Review: Boox Note Air4 C e-Ink tablet (2024)

Review unit provided by Onyx

The Onyx Boox Note Air4 C is a 10.3-inch e-Ink e-reader tablet released in October 2024. This is a minor update over the Onyx Boox Note Air3 C (reviewed in 2023). The user experience with this new model is mostly similar to the previous model.

As this new e-reader is quite similar to the previous model, I've repeated portions of the review from the previous model below.

Shown below are the key differences between the two models.

The upgrades include an increase in CPU performance (company claims 50% better), more RAM from 4GB to 6GB, better refresh rate, and an "improved Kaleido 3 screen" with "lighter background color".

From what I see online, the company did not list the processor for the previous Note Air3 C (CPU-Z shows SD 665), and there were actually reports of different processors and even battery capacity (3700 vs 4300 mAh).

For this tablet, Geekbench 6 listed 6x 1.71Ghz and 2x 2.07Ghz. CPU-Z listed Qualcomm Snapdragon 750G. DevCheck listed Qualcomm Snapdragon 690 (SM6350).

Bottom line

The Onyx Boox Note Air4 C is a beautiful e-Ink tablet with solid build quality. This tablet is quite responsive by e-Ink tablet standards and web browsing is actually usable. The 10.3-inch display is suitable for reading PDFs, comics and magazines compared to 8-inch tablets. Google Play Store is available so you can install your own e-book store apps. Battery life is decent.

Colours look muted which is not surprisingly for an e-reader. I no longer have the previous model to compare so I can't say for sure if there's any improvement to the colour vibrancy, or if the e-ink gray background is indeed lighter.

Having said that, the colours and gray background look alright to me. From what I can remember, the visual quality looks identical to the previous model.

Downsides. An e-ink display will not have instant responsiveness which is to be expected. Performance is smooth enough though. Main downside is the apps stored in memory has a tendency to quit after some time. Five apps can be opened but when you swipe up to switch to another, some apps would be gone. Interestingly, the increase in RAM wasn't able to store more apps in memory.

Things included

• Tablet
• USB-A to USB-C charging cable
• SIM ejection tool
• BOOX Pen Plus, with cap
• User guide
• Warranty guide

The magnetic flip case protects the front and back of the tablet, but not the sides. There's auto-wake and sleep function.

The flip case is quite thin but well made. There's a magnetic flap that prevents the pen from falling off from the side, and can attach to the back of the cover. The flip case does add some weight to the tablet but you can always remove it to use the tablet alone.

The case can deploy the e-reader horizontally and vertically (shown above).

Design

6.7-inch phone beside the 10.3-inch e-Ink display

The tablet is quite thin at 5.8mm and weighs 420g. The power button has a fingerprint sensor which works fast and effectively.

On the side with the thicker bezels, there's the USB-C charging port, microSD card slot and two stereo speakers with low volume and hollow sound. There's no 3.5mm audio jack so to listen to audio books, it's best to use wireless earphones for best audio quality.

Due to where the USB-C port is, the flip case has to be opened for charging. USB-C port has transfer speed of 230 MB/s (measured).

The bezels are thin except for the one thicker side for your hand to hold. There are no physical page flip buttons so you'll have to rely on the touchscreen to flip pages.

The Onyx Boox Note Air4 C uses a 10.3-inch display with Kaleido 3 technology which supports 16 levels of grayscale (300PPI) and 4096 colours (150PPI).

The company claims this is an improved display with lighter background, faster refresh rate and is able to show off muted colours better.

The 10.3-inch display is a good size for reading PDFs, comics and magazines because text can be presented larger. If you don't read PDFs, comics or magazines often, there's no compelling reason to get a larger display, and you consider an 8-inch e-reader which is smaller and lighter.

One advantage of the larger display is there's space to put the Android navigation bar below with 5 shortcuts instead of using the swipe gestures.

The display has BW resolution of 1860 x 2480 with 300 PPI and 150 PPI for colour resolution.

An 8-inch display is actually more than big enough for just reading text. A 10.3-inch display can show larger text and is good for those with poor eyesight.

Contrast of the text against the gray e-ink background looks good when your room is bright. If you're reading with curtains closed, increasing the brightness to 50-75% would improve contrast greatly. Using higher brightness will drain battery faster, but battery life is good even with the extra brightness.

I don't really have any major issues with the gray of the e-ink background.

This display is so big you can hold it horizontally (there's auto rotate) and display 2 columns of text.

