Last time we looked at reconfigurable filters, filters that include switches to rearrange parts of the circuit during normal use. However, that’s not the only way to produce different responses from a single filter circuit. This time, we’ll look at another approach: pole mixing. “Pole mixing”? It sounds like stirring a cake with a broom handle… […]
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 […]
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 […]
Or how to get a vintage 1980’s drum machine sound without selling your kidneys! 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 […]
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, […]
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 […]
Can we make a modern reproduction of the classic top octave generator / top octave synthesiser chips of the 1970s, as used in classic string synths and combo organs? What would be involved? Can we improve on the originals in any way? This page is a summary of what I learned by doing it. A […]
This post is a place to gather my thoughts about one of the most important parts of synthesizer design: the timbral evolution of sounds. It also presents the results of my analyses of some classic synth sounds. There have been many methods developed over the years to achieve timbral evolution. The voltage-controlled filter is the first […]
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 […]
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 […]
