Let’s continue our deep dive into analogue drums with a look at something even earlier – the Korg KR-55. This is a preset drum machine from 1979. It uses a Read-Only Memory (ROM) to store patterns, but it has no processor, unlike the Boss Dr. Rhythm we looked at. Consequently the digital side of this […]
I was exchanging a few emails with a customer recently, and they suggested designing a chip that allowed you to define an LFO shape with a set of controls – obviously sliders would be perfect for something like this, like a Graphic EQ for LFOs! The idea was that you’d have some waveform sliders, plus […]
I’d like to share a couple of things I’ve had kicking around on my desk for a long while. They also show a couple of ways to use vactrols. One is a simple optical tremolo, presented below, and the other is a modulated delay effect. StompLFO Optical Tremolo One very simple way to produce a […]
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 LM13700 is a bonafide classic synth chip, plus it’s cheap and *still* available decades after it was originally introduced. Ok, it’s no longer the state of the art, and its noise and distortion figures are pretty poor, but that’s actually a part of its charm. It’s definitely got that “vintage sound”. So let’s have […]
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 […]
The Electric Druid range of chips now includes four noise generators, so the table below summarises the differences between them to help you select the best chip for your application. White Noise Outputs Pink Noise Outputs Digital Control? MN5837 replacement? NOISE1B 1 0 No Yes NOISE 2 1 1 No No PENTANOISE 5 0 […]
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 […]
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 […]
