Mindset Update - April 2019
The last 6 weeks have been full of surprises and great progress - read on to see our latest prototype batch in action!
Jacob Flood, May 8, 2019
The last 6 weeks have been full of surprises and progress for us. With the hardware team back in Montreal this month, we’re excited to share our latest prototype batch with you – with pictures, explanations, and videos this time.
We’ve received our latest batch of headphones in Montreal, and they’re looking great. We’ve posted several pictures and videos of the product in action below.
We found several minor issues with this batch, which we’ve since fixed. With this successful batch, our next iteration will be a mass production batch. If this batch is successful, we’ll start shipping each subsequent batch, with a ~6 week lead time each – we’re very excited about this.
Our audio and ANC tests came back with very positive results. Due to a supplier issue, we had to change (read: upgrade) ANC chip providers – with the new system, our preliminary ANC tuning shows a 30dB attenuation, which is on-par with other high-end ANC headphones available today.
Finally, we made some tweaks to the industrial design. Next update we’ll be sharing our new app design as well. We’re in the home stretch!
We’ll start this update with good news: we’ve received the latest headphones in Montreal, and they are AWESOME!
In our previous update, we discussed that our goal this month was to validate the latest prototype to ensure there weren’t any major issues. During this time, we successfully validated the main points:
- There are no major issues fitting and wiring the electronics in the headphones.
- The headphones meet our requirement for head fit and comfort.
- The electronics system behaves as expected and meets our EEG signal quality requirements.
- There are no issues tuning the audio and noise cancelling to match our requirement.
With these major validations, we’re excited to put our stamp of approval on the design, and move towards mass production. Having finished units in our hands has been a huge motivator for us – we’ve never been more excited to share our progress with you.
With this successful batch, our next iteration will be a mass production batch. This will come in ~6-8 weeks. If this batch is successful, we’ll start shipping each subsequent batch, with a ~6 week lead time each.
The rest of the update is going to focus on the challenges we faced with this latest batch, and the changes that we made to the design in order to overcome these issues.
Below we’ve included several pictures of the prototypes, in different stages of assembly. We’re incredibly happy with the results.
While there are still a few minor kinks and glitches, these will get resolved in the course of the next few months as we ramp up towards mass production – the difference between minor issues (aesthetic glitches) and major issues (which can scrap the tooling) is hard to overstate. In order to illustrate what we mean when we say “minor issues”, we’ll expand on a few below.
But first, pictures!
ISSUE 1: Headphones cannot be adjusted to full slider length with full ear cup rotation
ROOT CAUSE: The portion of the flat cable assembly that is outside the headphones is too short.
SOLUTION:The length of cable outside the ear cups should be increased
ISSUE 2: Ear cup pushes against the head harder at the top than the bottom, which results in decreased performance and discomfort
ROOT CAUSE: The flat cable creates a force at the top of the ear cup which causes the cup to rotate and lift the bottom of the ear cup off the head, creating a sound leak and discomfort.
SOLUTION: We shaped the cable with bends to reduce cable bending force.
ISSUE 3: When pushing on the bottom edge of the Vol- button, or the top edge of Vol+ button, the button cannot be fully pressed
ROOT CAUSE: The UI PCB prevents the button from being pressed properly towards the edges.
SOLUTION: Adjust the shape of the PCB to allow full button travel when pressing on the far edges of the buttons.
ISSUE 4: Difficult to slide the cable into the slot.
ROOT CAUSE: Slot is too narrow for the custom cable we have made.
SOLUTION: Increase the slot size.
ISSUE 5: Assembly the lower band was difficult
ROOT CAUSE: Space inside upper band is too small.
SOLUTION: We have moved and rotated the printed circuit boards to create more space.
ISSUE 6: There are wrinkles on the fabric of the lower band
ROOT CAUSE:The fabric was wrapped around the lower band when it was flat.
SOLUTION: The fabric should be wrapped when the lower band is already curved so that in its resting curved position, it does not have wrinkles.
AUDIO, ANC, AND MICROPHONES
Before we dive into details, we made a quick video showing some of the audio functionality on the new headphone batch!
One of the big setbacks we had in the past few weeks has been related to the active noise cancelling (ANC).
After assembling the prototypes, we have learned that the manufacturer of the integrated circuit powering our ANC solution decided recently to stop all support for their chip. They will not be manufacturing them anymore, and will no longer be providing support. This was extremely unexpected – especially since the manufacturer we’re working with is a large player in the ANC space.
As a result, we had to work with our factory to switch to a new ANC solution. This gave us a chance to review our ANC design, and decide how to optimize the budget put towards this part of the product. We decided in the end to transition to a more stable and robust integrated circuit, with which our manufacturer is more experienced and comfortable. This comes with the trade-off of a cost increase, which we intend to absorb – we are committed to providing you with uncompromising quality and avoiding further delays at all costs. Since this decision, our manufacturer has integrated and tuned the new ANC solution with our product.
