SUNMAY Portable Wireless 20W Bluetooth Speaker With Power Bank Function Review

SUNMAY AJ-91 Speaker main

Image copyright belongs to Shenzhen Hutianmei Technology Co., Ltd

The SUNMAY Portable Wireless 20W Bluetooth Speaker With Power Bank Function was kindly provided to me by Senmei Technology free of charge in exchange for a fair and unbiased review on and No additional compensation was given in exchange for posting this article on my blog.

The SUNMAY Portable Wireless 20W Bluetooth Speaker With Power Bank Function is available in the UK from in Silver, Black or Gold at a cost of £46.99 with all options being Fulfilled by Amazon. In the US the speaker is available from in Silver ($53.99), Black ($54.99) or Gold ($53.99) with all options being Fulfilled by Amazon. (Prices correct at time of posting).


To enlarge an image and view its description, please click on the image.



The SUNMAY Portable Wireless 20W Bluetooth Speaker With Power Bank Function comes supplied within retail style rigid cardboard box with quite a thick clear plastic sleeve over the box to protect it. Inside you will find…


The speaker wrapped in plastic and is further protected with a cellular foam surround insert on either end. Underneath the speaker is a small instruction leaflet in roughly translated English as well as Chinese.


Also within the box there is a basic quality 3.5mm Male to 3.5mm male audio cable that is black and round and there is also a USB A to Micro B cable, also basic, black and round.



The speaker measures taken at its greatest points…

173mm wide, 61.39mm high (including silicone base pad, but excluding buttons which slightly protrude at the top) and 52.76mm deep. The speaker buttons each measure 14.96mm in diameter.


The USB A to Micro B cable measures 72cm long (excluding connectors) and 2.8mm in diameter. The 3.5mm male to 3.5mm male audio cable measures 41.5cm long (excluding connectors) and 2.75mm in diameter.



To connect the speaker to your phone or tablet simply hold the speaker power button (on the top far left) down until there is a spoken audio prompt in a well pronounced English accent saying “Bluetooth player” and the other three buttons on the top of the speaker begin flashing blue.

Enable Bluetooth on the device that you wish to pair with and the speaker will show up as “AJ-91” on the Bluetooth device list. Simply tap “AJ-91” and within a few second the speaker will be paired and ready to use. There is a vocal prompt saying “Bluetooth connected” and three of the buttons on the top of the speaker continue to flash blue at the same rate. (Rather annoyingly these lights always flash).

The speaker does not require a password to pair and there is no mention of such within the manual. Should you wish to add a pin to the speaker to prevent unauthorised access, it is not difficult to do so. (The process differs depending on your version of Android, but is usually accessed via the small settings icon next to the device within the Bluetooth menu).



When testing indoors with a direct line of sight the greatest range I am able to test is 8.5m which the speaker handles without problem.

Testing with no line of sight I placed my Samsung Galaxy Note 10.1″ on a shelf at a height of 1.2m at the front of our house. I walked into the dinning room with a stud wall obstructing the speaker at a distance of 5m the speaker continued to work. I then entered the kitchen the speaker now obstructed by a stud wall and a solid pine door at a distance of 8m the speaker still continued to work.

I then entered the utility room with the speaker obstructed by 2 stud walls, a solid pine door and various white goods (a tumble drier that was inactive and an active washing machine and freezer) at a distance of 8.5m the speaker still continued to work. I then proceeded to exit the house into a back porch (leaving the back door open) and the speaker continued to work without impairment for a further 3.5 meters and even then it didn’t cut out totally it just started to cut in and out occasionally.

That’s an effective range of about 12 meters through 2 stud walls, a solid pine door and a wall of white goods. When it comes to range the SUNMAY AJ-91 is highly impressive. Further testing with a single, double brick wall did limit the effective range to about 5m.



A USB Type A Male to USB Type B Micro Male cable is supplied to charge the speaker. The charging port for the speaker is found on the right edge of the speaker behind a large non removable white silicone flap. Sadly, there is no charge indicator on the speaker, but there is however an audible warning when the battery is nearly dead.
There appears to be a slight degree of uncertainty about the size of the battery in the AJ-91 speaker. The Amazon product listing and manual claims a capacity of 4400mAh yet the box states 4000mAh. Some further digging on the net would imply that the battery is indeed 4400mAh.

When the speaker is switched on and paired it never enters standby, if the speaker is not paired it switches itself off after about 10 minutes. How long the battery will last during playback for the most part depends on the volume that it is used at, when used at around 30% to 50% playback time of at least 25 hours is entirely achievable.

When charging the speaker via a Samsung 2 Amp wall charger the following readings were obtained using a DROK multimeter.

5.01 Volt, 3.463 Watts, 0.69 Amps.

Timed testing over 20 minutes the speaker battery charged exactly 230mAh, without knowing the exact level of charge before starting this test sort of makes it irrelevant as the higher the current capacity of the battery the slower the rate at which it charges. As such, just consider it a guide as the capacity was unknown at the time of the test.

In an unmonitored test the speaker took between 6 and 7 hours to charge from dead to full using an Anker 40w 5 port USB wall charger.



