The Xiaomi or Mi brand has been gaining prominence in Asia for providing functional, quality and elegant products at very reasonable prices. Initially focusing mainly on smartphones, they have diversified into power banks, tablets, audio and mobile phone related accessories. In previous reviews and teardowns of Mi power banks, they have made an excellent impression, showing that Chinese products can deliver great value and quality.
The Mi Mini Bluetooth 4.0 Speaker is a fairly new item. You won’t find it on the English website, only on the Chinese site. This is a small, third-of-a-can-of-drink sized mono speaker which is compatible with devices supporting A2DP high quality stereo audio, or hands-free profile (HFP) speaker and mic connections, with connection up to Bluetooth 4.0. It has an integrated rechargeable battery with a rated 12 hours playback time. This unit features AVRCP for remote control of the source, and a 10m Class 2 range, which is common amongst most Bluetooth products. The speaker claims a power output of 3W, which might not sound like much numerically, but is plenty for enjoying some music at reasonable volumes in a room.
These products have become relatively popular lately, and are an inexpensive way to “share” music with your friends for a party atmosphere, and fill a room with sound without breaking the bank on dedicated phone docks, or pushing mobile phone or tablet speakers to their extreme edge of tinniness. While they won’t normally offer you true hi-fi or even stereo sound, they should offer a marked improvement over that of just using phone speakers in terms of sound quality and volume without being too bulky to travel with.
As a bonus, it is also convenient for end users who want to play music with their phone, while using the phone, as it means they can move the phone around without worrying about getting tied in cables.
As is traditional with Mi products, the product came packaged in box with a clean and simple design. The wood-coloured cardboard box is sturdy, and has its two nested halves taped together at the rear to prevent it coming apart in transit. The rear of the box features a label which advertises its main specifications in Chinese.
Cutting the tape and lifting the lid up, we are greeted by the top face of the speaker, which shows a very elegant and neatly fine-cut metal grille, along with the main metal body with a shiny edge.
Looking at the unit, we can already see the driver occupies about half the diameter of the body of the speaker. The exterior of the unit is finished in an elegant matte black metal finish, except for the base which is a matte black plastic, and the “clear” plastic ring in-between which is used for the indicator LEDs. In use, the only visible marking is the Mi logo on the front of the unit.
Removing everything from the box, we can take an inventory of what is included – the speaker, a charge-only USB A to micro USB B cable, a Chinese only user manual, and a Chinese warranty statement.
Unfortunately, for English speakers, there are no English instructions included. However, it is simple enough to use that you should be able to get by with experimentation (or reading the rest of this review).
The underside features the operation buttons and the model and regulatory markings.
Initially, it might seem strange that the unit has the operation buttons as rubber buttons on the underside of the unit – but as it turns out, it’s a great design feature. Provided you sit the speaker on a clean flat surface, this allows you to “touch” the top of the speaker to activate the buttons. For example, to activate the power/play/pause button, you press down on the part of the speaker nearest the Mi logo, and likewise, for volume down/previous track, you press on the rear left of the speaker, and for volume up/next track, you press on the rear right of the speaker. This avoids having any visible buttons and keeps the design elegant. How nifty!
The unit itself is 8cm in diameter, and 5.5cm tall. It weighs 194 grams, which isn’t particularly heavy or light. It feels solid, and doesn’t have any give or creaking in the case when “squeezed”. I am impressed by the build quality and the finish – it really has a high quality simple motif.
I suppose this is the most interesting part – since now we get to find out what it is made out of. How do you get one of these open? Well after a bit of prodding, I discovered there are four screws under the label with the regulatory markings.
Removing the label, and then removing the screws, the unit didn’t want to come apart easily. This seems to be because it was built with some adhesive and “sealing” inside to make the unit partially air-tight. After some gentle prying, we can get the unit open.
