Analog Reverb Unit


This is a spring reverb unit I built using Tombola's spring reverb circuit that I found on I put it in the chassis of my first bass combo amp that I blew up on accident and then added an extra reverb tank with a tank selector switch, and a hinged top so I can mess with the springs. It's a standalone effect, so it works like a pedal in a signal chain.

If you have no idea what I'm talking about: "reverb" is the effect you hear when you yell something in a large room -- the sound gets drawn out/prolonged and fades out. This thing simulates that effect by taking an input signal like an electric guitar, then using that signal to shake some metal springs. Because physics, the springs continue shaking after the original signal has changed or stopped. The shaking of the springs is converted back into an audio signal and then sent out to an amplifier.


The spring reverb tank was invented by Bell Labs at some point and then patented in 1939 by Laurens Hammond for Hammond Organ Company who produced and sold organs to churches, and for the first time, normal households. The problem was that the dumb people in stupid households were expecting the reverb effect you'd get in a huge church, and in a small house you don't get that, so Hammond adopted the invention and put it in the organs to get the same effect and then the stupid idiots were happy. Eventually in 1959 the invention was made smaller, which made it more practical for cooler instruments. Leo Fender started adding them to his guitar amps and it changed the music world forever, like actually -- rock put it on the map with 60's surf, rockabilly, etc., and now it's used in every genre to some extent. Nowadays almost all reverb is digitally simulated -- a microchip processes your input signal and applies an algorithm to it that adds an approximation of the reverb effect. Digital reverb sounds really clear and clean, but it's so clear and clean that some people think it sounds artificial and weird -- similar to the differences between digital audio and vinyl audio, it's that sense of warmth/presence that vinyl offers while digital audio sounds more processed. I'm not an Analog Purist Dick but I was so interested in the concept of the electronic signal being converted to a physical vibration and then back into an electronic signal that I built my own :+)

Technical Info

The basic spring reverb setup is made of a drive circuit, which drives the spring, then after the spring, a recovery circuit to bring the volume back up. For a while when I was experimenting with springs, I had tried several different amps that didn't work, so I found a schematic and then a stripboard version (linked in intro section) that had everything needed for the circuit, including two drive controls, wet/dry, and a tone control. The thing I was missing in my attempts was that the drive circuit needs to be a constant current amplifier rather than a regular amplifier. I built the stripboard circuit with mostly salvaged components, except the power supply, which is a dual supply of 12v -- the reverb circuit needs a +12v, -12v, and ground. I didn't feel like building that so I bought a Velleman K8042 kit and used it with a 120v to 18v transformer I found somewhere (the supply drops some voltage, so 18v in gets you 12v out.)

I had two reverb tanks: the blue one is an Accutronics AMC2BF2 (can't remember if it's the 150 ohm or 600 ohm input one) and the other one is a weird Belton one that I pulled from a friend's old Kustom practice amp. I put in a switch that lets you select one tank, the other, or both. It sounds a lot less muddy than I thought with both tanks at the same time, I couldn't tell ya why. The Accutronics one actually picks up a lot more noise than the Belton one -- I had to move the transformer as far as I could to avoid the 60hz hum, so I put it into an electrical work box, cut the power cord in half and spliced it between the two ends. 

The first Drive knob controls the drive into the reverb tank. The second one (I believe) controls the amount of recovery. These two can be adjusted for different tank impedances, which weren't really an issue for me with this circuit. In the video above I keep the drives pretty high cuz I like the distortion it gives, but if you dial it in carefully you can get surprisingly clean sound. This thing also somehow sounds great with bass! The EQ knob doesn't do anything noticeable for me, so I was going to change it, but I decided I'm fine just using the tone knob on my guitar/bass. 

I used a pedal in front of the reverb in the video because the output level from the reverb unit was too low without it and it sounded shitty -- it's possible the spring wasn't being driven hard enough. A booster at the input of the reverb circuit would be the best improvement to the circuit. 

A fun project! If anyone knows an easier way to do all this, let me know -- I'm still learning all this, but I'm wondering if the circuit could be modified to be powered with a DC adapter instead, it'd be way easier than doing the whole dual supply + mains wiring thing. 

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Sound Scanner

This is a thing I made in Max/MSP/Jitter for an assignment with the idea of translation. The original program took a webcam feed of someone standing in front of a black curtain, scanned the image from left to right, and converted the image data into sound while playing the sound in realtime and projecting the scanning line onto the person's body. The script looks for 4 pieces of data and assigns it to sound parameters: hue translates to panning, saturation to volume, lightness to frequency, and y-position of pixel to index number in the bank of oscillators. In other words, each pixel in a given column makes a sound depending on the pixel's color, saturation, and lightness.

I used this thing along with some feedback samples and a drum machine to make this composition:

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3D Printed Speakers 2.0: the Ear to Hell

The Ear to Hell was my senior project at the UO, the art department's equivalent of a senior thesis. It's an expansion of my last 3D printed speaker project, an effort to make an art tool with a unique voice and tonal characteristics for use in rock-type music production. Compared to my first 3D Printed Speakers project, the Ear to Hell is also intended to be an art object in itself.

Technical differences between this iteration and the first include a larger and more powerful magnet, a smoother material for the coil former, a larger-diameter voice coil, a 2x-larger cone, the addition of a smaller cone, and an acrylic sealed enclosure. These modifications push the speaker's frequency range into lower territory, letting it produce sounds of greater depth than the first speakers.