Located alongside the Micro B port for charging the speaker there is a USB A output port which offers a power bank feature to charge your phone, tablet, headphones or even other speakers. When using the speaker to charge my Samsung Galaxy Note 10.1″ tablet the following readings were obtained using a DROK multimeter.

4.97 Volts, 2.286 Watts, 0.46 Amps.

The charge of the tablet was 75% at the start of the test and after 33 minutes the tablet had been charged by 270mAh. It should be noted that during the charge the battery icon on the tablet had a red cross through it indicating that it insufficient power was being provided to charge the battery properly.

Double checking the tablet with the official charger confirmed there was no problem with the tablet or the battery and during the charge test with the speaker the battery capacity of the tablet had risen to 78%.

A second test, this time with an old Samsung S2 that had a flat battery gave readings of…

5.03 Volts, 2.213 watts, 0.44 Amps.


Again the speaker was offering insufficient power to properly charge the phone with a warning icon shown on screen. After 30 minutes of charging the multimeter indicated that the phone had been charged exactly 200mAh. Switching the phone on it showed a charge of 10%.

I think a fair statement would be that the power bank function is serviceable, but slow and that given the low output it isn’t going to be much use with Apple mobile devices.



The speaker is encased within a square shaped tube made from a single piece of aluminium that measures exactly 0.99mm in thickness. This metal has a satin silver finish that has a few points of detraction from an otherwise premium looking speaker.

Firstly the ends of the aluminium tube are a little roughly finished, the right edge has 4 clearly evident cut marks and 5 small dents and the left edge is so roughly cut it is frankly littered with too many cut marks to count. When looking straight and level at each of the ends of the speaker it is also clearly evident that the back edge of the aluminium frame on the right side is very slightly concaved inwards which it notably isn’t when looking for the left edge of the speaker.


The top surface of the aluminium appears to have a front to back, faint brushed effect which notably none of the other surfaces have, I do not know if this is by design but it does look a little mismatched.


On the front of the speaker there are 90 holes in the aluminium frame each measuring 5.20mm in diameter arranged in a 18 by 5 pattern. Behind these holes you will find the metal speaker grille that is painted white. I am glad to report that the edges of each and every one of these holes has been slightly rounded off and there are no rough edges to be found.

The rear of the speaker is entirely smooth with no features to be found, on the underside is a 16cm x 3.7cm silicone pad that is marginally over 1mm in thickness. This has a decent non slip capability, but more importantly protects the aluminium frame from any surface it is placed on and vice versa.


Curiously the silicone pad on the underside isn’t entirely flat, there are at least 6 tiny little dimples that are raised on the surface, it would appear that under the pad there is something causing lumps in the padding. Regardless of this the base is entirely stable on any flat that it is placed on.

On the left end of the speaker is a white silicone edge around the aluminium frame and a white silicone end cap with a grid pattern. The edging around the frame isn’t secured to the frame and can be pulled away with a fingernail and there are some slight gaps around the edges. The end cap isn’t entirely accurately aligned, there is no noticeable gap on the right side but there is on the others.

On the right end there is an identical silicone surround on the inside edge of the aluminium frame with a far more prominent gap evident in the top right corner. There is also a matching end cap, but there is a small pull tab with indented lettering stating “open”. The silicone cover on this side is actually a non removable flap that is secured to the speaker providing access to the various ports.

Using your fingernail push the tab upwards to gain access to the ports behind.


On the inside edge of the flap there are two protrusions that actually serve to fill the Micro B and 3.5mm ports which more than anything serve to keep the flap securely in place and prevent unintentional movement.

There are two points of note regarding the flap and ports.

  1. With the speaker sat on its base the ports are actually aligned facing the front speaker grill, it’s a minor point but they are mounted sideways.
  2. The hinge for the flap is at the top of the speaker and the two retainers are rather short. This does mean you have to hold the flap open with one hand while trying to put your cable or memory card in with the other hand. This does make it a little awkward and even put unnecessary strain on the flap hinge. It’s a shame the hinge isn’t on the back or bottom edge.



When a MicroSD card is inserted into the speaker it automatically switches to the relevant playback mode. The supported formats are unknown, but I believe the speaker to only to support MP3s. Personal testing with a 16GB Sandisk Ultra memory card using MP3 files that were located in the root directory worked fine but WMA and WAV did not.

Tapping the play previous / play next buttons change the tracks, although there is no support for playlists or randomising. (Holding play next turns the volume up and holding play previous turns the volume down).



Some speakers with a MicroSD card support allow you to plug the speaker into a PC to enable direct transfer between a memory card installed in the speaker and the PC connected to. Sadly, in the case of the SUNMAY speaker it does not, plugging into a Toshiba S70-B-10N all that happens is the speaker begins to charge.



The first test is to compare 235kbps Amazon tracks to some of my own 320kbps tracks. Few budget speakers highlight the difference, but given the price point of the AJ-91, 320kbps tracks should sound superior.

The track for testing was George Ezra, Budapest.

@ 235kbps the track sounded slightly tinny and somewhat laid back lacking depth.

