Kingston Duo 3C - magic wand for microSD memory cards

Whatever Jobs is a genius, MicroSD on the phone is awesome. Of course, taking away the possibility of expanding memory from users, Apple has greatly increased the popularity of its cloud services, subscriptions, and expensive versions of smartphones with normal volumes of embedded data storage. Moreover, many vendors picked up the trend, and some time ago, finding a smartphone with a slot for MicroSD was a real epic.

Fortunately, we have USB-OTG and Kingston Duo 3C: maybe not a convenient way to add extra gigabytes to the gadget, like a regular connector, but much more universal.

Memory Cards in Mobile Gadgets

The memory card slot in smartphones is a variable thing. When the built-in memory was expensive, and MicroSD was the only suitable way to establish a sufficient amount of storage - they were used, despite the fashion trends in the market and the aggressive policy of the apple company. Everyone didn’t care about Jobs’s opinion, and the memory card slot was an advantage over iPhones - 2-4 of its own, yes 4-8 added, and a file manager for every taste ... Today 16 GB is the most common size, 32-64 are considered the norm , 128 and even 256 are no longer frightening in their volumes.

Unfortunately, in the world of Android devices, not only memory cards flourished, but also platform fragmentation that accompanied the rapid growth of smartphones. Dozens of competing technologies with minimal differences tried to win a place under the sun in the memory of the device. Applications from year to year continued to gain weight, 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 fast embedded memory has fallen. Some vendors took the path of Apple and abandoned the card reader, others picked up this disastrous trend.

The darkest hours come before dawn. Powerful cameras in smartphones, high-quality audio chips that can truly uncover headphones above average and clearly show the difference between mp3 and loseless formats and voluminous games on mobiles have breathed new life into memory cards. There were new APIs in Android that taught the system to work with external memory as if it was in the phone from the factory: special formatting, file system encryption and integration with the built-in storage device turned MicroSD from an inconvenient crutch into a full-fledged way to expand the capabilities of a smartphone. True, we have lost the ability to read this card on a PC, and it will no longer be possible to use it as a backup storage.


The size of the reader is largely due to the size of the connectors. USB Type-C and Type-A occupy ⅔ space, the rest - the body itself. If the engineers could have made the Kingston Duo 3C even less, they would have done it.

Since the gadget is present Type-C - will work wherever there is such a connector. For phones and tablets, you will need support for the OTG standard (now, probably, everyone has it). Macbooks and other devices earn and so. USB 3.0 Type-A is provided for connecting to PCs and classic notebooks. We tested Kingston Duo 3C on four smartphones, three laptops, one tablet, two computers - everywhere worked without drivers and instantly


The most interesting is speed tests. Since the speed of this thing depends not only on the gadget, but also on the card, it makes sense to test on the fastest of the popular specifications. Previously, memory cards were divided into "classes" (from 1 to 10), now I want the MicroSD XC standard 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, it requires memory cards with double row of contacts, powerful controllers and connection to shared memory at high speed), so for the tests we will use the most common Class memory card 10 / UHS-1, which usually stands in the Olympus mirrorless.

Atto Disk benchmark

We test in the classic ATTO Disk Benchmark utility. Features of the device memory cards make it inappropriate to complete testing (with blocks up to 1 MB so accurately - the results will be near-zero), so let's do an abbreviated version. 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 for the effective result.

As a test platform - a Macbook Pro with Windows 8.1 installed on it in BootCamp - there is no doubt about the speed of its USB 3.0 controller, and there is a built-in card reader to compare with. The flash drive is formatted in the usual exFAT, about 40% of it is occupied by RAW files with photos. To begin with - the results of the laptop itself.

The best result for 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 increasing file size — the effect of the small cache of the embedded 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. Reading speed increased by 10% - up to 95.1 Mb / s at the peak - not much, but noticeable. The write speed showed a much more serious increase - 5.5 (!) Times, up to 64.5 MB / s space . This is similar to the results from 2017, and not something higher.

The stability indicators increased even more: while testing the card through the built-in reader, each pass became worse (the card heated up and did not have time to cool down), the aluminum case of the portable device dissipated heat well - the fluctuations of results from benchmark to benchmark did not exceed 5%.

Mobile phones

The presence of the USB Type-C connector allows you to connect not only to the new-fashioned macbooks with one and a half connectors, but also to mobile gadgets based on Android. For tests, Sony Xperia XZ Premium is perfect - the golden handsome has its 64 GB, connected according to the UFS standard, plus the built-in slot for memory cards, but the main thing is its SoC.

Snapdragon 835 logically must fully support USB 3.0 OTG at full speed. Unfortunately, the recording speed does not set records either on the flagship smartphone or on other models:

However, there is another question, who is to blame. It is unlikely that drawdowns are provided with a slow memory subsystem or a weak processor, rather, no one just steamed on the topic of multi-threaded writing in a simple Android file manager. And there is a little confirmation. Using the Android version of Total Commander made it possible to copy a 3 GB file from the phone in 7 minutes: that is, the write 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 is good at compressing data, a 4K video with 60 frames per second received a bitrate of around 75 MB / s. Not to say that video in 4K @ 60FPS is a common scenario for a mobile phone, however, it is reproduced without the slightest stuttering, which means data transfer from the card is at least as slow as an average laptop.

That is, you can take a memory card, stick it directly into your mobile gadget and quickly send the footage to the editor or save it to the cloud. Encrypted card with music and personal photos at the same time do not have to get.


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

We have a lot of interesting gadgets, great memory and fast drives, which we love to talk about. Kingston's YouTube channel is in full swing with a cool gift contest.

Participate and win. And subscribe to our blog, we promise, it will be interesting!


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