300 PPI text is sharp and looks great. Reading experience is very satisfying.

You can install dictionaries as well.

Shown above is the e-Ink Kaleido 3 display against LCD (Ugee UT2. Obviously e-Ink cannot reproduce colours like LCD displays. The selling point of e-Ink displays is they are more comfortable to eyes for reading, especially for long periods of time. Reading on e-Ink canvas is not very different from reading on paper.

When using a web browser, the scrolling animation is quite smooth and responsive despite the latency. Even Amazon Kindle app's annoying page flip animation looks alright.

Web pages can load fast so I actually don't mind browsing the web (for reading purposes) with this tablet. The larger 10.3-inch screen is about to display webpages quite well, and the text is big. The experience will be still better with reading text than viewing images due to the limited colour support and contrast. Gray coloured checkboxes and radio buttons will not show. Tabs will reload often due to lack of RAM or how RAM is allocated. UI scaling cannot be changed.

To access the e-Ink settings, you can set a shortcut to swipe up from the bottom, or swipe from the top right to show the control panel. I prefer to have the 5-button Android navigation bar at the bottom instead.

The refresh modes available are:

• HD - Good display effect, suitable for general text reading
• Balanced - With slightly heavier ghosting, suitable for thumbing through documents
• Fast - With slight detail loss, suitable for browsing websites
• Ultrafast - With heavy detail loss, suitable for playing videos
• Regal - Minimal ghosting, slightly flickering on dark backgrounds, suitable for light-coloured backgrounds

Reach refresh mode is a compromise between page refresh speed vs amount of ghosting.

The best refresh mode in my opinion is Balanced with slight ghosting and reasonably fast page refresh speed.

There are actually more settings hidden on secondary page of the e-ink settings:

• System Refresh - Automatic full-refresh after dragging and releasing
• Drag to refresh: 1s to 5s
• Page scrolling speed: HD, fast
• Full-refresh by tap count: Specific to the active app. Global setting for this (for all apps) is located Settings -> System Display
• Animation Filter Time: 0 - 3000
• Display Enhancement
• Anti-flicker: 0 - 32

This is how a coloured comic page would look with default settings.

Here's a look how coloured comics look at default settings: 30% dark colour enhancement, 0% vividness enhancement, 0% colour brightness.

This is with 30% dark colour enhancement, 100% vividness enhancement, 0% colour brightness.

This is with 30% dark colour enhancement, 100% vividness enhancement, 100% colour brightness.

The visual difference when increasing both vividness and colour brightness to 100% isn't that noticeable unless you have two tablets side by side to compare.

This is with 100% dark colour enhancement, 100% vividness enhancement, 100% colour brightness.

Increasing dark colour enhancement produces a visible difference but it's not for the better.

The best way to make the colours look better is keep the default settings and increase the front light brightness.

Obviously having colours is better than having no colours. So despite the limited colour support, the addition of colours does improve the satisfaction of reading colour comics or magazines. Hopefully the colour technology can improve soon.

If you don't read comics or magazines, then you won't benefit much from a colour display.

Front light

The front light is quite even. To adjust the front light, you can swipe down from the top right for the slider controls. Or you can go into the settings to set invisible virtual sliders on screen on the sides if you change the lights often.

This is how the warm light looks.

General performance

This tablet runs on Android 13 and has 6GB of RAM and 64GB of internal storage. Most of my e-books are accessed from the cloud so I'm not too worried about storage capacity, but you can always add a microSD card for more storage.

There's some discrepancies as to what the processor is. Geekbench 6 listed 6x 1.71Ghz and 2x 2.07Ghz. CPU-Z listed Qualcomm Snapdragon 750G. DevCheck listed Qualcomm Snapdragon 690 (SM6350).

Overall performance is smooth enough for an e-ink tablet but can't compete with normal tablets obviously. Apps are able to open fast, multi-tasking is smooth, and even web browsing is usable.

Software and OS

Onyx is running their own UI on top of Android 13 and it's a minimalist UI without many features. It's also good to see there isn't much isn't any bloatware.

The homescreen UI now looks like a typical Android tablet home screen instead of having a section tab bar by the left, and there's no option in the settings to change the home screen.

Like most Android tablets, you can swipe down from the top right to access the control panel. Here you can access the E Ink Centre to adjust colour and page settings, and adjust brightness among other settings.

