Future Retro XS User Manual

semi-modlar analog synthesizer

Operation Manal

Written and produced by Jered Flickinger

Future Retro Synthesizers

TABLE OF CONTENTS

Introduction

2. Welcome Overview Power Care Warranty

Rack-Mount or Desktop

3. Installing the side pieces

Getting Started

4. I want to play it now! Basic system setup

5. Basic Patch Sheet

Connections

6. MIDI and 1/4” Connections

7. 1/4” Connections

8. 1/4” and Power Connections

Overview of Analog Synthesis

9. Frequency Harmonic Content

10. Amplitude

Internal Signal Routing

11. Diagram

Controlling Your XS

12. Using MIDI

13. MIDI to CV/Gate Converter

14. Using CV/Gate Control Signals

Analog Controls

15. Glide Time CV Track

16. Low Frequency Oscillator

17. Oscillator A

18. Oscillator B

21. Wave C

22. Oscillator A Modulation

24. Oscillator B Modulation

25. Mixer

26. Multimode Filter

27. Filter Modulation

30. Envelope 1

31. Accent

32. Envelope 2

33. Amplifier

Patch Sheets

34. Blank Patch

35. Noise Kick

36. Techno Kick

37. Snare Drum

Patch Sheets

38. Hand Clap

39. High Hats

40. Distorted Bass/Lead

41. Funky Trance Lead

42. Classic Sync Lead

43. Phat Saw

44. Acid Bass

45. Jungle Bass

46. Winding Down

47. Buzzy Bass

48. 8 Bit Talking Bass

49. Electric Bass

50. Phat Stack Phased

51. Grinder

52. MIDI Synced Pseudo Arp

53. Computer

54. Strange Beats

Tips and Tricks

55. Latch a Note Special uses for the oscillator outputs

56. Using CVIN as an additional mod source Using the VEL IN as an FM source A/B Envelope signals are Velocity-sensitive Envelope signals that are not Velocity-sensitive Using audio to trigger the envelopes

57. Sub oscillator sync Sub oscillator self modulation Overdriving the filter with two oscillators Using the overdrive Summing signals at the filter output

Trouble Shooting

58. Common Problems

Specifications

59. MIDI LFO Oscillator A Oscillator B Wave C Oscillator Modulation Mixer Filter

60. Filter Modulation Envelope 1 Accent Section Envelope 2 Amplifier Inputs/Outputs

INTRODUCTION

Welcome to the world of XS!

Thank you for choosing the XS semi-modular analog synthesizer. Please take time to read through the entire manual for a complete understanding of the operations and procedures needed to master this instrument.

Contents

Included with your XS synthesizer, you should find an external power supply, optional desktop ends, owner’s manual, and warranty card. If any of these items are missing, please notify the dealer you purchased the unit from or contact Future Retro directly. Please keep the original box and all packaging material your unit came with, as this provides the best protection should you ever need to ship your unit.

Overview

The XS is a true semi-modular analog synthesizer with a universe of sonic possibilities just waiting to be discovered. The unit’s versatile design allows it to be used as either a tabletop or rack-mounted instrument and its compact size makes it ideal for musicians on the go. In its simplest form the XS is an extremely powerful monophonic synthesizer with internal signal routings pre-wired in a way that allows the unit to act similar to traditional synthesizers. The unit also provides numerous inputs and outputs that can be connected in various ways to override the pre-wired signal routings and interface the unit with other instruments in a modular fashion, and even process external audio. The XS can be controlled by both MIDI and CV/Gate control signals in a variety of ways so that interfacing it with other instruments, old or new, is simple. The XS can also act as a MIDI to CV/Gate converter, allowing MIDI information received by the unit to be transmitted as CV/Gate signals for controlling other analog instruments.

Power

The power supply provided with your unit is designed specifically for this product. Do not substitute the use of other power supplies. If your power supply ever becomes lost or damaged, please contact us for a replacement.