On the left, we have the bulk of the speaker assembly. Don’t be fooled – what you’re looking at is not a driver unit – it is merely a passive diaphragm for the speaker chamber which is held together by four more screws and is sealed at the edges to be air tight. You will see inside this later in the teardown. A sealed chamber provides the back-pressure on the speaker that makes it more efficient, but also leads to “resonance” at a particular frequency which results in boominess, muddiness, and a lack of clarity. By having the diaphragm, I believe they can increase the bass response and improve the clarity by not having one resonant frequency but a “band” of resonant frequencies.
On the right, we have the “translucent” plastic disc, which acts as a light pipe for the indicator LED on the PCB to shine out of the edge of the unit. The disc has a hole for the speaker wires to be fed through.
Here, we can see the main PCB which seems pretty bare. Starting from the bottom, we can see the charging connector, and U3 which is a dedicated charge controller for the battery, connected on the other side of the PCB. The Bluetooth is handled by a module which uses the CSR 8615 chipset. A wire is soldered to the antenna on the module and extends to the base to improve the sensitivity of the module. SPI from the module is broken out to four pads just to the bottom of the module. In the middle is a bi-colour high-intensity surface mount LED to provide status feedback to the user. At the top, involving U4, is the speaker amplifier circuitry, which drives the speaker, and to the left, involving U2, seems to be the microphone pre-amp circuitry for the microphone connected at the top left (and glued into the base of the unit).
There are cut-outs on the right side, where two no-brand capacitors are fitted – these are likely for some power conversion circuitry at the rear. I try to flip the board over, but there’s some resistance – it turns out the battery is wedged underneath along with double-sided tape.
From this image, we can see that the Bluetooth module is a Boomtech BT1213. More detailed specifications are available in the datasheet here. Despite using a CSR chipset, it doesn’t seem this product offers the higher quality apt-X codec. The surface mounted switches are visible, which form the “button-feet” of the unit.
The unit’s PCB is dated Week 52 of 2014, making this a pretty fresh unit. The battery is a lithium polymer cell from Kanyo, rated at 1300mAh 3.7V, for a total energy of 4.81Wh. Having thoroughly explored the base of the unit, lets take a look at the speaker chamber itself.
Mi have taken great care to ensure the rear of the speaker chamber is sealed, thus opening this up took quite a bit of careful prying. The sealing is necessary to ensure the speaker performs as designed.
Despite the unit claiming a power output of 3W, the speaker itself is marked 40-12A 3 ohm 5W. This is another great sign as the speaker itself is being operated underneath its maximum power rating, ensuring distortion is kept in control. A great decision by Mi. The speaker itself is somewhat small for the power rating, and that is because it uses a “high displacement” design, where the diaphragm moves significant distances and the cone is held by a foam surround suspension. While these units are generally smaller, they also can suffer from issues reproducing higher frequencies.
I suppose one question more seasoned electronics-minded people would be asking is, why a three ohm speaker? Speakers commonly come in two, four, six or eight ohm designations, so a three ohm speaker is actually pretty uncommon. Well, there’s a good reason for this – as the supply voltage is from a battery, with no step-up circuitry, the maximum power that can be dissipated across a resistive load is given by P=V^2/R.
With a Li-Poly cell, the voltage can be anywhere from 4.2v (fully charged) down to about 3v (discharged). As a result, if we had an ideal rail to rail op-amp driving the speaker, the power output at the discharged state is exactly 3W. Consequently, when fully charged, it theoretically might be able to put out 5.88W.
If they went for a 4-ohm speaker, as they’re very common, at the discharged state, the maximum power the speaker can put out is 2.25W – a whole 0.75W (25%) less power.
Anyway, enough with the diversion – the only way to know how well it works is to test it out!
In use and Testing
How Do I Use It?
Given that the unit doesn’t have an English user’s manual, newcomers may feel a little bit lost. As a result, I might as well give you a few pointers as to how to use the unit:
- Charging: Attach the USB cable to the rear port, and plug the other end into a PC or charger. The ring will have a red glow as long as it is charging, which will turn off as soon as charging has finished.