I built the amplifier specifically for this project but it can be used for other things as well. I wanted to use a clean amp that didn't need a preamp, as opposed to my last project: the HP speaker amp I was using sounded like it was boosted in the low-mids through normal speakers, which is something I didn't want. I put the amp in the case of this antenna-TV sync thing that I found at Goodwill, and I remade the front panel. I used it because it has a tiny internal speaker mounted to the top already, and I thought it'd be cool to make a tiny combo amp out of it that plays out of the internal speaker when no speaker cabinet is connected, but plays through the speaker cab when one is connected. 

The project's intentions are multi-tiered, but aside from being a usable art tool, the project aims to make the viewer question the value of art tools versus the value of art itself. To me, the project's materials are significant: the age-old design of the speaker has been redone with today's modern 3D printing technology and materials. 

Guitar samples by RA Suarez

Featured on

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First Friday Art Exhibitions at The Boreal

During 2014-2015 I organized a series of art exhibitions at The Boreal, the local DIY music space in Eugene, OR. There were four shows total with some awesome up-and-coming artists showing their work to friends and the public. Visitors also bought records and books from the venue's infoshop. All of these artists were personally selected for good reason, so check out their websites linked below!

The first show included work by Miles Bowers, Brinkley Capriola, Katelynn Erb, Saumon Ghaemi, Emma Haskins, and Cole Hersey.

The second show was a collaboration with Sam Krop at the Boreal, an art teacher at a local art high school. There were around 30 of her students in the show (Sam did most of the work.)

The third show was titled "Fragments" and dealt with the theme of fragmentation and any related concepts. The show included work by Rachel Lemme, Stephen Leveckis, Gabriel Lutes, Riley McLaughlin, and Reyn Yeager.

The fourth show was titled "COOL FUTURE" and was about the future, modernity, and/or newness. The show included work by Clara Munro, Johannah Roake, Taylor Wilson, Tanner Henderson, and myself.

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3D Printed Speakers

This is an experiment in inventing a new tone as a tool for musicians. Speakers were invented between the 1860s-70s and have more or less been constructed with the same materials since. There was something interesting to me about reproducing a classic design with a cutting-edge technology and modern materials, so I did that. As the speaker's utilitarian and scientific roles have been fulfilled for decades and are now used as art tools, I wanted to treat them as art tools. The printed parts were done on a consumer-level Rigidbot extrusion printer. There's still development to be done on this project and I look forward to it.

Featured on Adafruit and MakerDiwo

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Empire of Dust

Empire of Dust is a short game I made in Unity 4. It goes in two stages: a representation of life and then an approximation of the afterlife. If you'd like to play it yourself, download it here (PC Only): 32-bit or 64-bit (if in doubt, choose 32). The Mac version that Unity exported crashes every time, sorry!! The video above shows the whole game. 

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3D Model Viewing Interface

This is an experimental 3D modeling interface I worked on in a group project. The idea was to develop a solution to a problem I've encountered: I love 3D modeling, but haven't seen a lot of it in gallery or museum settings, presumably because it's a format we're not used to -- so how do we fix that? This prototype demonstrates a combination of two solutions. The digital version of the object (a 3D-scanned model of the Venus de Milo) is rotated on-screen at (ideally) the same rate as the rotating physical interface, a lazy suzan. There's also a 3D-printed version of the model right in front of the user to give a physical representation of the model file. The model-viewing program has 3 controls: a rotation reset button, a switch to change rendering modes between solid/wireframe/pointcloud, and a switch to increase/decrease lighting on the model.

The artistic part of this project, in my opinion, is about how it calls a material object into question. 3D scanning the Venus de Milo is not an exact copy of the object, as virtual vertices are mapped to various points on the object's surface in order to generate a representation of the object in the form of a mesh -- so even with a high-end 3D scanner, you're going to get an approximation of the original object, with small details coming out distorted or missing. When you 3D print it, the difference in representation is even more drastic because you're limited to the physical abilities of the printer and the material you're using -- for instance, the ABS in the Fused Filament Fabrication printer we used can't do overhanging edges past a certain angle, so certain spots are missing or bulging or otherwise weird. At that point, what we have is a hollow chunk of plastic that resembles the Venus de Milo -- and what's that worth? Aside from that, if you make your own sculpture with 3D software and then print it out, or render the model as an image, which is the piece with the most value?

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Modified Homedics Sound Spa

The Sound Spa is a mass-produced device designed to create 6 soothing sounds to help people relax or go to sleep. So I amplified it, added a speed control and 2 adjustable feedback loops, and switched out the internal 2.5" speaker for a custom speaker cabinet with a 10", two 4"s, and the original 2.5" speaker.

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Arduino Step Sequencer

This is a step sequencer I made with an Arduino. There's 1 button for each step, holding the button sets the pitch of that note. (Ideally each note would have its own slide potentiometer but the Arduino I have only has 6 analog input pins so I had to improvise.) Sliding the potentiometer sets the pitch of the note you're changing. The right knob sets the tempo, and the left knob increases the amount of a weird under/overtone effect I made, which one of my housemates unlovingly deemed the "Clown Funeral" effect. I made this using the freqout function and some debugging help from Beavis Audio's Arduino Punk Console.

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Boombox Guitar Amp

I found this cool portable stereo at a flea market in Santa Cruz for $5. I took it home, took out all the insides, made a tiny Smokey amp and hooked it up to the internal speakers, then added a 9-volt adapter input and 1/4" input, making it a portable guitar amp. It can also run off a 9-volt battery if you want to take it to the beach or swamp.

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