Care

Avoid exposing the unit to smoke or damp, dusty, or extreme hot and cold environments. To clean the unit, use a soft damp cloth. Do not use any abrasive cleaners, as these may harm the surfaces and finish of the unit.

Product Warranty and Support

The XS comes with a 1 year limited warranty covering mechanical or electrical defects. To validate your warranty, fill out the warranty card included with your unit and mail it within one month of the original purchase date. The warranty does not cover damage due to misuse or abuse of the product. Any modifications performed to the unit will automatically void the warranty. Future Retro will not be held liable for any accidents or damages caused to the user or their surroundings when using this product. Should your unit become damaged within the warranty period, please email product support: support@future-retro.com You will need to obtain authorization to return the unit to us for repairs.

Please visit the Product and Support pages of our website for the latest information about this product, and any additional updates which may become available: www.future-retro.com

RACK-MOUNT OR DESKTOP

Have it your way

The XS can be used as either a rack-mount or desktop unit. All units come assembled with the rack ear option installed at the factory. If you prefer to place the XS on a desktop, the rack ears may be removed and these desktop pieces may installed in their place.

Remove the two Phillips screws on each of the rack ear end pieces, and install the desktop pieces as shown below. The Phillips screws that are used to fasten the rack ears can be reused for mounting the desktop pieces.

6. Now you can play around with the various analog parameter settings to adjust the sound that

GETTING STARTED

I want to play now!

To play the XS, follow these directions in order.

1. Connect the XS to an audio system as shown in the illustration below.

2. Connect the MIDI IN of the XS to the MIDI OUT of your controller keyboard or sequencer.

3. Set the front panel controls of the XS as shown in the illustration on page 5.

4. You’ll need to set the MIDI channel control on the XS to the same MIDI channel your keyboard or sequencer is sending MIDI information on.

5. Press the power switch of the XS to turn the unit on, and slowly increase the volume control on the XS to a suitable listening level (without overdriving the input of your mixer) while you play your keyboard or sequencer.

the XS is creating.

7. When you are finished playing, press the power switch again to turn its power off.

Remember, we’re just getting started here. For a full understanding of this product and its features, please read through the entire manual.

Note: As a general rule, first turn on the XS, then your mixer, and then your amplifier. When turning your studio equipment off, you’ll want to turn off the amplifier first, then proceed with turning off the rest of your equipment. This will prevent any power surges to your amplifier and speakers, which could damage them.

CONNECTIONS

MIDI IN: Information received at the MIDI IN jack can be used to play the sounds of the XS.

Use a MIDI cable to connect this input to an external sequencer or keyboard’s MIDI OUT.

MIDI THRU: All information received at the XS MIDI IN jack will be sent out the MIDI THRU jack. Use a MIDI cable to connect this output to another device’s MIDI input for creating a daisy chain between multiple MIDI units.

CV IN: Connect this input to a 1V/Oct standard CV output of another device, in order to control the pitch of the oscillators in the XS.

CV OUT: MIDI note/pitch data received at the XS MIDI IN jack will be converted to a control voltage of the 1V/Oct standard. You can connect this CV output to the CV or modulation inputs of any device to control the pitch of its oscillators or other circuits.

MOD W OUT: Mod Wheel data received at the MIDI IN jack will be converted to an equivalent control voltage ranging from 0 to +10 volts. Connect this output to the CV or modulation inputs of any device you wish to control with the mod wheel.

VEL OUT: MIDI Note/Velocity data received at the XS MIDI IN jack will be converted to an equivalent control voltage ranging from 0 to +10 volts. Connect this output to the CV or modulation inputs of any device you wish to control with Note Velocity.

LFO OUT: The waveform currently selected in the LFO section will be available at this output. All LFO waveforms have a range of –5 to +5 volts. Connect this output to the CV or modulation inputs of any device you wish to control with the LFO.

OSC MOD: This is the external modulation input for the oscillators. Connect this input to the output of any CV or modulation source you wish to modulate the oscillators with. The external signal can be used to modify each oscillator’s pitch individually, as well as the pulse width modulation of Oscillator B’s square/pulse waveform. Set the Mod Select controls to EXT for any of these three sections you wish to control with the external source.

