Welcome to the world of craftsmanship
*Project Author: Hillier Productions
My high school project plan was to convert an upright piano into an automatic piano controlled by MIDI.
However, I stumbled upon the reed organ and developed a keen interest in its sound and history from knowing nothing about it.
Thus, I changed my plan to convert the Estey reed organ into a MIDI-controlled reed organ.
First, I will explain what a reed organ is, how it works, and how to mechanically control the keys.
Then, I will introduce its driving electronics. Finally, I will present the software for decoding MIDI and pressing the keys according to instructions.
Step 1: What is a Reed Organ?
A reed organ, also known as a pedal organ, is an instrument that produces sound by vibrating brass reeds. It shares the same sound production principle as accordions and harmonicas, resulting in similar timbres.
Similar to large pipe organs found in churches, most reed organs have several stops that can change the pitch of the sound. Just as a pipe organ has multiple sets of pipes, known as ranks, most reed organs also have multiple sets of reeds that can be opened or closed by changing the stops. Each set of reeds has a unique pitch, allowing for the overall tone and volume of the instrument to be blended by selecting which sets to activate.
If you want to modify your own reed organ like I did, you may want to find a way to automate the opening and closing of the stops using a computer. Otherwise, you will have to do this manually during play or use the same tone throughout.
However, the reed organ I created is quite unique: it has 88 keys like a modern piano. Additionally, it is housed in an upright piano casing, making it visually indistinguishable from an upright piano unless played.
My reed organ has a knob slider on each of the two cheek plates that connect to the second set of reeds internally. This is its only “stop”. The left slider controls the opening and closing of the second set of reeds for the lower half of the keyboard, while the right slider controls the reeds for the upper half of the keyboard. By changing these stops, you can alter the sound of the reed organ since the second set of reeds differs from the first: in the bass range, the second set is an octave higher than the first, while in the treble range, the second set is intentionally tuned slightly differently. The second set of reeds makes my reed organ sound very much like an accordion!
Additionally, there are dynamic expression shutters (not shown). These are essentially large shutters that can cover or expose different numbers of reeds. When the reeds are uncovered, the timbre of the reed organ is brighter and louder than when the dynamic expression shutters are closed. By controlling the air pressure in the reed organ and the position of the dynamic expression shutters, the sound and volume of the reed organ can be significantly altered. My reed organ is equipped with a device called automatic expression, which automatically opens the dynamic expression when the air pressure supplied to the reed organ increases.
Step 2: Overview
This is a large and complex project. Before detailing, I think I should provide an overview of the components used and their purposes. After that, I will list one or more specific steps for each component and elaborate on them.
Please refer to the block diagram above indicating all components of the control system.
(Throughout this tutorial, I will refer to images/charts multiple times. They depict things better than words, as shown below.)
Let’s build from back to front. The keys of the reed organ need to be physically pulled. I installed electromagnets on the guide rails in front of the reed organ’s linkage device to pull the keys from below. We will use Arduino to turn these electromagnets on and off, for which you will need a simple MOSFET circuit to switch high current/voltage electromagnets on and off from the low current/voltage input/output (I/O) pins of the Arduino. To achieve this, I designed a custom printed circuit board (PCB). Each board can control 16 electromagnets. All Arduinos will run software to decode MIDI data (transmitted via Bluetooth) and accordingly activate and deactivate the electromagnets to control the corresponding keys.
The path of the MIDI data stream is transmitted via Bluetooth to the Bluetooth serial communication (COM) port, then to three Arduinos controlling the keys, which activate and deactivate the correct electromagnets to pull the keys.
Step 3: Bill of Materials and Costs
Overall, the cost of this project is about what I expected. Here is a list of all the materials needed for this project:
· A reed organ! As mentioned, I got one for free on Craigslist.
· Electromagnets (ZYE1-0530Z) x95
· 1N4001 diodes x100
· IRLZ44N MOSFETs x100
· Arduino Mega 2560 clones x3
· HC-06 Bluetooth COM port
· 12V 40A power supply modules (PSU) x2
· Custom electromagnet driver PCBs x15
· 220 Ohm resistors x100
· 10K Ohm single in-line (SIP) resistors x15
· Aluminum guide rails 8′ (Home Depot)
· 3.5mm dual terminal blocks x100
· Dupont wires and connectors (not listing each small item)
Additionally, there are some extra costs. First, it assumes you already have basic materials for prototyping, like breadboards, etc. I will also add servo control for the stops, as well as a vacuum engine controlled by an Arduino speed controller and Arduino expression control. I expect this will add about $100 to the project. You may also need hardware MIDI input: I used a Bluetooth serial receiver and software called Hairless MIDI, which sends MIDI data to a standard serial port. If you want to add a hardware MIDI port, buying a MIDI Arduino expansion board or making one yourself will cost about $15.
Step 4: Introduction to the Reed Organ Linkage Device
When a key on the reed organ is pressed, the linkage device allows airflow through specific brass reeds, thereby producing the correct note corresponding to that key.
Please refer to the above image. When the key is pressed, it pushes down on a small rod in the center, which in turn pushes the bottom pallet (a valve) open (as shown in the bottom box of the image). Below the linkage device is a partial vacuum created by the bellows, and when the valve opens, air flows in from the atmosphere, through the reeds flush with the base of the linkage device (the flat wooden block in the image), and then exhausts from the bellows.
Step 5: Removing the Linkage Device
The “linkage device” of the reed organ includes the keys, reeds, all parts between them, and the base where the linkage device is located (essentially a soundboard). To perform any work involving the linkage device, we must remove it.
Typically, I wouldn’t detail such operations because, frankly, if you’re trying to do this project, you should figure out a simple way to remove the linkage device yourself. However, there are some clever ways to assemble all components together to hide screws as much as possible, so I’ll provide a few pointers.
First, remove the back panel. This allows access to the connection points of the front panel to the casing. Remove the front panel and key cover. Then remove the key return bar covered by the front key cover. Next, remove the two cheek plates. They are secured together with a single spiral, a pin, and drilled holes. This is a tricky device; once the single spiral is removed, you can easily pull the cheek plates straight up.
Now, you can remove the various pedals connected to the linkage device, unscrew all screws that secure it to the base, and then carefully place it on a flat surface.
Step 6: Mechanical Modification Part 1: Introduction to Electromagnets!
We will use electromagnetic devices known as solenoids to pull the keys. Although solenoids are a large topic in themselves, at their core, they are quite simple. A solenoid consists of a coil and a metal rod within the coil. When power is applied to the coil, the metal rod, called a plunger, moves linearly.
The above image may clarify how solenoids pull keys better than my written explanation. It is worth noting that this image only applies to white keys. Black keys are more complex because they do not extend all the way to the front of the keyboard; we will discuss black keys later.
I am using ZYE1-530Z solenoids, rated at 1A @ 12VDC. These solenoids are cost-effective for this project (priced between $2.15 and $2.60 each, depending on your purchasing channel and quantity), and they are easy to buy online. I ordered 95 pieces for $220 from a supplier in China, with no shipping fees. Each costs $2.31—not the cheapest, but quite affordable.
If you ultimately do not choose the ZYE1-530Z solenoid, I will briefly outline the process of selecting a solenoid below.
When choosing a solenoid, consider the following points:
· Type: Solenoids are categorized as push, pull, and push-pull. The distinguishing factor is which end of the solenoid can connect to other components. Push solenoids have threaded shafts at the push end, while pull solenoids have U-clips at the pull end; push-pull solenoids combine both. For this project, you need a pull or push-pull solenoid, as we will be pulling the keys from below.
· AC or DC: For this application, we want to use small DC solenoids. AC solenoids are typically used in larger industrial applications.
· Voltage: For this application, solenoids rated at 12V or 24V may be required. Low-voltage solenoids will draw more current and/or may not have enough power to pull the keys.
· Current consumption: You need to check the current rating on the solenoid’s datasheet. The higher the current, the more powerful the solenoid may be, but it also consumes more power, requiring a larger power supply. According to Ohm’s law, if a high voltage is supplied to the solenoid, it will draw more current; if a lower voltage is supplied, it will draw less current. To put it simply, as long as the resistance of the solenoid remains constant, voltage and current are proportional.
· Force: This is one of the most critical considerations. Typically, the solenoid’s datasheet will provide the force, measured in Newtons (N), for each stroke (the distance to the midpoint of the solenoid) at various power levels. The datasheet will also give you a holding force, also expressed in Newtons. This number is crucial for selecting a solenoid suitable for this project. Next, I will demonstrate how to calculate whether a specific solenoid can press a reed organ key.
Calculating the force required to press a reed organ key:
1. First, you need to measure the mass required to press the key quickly on the organ. The tool I used is a coin—it’s a simple, quick, and fairly accurate way to measure small weights.
2. After measuring the mass, convert it to kilograms (kg).
3. The solenoid has a force measured in Newtons, and we have obtained the mass in kilograms that is required to press the key under the influence of gravity. Therefore, we can multiply that mass by the gravitational constant to find the force exerted on the key by that mass under gravity: (Force, N) = (Mass needed to press the key, kg)(9.8m/s)
Now you know the magnitude of the force needed to press the key! Go find a solenoid with a holding force greater than the force you calculated. Ideally, this solenoid’s force needs to be several times greater than the force required for a quick, precise key press.
Step 7: Mechanical Modification Part 2: Modifying Solenoids
The solenoids produce a very loud clicking sound. This certainly does not work for our project. Therefore, we need to modify them to make them quieter.
There are two main locations in the solenoids that generate the clicking sound. The above image highlights these two points in red circles.
The nut (left red circle in the image) strikes the bottom of the solenoid when it comes off. We can easily resolve this issue by removing the nut from the push end of the solenoid. The reason the nut is unnecessary is that the solenoid’s plunger connects to the key, and the key is covered by a key cover. This means the plunger cannot rise any further.
The solenoid’s plunger strikes the bottom of the solenoid from the inside when engaged (right red circle in the image). We need to place something between these two components to avoid metal-to-metal contact when engaging. I used very small heat shrink tubing on the solenoid’s plunger. It is hard to notice, as shown in the image.
After removing the nut and placing the heat shrink tubing, the solenoid now produces a slight thump when engaging, and no sound when disengaging. Previously, the solenoid would produce a harsh metallic click, and the aluminum would exacerbate the situation.
Step 8: Mechanical Modification Part 3: Black Keys!
Unlike white keys that can be pulled directly from the front, black keys are set back compared to white keys (which is evident if you’ve seen a piano keyboard). Therefore, we cannot pull black keys in the same manner as white keys.
My solution was to extend the black keys down to the front of the white keys. This requires significant modifications to the organ’s keyboard, but once assembled, the alteration is completely hidden beneath the white keys.
Here’s how I extended the black keys:
1. I created a channel extending from the side of each black key. I made a jig to speed up and improve this operation; it took only about an hour to process all the black keys.
2. I inserted popsicle sticks into the channels I created. These popsicle sticks must be positioned to extend to the front of the key frame but not reach the front end.
3. I carved out material from each black key’s adjacent white keys so that the popsicle stick extensions could fit between the white keys and move freely.
As shown in the image of the linkage device, the way the electromagnets connect to the black keys is almost identical to how they connect to the white keys, except longer wires are used. This is because the electromagnets are too wide to fit in the same row. Therefore, the black keys have another row of electromagnets beneath the white keys.
Step 9: Installing the Electromagnets
Once you have a linkage device with extended black keys and modified solenoids that no longer click, you can actually assemble them together. My keyboard is exactly 48 inches wide, so I used an 8-foot aluminum L-bracket from Home Depot, cutting it in half to get two 48-inch pieces.
One bracket is used for the white keys, and the other for the black keys. The electromagnet crossbar for the white keys connects to the underside of the key frame, while the other crossbar connects to the bottom of the linkage device base (again, please refer to the images; they illustrate these matters better than I can with words).
The electromagnets have M3 mounting holes, so I purchased 200 3mm M3 bolts on eBay for $8. This is a pretty good deal compared to the $47 price on Aubuchon!
I used a jig on the drill press so that all holes were the same distance from the edge of the L-bracket. I also used a slightly larger drill bit to allow for some movement in the electromagnets later, increasing tolerances.
Step 10: Connecting the Electromagnets to the Keys
Now that the electromagnets are attached to the linkage device, it’s time to connect them to the keys.
Sounds simple? Not quite… We must connect the electromagnets to the keys while ensuring there is no gap between the keys and the electromagnets. Any gap will lead to metal striking each other, creating noise, and will also result in inconsistencies felt when playing manually. Remember, we want to minimize the impact on the linkage device as much as possible.
I designed a clever method to connect the keys. Please refer to the images; they clarify it better than a written description.
White Keys:
First, drill two holes on each key: one from the bottom of the key upwards about halfway, and another from the left side of the key inwards about halfway. These two holes form an L-shape inside the key. See the above image.
Now, you can bend a segment into an L-shape and glue it to the key. Just bend it into an L-shape and stick it in! Note that you may need to widen the holes to secure the segment in place.
Next, cut a small segment of wire for each electromagnet (about 1/2 inch), and insert it as a pin into the U-clip. Then bend it into an L-shape so that the U-clip of the electromagnet is equipped with a pin.
Now place the key back on the key frame and align it so that the wire is in the right position (directly extending down to the electromagnet and internally passing through the pin). Mark the position where the wire coming from the electromagnet passes through the pin. Slightly bend the wire below that point so that it extends outward from the front of the keyboard.
Now place the wire into the U-clip of the electromagnet, ensuring its bent part is directly beneath the “pin” made from the wire. Pull the electromagnet forward so it faces down. However, if you pull it too far, it will create a gap, which we want to avoid. If you do not pull it far enough, the solenoid’s plunger will experience excessive friction inside the solenoid, causing it to jam the key. This situation should also be avoided. So you need to bend the electromagnet’s plunger into this optimal position.
Black Keys:
The process for handling black keys is essentially the same as for white keys, except the segments are longer and attached to the popsicle sticks. Check the above images to see how they are attached to the popsicle sticks. These images are self-explanatory.
One point to note about black keys is that you can adjust the tightness of the electromagnet’s plunger by bending the pull wire forward or backward. This is great because you can do this without removing the plunger, while you cannot do this with white keys.
Step 11: Control Electronics Part 1: Introduction to MOSFETs
So now we have solenoids that can pull the keys. Yay!
However, we still have no way to control those solenoids with Arduino to make meaningful music. This is where the MOSFET comes in. In short, a MOSFET is a special type of transistor that can switch larger voltages and currents on and off. In our application, they essentially act as switches controlled by another electronic device, which in this project is the Arduino.
MOSFETs have three pins: Source, Drain, and Gate (abbreviated as S, D, G). When you apply a voltage above a certain threshold to the Gate, it “turns on” and allows current to flow from the Source (-) to the Drain (+).
The attached diagram shows the simple circuit we will use for each solenoid. As you can see, it also includes a few other components. Here’s what each component does:
In short (again), the diode protects the MOSFET from voltage spikes generated by inductive loads like solenoids. R2 is a pull-down resistor that ensures the solenoid is turned off when disconnected from the Arduino for any reason. R1 is not necessary; it is a current-limiting resistor that ensures the MOSFET does not draw too much power from the Arduino and burn out its pins.
So now we just need to make 88 of these circuits!
Step 12: Control Electronics Part 2: MOSFET Driver Board
Making 88 circuits on a breadboard or perfboard is unprofessional and impractical; it is not a good long-term solution. Therefore, I designed a PCB that can turn on and off 16 solenoids.
Additionally, this PCB has two extra MOSFETs—each controlling the total power for 8 channels. They were originally intended for a PWM power control mechanism, but that was not implemented as there was no demand for it. So now, just pull up the gates on these two MOSFETs. Alternatively, you can save some MOSFETs and wires by soldering jumpers between the Source and Drain holes (the bottom two) on these two MOSFETs. If you take this approach, you won’t need to install these two MOSFETs.
The first image above is the circuit diagram for half of the PCB. The two halves of the circuit are identical. The second image shows the PCB design itself, and the third is a test component on the printed circuit based on the design to ensure reasonable spacing between components.
If you want to make these yourself, please refer to the attached Fritzing design file. Note that I actually did not solder the MOSFETs; they are push-fit; the holes in the file are too small for the wires to pass through. If you want to solder the MOSFETs, modifying this is not difficult.
The materials I used were manufactured by FirstPCB.com. They did a great job, and the price was cheap: it cost $50 to have it shipped to my door via air mail in 2 days (which turned into a week due to customs…).
If you are making these parts yourself, you will need to order copper that is thicker than the default thickness. I chose 2 oz copper; the copper you use cannot be below this standard. If you want to activate all keys on the driver board, the circuit will quickly burn out because a solenoid consumes 1.3A of power. Dividing the driver board into two parts and widening the traces as much as possible mitigated this issue, but the problem still exists. Note: Do not attempt to play a MIDI file that presses all keys at once.You may burn out your driver board.
Please refer to the attached images to understand the other manufacturing settings I applied (screenshot of my FirstPCB.com order page).
Step 13: Control Electronics Part 3: Soldering the MOSFET Driver Board
I developed a very efficient soldering process for the driver boards: I came up with this method about a second after soldering the first two points. Even so, soldering these 6 driver boards took me several hours.
The trick to quickly soldering them is to solder the shortest components first, then the tallest components. I also used an assembly line approach to solder: for example, solder all the resistors to the 6 driver boards first, rather than completely assembling one before starting the next.
The order I soldered the components was:
1. 220 ohm resistors and a single 10K resistor
2. Diodes
3. SIP resistors
4. Terminal blocks
5. Pin headers
Then you can place the driver board into the MOSFETs. Since the holes were not large enough, I did not solder them, just pushed them in. This way, I can easily replace the MOSFETs, as they are the most likely components to randomly fail.
Note: As I mentioned in the previous step, you can omit the two vertical MOSFETs and solder jumpers between the bottom pins instead. If you take this approach, you won’t need to connect the Dupont wires to the “5V” pin (as marked on the driver board) and won’t need to install the MOSFETs at the jumpers.
Step 14: Wiring Part 1: Installation
Now that all components are ready, it’s time to assemble them and connect all components!
I will mount all control electronics (Arduino and driver boards) onto a 4-inch wide circuit board, which is as long as the linkage device. Now we can easily handle the control electronics (when the linkage device is outside the casing).
This part will ultimately be installed at the bottom of the reed organ casing (in front of the player’s knees). This allows us to more easily perform maintenance on the control electronics while also providing a simple way to remove the linkage device.
There are also two large power supplies that need to be installed somewhere. When the linkage device is not in the casing, I place them on either side of the linkage device. When the linkage device is installed in the casing, they are placed beneath the casing (see images, especially the ones in the next step).
All Arduinos and control boards can be mounted using wood screws and nylon standoffs.
Step 15: Wiring Part 2: Electromagnet Wires, Power Wires, and Power Supply
First, you must connect 88 pairs of wires from the electromagnets to their respective terminal blocks. The electromagnets are non-polarized, so it does not matter which wire connects to the positive and negative terminals. Additionally, ensure that you skip the power input connections when connecting the electromagnets (refer to the driver board pinout diagram above to understand what I mean).
Next, connect the power wires from the power supply to the driver board. I placed these power supplies at either end of the control electronics. The left three driver boards are powered by the left power supply, while the right three driver boards are powered by the right power supply. Dividing the driver boards and supplying them separately enhances their current-carrying capacity. Ensure the power wires are neatly laid out and of appropriate size. Each wire can power up to 8 electromagnets, thus 8 x 1.3A = 10.4A. This is quite a current, so do not skimp on this part. I used 14Ga. (gauge) automotive wire; it may be overkill, but it was on hand.
Since the power supply is hardwired AC, you need to connect the AC power supply. I installed a light switch on one side beneath the keyboard for the two power supplies (as shown; ignore the USB port, which was the port I added before the Bluetooth was included) and ran a standard three-prong device power cord from that switch box. This results in a wiring setup that looks both nice and professional, and it allows you to easily turn the instrument on or off with the switch.
Step 16: Wiring Part 3: Dupont Connectors!
Now you need to connect the control board to the Arduino. We will use Dupont cables to do this. These are small crimp connectors that can be installed in housings with different numbers of pins. Each Arduino uses pins 22-53 as output pins (except the last one, which uses only pins 22-37). These pins are located on the bottom pin header of the Arduino, which is a 2×18 specification. Unfortunately, the 2×18 pin header is a bit hard to find, so you can use a 2×20 Dupont connector housing like I did. On the driver board, you need a 2×10 Dupont connector housing. Refer to the driver board pinout diagram to figure out which outputs correspond to which inputs, then go ahead and insert the Dupont cables. The cables simply push into the housing.
Besides the driver board cables, we also need to connect our MIDI line and power to all the Arduinos. For this, I used some old telephone wire (4 wires). The red wire inside the telephone line connects to the +12V of the power supply and the VIN pin of each Arduino. The blue wire connects the ground of the PSU and the ground pin of the Arduino. The yellow wire is used for MIDI data transmission, connecting to the TX pin on the Bluetooth receiver and the RX1 pin on the Arduino.
Once you have completed these connections, you can move on to the software part!
Step 17: Arduino Code
The operating code for the reed organ is quite simple. It uses the following code to decode MIDI data:
http://forum.arduino.cc/index.php?topic=22447.0 (thanks to Arduino forum user leKuk), while controlling the corresponding digital pins.
The only differences in the operating code for the three Arduinos are their pin numbers and the “offset” between the MIDI note numbers they respond to.
