Team Homebrew Synth

Posted on 11 dec 2010 by Webmaster


The blackbachs synthesizer is a device designed for musicians, music producers, DIY enthusiasts, and audiophiles.  The blackbachs is a hybrid synthesizer offering digital control of analog components.  Analog components produce a desired sound many synthesizer musicians and audiophiles connect with.  Audiophiles also describe the sound as natural and continuous.  These particular sounds contain a nostalgic presence that cannot be reproduced digitally.  Bob Moog describes in a documentary that “musicians begin to feel what the [analog] circuits are doing and make contact with the [analog components].  For nostalgic reasons, the most used controls for the blackbachs are analog potentiometers where other controls are rotary encoders.  Interfacing for the analog components is handled through the use of an Arduino Duemilanove development board, which also serves as a waveform oscillator.  The microcontroller sends different waveforms to our analog hardware known as The Buchla Lopass Gate (LPG).  The LPG implements a PWM controlled amplifier, filter, and resonant circuit.   Basic functionality of the blackbachs will be to select different waveforms to be synthesized, switch between different modes of the LPG, adjust resonance, adjust envelope parameters, define and save presets, and switch to different presets. Moreover, full programming capability is utilized with a user control interface in the form of an LCD display.  The target price of the blackbachs is between $250 and $300 per unit, making it less expensive than current feature-heavy monophonic analog synthesizers which are in the range of $180 to $4000. There will be two versions of the blackbachs offered to target musicians, music producers, and DIY synthesizer enthusiasts. The first version is completely assembled and targeted at music professionals and musicians.  The second version is targeted at DIY enthusiasts and includes the components necessary to build the synth and assembly instructions.


Underlying technology

Posted on 27 oct 2010 by Flyynerd  | 


The Lopass Gate was created in 1970 by Don Buchla in the form of the Model 292 Quad Voltage-Controlled Lopass Gate [3]. The Model 292 is a vactrol based circuit that gives the user options to switch from a VCF, VCA, and a setting that takes advantage of both circuits. The electro- optical coupler based circuits in the Lopass Gate gave Buchla his trademark sound due to the natural slewing of the vactrol. This slewing of the vactrol makes the attack soft and has been described as "natural" [4]. Since the advent of the Model 292, variations of the Lopass Gate have enabled resonance control and a dedicated crossfading output [5].

Arduino Microcontroller Development Platform
Arduino microcontroller development systems are based on the Atmel AVR family of 8-bit mi- crocontrollers; these microcontrollers come pre-installed with an Arduino bootloader, which serves as a communication hub between Arduino's software and the AVR's hardware. Because of this, Arduino's software libraries are written in the C programming language and are compiled using avr-gcc and avr- libc, a widely-used compiler and C library for Atmel AVR microcontrollers, respectively. The software libraries provided by Arduino establish the layer of abstraction of programming Arduino systems ver- sus others on the market. The aforementioned Arduino software libraries are available by use of the Ar- duino programming language.

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