WAVE A: This is a dual-function output of the waveform selected for Oscillator A. This is a stereo output, although mono cables can be used here without any problem. If using a mono cable, you can insert it all the way for the tip signal, or pull it out one notch for the ring signal. The tip of the jack provides a continuous output of Oscillator A’s selected waveform. The ring of the jack provides the same waveform, but the amplitude of this waveform is controlled by Envelope 1. Either output can be connected to the input of any other device, allowing the oscillator to act as an audio or modulation source. The waveform’s output signal will have a range of –5 to +5 volts.

CONNECTIONS

WAVE B: This is a dual-function output of the waveform selected for Oscillator B. This is a

stereo output, although mono cables can be used here without any problem. If using a mono cable, you can insert it all the way for the tip signal or pull it out one notch for the ring signal. The tip of the jack provides a continuous output of Oscillator B’s selected waveform. The ring of the jack provides the same waveform, but the amplitude of this waveform is controlled by Envelope 1. Either output can be connected to the input of any other device allowing the oscillator to act as an audio or modulation source. The waveform’s output signal will have a range of –5 to +5 volts.

WAVE C: This is mono output of the waveform selected for the WAVE B control. The three sub oscillator waveforms will have a range of 0 to +15 volts, while the ring modulator and white noise source will have a range of –5 to +5 volts. This output can be connected to the input of any other device allowing it to act as an audio or modulation source.

AUDIO IN: This is a mono audio input that can be connected to any line-level external audio source output. When a cable is plugged into this jack, you can use either the WAVE A or WAVE C control to select EXT which will select this external audio source as its waveform.

FILTER MOD: This is the external modulation input for the filter. Connect this input to the output of any CV or modulation source you wish to modulate the filter with. Set the Mod Select control in the filter section to EXT if you wish to use the external source.

VEL IN: This is the external Velocity input, allowing external control voltages to override the Velocity control generated by the internal MIDI to CV converter. Generally, you will want to connect this input to any control voltage ranging from 0 to +10 volts. This external signal will then control all Velocity-sensitive parameters throughout the analog section.

GATE IN: When nothing is plugged into the Gate In jack, the envelopes in the XS will be triggered by Note On messages received via MIDI. If you connect a positive polarity gate output of another device to the gate in of the XS, this external gate can then be used to trigger the envelopes in the XS. Once the external gate signal reaches +1.5 volts or higher, the envelopes will be triggered.

GATE OUT: All MIDI note message received by the XS will be converted to a positive polarity gate ranging from 0 to +15 volts. Connect this output to the Gate In of any other device you wish to control with gate signals.

CONNECTIONS

ENV 1+/-: This is a dual-function output of Envelope 1. This is a stereo output, although mono

cables can be used here without any problem. If using a mono cable, you can insert it all the way for the tip signal or pull it out one notch for the ring signal. The tip of the jack provides a positive polarity of Envelope 1 ranging from 0 to +10 volts. The ring of the jack provides a reverse polarity of Envelope 1 ranging from +10 to 0 volts. Connect either of these outputs to any modulation input you wish to control with Envelope 1.

FILTER OUT: This is the output of the Filter and Overdrive section. You can connect this output to any audio or modulation input. The signal coming out of the filter can range from 0 volts (nothing) to +/- 15 volts, depending on the level settings in the mixer section.

AMP IN: This is the main input for the Amplifier section. When nothing is plugged into the Amp In jack, the output of the filter will be connected to the amplifier’s input. Once a cable is inserted into the Amp In jack, audio coming from the filter’s output is disconnected from the amplifier, and only the external signal will be routed through the amplifier.

MAIN OUT: This is the main output of the Amplifier section. Typically, you will connect this output to the input of your mixing console or amplifier. This output is monophonic.

Note: All 1/4” connectors are monophonic unless specified as stereo in their description.

