Using the Hot Springs Reverb

Hot Springs Reverb Schematic

In The Studio: The Hot Springs tanks and circuit board should be mounted in a location that is free of ambient electro-magnetic fields.  The input and output jacks are typically connected on a patch panel with other effect’s inputs and outputs.  In use, the effects or aux send buss of the console patches to the…

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4 Bit Digitizer Flash Converter

4 Bit Digitizer Schematic

by John Simonton This 4 bit digitizer originally appeared in my Lab Notes column in Polyphony magazine. This type of analog to digital converter is usually called a flash converter because conversion happens asynchronously, with no clocks or strobes. Input a voltage and the digital output appears in a flash 🙂 This design is fast enough to digitize signals into the…

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QuadraFuzz: Design Analysis

QuadraFuzz Schematic

You don’t have to understand the theory behind the QuadraFuzz to build it or use it but the circuit demonstrates a lot of basic principles of musical electronics. IC1B is a preamp which accepts either a high level input (via J1) or a low level input (via J2). ATTACK control R52 sets IC1B’s gain from…

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How MS Stereo Works

MS Decoder - A-B stereo mix placement captures level differences and time differences.

by John Simonton Usually the most intuitive way to perform a task is the best … but not always. Since we have Left and Right ears, the most intuitive way to encode stereo sound information is as Left and Right channels. And stereo delivery media such as CD, tape, vinyl and older film do it…

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How to Build a 2 Note Ribbon Controller

2 Note Ribbon Controller

by John Simonton Even if you’ve never played with a ribbon controller you have at least seen one and know what they are. They are far and away the most organic and intuitive controller available for synthesizers. Sliding a finger up and down the ribbon can control the pitch of an oscillator or some other…

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A Practical MS Decoder Circuit

MS Decoder

by Jules Ryckebusch The schematic diagram of the MS Decoder may look complicated but is actually quite simple. Both the Mid and Side signals are initially buffered by unity gain inverting buffers formed around IC1b and IC2 b. This is necessary for two reasons, first to ensure enough drive current for the following sections. Second,…

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Touch Switches

Programmable Drum

One of the unusual features of the out-of-production Programmable Drum Set was its use of touch switches for control. Like most touch switches, these detect the difference in the capacitance of a plate when it is being touched by a finger versus the parasitic capacitance of the plate alone. The capacitance added by touching the plate is…

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