- Turning On/Off: Press the front power/play/pause button and hold for a few seconds until you hear an ascending chime (power on), descending chime (power off).
- Pairing: The unit is ready for pairing when it flashes alternating red-blue very quickly. On first start, the unit will go into pairing mode. You just need to search for and connect with the device from your Bluetooth device. If an already paired device is available, it will automatically connect (and make a pip sound).
- Connected: The unit will flash a blue flash every three seconds.
- Disconnect: You can do it from your device, or you can press and hold the front power/play/pause button until you hear a quick two-beeps and a return to red-blue flashing. Then you can pair a new device.
- Changing Volume: The volume can be changed smoothly by pressing and holding either the + or – button until the desired volume is reached, or it reaches a limit (and issues soft beeping to indicate it has reached a limit).
- Remote Control: Short pressing the front button issues a play/pause command, and short pressing the – performs a previous track command, whereas short pressing + performs the next track command if supported by your device. Unfortunately, this may occur when changing the volume as well, as the device doesn’t distinguish very well between volume changes and previous/next.
- Low Battery: During playback, the speaker will play a 5 note (low-high-low-high-low) warning signal, and shut-down shortly after.
That’s about all you need to know to get it going and use it effectively.
I had no issues pairing the unit with a CSR-based USB Bluetooth dongle connected to a PC running Windows 7 using the Harmony stack.
I also tested it on an Android phone, and an iOS device. Because it seems the device supports the newer secure-simple-pairing scheme, you don’t even have to enter a passcode. Easy as pie!
Audio Quality and Performance
From a lot of listening to different sorts of music, from radio to CD-quality audio, I was quite impressed with the quality of the speaker. For the price, and for the size, I would have expected some tinnyness, a lack of bass, some mid-range resonance. What I got was mostly none of that. The speaker itself provides a balanced amount of bass, not an overwhelming amount, but enough to vibrate the table it is attached to and use it as a sound board (and in extremes, cause the speaker to start dancing). The mid-range is generally quite present, and clear, with a little dip and muddiness near the upper-midrange which isn’t particularly bad even compared to low-end computer speakers. The treble, however, is much crisper than I expected for a high displacement driver and easily gives even more expensive computer speakers a run for their money.
In fact, it sounded much better than some portable digital radios I’ve tried. Another bonus is that the speaker does play quite loudly. The 3W output is very believable, as it gets loud enough to get heard two rooms away when on full volume. Turning the volume up isn’t a big problem either, as the unit doesn’t sound like it’s straining and the distortion levels are well under control. This cannot be said for many of the low-cost compact units out there.
The chipset is also very much up to the task, when playing silence, only a very faint “blipping” can be heard from the speaker when held directly to the ear. When actually using the speaker, these chipset-induced noises are completely inaudible. Despite not having apt-X codec support, I didn’t notice any particular harshness or artifacts in the audio from casual listening. There were no issues with pairing with a variety of A2DP-capable devices (PC, Android and iOS).
The small-size driver seems to have been well integrated in the design, but the small size does mean that it doesn’t quite “fill” the room with sound as “evenly” as a larger speaker might. Instead, depending on placement, you might have some areas with louder audio than others, and you get the sense of directionality of the source. Of course, you don’t get stereo imaging either with the mono speaker. However, these are all expected issues with small compact portable speakers.
One of the key performance parameters owners will be looking for is to know just how long they can keep the tunes going. Mi claims an approximate battery life of 12 hours, so I put this to the test over several days, listening to streaming radio and my music collection while running experiments and going about my daily work.
When it comes to battery life, I think Mi have gone extremely conservative in their estimate – while I kept my music playing at comfortable volumes to fill a small 3x4m room at all times, I well exceeded their estimates over several listening sessions throughout the week, with the battery only giving out after an astonishing 53 hours and 6 minutes on a full charge! Rest assured, I thought I was losing my mind when it just wouldn’t stop playing but my time logs don’t lie. As a result, it lasted me a whole week of (reasonable) listening without being charged.