Note: In some of the stereo jack descriptions, we state that you can pull the cable out one notch. It may be more accurate, however, to say pull the cable out completely and then reinstall the cable so it is just touching the first contact of the jack. If the cable were actually pulled out one notch, it would end up shorting both tip and ring connections of the jack, which may cause operations other than described here in the manual, though not harmful to the unit.

POWER: Use only the factory-provided power supply that came with your XS. This is a special power supply that has multiple output voltages. Connect the mini-DIN connector of the power supply to the power jack, located on the bottom of the unit. Connect the power mains connector to your wall outlet. The power supply can operate on power main voltages ranging from 90—260 volts AC, which should be compatible with most power standards worldwide. The power cable which connects from the body of the power supply to your wall outlet can be changed out with standard IEC type cables, which can then support the various pin arrangements of each countries power main standards.

OVERVIEW OF ANALOG SYNTHESIS

The XS is a true analog synthesizer, which is capable of producing an infinite amount of sonic textures. All aspects of a sound can be changed instantly by the controls and switches located on the front panel. The settings of these controls are never digitized or stored in memory. Therefore, the sound the XS produces is always a direct representation of the actual control settings.

By keeping the controls of the XS completely analog you get infinite resolution of each parameter, whereas digital synthesizers typically provide only 128 defined steps for each parameter. We feel that digitizing the controls of an analog synthesizer will ultimately limit the precision that analog provides.

If you are new to synthesizers or analog synthesis, fear not. It’s actually quite easy and rewarding, to say the least. No messy menus to fuss with, only hands-on manipulation of sound. With a basic understanding of sound, you too can create an infinite pallette of sounds.

All sounds can be broken down into three basic elements, which are Frequency (pitch), Harmonic

Content (tone), and Amplitude (volume).

Frequency is measured in Hertz (Hz). Hz is the number of times an oscillator repeats its periodic

waveform within one second of time. For example, the range of human hearing is from approximately 20 Hz to 20,000 Hz (referred to as 20 kHz). The human ear perceives a low frequency as having a lower pitch, and a higher frequency as having a higher pitch. The XS is capable of producing frequencies covering the entire audible range of hearing as well as those above and below the 20 Hz to 20,000 Hz range. The frequency that the oscillators produce in the XS can be controlled in a variety of ways that will be discussed later in the Analog Controls section of this manual.

Harmonic Content refers to the amount of frequencies contained within a sound. The most dominant or perceived pitch in a sound is called the fundamental frequency. All other frequencies in the sound are harmonics of the fundamental frequency. Each harmonic is simply another sine wave at a reduced amplitude of the fundamental frequency. Harmonics are often referred to as the 2nd, 3rd, 4th, and so on. The number of the harmonic simply describes the number of cycles this harmonic produces for each single cycle of the fundamental frequency.

The shape of an oscillator’s waveform is relative to its harmonic content, and there are four common waveshapes generated by a musical oscillator. A sine wave (the one that looks like an S turned sideways), for instance, is the most basic waveform, having only a fundamental frequency and no additional harmonics. Sine waves sound very thin and are pure in sound. A triangle waveform contains a fundamental frequency and all odd harmonics (3rd, 5th, 7th and so on) of that frequency. This causes it to sound slightly fuller than a sine wave. A square wave also contains a fundamental frequency and all odd harmonics of that frequency. The difference between a square and a triangle waveform is that the harmonics are more pronounced in the square wave, giving it a somewhat hollow yet fuller sound than the triangle. In the XS, the duty cycle of this square wave can also be varied to create what is known as a pulse waveform. The width of this pulse alters the harmonic content of the waveform. Consider the true square wave whose pulse is 1/2 the period of the waveform. We know that the 2nd harmonic and its multiples have been eliminated, leaving only the odd harmonics. Let’s say the pulse width is changed to 1/3 the period; this then eliminates the 3rd harmonic and its multiples such as the 6th, 9th, and 12th harmonics. A pulse width of 1/4 the period would then eliminate the 4th, 8th, and 12th harmonics.