@ 320kpbs (using the same volume obviously) the track was notably warmer and more filling and exciting. Bluetooth vs Aux in. (When a 3.5mm audio cable is insert the speaker it automatically switches to Aux In playback mode).

When the speaker is used in Bluetooth mode within 1m of the speaker there is a faint hiss from the speaker that is only detectable when there is a break in the audio. When music is playing at a volume of 30%, this is only detectable within 30cm. With normal use unless the speaker is sitting right in front of you the hiss is most of the time, undetectable and it never has an effect on audio quality.

Unfortunately the same cannot be said when the speaker is used via Aux In. When music is played through the speaker from either my Note 10.1″ or Moto G 2nd Gen the hiss is amplified by a magnitude of two or three times, so much so that it affects the quality of the audio output.

I tested Aux In playback through the speaker using the bundled cable, an Ibra and an IXOS cable and the result each and every time was the same. The noise level of the hiss is completely unavoidable and totally unbearable.

All is not doom and gloom, however. Yes Aux In playback is to be avoided and when playing audio via Bluetooth there is a detectable hiss close up with a low volume. However place the speaker about 1m away and turn the volume up (there is no detectable distortion at higher levels) and your ears will be rewarded.


The following tracks I could not find fault with

Dido, No Freedom 320kbps

Fugees, Killing Me Softly, 320kbps

Train, Hey Soul Sister, 320kbps

George Ezra, Budapest, 320kbps

Sam Smith, Lay Me Down, 320kbps

P!nk, Try, 320kbps

Carol King, Tapestry, 320kbps

Alisha’s Attic, Stone In My Shoe, 235kbps


The following tracks out of those tested notably did not sound as good as others.

ELO, Mr Blue Sky, 320kbps – A little underwhelming lacking depth.

Queen, Play The Game, 235kbps – Slightly tinny, lacking depth.


On one final note regarding audio quality is that the speaker very much needs to be placed directly onto a firm hard surface, if you fail to do this it has a serious detrimental effect on the bass quality of the speaker.

Out of the 20-30 speakers of this style / size that I have reviewed this clearly stands above all others. Side by side with my Sony SRS-BTM8 however, it just doesn’t compare, obviously such a comparison is unfair but it does put things into perspective.



The following testing was conducted with a call to my mother on her Panasonic KX-TGJ322EB land line and the speaker was held with the grille facing me at a distance of 30cm. Mother advised that I sounded perfectly loud and clear as though I were speaking from a land line.

This is a very impressive result and quite possibly the best microphone of any speaker that I have tested. Usually in such tests, even holding the speaker within a few centimetres of my mouth, she claims I sound very quiet and distant almost like I were in a large tunnel. Such a result at a distance in perspective is very good.

There is, however a slight problem. Every time mother spoke, she received feedback of her voice and there was an echo of what she was saying through her handset. This again is a first and not something that we have ever noticed before when testing such speakers. The microphone is brilliant but it’s placement, perhaps isn’t.

The audio quality of mother’s voice through the speaker was ok, in fairness “ok” might be being a little harsh. It was largely as good as my Moto G 2nd Gen handset speaker, but there were noticeable frequent patches of distortion or interference. I was at all times entirely able to hear and understand what she was saying, but the performance not what one would expect for such a premium device.



One of the main reasons for starting this blog was to enable me to post certain information that Amazon would never allow me to such as what follows.

The SUNMAY speaker is an OEM rebrand that is made by Shenzhen Hutianmei Technology Co., Ltd who are based in Guangdong, China and have been in operation since 2014. The speaker is available wholesale for $18 to $27 per unit depending on the number ordered. There are obviously additional costs such as shipping and rebranding as well as Amazon Fulfilment to factor in.

I will freely admit that my experience is lacking when it comes to such matters, leaving me unable to make comment on whether the SUNMAY speaker represents good value in comparison to the costs involved. It would however be worth shopping around as you are likely to find the identical speaker available form numerous other sellers under a different brand with different packaging and even different model numbers.


Thank you for taking the time to read this review, I hope it has been helpful to you. If you have any questions or comments regarding this review, please post a comment below and I will do my best to answer them.


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2 thoughts on “SUNMAY Portable Wireless 20W Bluetooth Speaker With Power Bank Function Review

  1. Thank you for this accurate review. I have ordered 2 of these at GearBest (not branded as Sunmay but as AJ-91) for 29.55€ each, I haven’t received them yet. I bought them for teaching purpose (primary school) and should buy 2 others now they are in stock again. I suppose it won’t compare to my own Bose Soundlink colour I currently bring at school, but it’s a start 🙂


    • Ludivine while the audio quality of the AJ-91 is easily worth the price you paid I have to confess to having mild concerns about the build quality (the issues are rather evident in my pictures) I also believe it is more suited as a personal audio solution in a small room such as a bedroom rather than a listening group in a large room such as a classroom. Ludivine, I am guessing from your email address that you are based in France, if this is correct and you are able to cancel or return your order I would very much like to offer to send you as many speakers as you need for your class, they sadly would not all be the same make/model but it would at least save you some money, especially if you are paying for them out of your own pocket.


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