Spectral Audio Neptune Owner's Manual

Owner's Manual

Bedienungsanleitung

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Contents

Page

1. Introduction 3

2. Operating and safety instructions 3

3. Guarantee 3

4. Operation and functional description 4

4.1 The Neptune signal flow 5

4.2 Subtractive Synthesis (Theory) 6

5. Initial start-up 6

5.1 Using the external audio input 6

5.2 Technical data of the CV and Gate In- / Output 7

6. Trouble-shooting 7

7. MIDI functions 7

7.1 Normal operating mode 7

7.2 Learn mode 8

7.2.1 Note-on Command 8

7.2.2 Program-change Command 8

7.3 Re-trigger 8

7.4 Filter dynamic operation 9

7.5 Filter TB303 velocity mode 9

8. Notes 9

8.1 Registered trade marks 9

8.2 Software service via Internet 9

9. MIDI implementation chart 17

10. Neptune Sounds ! 18 - 20

Deutsch siehe nächste Seite

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Inhaltsverzeichnis

Seite

1. Einleitung 10

2. Betriebs- und Sicherheitshinweise 10

3. Garantie 10

4. Bedienung und Funktionserklärung 11

4.1 Signalfluss des Neptune 12

4.2 Substraktive Synthese 13

5. Inbetriebnahme 13

5.1 Benutzung des externen Audio Einganges 13

5.2 Technische Daten des CV und Gate Ein- /Ausganges 14

6. Fehlersuche 14

7. MIDI Funktionen 14

7.1 Normaler Betriebsmode 14

7.2 Learnmodus 15

7.2.1 Note-On Befehl 15

7.2.2 Program-Change Befehl 15

7.3 Retrigger 15

7.4 Filterdynamischer Betrieb 16

7.5 Filter TB303 Velocitymode 16

8. Hinweise 16

8.1 Eingetragene Warenzeichen 16

8.2 Software-Service via Internet 16

9. MIDI Implementation Chart 17

10. Neptune Sounds ! 18 - 20

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1. Introduction

Thank you very much for buying the Neptune synthesizer.
The Neptune is a purely analog synthesizer with MIDI control. It offers special features and is simple to use

because it has a button or swich for each parameter.
The audioinput enables to process external signals.
In order to use the Neptune professionally, we recommend that the following chapters are read carefully.
We wish you a lot of pleasure with your new synthesizer and, of course, successful productions!

This manual has been produced with greatest care. Spectral Audio is nevertheless unable to accept any
responsibility for errors or omissions. Reproduction is permitted only with the consent of the manufacturer.

2. Operating and safety instructions

The instrument is intended only for the form of use described in this operating manual. It is to be used in dry
rooms only. Do not allow any liquids to enter the instrument. Should this happen, the instrument requires
cleaning by a specialist.

Use only the original PSU (15VAC, 500mA).
Do not expose the instrument to direct sunlight. Do not use the instrument in the vicinity of a heater or any other

source of heat. Do not expose the instrument to temperatures above 50°C (degrees Celsius) or below -10°C.
The minimum operating temperature is 10°C. Handle the instrument with due care when on transport.

Use only the original packing when returning the instrument to our company for guarantee service, software
updating, repair work, etc. Other forms of delivery will not be accepted due to the danger of damage caused in
transit. Please make sure you retain the packing containers for such purposes.

3. Guarantee

A one year´s guarantee period from the date of purchase applies for manufacturing defects. Should the
instrument be interfered with in any way, the guarantee coverage will cease immediately.

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4. Operational and functional description

The basic principle of the Neptune corresponds to the proven analog synthesizer principle equipped with
VCO, VCF, VCA, envelope generator and LFO. This principle is called subtractive synthesis.

To make the Neptune suitable for MIDI, an additional MIDI to CV converter is applied which converts the
MIDI signals into analog signals. These control the VCOs, the filter, as well as the envelope generator.

The raw material for the sound is provided by the VCOs (Voltage Controlled Oscillator) in the form of a
sawtooth or rectangular signal as well as the noise generator (for effects such as wind and thunder sounds).
VCO2 is synchronised by the VCO1 with the SYNC switch. The sound becomes interesting when the TUNE
regulator of the VCO2 is turned (or modulated by the LFO VCO2), resulting in a typical "Sync-Sound". By
means of the external VCO input, other sounds can also serve as raw material.