OVERVIEW OF ANALOG SYNTHESIS

A sawtooth waveform is one of the most complex shapes, since it contains a fundamental frequency and all harmonics of that frequency. Sawtooth waves are very full sounding and have a unique raspy quality to them. In addition to these four common waveshapes, there are other items which can also be used as audio sources which will be described in more detail later on. You can mix the waveforms of oscillators and other audio sources, together to create more complex tones. This method is often referred to as additive synthesis.

The most common way to alter the harmonic content of a waveform, however, is by using a filter. This is referred to as subtractive synthesis, where instead of adding more harmonics, we are actually taking away or modifying the harmonic content of the oscillator waveforms and other audio sources. The filter in the XS provides four filter types: lowpass, highpass, bandpass, and notch. Each filter does just what it sounds like. With the lowpass filter, low frequencies are allowed to pass through the filter while higher frequencies are attenuated. A highpass, on the other hand, allows the high frequencies to pass through the filter while the lower frequencies are attenuated. The point at which frequencies pass or are attenuated by the filter is determined by the filter’s cutoff frequency, which is variable over the entire audio range. A bandpass filter allows only the frequencies closest to the filter’s cutoff frequency to pass through, while attenuating all frequencies higher and lower than the cutoff frequency. A notch filter has the opposite effect of a bandpass filter, where the harmonics closest to the cutoff frequency are attenuated while all other harmonics are allowed to pass through the filter. Each filter type also provides resonance, which boosts the amplitude of the frequencies closest to the cutoff frequency of the filter. The cutoff frequency can be manually adjusted or animated by the use of modulation sources. Modifying the harmonic content of your audio sources are key to breathing life into your sounds and making them interesting.

Amplitude is a term used to describe the level of a waveform, or a sound’s overall volume. The volume of traditional instruments is usually determined by how hard a surface is struck, a string is plucked, or the force of air blown through a wind instrument. Synthesizers use amplifiers to boost and attenuate a sound’s amplitude in a similar fashion to increasing and decreasing the volume on your stereo. All sounds have their own unique shape of volume. This shape can be described as the envelope. The XS provides four envelope types to help shape the amplitude of a sound. In essence, envelopes are a way of automating the volume. The controlling envelope can be defined as having attack, decay, sustain, and release. When a note is played, the attack parameter determines the amount of time it takes to go from silence to the loudest possible volume. Once the loudest volume level is reached, the decay parameter then determines the time it takes to go from the loudest level back to silence or some other defined level. This defined level is referred to as sustain. Once the sustain level is reached, the sound will remain at this volume until the note is released, at which point, the release parameter will determine how long it takes for the volume to return to silence. The XS also uses Velocity information, which determines how soft or hard a note is played, to control the amplitude of sounds. So when a note is played softly, the sound is quieter. And as you play harder, the sound gets proportionally louder. And finally, the main volume control is also used to set the overall output level for all sounds.

Pay attention to the everyday sounds all around you and consider the frequencies, harmonic content, and amplitude it takes to create them. And before long, you too will be able to create any sound imaginable.

CONTROLLING YOUR XS

There are several ways to control your XS. One way is to use MIDI (Musical Instrument Digital Interface), a standard developed to allow one electronic instrument to talk to another using only a single 5-pin DIN cable. Nearly all modern electronic instruments have and support MIDI. Before MIDI was developed, the standard practice was to use control voltages and logic gate signals as a means of controlling, modifying, and triggering electronic circuits in synthesizers. The XS supports both standards, old and new, and even allows you to mix the use of both at the same time. The XS also converts MIDI data it receives into control voltages and logic gate signals to control other pre-MIDI instruments, sound modules, and other circuits.

