Future Retro XS - Manual (Page 11)

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 sin-
gle 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.
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