Kingston Duo 3C – wand repair for MicroSD memory cards

Whichever Jobs was not a genius, MicroSD in the phone is cool. Of course, having deprived users of the possibility of expanding memory, Apple has greatly increased the popularity of its cloud services, subscriptions and expensive versions of smartphones with normal volumes of built-in data storage. Moreover, many vendors picked up the trend, and some time ago to find a smartphone with a slot under the microSD was a real epic.

Fortunately, we have USB-OTG and Kingston Duo 3C: maybe it's not such a convenient way to add a gadget of extra gigabytes, like a normal connector, but much more versatile.
Memory cards in mobile gadgets

A slot for a memory card in smartphones is a thing of a variable. When the built-in memory was expensive, and MicroSD were the only suitable way to install a sufficient amount of storage – they were used, despite the fashion trends in the market and the aggressive policy of the apple company. Everyone did not care about Jobs's opinion, and the memory card slot was an advantage over the iPhones – 2-4 of its own, yes 4-8 add, and the file manager for every taste … Today 16 GB is the most popular size, 32-64 are considered as the norm , And 128 and even 256 do not scare their volumes anymore.

Unfortunately, not only memory cards thrived in the world of Android-devices, but fragmentation of the platform, accompanied by rapid growth of smartphones. Dozens of competing technologies with minimal differences tried to win their place under the sun in the memory of the device. Applications continued to gain weight from year to year, and the functionality of memory cards did not develop in any way, which aggravated the existing problems associated with the placement of data in smartphones. In addition, the price of a fast built-in memory dropped. Some vendors have followed the path of Apple and abandoned the cardreaders, others have picked up this disastrous trend.

The darkest clock comes before dawn. Powerful cameras in smartphones, high-quality audio chips that can really open headphones above average and clearly show the difference between mp3 and loseless-formats and voluminous games on mobile breathed new life into memory cards. There were new APIs in Android that taught the system to work with external memory as if it were in the phone from the factory: special formatting, file system encryption and integration with the built-in drive turned the MicroSD from an uncomfortable crutch into a full-fledged way to extend the capabilities of the smartphone. However, we have lost the opportunity to read this card on a PC, and it will no longer be used as a backup storage.


The size of the reader is mostly determined by the size of the connectors. USB Type-C and Type-A occupy ⅔ places, the rest – the body itself. If engineers could make the Kingston Duo 3C even smaller – they would.

Since the gadget has Type-C – it will work wherever there is such a connector. For phones and tablets, the OTG standard will be required (now, probably, everyone has it). MacBooks and other devices will work well. For connection to PCs and classic notebooks, USB 3.0 Type-A is provided. We tested the Kingston Duo 3C on four smartphones, three laptops, one tablet, two computers – everywhere it worked without drivers and instantly


The most interesting is speed tests. Since the speed of this piece depends not only on the gadget, but also on the card, it makes sense to test it on the fastest of the popular specifications. Previously, memory cards were divided into "classes" (from 1 to 10), now I want to standard MicroSD XC with a new data transfer protocol. The new UHS protocol is divided into three classes 1, 2 and 3: they are backward compatible (newer cards will work in older devices at lower speeds). Unfortunately, now most of the gadgets use UHS-1 (since UHS-2 is more expensive, requires memory cards with a double row of contacts, powerful controllers and connection to shared memory at high speed), so for tests we will use the most common Class 10 / UHS-1, which usually stands in the mirrorless mirror Olympus.

Atto Disk benchmark

We test in the classic utility ATTO Disk Benchmark. The features of the device memory cards make inappropriate full testing (with blocks of up to 1 MB so it is exact – the results will be near-zero), so we'll do a shorter version. We test the card with an array of 1 GB on files from 4 to 32 MB. All tests will be performed five times, the "average" run will be taken as the effective result.

As a test platform – Macbook Pro with Windows 8.1 installed in it – in the speed of its USB 3.0 controller, there is no doubt, and there's an integrated card reader, it will compare . The flash drive is formatted in a regular exFAT, about 40% of it is occupied by RAW-files with photos. For starters, the results of the notebook itself.

The best result for the reading is 86 MB / s the record is a modest 11.4 MB / s . At the same time, the graph shows how the read and write speeds decrease with the increase in the file size – the effect of the small cache on the built-in controller affects. Now we insert the USB flash drive into Kingston Duo 3C and repeat the test with the same parameters.

The difference is obvious. Speed ​​ reading increased by 10% – to 95.1 MB / s in peak – not much, but noticeably. The speed of record also showed a much more serious increase – in 5.5 (!) Times, to 64.5 Mbps space . This is similar to the results of 2017, and not something higher.

The stability indicators grew even more: if with the testing of the card through the built-in reader each run was getting worse (the card was hot and could not cool down), the aluminum case of the portable device was good for dissipating heat – the oscillations of results from the benchmark to the benchmark were not Exceeded 5%.

Mobile phones

The presence of the USB Type-C connector allows you to connect not only to new-fangled macbooks with one and a half connectors, but also to mobile gadgets based on Android. For tests, the Sony Xperia XZ Premium perfectly suits – the golden handsome has its own 64 GB UFS + connected built-in memory card slot, but the main thing is its SoC.

Snapdragon 835 by logic of things should fully support USB 3.0 OTG at full speeds. Unfortunately, the recording speed does not set records either on the smartphone-flagship, or on other models:

However, there is another question, who is to blame. Hardly drawdowns are provided by a slow memory subsystem or a weak processor, rather no one was simply floating on the topic of multithreading in an unpretentious file manager running on Android. And to that there is little confirmation. Using the Android version of Total Commander, it was possible to copy a file of 3 GB from the phone in 7 minutes: that is, the recording speed was about 7.1-7.2 megabytes per second.

But with the speed of reading everything is in perfect order "out of the box". The .h264 codec can compress data quite well, a video in 4k format with 60 frames per second received a bitrate in the region of 75 MB / s. Not to say that the video in 4k @ 60FPS is a common scenario for the mobile phone, but it is reproduced without the slightest stuttering, which means that the data transmission from the card is at least not slower than in the average laptop.

That is, you can take a memory card, stick it directly into your mobile gadget and quickly send the footage to the editorial office or save it to the cloud. An encrypted card with music and personal photos will not be obtained at the same time.


Kingston Duo 3C is a great little helper in everything that concerns transferring information from the device to the device. Send photos from the camera, take a copy from the smartphone, transfer the video to the tablet and mount it, and so on, and so on. Places do not occupy, it connects to new and old gadgets (and with the adapter MircoUSB Type-A on Type-C – so also to smartphones of past years), the reading speed is higher than many built-in readers. In general, if you ever needed such a thing, you probably already are looking for where to buy it.

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