If you apply a constant voltage to an integrator, it will create a consistent increase or decrease in the output voltage over time (a ramp): In this case the input and output signals are both voltage. The purpose of an integrator is to produce an output signal that changes (increase or decreases) at a rate that corresponds to the magnitude and duration of the input signal.
This is a fancy word from calculus but don't be afraid- it's actually pretty straightforward in practice. The integratorĪn integrator is an electronic circuit that performs the mathematical operation of Integration.
#ROLAND JUNO 60 GENERATOR#
Before getting into those differences, let's look at the heart of the ramp generator that's shared between both designs: the integrator. The difference in the type of input signal has a significant impact on the circuit design. For a DCO, the frequency input signal is a digital clock, hence "digitally-controlled". For a VCO, the frequency input signal is a control voltage, hence "voltage-controlled". The ramp generator is the beginning of how an oscillator turns a frequency input signal into the various useful waveforms that are used to make musical sounds.
As shown in the block diagrams above several designs for VCOs and the Juno DCOs are designed around a ramp generator (sometimes referred to as a ramp core) which creates a sawtooth (ramp) waveform: The ramp generatorīefore jumping into the difference between DCOs and VCOs it's useful to discuss the similarities. Now that you've got a high-level overview of the sound generation inside of these synthesizers, let's take a deeper look at the components involved in sound generation. Instead, it uses analog circuitry to create a control voltage which determines the oscillator's frequency: This is in contrast to a common design for a voltage-controlled oscillator ( VCO) where a CPU isn't required. The frequency of the clock determines the frequency/note that the oscillator plays.
#ROLAND JUNO 60 SERIES#
Sound generation starts with a square wave controlled by the microntroller and then goes through a series of waveshapers which generates a ramp/sawtooth waveform, a sub waveform (which is a square wave at half the frequency), and a pulse waveform. Here's a block diagram that should help visualize the different parts at play: These oscillators are controlled by the microcontroller. Each voice has a single oscillator that can generate three different waveforms. An overview of the Juno's sound generation Also, this article will refer to these three synthesizers - the 6, 60, and 106 - as the Juno, but note that this isn't necessarily applicable to later models. This article will discuss and analyze both designs, but before getting into the nitty-gritty details let's take a look at the overall sound generation design of the Juno. It still used the same digitally-controlled oscillator concept from the 6 & 60, but its implementation is a little bit different. It offered some feature upgrades over its predecessor such as pitch bend, modulation, and support for a new thing called MIDI. Roland followed with the Juno-106 in 1984.
This imparted a unique sound to the Juno series and one that's become a favorite of many musicians. The DCOs operate with the same fundamental analog circuitry but differ in that they are controlled by a microcontroller. The DCO was designed to overcome the tuning instability of the usual voltage-controlled oscillators ( VCOs) in contemporary polyphonic synthesizers. The Juno notably featured digitally-controlled analog oscillators. The Juno was a 6-voice polyphonic synthesizer that was an incredible value considering its array of features. Roland introduced the incredible Juno-6 and nearly identical Juno-60 in 1982.
I've tried my best to make this approachable for anyone with basic electronics knowledge, so if you feel confused or overwhelmed please reach out and I'll be more than happy to include more details or change something so that it's easier to understand. This article is somewhat lengthy and there is a lot of information here. This article will cover a little history of the Juno, discuss the theory of operation behind digital-controlled oscillators, analyze the circuit designs for the Juno 6/60 & the Juno 106, and discuss practical aspects of using DCOs. I fell in love with the Juno early in my synthesizer journey and I've spent the last year or so doing research on its design so that I could create my own Juno-inspired DCO, Winterbloom's Castor & Pollux. This article is a comprehensive guide to the Roland Juno's digitally-controlled analog oscillators ( DCOs).