[Josh] wrote in to tell us about an experimental instrument he’s been working on for a couple of months. We’re glad he did, because it’s a really cool project. It’s an organ that uses the principle of back-drive—applying torque to the output shaft of a motor—to create sounds. [Josh] is back-driving four octaves worth of stepper motors with spinning wooden disks, and this generates alternating current. At the right speeds, the resulting sinusoidal waveform falls within the range of human hearing and can be amplified for maximum musical enjoyment.
[Josh] built this organ from the ground up, including the keys which are made from oak and walnut. Each of the forty-nine stepper motors has a corresponding wooden disk. The larger the wooden disk in the stack, the higher the resulting pitch. [Josh] says that if he built it for a full 88 keys, the highest note’s disk would be sixteen feet in diameter.
This stack of disks is driven independently by a separate DC motor, and the speed determines the key it will play in. When [Josh] plays a note, that note’s lever is actuated and its stepper motor makes contact with its disk in the stack. When they meet, the motor is back-driven by the spinning disk. In other words, they work in concert to produce some cool, eerie sounds.
Here’s a somewhat similar sort of build made from lasers and fans, if you consider that both instruments create music from objects that weren’t built to do so. Watch [Josh] play his stepper organ after the break. He has several build videos on his YT channel, and we’ve also embedded the one that covers the motor, power, and electronics part of the build.
Continue reading “An Organ Made from Back-Driven Steppers”
Here’s a short film made by the Hammond Organ Company with the intent to educate and persuade potential consumers. Right away we are assured that Hammond organs are the cream of the crop for two simple reasons: the tone generator that gives them that unique Hammond sound, and the great care taken at every step of their construction.
Hammond organs have ninety-one individual electromagnetic tone wheel assemblies. Each of these generate a specific frequency based on the waviness of a spinning disk’s edge and the speed at which it is rotated in front of an electromagnet. By using the drawbars to stack up harmonics, an organist can build lush walls of sound.
No cost is spared in Hammond’s tireless pursuit of excellence. All transformers are wound in-house and then sealed in wax to make them impervious to moisture. Each tone wheel is cut to exacting tolerances, cross-checked, and verified by an audio specialist. The assembly and fine tuning of the tone generators is so carefully performed that Hammond alleges they’ll never need tuning again.
This level of attention isn’t limited to the guts of the instrument. No, the cabinetry department is just as meticulous. Only the highest-quality lumber is carefully dried, cut, sanded, and lacquered by hand, then rubbed to a high shine. Before it leaves the shop, every Hammond organ is subject to rigorous inspection and a performance test in a soundproofed room.
Continue reading “Retrotechtacular: Building Hammond Organ Tones”
It was about ten years ago that [Richard] received an old musical organ. Moving to a new house meant it would be cumbersome to move the organ with him, so he opted to harvest some interesting components instead. Specifically, he kept the Leslie speaker.
A Leslie speaker is a special kind of speaker mechanism that creates a tremolo effect as well as a vibrato effect. You can hear this effect in [Richard’s] video below. Simple effects like this would be easy to do on a computer nowadays, but that wasn’t the case several decades ago. Before digital electronics, musical effects were often performed by analog means. [Richard’s] Leslie speaker is a small speaker behind of a Styrofoam baffle. The baffle spins around the speaker which changes the reflection angle of the sound, producing the musical effect.
[Richard] tried hooking this speaker up to other musical instruments but found that turning off the electric motor created an audible pop over the speakers. To remedy this, he build a simple “snubber” circuit. The circuit is just a simple 240 ohm resister and a 0.05 uF capacitor. These components give the transients a path to ground, preventing the pops and clicks when the motor is powered up. Now [Richard] can use this classic piece of audio equipment for newer projects. Continue reading “Organ Donor Gives Up a Leslie Speaker”
What do you do if you’re in a band and have an old, dead organ lying around? Build a MIDI foot controller, of course.
After dispensing of the old organ guts, [Mark] mounted the pedals in a handsome road case and started working on the electronics. His first inclination was to mount an Arduino Pro Mini on a piece of stripboard, but after that failed decided to learn Eagle and fabricate a PCB. each key of the organ pedals are connected to a switch read by the Arduino which sends data to a Korg Microsampler over MIDI.
The swell pedal from the organ was also reused, but because the old incandescent light in the pedal was toast, this was replaced with an LED. It still works, allowing [Mark] to do volume swells on his new, fancy, MIDI foot controller.
You can check out a video of the controller below.
Continue reading “Tearing apart an organ and making a MIDI keyboard”
[Michael] loves this old organ of his, but recently he wondered if it would be possible to add MIDI out without altering its original functionality. With a bit of research and more than a bit of hard work he accomplished his goal.
The nice thing about working on a quality piece of hardware like this is the resources you can find regarding how they work (which we bet is tailored for how to repair them when they break). [Michael] found a website with plenty of info on the circuit boards and how they work. From this he was able to locate a few chips which stream serial data regarding which keys have been pressed. Bingo!
Once he located the three signals he was after he built a board to translate them to the MIDI protocol. His circuit is based around an ATtiny2313. It is supported by a liner voltage regulator circuit as well as a buffer chip which converts the incoming signals to the 5V levels needed. His home etched board is clean and well mounted, and the success of the project can be heard in the clip after the jump.
Continue reading “MIDI out for a Korg CX-3 organ”
Since his string bass player isn’t always around [Antoine] built his own electric bass stand-in using the pedals from an old organ. The project — which he calls the Organ Donor — was inspired by a similar standalone organ pedal bass project. That instrument was built using a 555 timer to generate the sound. But [Antoine] has a little more room for growth as he’s using an old microcontroller development board to generate sound.
The octaves worth of pedals were pulled from an old broken Yamaha A55 Electone organ. After extracting the assembly from the instrument he built a nice wooden case around it. This doubles as a stand for the amplifier which broadcasts the sound. An old Freescale development board is wired up to twelve of the keys (the top C is unused). It generates a square wave at the appropriate frequency for each key. This signal is fed through a low-pass filter before being routed to the audio jack on the back of the case.
Future improvements include building an amplifier into the pedal assembly. We would also love to see different signal processing to expand the range of sounds the pedals can generate. We’re not sure of the capabilities of that microcontroller, but it would be neat to hear tone generation using stored samples.
[Jon Ferwerda] managed to fry the analog electronics on an old electric organ while conducting some circuit bending experiments. It’s a loss, but he’s still left with some cool equipment to play with. Recently he got to work generating tones using the organ’s foot pedals.
There were two types of foot pedal included with this organ, the set that is arranged like a keyboard, and a rocker pedal similar to what you might use with an electric sewing machine. Since the music generation was handled by those fried bits of organ [Jon] got to work interfacing the foot keyboard with a 555 timer. He used a fairly large capacitor to get the frequency into the bass range and wired individual pedals to different parts of a resistor network. But he didn’t stop with that. The rocker pedal has its own variable resistor hardware which lets him bend the pitches are they are being generated which sounds alike like a guitar whammy effect. He shows his work in the clip after the break. We think he nailed it! This is a perfect supplement to any type of electronic music setup.
Continue reading “BaceMaker weds organ foot pedals with guitar whammy effects”