USING MIDI

The XS responds to MIDI Note On/Off, Pitch (C2-C7), Pitch Bend, Mod Wheel, Velocity, and MIDI Clock messages. Any MIDI instrument capable of sending this data can be used to play the XS. The most practical way to play the XS would be to connect it to a MIDI keyboard or MIDI sequencer. Simply connect the MIDI OUT of your keyboard or sequencer to the MIDI IN of the XS using a 5-pin DIN MIDI cable. The XS can receive MIDI data on only 1 of the 16 possible MIDI channels at any time. In order for the XS to receive MIDI data from the keyboard or sequencer, you must first set both instruments to the same MIDI channel. Setting the MIDI channel that the XS will receive data on is done with the MIDI Channel control. Simply rotate this control so its indicator points to the desired MIDI channel.

Note: Changing the MIDI channel selection on the XS while notes are currently being played may cause these notes to become latched, which prevents them from turning off. Avoid changing the MIDI channel selection while notes are being played. Should notes become latched, first stop the master device sending MIDI data to the XS, then turn the XS off and then back on again.

If you have multiple MIDI devices in your studio that need to be controlled by your main MIDI keyboard or sequencer, you can connect the MIDI THRU of the XS to the MIDI IN of another device.

Using this method, all MIDI information the XS receives will be then be sent on to the other MIDI device.

CONTROLLING YOUR XS

is converted to

MIDI TO CV/GATE CONVERTER

When MIDI information is received by the XS, the MIDI data is then converted into control voltages and logic gate signals that control the internal analog sound section. These control voltages and logic signals are also available at the 1/4” output jacks, which allows you to control other external analog circuits.

The CV OUT signal generated represents the pitch of MIDI notes received. This control voltage follows the 1 V/Oct (volt per octave) standard, where each semitone note equals 1/12th of a volt,

and each octave equals 1 volt. Since the XS responds to MIDI notes C2 through C7, this control voltage can range from 0 to +5 volts. MIDI pitch bend messages will also affect this control voltage, causing a note’s voltage to become slightly more positive or negative than typically produced for that note. If more than one note is played at a time by the MIDI controller, the XS will activate its internal glide circuit which will slew the voltage from one note to another at the rate set by the Glide Time control. This output can be used to control the pitch of oscillators, filters, or other voltage-controlled circuits.

The GATE OUT signal generated represents Note On/Off messages. When no notes are being played, this logic signal will output 0 volts. When a notes is being played, this logic signal will output approximately +14 volts.

This output can be used to trigger envelope generators or circuits with other logic inputs.

The VEL OUT signal generated represents the Velocity of MIDI notes received. This control

voltage can range from 0 to +10 volts respectively, so notes with a higher Velocity value generate

higher voltages. This control voltage is generally used to affect the volume of sound by controlling an amplifier, but could also be used to affect a filter’s cutoff frequency or any other voltage-controlled circuit.

The MOD W OUT signal generated represents any MIDI Mod Wheel messages received. This control voltage can range from 0 to +10 volts respectively, so as you increase the mod wheel

amount this voltage increases. This control voltage is generally used to add expression to a sound, by assigning it to modify various parameters within a synthesizer.

TIP: You can use this MOD W control voltage as a way to animate and record parameter value changes in a sequencer. Let’s say you assign the MOD W control to a filter’s cutoff frequency. You have a sequence playing notes already, and now you wish to record some tweaks to the filter cutoff. Simply move the mod wheel of your master MIDI controller, and record this data into your sequencer.

CONTROLLING YOUR XS

USING CV/GATE CONTROL SIGNALS

External control voltage and logic gate signals can be used at any time in any combination to control the XS, even while MIDI note data is being received. Receiving MIDI data is the default way to play the XS. But when an analog voltage or gate signal is inserted into one of the control inputs it can either be selected to modulate a specific parameter, or in some cases will automatically override the control signal being generated by the internal MIDI to CV/Gate converter.

The CV IN input is routed to the CV Track control in the PITCH CONTROL section. This control determines which source Oscillator A and B will use to control their pitch.

In the A B position, both oscillators will be controlled by MIDI notes received. In the A BX position, Oscillator A will respond to MIDI notes received, while Oscillator B will be controlled by an external voltage inserted into the CV IN jack. In the AX B position, Oscillator A will be controlled by an external voltage inserted into the CV IN jack, while Oscillator B will be controlled by MIDI notes received. In the ABX position, both oscillators will be controlled by an external voltage inserted into the CV IN jack.