Unfortunately, there is no way to tell the battery status during usage, and the low-battery alert chime (a 5-tone chime of alternating low-high-low-high-low) only comes on one minute prior to the unit shutting down. As a result, it’s best to charge the unit anyway, even if you don’t think it needs to be charged.
Recharging the unit via USB is best done with a 1A or higher power adapter, as it is rated for 1A. A quick check of this, using a blue USB Charger Doctor unit shows the Mi speaker taking a stable 630mA in the bulk stage of the charge, and thus a full charge is expected to take between 2.5 to 3 hours. Not bad at all, especially when the play time is considered.
This seems to suggest the design has been very carefully done to use a very efficient speaker design and the newest CSR Bluetooth chipsets which are very efficient especially when receiving from Bluetooth 2.0 or newer radios.
If that’s still not enough for you, it seems the Mi has another trick up its sleeve. Because it uses an external Li-Poly charger chip, it is one of the few units that I’ve encountered that is happy to charge AND play at the same time. This means that you might not need to stop at all! That being said, I have to say that the internal battery is more than sufficient for most users.
I did test the range by taking the speaker outside the house, and the range seems to be quite plausibly 10 meters when used with a CSR Class 1 “50m” Bluetooth dongle. Compared to other “in ear” Bluetooth hands free sets and A2DP clip-on receivers, the range is slightly better, as the Mi is able to work outdoors, and most others have dropped out a few meters before I reach the door. This indicates that its range is good for use across a room, and is generally better than other products of the same class.
In my testing, I did let the speaker sit outside in direct sun for several hours, despite its negative impacts on battery lifetime, and despite the unit getting hot, it did not malfunction. I even sat it in a bathroom as it fogged up from condensation, and it did not faulter at all. I tortured it by turning the volume up to the maximum and playing fairly loud music, and despite “dancing” across the table because of the moving diaphragm mass, it didn’t sound noticeably distorted and it did not fail. It seems the design is very good.
As the unit supports HFP as well, it should be possible to use the unit as a hands-free device. I tested this in the house with the CSR based Bluetooth dongle, and the microphone was very sensitive, picking up my voice easily from a distance of 2m, with three computer fans in the background. The quality is as expected from the “telephone quality” Bluetooth link, and the voice was easily intelligible, meaning you can probably have a good telephone conversation with it.. Again, the attention to design in this unit shows.
A portable Bluetooth speaker isn’t a very difficult piece of equipment to get right, but it seems that Mi has once again shown us how it should be done. The Mi Mini Bluetooth 4.0 Speaker sounds great for its size and price, and plays very loudly with a mostly balanced sound signature. It uses a new chipset from a quality manufacturer, along with a sophisticated speaker rear chamber design with diaphragm. Because of careful component selection, the unit doesn’t distort even at high volumes and is pleasant to listen to. It far exceeds its battery life claims, which is a big surprise, and meets its expected transmission range. The microphone on board is also very sensitive and produces very clear speech, which makes it useful even as a hands-free speakerphone device.
It is very hard to criticise, because it delivers on pretty much everything that matters, while also featuring an elegant and simple design that has a premium texture finish. The only real niggles are the issues that the volume up and down buttons also send next/previous commands over AVRCP, causing you to change songs when you wanted to change volume. I would have to recommend it for your consideration if you’re in the market for a speaker to free yourself from the tinny sound from your phone/tablet.
Of course, if you would like to purchase one for yourself, it’s currently available at AU$32.36 from Gearbest here. Thanks to Gearbest for supplying the unit for review.
I’ve just been told by Gearbest that if you use the coupon code XMBS, you can get it at US$21.09 or AU$27.67 which is handy if it’s not on special. So why not give it a try?