Delay.
The e7 synthesizer allows you to intuitively access a wide variety of functions in a
limited number of knobs and buttons. In this way, we guarantee to give you the
greatest possible features in a small, lightweight and easy-to-use device.
OSCILLATORS (VCO)
MIXER
Two voltage-controlled oscillators (VCOs) that generate Triangular, Tri-Saw, and
Sawtooth waveforms. In turn, each one is linked to a variable pulse width
generator.
The mixer allows you to adjust each oscillator and its associated sub-oscillator
level. You can also mix the noise generator or the external audio input.
FILTER (VCF)
A low-pass voltage-controlled filter (VCF) with a 24 dB/Oct slope and resonance
control.
FRONT PANEL
AMPLIFIER (VCA)
The amplifier is the section that allows you to control the dynamics of the
amplitude of the resulting audio signal.
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ENVELOPE GENERATORS (EGS)
EFFECTS
MAIN OUTPUT
REAR PANEL
Two ADSR-type envelope generators (EGs). EG1 is oriented to control the filter
cutoff frequency. The EG2 is oriented to control the amplifier. However, both EGs
can also modulate several other parameters simultaneously.
The e7 is capable of processing the audio generated with Chorus and Delay.
LOW-FREQUENCY OSCILLATORS (LFOS)
The e7 has three low-frequency oscillators (LFOs). These oscillators generate
periodic waveforms whose frequency is usually below the audible range. These are
useful when you want to periodically vary a parameter.
Balanced Mono or Stereo (L/MONO, R) with TRS ¼” connector.
HEADPHONE OUTPUT
Stereo headphone output with TRS ¼” connector.
EXTERNAL INPUT
CONTROL INPUTS
MIDI
External audio input with TS ¼” connector.
Control voltage (CV) inputs for controlling Pitch, Cutoff frequency and Gain.
DIN MIDI and USB MIDI input and output to communicate the e7 with external
devices.
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OUTPUT
Master volume control.

SiGNAL PATH
BASIC OPERATION
COMPONENTS AND CONTROLS
The e7 responds to MIDI messages on both DIN and USB MIDI inputs. The e7 has
an LED that indicates activity on either the DIN MIDI or USB MIDI connector. In
addition, e7’s knobs and buttons receive and transmit MIDI Control Change (CC)
commands, allowing parameter adjustments to be captured by any MIDI-recording
device and to control multiple parameters simultaneously from your computer.
Here we will tell you about the various parameters that you can control in each
component of your synthesizer. You will notice that some of the knobs on your
e7 have two labels. These labels indicate the parameters to be controlled with
the same knob or button: the main one and the alternative one (highlighted in
white), which is accessed by pressing the SHIFT button beforehand. When you want
to give up control over an alternative parameter, remember to press SHIFT again.
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OSCILLATORS (VCOS)
WAVEFORM SELECTOR
The oscillator is the main sound source in a subtractive synthesizer. The e7
features two oscillators designed to ensure minimal pitch variation over more than
7 octaves.
You can choose between three waveforms: Triangular, Tri-Saw and Sawtooth. A
light will indicate which waveform is selected. If no indicator is lit, no waveform
has been selected.
Selects the oscillator waveform.
In case you want to use only the pulse generator, make sure that none of the LEDs of the waveform
selector are on.
Adjusts the VCO frequency within a +/- ½semitone range.
Transpose +/- 24 semitones range (2 octaves) the note played
by the oscillator in relation to the note sent by MIDI or CV.
TUNE
TRANSPOSE
Sets the amount of modulation from the LFO1 to the VCO the pitch.
LFO1 MOD
Sets the amount of modulation from the EG1 to the VCO pitch.
EG1 MOD
Sets the amount of modulation given by the LFO2 to the VCO pitch.
LFO2 MOD
Sets the amount of modulation from the LFO3 to the VCO pitch.
LFO3 MOD
Switches the pulse generator ON.
To play this waveform only, you will need the main selector indicator to be OFF.
In case both are ON, both waveforms will be mixed at the same level.
PULSE GENERATOR
Execute the synthesizer's auto tuning calibration. This process takes
about two seconds.
AUTOTUNING (1)
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The self-calibration algorithm considers the applied voltage at the PITCH CV input. If you want a 0V input to
correspond to no modulation, it is recommended that you disconnect any signal from this input. The algorithm
is also capable of adjusting the tuning based on some preferred voltage in the 0 to 5V range applied to
this input.
Mixes the oscillators, the sub-oscillators and the white noise or external input.
Synchronizes both oscillators in "Hard Sync" mode.
SYNC (2)
Sets the pulse width between 10% and 50% duty cycle.