Note: If no signal is inserted into the CV IN jack, and one or both of the oscillators are selected to use the external voltage, these oscillators will produce a stationary pitch, which can be useful for certain effects.

The GATE IN input is used to trigger the internal envelope circuits. Any time a cable is inserted

into this jack, it will override MIDI triggering of the envelopes. Typically, you will want to use any logic gate signal ranging from 0 to +15 volts. Any voltage received higher than +1.5 volts will be considered as a Gate On, and any voltage less will be considered as a Gate Off. This input can also accept negative voltages without harming the unit, but if they do not exceed the +1.5 volt trip level, no gate will be produced.

TIP: With a trip point of +1.5 volts, you can also use audio signals to trigger the envelopes in the XS.

The VEL IN input is used to control the amplitude of both envelopes (depending on the velocity

amount setting used for each), and can also be used to directly modify the pitch of Oscillator B and the pulse width duration of its square/pulse wave. Any time a cable is inserted into this jack, it will override the MIDI Velocity control voltages being generated to control these parameters. Typically, you will want to use any control voltage ranging from 0 to +10 volts as the VEL IN source, although input voltages can range from –15 to +15 volts without harming the unit.

TIP: Using Velocity control signals that swing both positive and negative can have interesting results. For instance, if the Velocity input goes negative and is controlling Envelope 1’s amplitude, it will cause the output of this envelope to become inverted. However, negative control voltages applied to Envelope 2 (the amplifier) will not allow the amplifier to pass audio to the output during the negative period. If you do not desire this effect on the amplifier, simply turn down the Velocity control for the amplifier.

ANALOG CONTROLS

PITCH CONTROL

This section determines how the pitch control voltage affects the oscillators.

GLIDE TIME: If more than one note is played at a time by a MIDI controller or sequencer connected to the MIDI input of the XS, the XS will activate its internal glide circuit which will slew the voltage from one note to another at the rate set by this control. With this control rotated fully counter-clockwise, the glide time from one pitch to another will be instant, with no apparent slewing of pitch. The glide time will increase as you rotate this control in the clockwise direction.

CV TRACK: This control determines which source each oscillator will use to control its pitch. In the A B position, both oscillators will be controlled by MIDI notes received. In the A BX position, Oscillator A will respond to MIDI notes received, while Oscillator B will be controlled by an external voltage inserted into the CV IN jack. In the AX B position, Oscillator A will be controlled by an external voltage inserted into the CV IN jack, while Oscillator B will be controlled by MIDI notes received. In the ABX position, both oscillators will be controlled by an external voltage inserted into the CV IN jack.

Note: If no signal is inserted into the CV IN jack, and one or both of the oscillators are selected to use the external control voltage, these oscillators will produce a stationary pitch that can be useful for certain effects.

ANALOG CONTROLS

LOW FREQUENCY OSCILLATOR

A low frequency oscillator (LFO), is a modulation source whose frequency is generally below the range of human hearing. The LFO provides multiple waveshapes and a variable rate at which it can modify other parameters of a synthesizer. Common uses would be to add vibrato or tremolo to a sound, or to create slowly evolving sweeps or changes to parameter settings.

WAVE: This control selects one of four waveforms for the LFO, including triangle, sawtooth, square, and random shapes.

The TRIANGLE waveform provides a smooth linear rising/falling waveform, which is ideal for vibrato and tremolo effects.

The SAWTOOTH waveform provides a smooth linear falling waveform with a quickly rising edge. The effect of this waveform is similar to a decaying envelope with a fast attack.

The SQUARE waveform has only two possible states: high or low. This may be useful for creating trill effects. In addition, the square waveform may also be used as a logical gate signal for triggering other circuits such as envelope generators, analog sequencers, or arpeggiators.

The RANDOM waveform will produce varying amplitudes of voltages at a rate which is once per every period of the other LFO waveshapes. This is useful when you wish to create sounds which are rather unpredictable, having parameters jump around to various settings.

