Classic Amp Revived With A Pi

July 5, 2022 by Jenny List 4 Comments

Guitar amplifiers have a hard life, and as anyone who’s run a venue can tell you, they often have significant electrical issues after a life on the road. [Dsagman] had a Vox amplifier with fried internals, and rather than repair the original he rebuilt it with a Raspberry Pi inside to provide a fully-loaded array of effects.

Though the subject is the Vox, it’s best to see this as more a tale of how to create a guitar effect array in a Pi than specifically put it in an amplifier. The Pi has an audio board and an MCP3008 ADC added to it, and using those two it takes its inputs from a series of potentiometers and process the audio passing through the audio board. In addition there are a series of LED indicators and an LED bar graph to keep the user in touch with what’s going on.

The whole lot is nicely integrated in the VOX case with all the potentiometers on an aluminium panel. He discusses amplifier choice, but as you might expect the final choice is a Class D module. All in all an amp many readers would probably go for.

As long-time readers will remember, guitar effects have made quite a few appearances around here. Continue reading “Classic Amp Revived With A Pi” →

Busted Wah Pedal Becomes New Synth Tool

July 8, 2015 by Bryan Cockfield 3 Comments

Sometimes we get lucky and find a part we need for a project in our parts drawer. [Scissorfeind] got even luckier and found a part for his project lying around in the street. It was a Crybaby Wah pedal, a classic effects pedal typically used for a guitar. Since it was somewhat damaged, [Scissorfeind] got to work creating a control voltage (CV) and volume circuit for his Korg synthesizer.

For those who aren’t synthesizer aficionados, CV is a method of controlling the pitch of a tone. A higher voltage creates a higher tone and vice-versa. The wah pedal has a rocker on it that allows one’s foot to control the effect, but this particular one has been modified for CV instead of the wah-wah sound these pedals normally make. [Scissorfeind] built in a switch that will allow it to control volume as well, which makes this pedal quite unique in the effects world.

[Scissorfeind] built the custom circuit out of other parts he had lying around (presumably not in the street) and put the entire thing together on perfboard, then fit it all back together in the pedal. Now he has a great control voltage pedal for the vintage Korg synthesizer he recently restored! [Scissorfeind] knows his way around a synth, but if you’re looking to get started on a synthesizer project we have a great tutorial for you!

Extrinsic Motivation: An Open, Modular Effects Pedal

September 4, 2014 by Brian Benchoff 18 Comments

Microcontrollers and Arduinos are cool and all, but dealing only in the digital domain does have its limitations. In fact, most of your electron heroes didn’t begin their electronics career by blinking pins on digital outputs; they were solely in the analog domain with their radios and, yes, guitar effects pedals.

[Josh]’s entry for The Hackaday Prize was by far the most analog project of the entire contest. It’s an open source effects pedal that takes advantage of the modular design of the most popular pedals in history.

A good number of the famous circuits for turning an electric guitar into an aural experimentation are based on small circuit modules, packaged and repackaged again until the desired tone is achieved. [Josh] wants to pack these modules separately on different boards, specifically shields, although no Arduino is used, so any sound can be created.

Already [Josh] has done some research to determine what circuits and circuit modules to clone. The list should be fairly familiar to anyone with a pedalboard – Tube Screamers, Fuzz Faces, Big Muffs, and Phase 90s are at the top of the list. He may not get to the complicated digital effects like pitch shifters and digital delays, but it’s still a great project for experimentation.

You can see [Josh]’s project video below.

This project is an official entry to The Hackaday Prize that sadly didn’t make the quarterfinal selection. It’s still a great project, and worthy of a Hackaday post on its own.

Continue reading “Extrinsic Motivation: An Open, Modular Effects Pedal” →

Improving A Cheap Guitar Pedal

November 29, 2013 by Brian Benchoff 12 Comments

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If something doesn’t suit your needs, just change it. That’s a motto we live by, and it looks like [Doug] took up the same creed when he modified a cheap effects pedal.

The victim of [Doug]’s soldering iron is a Danelectro BLT Slap Echo – a tiny, cheap pedal in Danelectro’s mini ‘food named’ pedal series. Stock, this pedal’s slap back echo is set to a fixed amount of time. [Doug]’s mod changes that.

The mod consists of desoldering a single SMD resistor and replacing that with a 50k pot [Doug] had lying around. After mounting the pot between the two stock knobs, the new and improved pedal had a variable length echo. There are a few more mods possible with this pedal – changing some of the resistors on the filter for a better sound, or even connecting the rate pot to a wah-style rocker pedal for some wobbly Echoplex or Space Echo action.

You can check out [Doug]’s gallery of pics here.

Putting Guitar Pedals In A Web Page

October 10, 2012 by Brian Benchoff 13 Comments

Only half of playing guitar – according to a few musician friends of mine – is moving your fingers up and down a fretboard and banging out some chords. The other half is the artistry of mastering your tone, usually through amp settings and stomp boxes.

Effects pedals – little boxes of electronics that go between the guitar and amp – are able to amplify and distort a guitar’s output, add reverb and delay, and even filter the tone via a wha or envelope pedal. These pedals can be simulated in software, but we can’t believe that they can now be emulated completely in JavaScript.

Pedalboard.js is a project put together by [dashersw], and aims to put a slew of pedals ‘in the cloud’ and turn editing and effects board as easy as building a web page.

The project is built around Webkit’s W3C audio API, allowing this virtual pedal board to work in Chrome, Safari, and other Webkit-enabled browsers. Pedals are programmed as nodes, each configurable to have and input, output, or analyzer that is able to modify the gain, wave shape, or filter of anything received by the line in on your computer.

Thee is a small demo of Pedalboard.js available here with a pre-recorded guitar track feeding into a few stomp boxes. It’s a pretty cool idea if you’d like to play around with a few guitar effect, but we can’t wait to see this bit of JavaScript implemented by effects pedal manufacturers allowing us to try before we buy.