Several comments recently asked what type of ANC we are using. We are using a Hybrid ANC solution - this means is that there are microphones located on the outside of the ear cups (which monitor external noises), and internal microphones located inside the ear cups (monitoring what you ear hears). Hybrid ANC solutions work by integrating all those microphones together to effectively cancel a larger range of frequencies. In the Mindset headphones, there is a total of four ANC microphones, located on the outside and inside of the ear-cups on each side. You can see the locations in the picture below:
Active noise cancelling technology is effective at cancelling low frequencies – specifically, sounds below 1000Hz. Above this frequency, passive noise cancelling (the type you get with earplugs or normal headphones) tends to predominate the isolation. In our preliminary tuning with this new chip, our ANC provides active noise cancellation of up to 30dB at a peak near 200Hz.
We’re incredibly proud of this result, which is on-par with top of the line ANC headphones by Bose, Sony, and Sennheiser. While the final specification may vary slightly, this test validates for us that Mindset headphones will deliver on the premium audio experience we imagined. We can’t wait for you to try it as well.
* * *
In addition to the ANC microphones, Mindset headphones contain two microphones used for speech. Reading through your comments, it became clear to us that using Mindset for voice calls is a high priority for many of you, so we invested some time in optimizing for this feature.
We decided to implement Qualcomm® cVc™ technology to reduce background noise and ensure the voice quality is good during calls. This uses two microphones (where traditionally there is only one), and leverages onboard signal processing to isolate your voice from the background noise. This allows for significantly clearer calls, and less audio disturbance due to office background noises.
You can see the two microphones on the picture below. You’ll notice that the microphones placement forms a line that points towards your mouth when worn – this allows for best performance of the voice enhancement system. While this feature wasn’t initially intended, we appreciate your feedback, and agree that the final product will be better for it.
Finally, we received a few questions last month about our speaker specifications. It turns out, this requires a bit of explanation to contextualize.
It’s no secret that our expertise as a company is neurotech and productivity science, not audio. When we started designing Mindset, as a result, we were quick to partner up with an audio company we knew could live up to our expectations for Mindset – in our case, Onkyo. Through this partnership, we’ve learned an incredible amount about what makes headphones good or bad.
The biggest insight from this process – and also the biggest surprise – was that the driver (read: speaker) you put in a headphone actually contributes very little to the quality of the headphone’s sound. While a bad driver can easily ruin a headphone’s quality, what differentiates a great headphone from an average one isn’t the driver: it’s the tuning.
Currently, we are using very standard, high-quality, 32ohm, 40mm drivers. These are tuned over the frequency range from 0Hz to 20kHz. Alone, these metrics don’t fully encapsulate the sound – higher impedance is not necessarily better. What differentiates one sound profile from the next is the audio tuning – from shaping the mechanical properties of the earcups, to the digital signal processing we do in the headphones mere microseconds before the sound hits your ear.
Building on the explanations from previous updates, we made a quick video showing our electronics stack, and some of the noise tests results we got with this latest batch!
As the design moves to mass production, we’ve been having in-depths conversations with the supplier producing our electrodes about longevity, robustness, and reliability. As they also produce medical grade electrodes, they’ve been able to make several helpful suggestions to improve the design.
As a result of these discussions, we’ve implemented the following two changes:
The electrode plating material was changed from Silver to Gold. While this will slightly increase the cost, the resulting electrodes will last longer and will provide more consistent signal quality over time. Our industrial designer ensured they would properly integrate with the rest of the design, as you’ll see illustrated below.
The electrodes connectors have been changed to snap buttons. This new design will be more reliable over time, and will allow for easy retro-fitting with future electrode designs. For replacement, removal, and future electrode upgrades, this connector will remove several layers of complexity.
We’re happy to have been able to integrate these changes quickly. Read-on below to see what that looks like in practice!
Lastly, as we move forward to the next steps of mass production, we made some final refinements to the industrial design to better match the fabrics and color tones together. These changes reflect the culmination of our work on the colors, materials, and finish of the products that will come off the assembly line.
Our preliminary renders below illustrate the changes - we’re really happy with how the design turned out. In particular, we love how the electrodes integrate with the design thanks to the gold-plating, giving the product a very premium finish!
These changes are being done in parallel to ramping up the production, and do not have any impact on our schedule. We’ll provide fully finished renders (and eventually photos) as the production batches come through. Until then, we’d love to hear any comments you have on the design!
That’s all folks!
Next month we’ll be mid-batch, so we’ll take the opportunity to share pictures of our new app UI, and describe some of the functionality that will be available at launch. Thanks again to those that helped out with the UX interviews and surveys - we’re excited to share what came of it!
If there’s anything you didn’t see in this update that you’d like more info about, please share it in the comments!
Lots of love,
- The Mindset Team