PULSE WIDTH
Sets the amount of pulse width modulation from the EG1.
EG1 PWM
Sets the amount of pulse width modulation from the LFO1.
LFO1 PWM
Sets the Oscilator1 level.
OSC1
Sets the Sub-oscillator 1 level (derived from OSC1).
SUB1
OSC2
MIXER
Sets the Oscilator 2 level VCO2 level.
Sets the Sub-oscillator 1 level (derived from OSC2).
SUB2
Adjusts the noise generator or external signal level.
The e7 has an external audio input on the rear panel. Here you can connect any instrument or line level
signal. The noise generator is disabled when an external signal is connected.
NOISE/EXT
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Each sub-oscillator is derived from its associated oscillator. It has a square waveform and half the
oscillator frequency (one octave lower).

A subtractive synthesizer takes this name because it is based on the generation
of complex waveforms (with high harmonic content) that are then attenuated or
“erased”. The filter is in charge of shaping these waveforms, subtracting energy
from the different harmonics of the signal.
The e7 has a 24 dB/oct low-pass filter, which means that it can attenuate the
level of harmonics above a particular frequency. This filter has resonance control,
which allows you to increase the level at frequencies close to the cutoff frequency.
Adjusts the low-pass filter cutoff frequency from 10 Hz to 25 kHz.
CUTOFF
Sets the amount of emphasis around the cutoff frequency.
By setting the RESONANCE level to its maximum, the filter will begin to oscillate. This is useful if you want to
obtain a sine-like waveform, commonly referred to as "pure tone."
RESONANCE
FILTER (VCF)
Sets the amount of cutoff frequency modulation from EG1.
EG1 MOD
LOW-PASS FILTER
frec.
amp.
Sets the amount of velocity-dependent cutoff frequency modulation from
EG1.
EG1 is intended to control the filter cutoff frequency (CUTOFF). If you
assign a value to this parameter, the filter cutoff frequency will be
affected by your controller Velocity.
VELOCITY EG1 MOD
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RESONANCE

Sets the amount of modulation from the EG1 to the cutoff frequency.
LFO1 MOD
Determines how the Filter cutoff changes within the whole notes range.
By setting this parameter to a non-zero value, the cutoff frequency will vary with the pressed key on your
controller. This is useful in case you want the "brightness" of the higher notes to be similar to that of the
lower notes. When set to the minimum position, the cutoff frequency will be the same no matter which key
note is pressed.
KEYBOARD TRACKING
MOD WHEEL
Sets the amount of modulation from the LFO2 to the cutoff frequency.
LFO2 MOD
Sets the amount of modulation from the LFO3 to the cutoff
frequency.
LFO3 MOD
Sets how much the cutoff frequency varies with Aftertouch.
Sets how much the modulation wheel affects the cutoff frequency.
AFTERTOUCH
AMPLIFIER (VCA)
In this section you can control the amplitude behavior. You can also add some
stereo spatiality.
Sets the level of the audio signal before the effects section.
If the synthesizer is configured to operate as a multitimbral synthesizer
(Page 21), this parameter controls the level of the selected Part.
Sets the amount of amplitude modulation from the LFO1.
LFO1 MOD
LEVEL
Sets the amount of amplitude modulation from the LFO3.
Sets the amount of amplitude modulation from the LFO2.
LFO2 MOD
LFO3 MOD
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Sets the degree to which the
amplitude follows the keyboard.
KEYBOARD TRACKING
Sets the stereo position of the seven
polyphony voices.
When the knob is in its center position, all
voices will be heard with equal amplitude
on the left and right channels. As the pot
is moved to the extremes, the voices will
be distributed from left to right.
When set to an anticlockwise position, voices 1-3 are progressively oriented to the right
channel and voices 5-7 to the left channel. Contrary, when set to a clockwise position,
voices 1-3 are progressively oriented to the left channel and voices 5-7 to the right channel.
STEREO SPREAD
Sets the degree to which the amplitude of the EG2 depends on the Velocity
value.
The EG2 is intended to control the amplitude of the signal. By assigning a
non-zero value to this parameter, the amplitude will depend on how hard you
press a key on your controller.
VELOCITY EG2 MOD
Adjust the motion between left and right channels for the seven voices
of polyphony.
Assigning a value to this parameter will allow you to modulate the arrangement in the stereo
image of the different voices. The modulation frequency is fixed.
The movement will be relative to the STEREO SPREAD value. In order to get the maximum stereo
motion, Stereo Spread should be at the center position.
STEREO MOTION
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ENVELOPE GENERATORS (EGS)
The e7 has two ADSR-type Envelope Generators (EGs). ADSR stands for Attack,
Decay, Sustain and Release.
