till.com  Articles

A collection of my articles on various topics. Some readers may find them interesting.

Guitar Electronics

A Discrete FET Guitar Preamp
A popular example circuit for a guitar preamp based on a single FET stage.

(In the early 2000's, Googling "guitar preamp" brought up this article first. Now it's number ten or so.)

An FET Preamp Cable
A phantom-powered preamp built into a 1/4-inch phone plug.


Pickups Part 1: Response Effects of Guitar Pickup Position and Width
Analysis, equations and plots of pickup response curves.

Pickups Part 2: Response Effects of Guitar Pickup Mixing
Analysis, equations and response plots of mixes of pickups.

Pickups Part 3: Pickup Response Demonstration Applet
Try it out!  Move pickups around, draw pretty curves.

Parts 1 and 2 were heavily referenced in Paiva, Pakarinen, Välimäki, "Acoustics and Modeling of Pickups", Journal of the Audio Engineering Society, October 2012.

Part 3 has become a little outdated. Java Applets used to be considered the best way to make interactive web pages, but that is no longer the case. Currently Java runs awkwardly or is unsupported in most browsers. There's a modern HTML5 version in the works.

Original Synthesizer Circuits

The Quadrature Trapezoid Voltage Controlled Oscillator
An original oscillator topology features quadrature waveform outputs and graceful thru-zero FM.

Voltage Controlled Duty Cycle Sawtooth Circuit
Some quick notes on a circuit I came up that can morph from a sawtooth to a triangle to a reverse sawtooth with a control voltage.

An Interpolating Scanner Circuit
An alternate approach to Juërgen Haible's interpolating scanner.

Keyboards and Synthesizers

Square Wave Variations New!
Square Waves may appear uninteresting at first...

Moog Synthesizers: Moog Patents
A project to dig up, research, and review all of the patents by Robert Moog and related to Moog synthesizers.

ARP Synthesizers: ARP Patents
A project to dig up, research, and review all of the patents related to ARP Synthesizers.

ARP/Rhodes Chroma: Upgrading the Power Supply ("Nuclear Powered Chroma")
Replace a Rhodes Chroma power supply with a modern switching unit.

Don's Mellotron Page
Mellotron resources, notes, projects, the Mellotronists mailing list and the tale of a restored M400 with Mike Pinder's autograph.

Mellotron/Chamberlin Patent Reviews
Reviews of the Harry Chamberlin Mellotron Patents, as well as the Birotron patents.

Analog Synthesizer Resources
[Outdated] My favorite synthesizer design links.  General, historical, manufacturers, design, schematics, research.

ARP Synthesizers: ARP Resources
[Outdated] A collection of resources for ARP Synthesizers, including the ARP/Rhodes Chroma.

Moog Synthesizers: Moog Resources
[Outdated] A collection of Moog resources.

Hohner Clavinet Resources
[Outdated] A collection of resources for the Hohner Clavinet.

Business and Economics

A New Business Model for the Music Industry
How record companies can actually win big in the next couple decades.