Including images for 2 separate projects using the same components. First project used a 2500mAh battery. The 2nd attempt used a gutted 3xAAA battery case with a 1500mAh battery to make it smaller to better fit into the sleeping mask. They only provided 1 Battery connector and 1 JST connector (product image misleading) so it's forced upon you to solder or buy another JST connecter which might delay your project, unless you have spare JST connectors laying around. Update: I purchased a 2nd unit and it came with 3 cables as shown in the product image. This board uses beeps for BT connection. No cheezy Engrish prompts. Eventually I desoldered all the JST connectors and replaced the capacitor with a new one laid on its side. I wanted as low profile as possible. I wish the capacitor was laid on its side to begin with. Even better would be an SMD only version with through holes for soldering to make it as low profile as possible. This board was already low profile but I wanted it slimmer. Update: The absolute slimmest it can be is about 9mm-10mm (both sides total height) with a new capacitor laid on its side. The only thing that gets warm on the board is the LED. Super bright blue blinking LED is very annoying. While paired during idle or max volume it's barely warm and holds that temp indefinitely, good enough for a wearable. We'll see about longevity since I do plan to use this daily. Don't try to reuse hair thin 32 gauge repurposed headphone wire with it. It'll get hot from the resistance. Use 22 gauge or thicker wires. If your board heats up it's user error. Found out the hard way. I had absolutely no problem with connection or hum. Unlike other bluetooth modules this one does not suffer from noise or hum, it has excellent audio quality. The only thing I don't like about this board is that upon pairing it automatically starts playing music on my phone without asking. It doesn't even open a music app. Music just comes out of nowhere. I have no idea how they do that or why. It's a bit disconcerting. The DWCT14+ is perfect for bluetooth headphone projects. The Adafruit 328 battery (2500mAh) & Adafruit 259 charging board work awesome with the DWCT14+ They remained stone cold through the entire process. Very impressed with the adafruit components. I used 32 Ohm .25W speakers. Yes they're plenty loud. You don't need 8 Ohm 2W speakers on your ears. ;) For a bluetooth headphone project that's all you need to make DIY 40+ hour bluetooth headphones. Read more

Not bad but this is a pain in the ass if you disconnect from it and leave it on after a while it will shut off and not turn back on until you unplug it and leave it for about 2 minutes then plug it back in then it will turn back on The original unit that was in the speaker box could be left plugged in for ever and you could connect to it anytime without having to touch it Read more

Great product, would recommend to electronics hobbyists. Perfect for DIY projects. Read more

Comes handy Read more

Summary: Great value for a dual mode, USB + Bluetooth audio module. Good performance of output power versus distortion. Bluetooth pairs and maintains connection well with both Android and iOS sources, and presents good wireless performance in crowded RF airspace and distances of at least 40 feet of line of sight. Packaging and included parts: The module comes in a static-safe bag, with supplied connectors for left and right speaker, and a battery. On all 3 connectors, one side is a JST 2-pin plug, and the other is bare wire, intended to be soldered on to a battery and speaker terminals. Given the height of the plastic connectors, and a relatively large electrolytic capacitor (not surface-mount), I would have liked to see some crush/impact cushion like foam or bubble-wrap. However, since Amazon usually ships with their own impact cushioning envelopes or box filling, I don’t see this as a big negative (though I would encourage the vendor to add some packaging to err on the side of caution) The bare wire and connectors are fairly flexible and robust, and I had no trouble soldering them to terminals Components and physical board: The module consists of some passive components and 3 main ICs: * JL AC19AP1R101 - Zhuhai Jieli Technology Co., Ltd Bluetooth IC There is not much data about this chip online. It does seem to be a popular BT IC found in many Chinese manufacturer’s products * (2x). NS4165B - 5W Mono, AB/D Class Dual mode audio amplifier This one has a full data sheet available online. The board itself appears well laid out with appropriate grounding and solder connections, especially on the connectors, were solid. There was no sign that the connector solder points were cold/loose or prone to breakage even with moderate pulling force applied to the connectors. The module claims to support a Li-Ion/Li-poly battery, directly connected to the battery terminals on the module, and that it can charge that battery when itself is connected via USB. Performance: For the purposes of evaluation, the module was connected to two general purpose (wide-range) 4 inch speakers, 4 Ohms and about 10W maximum power handling. Power was provided by the computer in the USB Audio case, and a USB battery pack (capable of 2+ Amp output) in the Bluetooth case. No Li-Ion battery was attached directly. * USB Audio The module enumerates itself as a generic audio device, with the name “JieLi BR21”. Querying capabilities shows support for a single playback mode, 16-bit, 48000HZ. Playback from various applications within Windows 10 was trouble free without stuttering. Varying volume was smooth and linear across both channels. Multiple plug/unplug was without issues. * Bluetooth Bluetooth functionality was tested with (1) an iPhone running iOS 13.1.3, and an a OnePlus 5 (Android) phone running Android 9. Both phones paired immediately with the module. Connection was stable in an environment with 6 different 2.4 Ghz channels in moderate use (WiFi). I tried it at line of sight distances up to 40 ft., and a single wall obstruction at around 30 ft. In both cases, playback continued without noticeable stutter or disconnections. Disconnecting the module from power and reconnecting - causing a BT reconnect - also worked flawlessly from both phones. On the downside, the module doesn’t seem to support APTX (the protocol for high def. audio over Bluetooth); I have used the OnePlus 5 with APTX compatible receivers and can confirm it supports it; it was unable to make the same type of connection with this module. However, I won’t consider this as a negative since it was never advertised as supported, and really it would be incredible for a module in this price bracket to support it (I believe Qualcomm charges fees for the use of APTX) * Audio output Sound presentation was clean using music with a wide spectrum. There was some clipping at the upper end of the volume range, but well within expectation for this type of module (and the amplifier used), and it is difficult - with my test setup - to attribute how much the speakers themselves contributed. The module is fairly sensitive to noise; Switching from a USB battery pack to a standard “USB charger” (the kind you plug into the wall to charge a phone), resulted in considerable noise to the output. On an oscilloscope, intermittent spikes of up to 200 mV were seen, when input was clamped to 0v. On clean power from the USB battery pack, noise spikes were less than 50 mV, and spurious (not periodic). This is fairly respectable for a module in this class. (Audibly, this was imperceptible on my test speakers) Playing back pure sine and square waves yielded fairly accurate waveforms on the scope, even at high output levels; the remained relatively consistent as power varied. There was some overshoot and distortion, but again it’s well within what I expect from this class/price-bracket of audio module. And again, in practice, the sound of the music used as test source was very clean and more than acceptable for most things one would use this module. Other notes: * The audio outputs are independent and do not share common signals; do not attempt to tie the negative (-) terminals together, in order for example, to connect to a set of speakers using a 3.5 mm Tip-Ring-Sleve (with a common ground; these usually feed into an amplifier anyways, and the signal in this case is amplified already). * Current draw from the USB port went beyond 1 Amp at high volume levels, but even with several minutes of playing, the 2 amplifier ICs remained only moderately warm. * I did NOT have a chance to test the Li-Ion battery connector/source, nor the charging capabilities of the module. VERDICT: 5 Stars. Read more