Amazon, with its Alexa-based Echo speakers, sets a new standard for digital audio playback systems that support voice control. Since then, audio companies including old brands such as Bose and Sonos, as well as other technology companies such as Google and Apple have followed suit; on the other hand, these old audio companies have also integrated voices from Apple, Google and Amazon. Assistant, the strategy of "multiple" choices.
For discerning users, although the audio quality of a single small speaker may not meet the theater-level sound required by professional audio players, it is certain that its ease of use and portability are good enough. Therefore, there are three important considerations for the user: the quality of the audio playback, the inherent quality and reliability of the wireless connection, and the ability of the device to recognize the voice assistant's activation trigger and associated instructions. Even in the face of a high volume, noisy background, it must still perform normally.
Ultimate Ears is Logitech's headset brand, which designed the Megablast for these three key indicators, while providing water and dust resistance up to IP67 (Figure 1), which is said to be immersed in water up to 1 meter deep for 30 minutes. Megablast has built-in Amazon Alexa, as well as Wi-Fi and Bluetooth; it takes only 5 minutes to set up and get started, streaming music from Amazon Music. In addition to Alexa's features, it also supports most popular standalone audio streaming media services.
Figure 1: Ultimate Ears' Megablast speakers use Amazon Alexa to provide voice control for high-quality audio playback systems while achieving IP67 waterproof and dustproof rating (Source: Ultimate Ears)
The Megablast measures approximately 237mm x 88mm and delivers 360° surround sound at up to 93dB maximum volume, supports 60Hz to 20kHz frequency range, and uses two 25mm tweeters, two 55mm midrange speaker drivers, and 2 A passive radiator of 85 x 50mm is used for the woofer. The speaker features a Li-ion battery that lasts up to 16 hours with a single charge and supports a Bluetooth connection up to 150 inches and a 330-inch 2.4/5-GHz Wi-Fi . The speech recognition subsystem uses multiple microphones to provide beamforming and noise cancellation.
This fun speaker also comes with a detachable D-ring that can be used as a hook to hang the speaker, or it can be removed to mount the speaker on a stand or a separate wireless cradle. Or, if you charge the AC adapter with a USB power cord, you must first open the back cover that covers the USB charging port.
Unique design but good user experience
From the cost of Megablast, you might expect it to be easy to connect with Bluetooth and Wi-Fi, but the sound quality is not expected: in fact, its sound quality is amazingly good. According to the laws of physics, the bass of a small speaker is generally not good, but the middle and high notes are clear and can perform as expected. Therefore, if you don't expect to vibrate the bass like a theater, you should be surprised by its audio quality and ease of use.
Megablast confirmed that it was able to capture the keyword (Alexa) ability among the full-fledged guests, and when testing its sensitivity, it was able to pick up a low-pitched whisper at a distance of about 5 inches. Curiously, the Megablast design does not clearly show whether Alexa is listening or hearing instructions unless it is placed below the eye's line of sight. Amazon's Echo and Echo Dot will have a sparkling blue circle on the top edge, while Megablast only emits a small beam of silver on the top, so you can only see if it is working when you look down.
How does it work?
Since the Megablast is waterproof, it must be judged empirically when disassembling its internal structure, and the Dremel circular cutting tool should be used with care. After removing the plastic cover at each end, four screws are exposed. When the screws are removed, the main structure can be opened to see the internal situation.
Then remove the colored overlay that covers the base, and we found three Micro Electro Mechanical Systems (MEMS) microphones evenly placed on top of the Megablast (Figure 2).
Figure 2: Using the Dremel round tool, remove the plastic cover on each end and loosen the screws underneath it to see the motherboard (top left) and the battery (bottom left). The line along the side of the base is used to fix the position of the speaker driver
Once the screws are removed, the microphone attached to the top board is removed, revealing two main top switches: the power and silent mode (Alexa Privacy Mode). The top board is also loaded with a Bluetooth radio's upright dipole antenna, which is connected from the backplane to the motherboard's radio frequency (RF) and audio processing modules (Figure 3). Figure 3: Three MEMS microphones are used to pick up sound and impart meaning through DSP Group DBMD5 audio SoC processing, while SPIL's Wi-Fi/Bluetooth RF IC ensures continuous uninterrupted streaming
The battery can be removed after removing the bottom module; the battery is custom designed in Japan and China and is rated at 7.2V, 3130mAh or 22.5Whr (Figure 2). Once the battery is removed, it exposes the chamber of the passive radiator and the bottom of the motherboard, which also comes with a small module.
Form the core module of Megablast
After further analysis, the small module connected to the motherboard contained two key secrets of the Megablast design: a seamless and reliable wireless connection for continuous streaming; and accurate speech recognition.
The wireless communication part comes from Silicon Precision Industries Co., Ltd. (SPIL)'s SB-WBM-N07P system-in-package (SiP), which includes two radio chips from Cypress Semiconductor: CYW43907 The IEEE Cortex Application Processor's IEEE 802.11a/b/g/n SoC supports data rates up to 150 Mbits/s and covers the 2.4/5 GHz Wi-Fi band. It is worth noting that although 150 Mbits/s is not the largest Wi-Fi range currently available, audio does not require high throughput, so reliability and coverage are more important considerations.
The second radio chip on the SPIL SB-WBM-N07P SiP is the CYW40707 Bluetooth baseband SoC with integrated transceiver. It supports Bluetooth low energy and, like CYW43907, originally came from Broadcom's wireless division and was later acquired by Cypress.
Three antenna traces are extended from the module: black for Bluetooth, connected to the top of Megablast, and two for Wi-Fi, for each side of the system - one with a dedicated board and the other with Megablast The volume keys share the board (Figure 3).
At the heart of the Megablast speech recognition is another chip on the module: the audio SoC from the DSP Group released at CES 2017 - DBMD5. Designed with the company's HDClear technology, the chip enables voice control in noisy environments and supports voice triggering and interleaving.
As the front end of Alexa, audio and speech processors are critical, so the DBMD5 is equipped with DSP Group's advanced speech enhancement algorithms, including echo cancellation, noise suppression, beamforming and far-field effects. Other features include voice buffering for smooth operation of automatic speech recognition (ASR) applications. The onboard dual core DSP supports both digital and analog microphones.
Below the module is Macronix International's MX25L25645G 256Mbit serial NOR flash chip that supports RF communications and audio ICs.
Structure and acoustic integrity
Before diving into the Megablast, you must remove the two wires that keep the speaker driver and radiator intact. After removal, the communication and audio processing modules were further exposed, as well as the interesting design of the midrange driver. These modules and components are bonded to the insulating foam via holes in the main board.
This further ensures structural integrity and adds a compact, compact, solid and well designed base and internal structure. The base itself is a piece of seamless plastic. For professional audio players, it is also important to consider the structural integrity, as this helps to minimize the vibration of the base and make the audio more versatile. It also provides a solid foundation for bass radiators: waterproof and high-end acoustic structural design, there is indeed a need for reciprocity.
The audio electronics on the motherboard are driven by three main chips: two NXP Semiconductors 1334B low-power audio digital-to-analog converters (DACs), and one Texa Instruments (TI) TPA3131 7W D from Texas Instruments (TI) Class stereo amplifier (Figure 4).
Figure 4: Driven by two NXP low power DACs and one TI Class D amplifier during the main audio processing and amplification stages
The 1334B DAC is designed for portable audio applications. It does not require analog post filtering, but uses a digital filter that performs digital pre-emphasis at a 44.1 kHz sampling rate. It also has an interesting feature that supports noise shaping, which shifts the quantization noise in the band to higher audio frequencies, thereby increasing the signal-to-noise ratio (SNR). Therefore, when the device uses a 3V power supply, a volume of 100 dB can be achieved.
The TPA3131 drives the speakers at 4 Ω up to 2 x 42 W peak power. It does not require a heat sink, but uses PowerPAD to dissipate heat to the board via the bottom.
Even the old aunt dances for it.
All in all, Megablast delivers outstanding portable audio and ease of use. It has a bit of a strange design, but because of its excellent performance, "Auntie" is also full of praise. When she asked, "Is this another gadget for you?", I have to say that it was. When I explained the function to the aunt, she waved her cane and refused to rebut: "Is it? But I bet it can't play the Blue Danube?" I suggested her. It is better to ask this equipment. The shocking result is that we heard it start playing this song in a few seconds. This made Aunt smile happily, dancing and screaming and welcoming Waltz into her warm car. During the vacation, she also asked if I could buy one for her. No problem at all!
Figure 5: Main components of Megablast
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