The ring modulator multiplies the signals of the two VCOs and this significantly amplifies the beats (frequency
difference).

Note:

When the SYNC switch is switched on, no beats are developed and the ring modulator has therefore

no effect.

The SLIDE regulator determines the time balance from one note to another and is valid for both VCOs and
the suboszillator. It is possible to switch the slide on or off by controller 65.

Afterwards, the signal flows through the voltage-controlled filter (VCF=Voltage Controlled Filter), within which
certain frequency ranges are suppressed. The lowpass filter allows low frequencies to pass and suppresses
the high ones, the highpass filter lets high frequencies pass and suppresses the low ones. The frequency
from which the signals are suppressed is called the limit or cut-off frequency. In the Neptune, this is formed
by various sources:

1. CUTOFF frequency regulator

2. ENV MOD regulator (influence of the envelope curve on the cut-off frequency)

3. LFO

4. KEYFOLLOW.
The KEYFOLLOW is always 100%. It causes the cut-off frequency to increase on higher notes so that the

audible freqency band always remains the same. Moreover the filter can be used as an oscillator, if the
resonance is set to the maximum. The resonance forms a feedback of the output to the input of the filter and
causes an amplification of the frequencies around the cut-off frequency.

Afterwards the signal reaches the distorter, witch provides two different ways of distortion. Before the signal
leaves the Neptune, it arrives at the VCA (Voltage Controlled Amplifier). Here the input signal is multiplied by
a control signal. In this way, the volume can be influenced by a control signal coming from the envelope
generator.

The LFO is particularly designed in the Neptune. The oscillator is either freely controllable or fixed to the
MIDI to CV converter. In this case it works as a suboscillator. Note: When using the LFO in a freely
controllable way, the description at the oct-switch does not apply. It is however possible to adjust a coarse
frequency. Using its signal, the pitch from VCO1 and VCO2 and thus the cut-off frequency of the filter can be
modulated. If the MIXER switch is on, the LFO output is directly audible. In this case, the MOD pot is the
volume.

The rotary switch allows 5 different signal forms to be selected from. Additonaly, the VCO 2 can be used as a
modulation source. The MIDI SYNC switch allows the LFO to be sycronized by the MIDI clock.

The envelope generator determines the chronological sequence of the volume after receiving a sound
command. The MIDI to CV converter then issues a gate signal (+5V) starting the sequence of the envelope
generator. The gate signal remains active at +5V until the 'sound off' command comes, i.e., when the key is
released:

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4.1 The Neptune Signal Flow:

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4.2 Subtractive Synthesis (Theory)

The VCOs produce very harmonic rectangular and sawtooth signals:

Noise contains an endless number of frequencies. This frequency spectrum is subsequently limited by the
filter:

The setting of the resonance regulator is an important factor as it amplifies the frequencies around the cut-off
frequency:

5. Initial Start-up

Connect the MIDI IN socket on the Neptune to your MIDI sender (master keyboard, sequencer, ...) via a MIDI
cable. If further MIDI units are used after the Neptune, connect the MIDI Thru socket to the MIDI IN socket of
the next equipment by means of a further MIDI cable.

Connect the audio output with the audio input of your sound mixer, amplifier or similar equipment.
Connect the mains cable.
Switch on the Neptune. The GATE / LEARN indicator must light briefly. The POWER indicator and the SLIDE

indicator must light. If you now play on your MIDI keyboard and have selected the correct MIDI channel and
reference note (see para. 5, MIDI Functions), it should be possible to hear something. If this is not the case,
please refer to para. 4, Troubleshooting. For the first start-up, the Neptune is set to MIDI channel 1.

5.1 Using the external audio input

In order for the external signal to be audible, turn the wave switch from VCO 2 to EXT and the volume regulator
VCO 2 on maximum. Moreover the Neptune must simultaneously receive a note command, so as to enable it to
drive the VCA. This means that a connection is required at MIDI In, even if the Neptune is only being used as a
filter.

5.2 Technical data of the CV and GATE In- / Output

The Controll Voltage (CV) has a slope of 1 V/Octave. The gate socket used as an output issues a signal of
+5V. If you use this as an input, input signals up to +15V may be applied.