RATE: The RATE control determines the frequency at which the LFO will produce its waveform. This control has two different modes of operation that are determined by the LFO SYNC switch. When the LFO SYNC switch is in the OFF position, the LFO will be free running at variable rates from 4 seconds to 18 Hz. Rotate this control counter-clockwise for slower LFO rates, and clockwise for faster LFO rates. The LFO LED will flash on and off at the rate of oscillation. When the LFO SYNC switch is in the ON position, the LFO will generate its waveform at defined divisions of a MIDI clock. There are 16 MIDI clock divisions in all, including 8 bars, 4 bars, 2 bars, 1 bar, 1/2, 3/8, 1/3, 1/4, 3/16, 1/6, 1/8, 3/32, 1/12, 1/16, 1/24, and 1/32 notes divisions.

In order to use the LFO MIDI SYNC function, make sure you have a MIDI sequencer or other MIDI clock source’s MIDI OUT connected to the MIDI IN jack of the XS. You’ll need to set up your MIDI sequencer to send MIDI clock/start/stop messages. When you first set the LFO SYNC switch to ON, your sequencer needs to send a MIDI start command in order for the LFO to start syncing. Adjusting the LFO’s rate while the LFO is syncing can cause the LFO waveform to become out of phase. To resync the phase of the LFO waveform, simply send a new MIDI start message from your sequencer.

ANALOG CONTROLS

OSCILLATOR A

Oscillator A is one of the main audio sources in the XS, although it can also be used as a modulation source. This is a wide range, ultra-stable oscillator capable of generating frequencies from approximately 0.5 Hz to more than 100 kHz.

OCTAVE: This control is used to transpose Oscillator A through its different ranges. Zero is the default setting for this control. If we were to play note C2 on a MIDI keyboard and switch through the different octave ranges, we would find that the –1 setting produces 16.352 Hz, the 0 setting produces 32.703 Hz, the 1 setting produces 65.406 Hz, the 2 setting produces 130.81 Hz, the 3 setting produces 261.63 Hz, and the 4 setting produces 523.25 Hz. If we were to leave this octave setting in the 4 position, and play our highest MIDI note C7, we would find that this oscillator produces a frequency of 16,744.04 Hz or

16.74 kHz. As you can see, using just this octave control and a 5-octave keyboard, we can cover the frequency range of 16 Hz to 16 kHz. We will discuss later in the manual how to access this oscillator’s full range.

NOTE: When using an external control voltage to control the oscillator, MIDI note C2 = 0 volts, C3 = +1 volt, C4 = +2 volts, C5 = +3 volts, C6 = +4 volts, and C7 = +5 volts. Therefore, with an octave setting of 0, if we input 0 volts into the CV IN jack, Oscillator A will produce a frequency of 32.703 Hz. If the CV IN voltage changes to +5 volts with the octave control changed to 4, Oscillator A will then produce a frequency of 16.74 kHz.

FINE TUNE +/-: This is the master fine tune control for both Oscillators A and B. When this control is set to its mid position marked with a “0” both oscillators should be in tune. This control covers a range of approximately 12 cents total, providing us with –6 to +6 cents in detuning. Rotating this control counter clockwise of the “0” mark will cause both oscillators to sound flat. Rotating this control clockwise of the “0” mark will cause both oscillators to sound sharp. You can use this control to match the pitch of the internal oscillators to an external reference if they are slightly out of tune with one another.

WAVE A: This control selects which waveshape will be used for Oscillator A. Although Oscillator A actually only generates the sawtooth and square waveforms which will track the playing of notes up and down a keyboard.

The SAWTOOTH setting selects Oscillator A’s sawtooth waveform. The SQUARE setting selects Oscillator A’s square waveform, which has a 50% duty cycle. The NOISE setting will select the internal white noise source, which contains an even amount of frequencies throughout the audio spectrum. The EXT setting will select any external audio source that is inserted into the AUDIO IN jack.

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Future Retro XS User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual