Unveiling the Final Design and Production Method for the N40 Music Box Comb's Damper
Muro Box-N40 Update #22
Hello everyone, I’m Dr. Chen-Hsiang Feng, the inventor of the Muro Box.
Regarding the shipping issue that everyone is most concerned about, we are pleased to announce that production has returned to normal. We are diligently assembling every day, so please rest assured.
We understand that many customers still want to know the exact shipping date for their units. However, the truth is that only by reducing the number of emails or messages inquiring about shipment status can we truly improve our efficiency. This will minimize the interruptions to our production team, allowing them to focus on assembly without having to pause and check the status for customer service requests.
Our noise detection has reached a somewhat obsessive level. We conducted blind tests with visiting customers, and most people couldn’t detect any anomalies. However, because our ears have been trained to identify any abnormal sounds during assembly, even a slight irregularity becomes highly noticeable. Once we know what the standard of excellence is, we truly cannot accept sending out a music box with even the slightest imperfection in sound.
Each Muro Box represents the culmination of nearly ten years of our technical expertise, and we will undoubtedly continue to discover new techniques to further enhance sound quality in the future. I know how much you care about this music box, and I approach it with the same level of dedication.
Because we want you to understand the effort we put in, I’m sharing the key to solving the problem here. Although revealing our design details may lead to some losses for the company, consider this as my contribution to the music box community. Perhaps other music box companies might even come up with better solutions as a result.
Explanation of the Damper Issue
We are facing a dilemma with the damper. If the absorption strength is high, the damper itself can cause noise. Conversely, if we reduce the noise from the damper, the absorption strength becomes insufficient.
The following image illustrates this damper structure:
Our design uses a metal spring as a buffer when the pins on the cylinder strike the comb. The “shock absorption capacity” depends on the size of the opening at the front end. A larger opening allows more deformation of the spring, which can absorb more impact force.
However, if the opening is too large, it becomes difficult to control the relative position between the front end of the spring and the front end of the comb, leading to noise.
Simply put, if the damper protrudes too much, it will make the comb too long, resulting in louder sound. This issue is relatively minor—though the sound is louder, it doesn’t reach the level of noise. But if the damper is too shallow, the pin will first hit the damper and then strike the comb a second time after detaching, creating a noticeable noise that is unacceptable.
All of this occurs within a 0.1mm range at the front end of the comb, and don’t underestimate even the slightest noise—human hearing is far more sensitive than vision. This 0.1mm difference is audible.
Past Attempted Solutions
We have previously struggled with precisely controlling the damper’s position to hit the ‘sweet spot.’ Despite improvements to our fixtures and recent attempts to correct the damper’s length through post-processing to achieve the correct position, we still faced a problem with low yield rates.
Each N40 Sublime music box has 44 musical notes containing dampers. Even if the defect rate for one note is just 1/10, the chance of assembling a fully successful N40 Sublime unit in one attempt is (9/10)^44 = 0.00969, or less than 1%. This probability is too low, resulting in a cycle of endless rework, which is the dire situation we faced before.
Note: One N40 Sublime music box uses 4 pieces of 20-note comb, so 1 N40 Sublime music box has 80 comb teeth in total. Only in the lower 11 notes of each 20-note comb has space for installing the damper, so no dampers are installed in the higher notes. Thus, each N40 Muro Box has 44 dampers in total (11 dampers per piece of comb x 4 pieces of comb in one N40 Sublime music box).
Final Solution
The key is to abandon the previous point of contention. Since controlling the position has reached its limits, we decided to address another cause of noise, which is the double impact sound. If the issue is the double impact, we simply need to find a way to make it only strike once. We changed the shape of the damper so that it “cannot” hit the comb anymore.
In simple terms, we made the front end of the damper tilt upwards to “wrap” around the front end of the vibrating plate. This way, the vibrating plate never makes contact with the pin; it is always separated by the damper. As shown in the image below:
This is our final solution. We modified the damper mechanism to suppress the noise caused by the damper itself.
Process of Discovering the Solution
It may seem logical that we found the solution step by step from the problem, but in reality, this solution was discovered by chance.
The true situation involved repeated failures and endless rework, to the point where the production team was on the verge of breaking down. At this time, Mr. Wang from Airwise Ltd. (our metal pressing manufacturer) suggested that we needed to address the problem from its root, so we began modifying the damper mold to conduct new tests. The first test we conducted was based on the design of classical music box arc-shaped steel wires, as shown in the image below. This design failed because the damper itself would vibrate and produce noise after it was hit, and the metal sheet alone was insufficient for shock absorption.
After reporting the test failure, I realized that our original design was actually closer to success. I then proposed a solution to modify the original design by bending the front end at a slight angle, allowing the pin to “slide smoothly” along the damper to the vibrating plate, thus reducing the noise from the second hitting.
However, Mr. Wang misunderstood my description and took the opposite direction, bending it almost vertically, causing the pin to strike directly at the vibrating plate. The test results were even worse than before, with the impact noise almost drowning out the music, making it completely inaudible.
The mold for this test was very expensive, and the results left me in a state of disheartened confusion. It was clear that a single failure couldn’t end the matter. Determined to give Mr. Wang an explanation, I took the new sample and contemplated whether there was any way to break through the dilemma. Eventually, I recalled the repeatedly validated principle that “solutions are often hidden in seemingly impossible methods”: since it already looked like this, why not make it even more protruding and have it wrap around the damper?
Unexpectedly, this incorrect bending angle opened up a completely different way of thinking. The final solution of having the damper enclose the vibrating plate was a fortunate mistake, discovered by accident from a failed design.
Thank you all for patiently following along. We have spent over a year developing the damper. Although it is not perfect yet, we will continue to optimize it. We hope that when you receive the N40 music box, you will appreciate the effort we have put into every detail and provide us with feedback so that we can continue to improve.
Current Shipping Status and Related Notices for the N40
As of today, August 26, 2024, we have accumulated a total of 233 orders for the N40 Music Box across three crowdfunding platforms: Wabay, Kickstarter, and Indiegogo. We have completed shipping 59 units, which is 25.32% of the total N40 Music Box orders. Therefore, any new orders will be scheduled for shipment between the end of 2024 and early 2025.
For customers expected to receive their shipments by the end of September, we have individually notified them to confirm the arrangements and laser engraving details, and to inform them of the estimated total amount for export customs duties so they can anticipate the import tariffs they need to pay. If customers have not responded in time to confirm that they are ready for receiving the shipment or have not paid for the N40 resonance box or international shipping fees, we will skip their shipping arrangement and proceed with the next customer on the upcoming shipping list.
If you have planned to travel abroad soon and are concerned about your package being delivered when no one is available to sign for it, please email us at support@tevofy.com to let us know after which period you would like us to avoid for delivery.
Next: N40 Crowdfunding in Japan
We plan to increase the price of the N40 Music Box on Wabay and Indiegogo in early September. Starting in September, 2024, we will begin advertising on the Japanese crowdfunding platform, GREEN FUNDING, and sales will start in early October. We have signed a contract with the platform, which requires us to launch this year and maintain a uniform global price to prevent Japanese customers from ordering on other platforms due to price differences. Customers who order through the Japanese crowdfunding platform are expected to receive their shipments starting in March next year.
For those who have been considering the N40 for a long time and have not yet placed an order, please remember to pre-order through the Chinese version of Wabay or the English version of Indiegogo before the end of August to secure the current best price! Customers who place orders in August will have to wait until the end of this year for shipment.