The Nav Ball feature is very useful, You can move the Nav Ball anywhere on the screen, press it and 9 customisable shortcuts will appear. I use this all the time. I use to go to the home screen instead of swiping up from the bottom of the display.

Having Google Play Store makes this tablet so versatile.

With Google Play Store, you can install your own e-book stores and access your existing e-books. You can install cloud storage apps to access your e-books from the cloud. You can install your own web browsers, note taking and drawing apps.

The default reader app NeoReader v3 is quite capable but if there are e-book formats you cannot open, you can install other e-book readers.

Note taking performance

The included pen has a nice matte surface, grooves on the body, and a good grip. The pen uses EMR technology and is not powered by battery and does not require pairing to work with the tablet. There is no side button and no eraser on the back.

The pen is almost cylindrical except for a flat side that attaches magnetically to the side of the tablet.

The pen uses Wacom EMR technology so this tablet can be used with other pens that use Wacom EMR tech too, e.g. Samsung S Pen.

The pen supports tilt, pressure sensitivity and palm rejection. Pen tip is quite firm and has minimal to no movement.

Extra pen tip are not included, but you can buy them from BOOX online store.

The Boox pen is great. However, the pen nibs are textured and may wear down faster on the textured display. To replace pen nibs, I recommend you research how much the replacement pen nibs are vs getting another Wacom EMR pen with more durable pen nibs.

Writing performance is satisfying. The display is laminated with almost no gap between the line and the pen tip. The display is matte textured so there's extra tactile experience when writing with the textured pen tip. Palm rejection works well for apps that support palm rejection. You can rest your palm on the display to write without fear of introducing stray strokes.

If you use the default note taking app, there's almost no latency which is quite incredible.

How colour swatches look with Microsoft OneNote

Microsoft OneNote also has similar latency performance, BUT the experience is different. When writing, the lines will be thin first and the line style will only update after a period of in activity.

For example, if you choose a thick pen, you can write fast and see what you're writing (thin line), the actual thick line will appear later.

Microsoft OneNote is the only third party note taking app that has improved latency. The other apps I've tested with lousy latency are Squid, Bamboo Paper, Inkredible and GoodNotes. That's even if you have enabled ultrafast page refresh.

Drawing performance

Latency with drawing apps is bad. This tablet is not suitable for drawing unless you use the default note taking app for that.

Cursor tracking is accurate. There are no gaps and no overshooting when joining lines.

There's tilt support, and the pencil texture from the default note taking app looks good.

The default note taking app actually has pretty good drawing performance and support for pressure sensitivity.

The anti-glare on the matte textured display is excellent when used under direct sunlight. Unlike other matte textured surface, this anti-glare does not diffuse reflections to make the whole display glaring and blindingly bright.

Conclusion

The Onyx Boox Note Air4 C is an e-ink tablet that looks good, has solid build quality, and rather responsive performance. Reading experience is satisfying on the 10.3-inch display. Page refresh is quite fast and ghosting isn't much of an issue.

This e-ink e-reader is ideal for those who often read PDFs, comics and magazines because the larger display can display text at larger sizes. The addition of colour also make reading coloured pages more enjoyable.

Google Play Store is a huge selling point.

The downsides or limitations would be the less than ideal audio quality from speakers, and the apps kept in memory often quit.

Pros and cons at a glance
+ Clean and simple design
+ Solid build quality
+ Larger 10.3-inch display is better for reading PDFs , magazines, comics
+ Matte textured surface for tactile writing experience
+ Anti-glare is excellent under direct sunlight
+ Visuals are sharp with 300 PPI for BW and 150 PPI for colour
+ MicroSD card slot
+ Power button with fingerprint unlock
+ Pen included
+ Pen is not battery powered
+ Pen supports tilt, pressure and palm rejection
+ Overall performance quite responsive
+ Page flips are quite fast
+ Minimal ghosting
+ Good writing experience
+ Google Play Store included
+ Navigation ball and shortcuts are very useful
+ No bloatware included
+ Rather even front light
+ 8 to 10 hours battery life
- e-ink canvas gray is kinda dark
- Colours could be more vibrant
- No physical shortcut buttons, no volume buttons
- Pen has no side button, no eraser
- Speaker has low volume and sounds hollow
- No 3.5mm audio jack
- Flip case has to be opened to charge the tablet

Availability

You can buy the Boox Note Air3 C from Boox online store.

From Singapore? You can buy it on Shopee SG.