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Category: Roland

Roland Jupiter 4 Oscillator

Posted on August 31, 2025September 17, 2025

The Jupiter 4 was Roland’s first polysynth in 1979. Given that the Prophet 5 had been released the previous year, Roland were definitely playing catch-up, and the design looks notably less “modern” than Sequential’s game-changing instrument. Nonetheless, the Jupiter 4 is well thought of and sounds great, with a character of its own. It’s the […]

Posted in Jupiter 4, Oscillators, Roland, Vintage synths   7 Comments on Roland Jupiter 4 Oscillator

Roland filter designs with the IR3109 or AS3109

Posted on May 27, 2025August 28, 2025
AS3109 Datasheet filter schematic

We’ve recently started stocking Alfa’s clone of the famous old Roland IR3109 filter chip. This is the chip that was inside a ton of Roland synths, including the SH-101, Jupiter 6 and Jupiter 8, Juno 6/60 and even the Juno 106, although in that case it was hidden in a potted module! I thought it’d […]

Posted in Filters, Juno, Jupiter 6, Jupiter 8, Phaser, Roland, SH-101, Synth DIY, Vintage synths   6 Comments on Roland filter designs with the IR3109 or AS3109

Analogue Drums: Boss DR-110 Drum Machine

Posted on October 21, 2023January 23, 2024

The Boss Dr Rhythm DR-110 was introduced in 1983 and was the second drum machine Roland had made under the Boss label, following the frighteningly basic DR-55 in 1980. It was also the last drum machine that Boss made before the Dr Rhythm series moved onto digital samples. The Linn Drum (LM-2) was released in […]

Posted in DR-110, Drums, Roland, Vintage synths   2 Comments on Analogue Drums: Boss DR-110 Drum Machine

A look at the TR-909’s noise generator

Posted on December 26, 2019January 11, 2020

The TR-909 uses a hardware implementation of an LFSR as its noise generator. We’ve dealt with LFSR noise generators in a few other articles, but we’ve only looked at firmware implementations, so it might be fun to see how the same thing is done in hardware. The circuit is composed of three parts; the shift register […]

Posted in Noise, Roland, Synth DIY, TR-909, Vintage synths   6 Comments on A look at the TR-909’s noise generator

Roland “Cross Mod” and “Metal Sync” – What do they actually do?

Posted on August 27, 2019June 26, 2025

What do Roland’s “Cross Mod” or “Metal Sync” really do? There are quite few people asking this question on the internet, but no-one has much of an answer. Here’s a few forum discussions I found about it: https://www.harmonycentral.com/forum/forum/Keyboards/acapella-18/330134- http://forums.rolandclan.com/viewtopic.php?f=59&t=54410 https://music.stackexchange.com/questions/57210/what-exactly-is-the-cross-modulation-on-roland-jupiter-and-jx-analog-synthesiz/71048 Ok, so Harmony Central was never going to provide a solid technical answer, but the Roland Clan […]

Posted in GR-700, Jupiter 6, Jupiter 8, JX-10, JX-3P, JX-8P, MKS-30, MKS-70, MKS-80, Oscillators, Roland   17 Comments on Roland “Cross Mod” and “Metal Sync” – What do they actually do?

A study of Sub-Oscillators (and Oscillator Waveshaping)

Posted on June 4, 2017June 11, 2023

This article is a look at sub-oscillators, a common tactic for fattening up the bottom end, particularly  in synths with only one oscillator, or only one oscillator per voice. Classic examples include the Roland Juno 106 and SH101, and the Korg Polysix. More recently, sub-oscs turn up on a lot of modern analog synths since […]

Posted in Korg, Oscillators, Polysix, Roland, SH-101, Synth DIY, Vintage synths   22 Comments on A study of Sub-Oscillators (and Oscillator Waveshaping)

CEM3340 VCO (Voltage Controlled Oscillator) designs

Posted on August 27, 2016February 6, 2020

To celebrate the 2016 return of the CEM3340 chip, I thought I’d do another page in my series looking at how various synths implemented classic synth chips (the others being CEM3320 Filter designs and SSM2044 LP Filter designs). This is especially useful right now, since many people have bought a few CEM3340s or V3340s or AS3340s for their […]

Posted in Memorymoog, MKS-80, Moog, OB-Xa, Oberheim, Oscillators, Prophet 5, Prophet T8, Roland, Sequential, SH-101, Synth DIY, Vintage synths   65 Comments on CEM3340 VCO (Voltage Controlled Oscillator) designs

SH-101 replacement processor – a feasibility study

Posted on August 25, 2016August 26, 2016

The Roland SH-101 is a late-era analogue monosynth which uses a microprocessor to perform keyboard scanning and various related functions, much like the Sequential Pro-One. Since the original uP is a 40-pin DIP, it would be possible to replace it with a more modern 40-pin DIP uP, like the PIC 16F777, or with a modern […]

Posted in Roland, SH-101, Synth DIY, Vintage synths   9 Comments on SH-101 replacement processor – a feasibility study

Roland Juno DCOs

Posted on May 21, 2008September 18, 2025

This page is a brief look at the technology of the Roland Juno series digitally controlled oscillators. The specific scheme presented here was introduced in the Juno 106 in 1984, but the same basic DCO design turned up in many Roland instruments through the 1980s (including the JX-3P, JX-8P, JX-10 and the MKS modules based […]

Posted in Juno, Oscillators, Roland   17 Comments on Roland Juno DCOs

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Druid code and schematics are released under a CC BY-NC-SA 4.0 license, so feel free to download and use Electric Druid code in your personal synth, pedal, or sonic blastertron 2000. Grab a copy of the schematics and tweak away to your heart’s content. If you don’t have a PIC programmer, you can order a chip from the shop. Check the legal stuff for more details.

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Electric Druid code and schematics are released under a CC BY-NC-SA 4.0 license. Please check the legal stuff for more details. If you’d like to use Electric Druid chips, code, or circuits in your commercial product, we’d ask that you buy chips from us to help support the development of further projects. We can supply programmed, labelled chips in whatever quantities you need. If this isn’t suitable, please contact us to discuss your requirements. Thanks!