I’m Melissa Ann from El Paso, Texas.
My people, the music people, artists,writers and lovers, God bless you, I enjoyed communing with you and sharing ideas. This was really a fruitful year however, I hope this new year (2016) is even better and it kicks a**. Love you all!
The Oscillator (Voltage Controlled Oscillator – VCO)
The Oscillator is the thing which creates the sound. This sound created is based on different geometric waveforms, their selected shape in particular. When a note is played, in this is where the signal will begin before feeding through the other modules of the synthesizer. The most common waveforms are:
- Sine Wave – Represents a single frequency with no harmonics. Sounds very pure and loud.
- Sawtooth Wave – The sound is often fuller as it contains all harmonic. Like the sound or timbre of a violin.
- Square Wave – Produces a very thin reedy, hollow sound (like an oboe) as it is missing the even harmonics. Like the sound or timbre of a clarinet.
- Pulse Wave – Produces a similar sound to the square wave but has the unique ability to have its width modulated.
- Triangle Wave – Produces sound like a filtered square wave however the higher harmonics arrive much faster.
- Noise – If the vibrations do not follow a pattern, the waveform can be random and the sound is discordant and called noise.
Oscillators, Frequency LFO and Primary Modulation with Direct Control and Pitch (Class Screen Shots)
(Voltage Controlled Amplifier – VCA)
After the signal is changed by the filters, it then passes through to the Amplifier which is usually a unity-gain type amplifier which varies the amplitude of a signal in response to an applied control voltage. The response curve may be linear or exponential.
The Amplifier determines the immediate volume level of a played note, and it will quiet the output at the end of the note. A VCA may be referred to as being “two quadrant” or “four quadrant” in operation. In a two quadrant VCA, if the control voltage input drops to less than or equal to zero, what happens is that the VCA produces no output. “In a four quadrant VCA, once the control voltage drops below zero, the output gain rises according to the absolute value of the control voltage, but the output is inverted in phase from the input” (http://introduction-to-music-production.blogspot.com/). A four quadrant VCA is what is used to produce amplitude modulation plus ring modulation effects.
The Envelope modulator is attached to the Amplifier to control its movements . Although envelopes can control different parameters, the last one in the synthesizer will usually be the Amplitude Envelope. The ADSR controls are:
- Attack time – the time for initial run-up from zero to peak level, beginning when the key is first pressed
- Decay time – the time taken for the subsequent come down from the attack level to the designated sustain level
- Sustain level – the level reached during the main sequence of the sound’s duration, until the key is released
- Release time – the time taken for the level to decay or decrease from the sustain level to zero after the key is released
These four controls define a path for the sound to follow and adjustments to each of these will have an what we hear with the human ear. For example, an organ envelope represents a switch, functioning almost “on and off”, and we can use it to emulate blown or bowed instruments that hold sustaining notes. To emulate a percussive sound, the sustain level will be at zero. The length of the note is controlled by the decay time. For a punctuated sustaining sound however, like that of a trumpet, the sustain level can be set somewhere in the middle to allow a decrease by decay.
Envelopes can be used really well on an existing patch to modify and perfect it until it sounds just right.
LFO or Low Frequency Oscillator
Low-frequency oscillator (LFO) is an electronic signal which is usually below 20 Hz which creates a rhythmic pulse or sweep. These signals are often used to modulate synthesizers, delay lines and other audio equipment in order to create audio effects in electronic music. “Audio effects such as vibrato, tremolo and phasing are examples” (https://en.wikipedia.org/wiki/Low-frequency_oscillation). LFO can be used n many ways. When routed to modulate to control pitch, it can create a vibrato and when it modulates amplitude, it can create tremolo.
What it is and the Basics
Differences between LFO rates also can be used or a number for a number of effects in modern music. For example, a very low rate can be used to modulate a filter‘s cutoff frequency, which shows up as the gradual sensation of the sound becoming clearer or closer to the listener (https://en.wikipedia.org/wiki/Low-frequency_oscillation).
Alternatively, a high rate can be used for strange ‘rippling’ noises or sound effects. For example, Dubstep and drum and bass are forms of electronic music which employs frequent use of LFOs, that are often synchronized to the tempo of the track, for producing bass sounds that have a “wobble” effect, by modulating the cutoff frequency of a low-pass filter to create a distinctive opening-and-closing effect. Because of this the LFO wobble is now being found in other forms of electronic dance music such as house music (https://en.wikipedia.org/wiki/Low-frequency_oscillation).
“That’s that’s all folks”-Bug Bunny from Looney Tunes
I learned a lot in this class, from zero to twenty percent, just kidding, at least around 80 percent. Always keep learning and growing even when you’re old like me. Life is a bowl of cherries although sometimes its the pits. Keep on rocking. Any questions or problems with this assignment, let me know because I’ll be here and I care. Bye!
Class Screen Shot on Voltage Controlled Oscillator