Attack refers to the time it takes to the Envelope to reach its maximum value.
Decay refers to the time it takes to reach the Sustain level once it reaches the
maximum. The Sustain level will remain constant as long as a key is pressed.
When released, the Release control sets the time it takes to the EG to turn off.
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ADSR
GATE PULSE

Sets the ATTACK time.
AT TACK
Sets the DECAY time.
DECAY
Sets how much the Velocity modifies the ATTACK time.
If you assign a value to this parameter, the harder a key is pressed, the
faster the envelope will reach its maximum value.
VELOCITY MOD
KEYBOARD TRACKING
Sets the degree to which the EG times follow the note played on the
keyboard, affecting ATTACK, DECAY and RELEASE.
VELOCITY MOD
Sets how much the Velocity modifies the RELEASE time.
The harder you press a key, the shorter the RELEASE time will be.
Sets the SUSTAIN level.
SUSTAIN
Sets the RELEASE time.
RELEASE
The vast majority of acoustic instruments (guitars, pianos, etc.) have different
amplitude dynamics depending on the note played. In nature, high-pitched sounds
are usually perceived shorter. With this control, you can simulate this phenomenon.
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LFOs 1 and 2 allow six different synchronism Modes.
LFO3 has the particularity that its amplitude is zero by default. To increase its
amplitude, you will need to use the modulation wheel (MODWHEEL) or Aftertouch.
LOW-FREQUENCY OSCILLATORS (LFOS)
The LFOs 1 & 2 have six different modes of synchronization:
Monophonic: The LFO is in phase for all of the voices.
Polyphonic: The LFO is generated to a slightly different frequency
for all of the keys pressed. This allows an interaction of the phases,
generating more complex modulations.
Keyboard Tracking (KB Tracking): The LFO frequency varies
according to the note played following the chromatic scale. The
frequency indicated on the display is the frequency assigned to the last
note played.
Keyboard Sync (KB Sync): The phase of the LFO applied to each
of the voices is different if more than one key are pressed in different
moments, still their frequency will be the same. The phase of the LFOs will be
the same when multiple keys are pressed at the same time.
Clock Sync: The frequency of the LFO is synced to the MIDI clock
signal. The e7 automatically detects the BPM of the clock signal.
It can be configured to generate different rhythmic figures:
Whole Note, Dotted 1/2 Note, Whole Note Triplet, 1/2 Note, Dotted 1/4
Note, 1/2 Note Triplet, 1/4 Note, Dotted 1/8 Note, 1/4 Note Triplet, 1/8
Note, Dotted 1/16 Note, 1/8 Note Triplet, 1/16 Note, 1/16 Note Triplet,
1/32 Note.
If the e7 does not detect any clock signal, the default tempo is 120 BPM
and it can’t be modified.
Keyboard + Clock Sync: The LFO frequency will be a sub-division
of the MIDI clock signal. Also, the clock will be reset each time a key is
pressed. The phase of the LFO will depend on when the key is pressed.
MODE (1 & 2)
Selects the waveform of the LFO.
You can choose from Triangular, Ascending Ramp, Descending Ramp, Pulse and
S&H (Sample & Hold) -only for LFO1 and LFO2-.
WAVESHAPE
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Sets the frequency of the LFO.
RATE
Sets how much the EG1 modifies the frequency of the LFO2.
This parameter works as long as the LFO Mode is configured to one different than Monophonic
or Clock Sync.
EG1 MOD (2)
Sets the degree in which the Aftertouch affects the amplitude of the
LFO3.
AFTERTOUCH (3)
Selects the type of Chorus to use.
The e7 Chorus has two algorithms for this effect: Basic and Ensemble.
The Basic algorithm is subtle and allows you to add some spatiality to
the resulting sound, while the Ensemble algorithm adds a different
dimension to the sound, simulating a string or vocal ensemble.
TYPE
Mix between the dry or unprocessed signal and the wet or processed signal.
Sets the degree to which the modulation wheel affects the amplitude of LFO3.
MODWHEEL (3)
Chorus is a delay-based effect that provides a greater sense of spatiality by
simulating what happens when different sources play the same note at slightly
different pitches.
This is achieved by replicating the original sound several times and applying a
small delay and slight detuning to each of these replicas.
CHORUS
Sets the modulation rate.
The time delay applied to the generated replicas is not static. On the contrary,
they vary continuously over time. This control changes the variation rate, which
is derived from an LFO within the effects processor.
RATE
Sets the intensity of the modulation.
Just as the speed of the internal LFO indicates the rate at which the replicas
are detuned, the amplitude of the internal LFO influences how much the effect is
perceived.
DEPTH
MIX
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