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 […]
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I recently saw an advert for the new EHX Slapback Echo reissue pedal and thought it was a cool little thing and would make a nice project. The original pedal came out in 1978 and was about as simple as it could get. There was one “Blend” knob to mix the straight and delayed signal, and […]
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 […]
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 […]
First, a quick history of overdrive pedals. Boss got the ball rolling in 1977 with the OD-1, one of the first pedals in their now-famous “compact” series, and the first proper “overdrive” pedal – before that, they were all called “Fuzz” or “Distortion”. This pedal was part of the three releases that started the series, […]
I’d like to share a couple of things I’ve had kicking around on my desk for a long while. The first one was a simple optical tremolo, and for this second StompLFO project, we’re going to use the StompLFO to apply modulation to a PT2399 delay. This is actually very simple to do! PTWobble, StompLFO […]
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 […]