This is the latter half of the playNote function on Arduino 1:
Here, the “offset” is 1: the electromagnet connected to the key corresponding to MIDI note 21 connects to pin 22 of the Arduino. Therefore, based on the given MIDI note, we must add one to get the correct Arduino output pin.
By changing these offsets, we can alter the MIDI range that the Arduino is set to respond to. Since the three Arduinos control different parts of the organ, their offsets differ.
Step 18: Programming the Bluetooth Module
Now that the three Arduinos are running the software, the Bluetooth module is not set up yet, so it cannot receive MIDI data.
The default communication speed of the HC-06 is 9600 baud. This is too slow for MIDI. The baud rate I have always used is 38400, which is the closest speed to the actual MIDI baud rate (31250).
To change the HC-06’s communication speed, we must set it to AT mode. This is a somewhat detailed process, especially if you do not have a USB to TTL converter/cable (if you don’t have one, you can use an Arduino). I won’t explain exactly how to do this; you can visit the following link and follow the HC-06 instructions: https://www.instructables.com/id/AT-command-mode-o…
Remember, our goal is to set the baud rate to 38400 and (optionally) set the name to your liking.
Step 19: Software and Sending MIDI to the Software
To be able to actually play any files received, you need to install a software called “Hairless MIDI Bridge”. This software pulls MIDI from the system bus or program output and sends it through the serial port you select.
I use a Mac, and once you pair with the Bluetooth module (the key is 1234), it converts to a standard hardware serial port (I’m not sure if this applies to Windows or Linux; I haven’t tested that). Then we open the Hairless MIDI bridge, select that serial port (it usually shows as “/dev/name-DevB”, where “name” is the name you set for the Bluetooth module in the previous step), select the input system bus (on Mac, it’s “IAC System Bus”) and enable the bridge. Be sure to set the baud rate to 38400 in the Hairless-MIDI preferences menu.
Now you can use any MIDI playing software, and to output, select the system bus bridged by Hairless-MIDI. The software I use to play MIDI files is Aria Maestoso or Rondo. Rondo has been officially discontinued, but if you email the developer explaining your project, he might still provide you with a license key. I want to publicly thank the developer: he is a very nice person who gave me a license for free.
Step 20: Pressure Regulator Based on PID Control
I am currently working on a pressure regulator or controller that can be driven by a vacuum cleaner. ~~This instrument will be showcased at Maker Faire on September 23-24, and I really hope to have a finished product by then so I won’t have to spend 5 hours each day pumping it up with a foot pump.~~ Edit: The instrument has been exhibited at the aforementioned Maker Faire. The following may read as if it has not yet been exhibited.
Vacuum cleaners typically lift a water column of about 60 inches (a measure of pressure). Depending on the required volume, the reed organ needs about 2 to 5 inches of water column pressure to operate. Clearly, we need to significantly reduce the pressure from the vacuum cleaner. During testing, I removed a belt from the front end of the bellows and wedged the vacuum hose into the hole at the front. I then wrapped it tightly with duct tape and opened the remaining holes to achieve the correct pressure. This “controlled” leak system works well, so I will use it to control the pressure in the reed organ.
I made a box with holes the size of vacuum tubing on both ends, a narrow opening at the top, and a lid that can slide open and closed via a servo system (see above images). One hole connects to the vacuum cleaner, and the other connects to the reed organ. When the top slider opens, more air will flow through the top narrow opening rather than the reed organ, thus reducing the pressure on the reed organ. When the slider closes, the situation reverses, increasing the pressure on the reed organ. Basically, I can also control the volume of the entire instrument via MIDI. I haven’t actually connected this system yet, but I will complete it within the next week to meet the Maker Faire exhibition.
Another thing I planned to do at some point is create a stop-changing device so that I can control two stops via MIDI. The effect of changing stops on the sound is significant; once I have them under my control, the entire instrument can be uniformly MIDI-controlled.
In fact, I did manage to servo-drive a single stop long ago, but I did not permanently install them because I was eager to get the keys playing.
Have a great day, and thank you for reading this lengthy article! If you have any questions or want to do something with this tutorial, please leave me a message.
Step 21: Further Exploration
At some point, I plan to create a stop-changing device so that I can control two stops via MIDI. The effect of changing stops on the sound is significant; once I have them under my control, the entire instrument can be uniformly MIDI-controlled.
In fact, I did manage to servo-drive a single stop long ago, but I did not permanently install them because I was eager to get the keys playing.
*Feel free to share on social media. If you wish to repost, please indicate the source and the original author.
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