Category: Synth DIY

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

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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 […]

NOISE2, a white and pink noise source in a single chip

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It’s been around ten years since I developed the original Druid NOISE 1B chip to produce good quality white noise. Finally it gets an update, and the new NOISE2 chip can produce pink noise as well as white noise, so there’s no need for external “pinking” filters. Here’s what it sounds like, white noise and pink […]

Experiments with variable rate drum sample playback

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There was a discussion on the SynthDIY mailing list recently about how the early digital drum machines like the LinnDrum or the Oberheim DMX used to change the pitch of drum sounds by simply changing the sample rate. They literally just played the samples back faster or slower, exactly like speeding up or slowing down […]

TAPLFO 3C – Squashing the bug

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We’ve discovered a bug in the recently-released TAPLFO 3 code (how embarrassing!). The problem only affects the tap tempo feature of the TAPLFO3. Other chips like the VCLFO or STOMPLFO aren’t affected. We’ve fixed the code, and while we were working on it, we also improved the switch debouncing routine to be more tolerant of bouncy […]

Electric Druid chips: The Next Generation

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In the last six months, we’ve been very busy here in the Druid workshop, developing and testing new versions of our PIC-based chips. This work is now complete, so I’d like to introduce the new chips. Why bother? What was wrong with the old ones? Ok, there wasn’t anything much wrong with the old ones, […]

Analog Renaissance? The rebirth of the impossible chips

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We live in interesting times. For many years, people have been wondering if it would be possible to reproduce the old CEM (Curtis Electro Music) and SSM (Solid State Music) chip designs from the late 1970’s and early 80’s. We’ve always been told that there wasn’t enough interest to make such a thing commercially viable, […]

Multimode filters, Part 1: Reconfigurable filters

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What is a “Multimode filter” anyway? It’s a filter which can provide more than one response. So it might offer a choice of 2-pole or 4-pole lowpass responses, or it might be switchable between lowpass and highpass, or it might have lowpass, bandpass, and highpass outputs. There are basically three techniques for building multimode filters, […]

A study of Sub-Oscillators (and Oscillator Waveshaping)

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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 […]