ThinkPad Stack Professional Kit delivers on interoperability and portability, disappoints on speed

Lenovo announced in January 2015 at CES the ThinkPad Stack series of accessories. The products use a unique arrangement of magnets and tiny rubber feet to align the pogo pins that transmit power and data through the stack, allowing the entire stack of accessories to charge from one cable, or operate from the Stack Power Bank.

The full line of Stack products include the aforementioned 10,000 mAh Power Bank (MSRP $69.99), the Bluetooth speaker (MSRP $99.99), and the Wireless Router / 1 TB Hard Drive kit (MSRP $219.99), all of which can be managed using Android, iOS, or from a (desktop) Windows program.

The big focus of the ThinkPad Stack is portability — the four components together weigh just under 2 pounds, and have a footprint of 5.3 x 2.9 inches; as such, it's very convenient to toss the Stack into a bag and go. The ThinkPad Stack is quite good at interoperability — it does not require any other Lenovo hardware to operate — providing a variety of interesting ways to use this with other hardware.

Stack Bluetooth Speaker

The Bluetooth Speaker comes with a 3.5mm cable and USB 2.0 A to micro-B cable for direct charging. The battery internal to the speaker is reported to work for 8 hours, though not at full volume. There is also an embedded microphone for phone calls or voice chat, which works well (just remember to speak into the microphone for optimum audio quality).

For playback, the audio quality is good, with caveats — it uses two 2W speakers, which is understandable considering the form factor, but distortion occurs in music that was already mixed poorly. The best example of this is "Some Might Say" by Oasis — the mastering is very center-focused, with the vocals barely distinguishable above the instruments, which completely meld together, a situation not helped by the reliance on dynamic compression. This is particularly problematic at higher volumes on the Stack Bluetooth Speaker, where studio headphones like the Sony MDR-7506 do not have an issue, though it is not a direct comparison.

Listening to speech — such as the TechRepublic podcast — is very clear, as is other music with less original distortion, and the total volume is certainly adequate to fill an entire room. The only points of concern are that the speaker lacks NFC (a standard feature on Bluetooth speakers in this price range), and that the red LED hidden in the letter "i" in "ThinkPad" blinks about every hour when it is turned off. The blinking "i" is a peculiar behavior that seemingly cannot be turned off — the manual indicates that "The red dot is a signal to inform users that the whole stack is in a healthy power supply status."

Stack Power Bank

The Power Bank is convenient to have for the rest of the stack, as it extends the power of the Bluetooth speaker to 48 hours on a single charge, and allows the router to operate without relying on electricity from the mains, which, depending on the circumstances, can be very useful. Upon plugging in my phone (a 2013 Moto X), it started charging immediately without issue, and it has enough capacity to charge the phone several times. The Power Bank comes with a USB 2.0 A to micro-B cable to charge the unit, or to connect other items for charging.

The battery has four LEDs on the front to indicate the current level of charge remaining in the battery; this works well, and is easy to understand. Unfortunately, this does not translate to the Stack Assist app — it provides the entirely useless statuses of "Charging" and "Discharging." The logic already exists inside the Power Bank to determine the charge level for use with the LEDs. When used in conjunction with the Wireless Router, it should be able to pass — at a minimum — the battery life percentage to the Assist app. Considering Lenovo's positioning of the ThinkPad line, and the Stack in particular as intended for professional users, providing access to advanced status information like rate of discharge (in mAh) that normal users are unlikely to care about would be a welcome addition here.

Stack Hard Drive

The Stack Hard Drive is a 1 TB Seagate ST1000LM024 (PDF) in an external enclosure with USB 3.0 mini-B connector. (Of note: The drive has 16 MB cache, though the specification sheet from Seagate only indicates 8 MB.) Connected to my ThinkPad W550s using the included cable, I was able to get a sustained read and write speed of 110 MB/s when transferring 1 GB files. Using the benchmarking tool in GNOME Disks with 10 MB samples, the average read rate was 89.1 MB/s, the average write rate was 67.6 MB/s, and the average seek time was 17.05 msec, averaged over 1,000 samples.

There are no screws on the enclosure, making replacement of the drive likely impossible. As a standalone drive, it is completely adequate, though the primary purpose of it is for use in conjunction with the Wireless Router.

Stack Wireless Router

This is the focal point of the Stack series of accessories, as much of the additional features of other Stack components rely on the Wireless Router to operate. The Stack Wireless Router requires the use of a Windows program or Android/iOS app to configure passwords and settings, though after the initial setup, it is possible to switch to a web-based management system, which is remarkably straightforward and feature complete in the number of management options available to the user.

The advanced management system allows for the manual tuning of Wi-Fi settings for the 2.4 GHz and 5 GHz networks, including channel number, channel width, among other settings, and firewall configuration, which includes port, ip, mac, and url filtering, port forwarding, creation of a DMZ, and custom VLAN settings.

The router is capable of connecting through Ethernet, USB LTE dongles, "Dial-up" (this menu item is for PPTP/L2TP connections), or by connecting to an existing wireless network. Additionally, it can act as just an ad-hoc network for users to connect to the Stack Hard Drive. It appears the USB dongle compatibility is determined by a hardware whitelist, for which the original firmware only supports three Huawei USB modems released in China. If you plan to use the Stack with USB modems, check with Lenovo for compatibility.

The router is very convenient, particularly for traveling — having consistent Wi-Fi credentials while on the go saves a great deal of time when joining networks, especially if multiple devices are involved. A battery-powered router has interesting potential use cases, such as providing internet access (by use of a USB modem) in construction sites, which do not have a functioning or complete internet infrastructure, though this requires the use of a whitelisted modem.

The router only utilizes 10/100 ethernet — not Gigabit—which limits its usefulness as a primary router in places such as small apartments in urban areas where fiber-to-the-premises is both a realistic and an affordable option.

Additional notes

Although no particular compatibility with Linux is claimed by Lenovo, everything generally worked as expected. Reformatting the hard drive from the factory-standard NTFS to ext4 worked perfectly — connecting it to the router afterward, it was still possible to access the data via DLNA on external devices such as the Nexus Player.

The bottom line

For a first-generation product, it is very well put together — the build quality is as solid as comparable ThinkPad notebooks, and the strategy of reducing the number of cords needed seems like an appealing one. Also, it holds up well to specific use cases and compatibility with Linux.

Some hardware limitations — particularly the lack of gigabit ethernet — make this a somewhat more difficult recommendation, though presently, a large percentage of the US is not able to utilize the speed increase that would accompany that change, due to poor ISP speeds. Another consideration is price — this form factor comes at a premium, and Lenovo's release pricing is higher than the announcement price at CES.

Overall, I like the kit and plan to purchase one — if the issues I mentioned are ironed out.

Disclosure: Leonovo sent me a test unit for this review.

What's your view?

Is a cord-reduced, stackable product like the ThinkPad Stack appealing? Can you think of a particular use case for the ThinkPad Stack — or, for an additional feature or stackable component? Share your thoughts in the comments.

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