How To Increase Bass On Alexa

CLICK HERE to download a fully detailed PDF of the MegaDot build instructions.

I have a small collection of Amazon Repeat Dots scattered around my house and use them for alarms, checking conditions and traffic, controlling lights, and of course playing music. The built-in speaker is a little, well...tiny...and doesn't exactly fill a room with thumping bass. I happened to accept an erstwhile subwoofer and pair of speakers waiting to be thrown out or repurposed. As they sat at that place occupying a corner of my room, an idea came to me. MegaDot!

Could I build a supersized Echo Dot that could shake the room? The project began innocently enough: an Echo Dot; the guts from a 250W 15" subwoofer; the crossovers, mid-range speakers, and tweeters from the smaller speakers; an FPGA-based embedded controller; and a strip of individually programmable RGB LEDs. The finish effect? A scaled-upward, 27" bore MegaDot with crisp highs and thumping lows, while retaining the full voice control of Alexa. It even includes the four buttons on summit (fully functional) and a calorie-free band around the top.

There were 4 master considerations for the design:

• Large amplified speaker subsystem
• Faithful reproduction of the outer LED band
• Fully functional buttons
• Standard Echo Dot adequacy, including vocalism command

This resulted in the following cake diagram:

Everything was designed around the speaker subsystem. I carefully measured the various dimensions of a standard Echo Dot and scaled it upwardly so that I could fit the 15" subwoofer, four.5" mid-range speakers, and i" tweeters. This left just enough room for the various power supplies, a mildly disassembled Echo Dot, the FPGA-based controller, and the push mechanicals.

Parts List:

Manufacturer/Vendor	Description
Amazon	Repeat Dot, 2nd generation
National Instruments	myRIO-1900 controller
HKBAYI	RGB LED strip, individually programmable LEDs, 60 LEDs/meter
eBoot	LM2596 12V to three.3V converter lath
URBESTAC	Momentary roller lever microswitches
DROK	TPA3116 sound amplifier
	Male headphone jack connectors
	Male RCA connectors
	eight position screw final connectors
	47uF capacitor
	12V ability supplies, >2A
	iv hinges
	four compression springs
	Extension cords
	Miscellaneous wire
	ane⁄four" and 1⁄2" MDF
	1/8" plywood
	Miscellaneous woods, screws, hot glue, paint, etc.
Cerwin Vega	15" 250W subwoofer
Polk Audio	4.5"/1" stereo speakers

BUILD INSTRUCTIONS:

Hacking the Repeat Dot

ane.) Disassembly

The start step was to disassemble an Echo Dot. I needed to figure out how to monitor the state of the LEDs and remotely press the buttons. The beginning step (which totally voids your warranty) is to pare off the rubber base of operations that hides the screws. Pop out the screws, and everything starts to autumn apart. Be careful with the subassemblies, as at that place are 2 PCBs joined past a flex circuit, and you don't want to damage the fine pitch connectors by dangling things around. All of the signals we need access to are on the uppermost board (the one with the LEDs, buttons, microphones, etc.). To make things more manageable, I asunder the flex circuit. Flip up the tiny, hinged agree-down and the flex excursion slips correct out.
2.) Accessing the LEDs

In that location are 12 RGB LEDs around the perimeter of the lath. My original plan was to monitor each LED directly, with the assumption that they were very probable driven by simple PWM signals. I would monitor each of the 36 LEDs (12 blood-red, 12 green, and 12 blue) with a myRIO by making 36 simultaneous PWM measurements.

It quickly became credible that all of the LEDs connected to a single IC, but I didn't recognize the part labeling. I assumed there was going to be a SPI or I²C bus for controlling this IC, then I probed around some more than. I plant that two lines too connected to some other ICs on the board, which turned out to be ADCs. Those were well labeled, so I could find their information sheets. Victory! They were all on a shared I²C bus and I am totally capable of soldering 3 tiny little wires (SDA, SCL, and ground). So I used the myRIO to snoop the I²C bus.

3.) Tapping into the Buttons

The four buttons (volume upward, volume down, pairing, and microphone) are simple dome switches. Pressing a push shorts the indicate to footing, so I could but put my own external switches in parallel with the dome switches. However, in that location wasn't a great identify to solder the fine wires to the switches themselves, so I traced them dorsum and institute they continued to some discretes (a pull-up resistor and probably a elementary RC filter). Now I knew where to solder all my wires.

iv.) Grinding off the Acme

Ultimately, the actual Echo Dot is going to be mounted in the top center of the MegaDot, and I wanted the microphones to be as close every bit possible to the outer surface. So I ground off the meridian of the Repeat Dot housing and added a cutout for my wires to pass through. The Echo Dot has a foam pad on the meridian surface, then I removed plenty housing and then that the foam would now be in direct contact with the new mounting surface. Now, everything can be held together nicely and I don't have to worry virtually dangling wires. I temporarily reassembled everything to make certain the Repeat Dot was still working, and fortunately it was.

Replicating the LEDs

i.) Snooping I²C

At this bespeak, I nonetheless hadn't actually looked at the data communication going to/from the LED driver chip. I had been using a DMM to effigy out the signal connections, but now needed to switch to an oscilloscope to come across the communication protocol. I quickly was able to see that at that place wasn't anything unusual going on, and that this was a standard IⁱⁱC bus and protocol. I would inquire Alexa questions, which would crusade her to bike diverse colors on the LEDs, and I could meet the changing I²C information in the transactions.

While I could take connected mapping transactions and reverse engineer the internal register map, I now felt I had enough data nigh the pinout and interface to search the Spider web again. I looked for LED drivers with 36 outputs and finally found what seemed to be the actual component. The pinout matched and the transactions I was seeing fabricated sense. This could work!

2.) Monitoring and Expanding the LEDs

Now that I had admission to the I²C jitney and knew the protocol, I needed a way to monitor it, replicate the appropriate portions of the register map, and aggrandize from the 12 RGB LEDs in the Echo Dot to the 128 RGB LEDs surrounding the MegaDot. I had been using my NI ELVIS III for its DMM and oscilloscope functionality to analyze how the Echo Dot worked internally. Now, I could use the RIO portion of the NI ELVIS Three to prototype these controller functions. Information technology includes an FPGA and command IO that can be programmed using LabVIEW FPGA, which fabricated it easy to image a quick solution. Using two digital inputs and an easy to follow diagram, I implemented digital filtering on SDA and SCL, a state machine to detect I²C accesses to the driver IC, arrays to hold the LED values, and the command logic to drive the LED strip (described in the next department).

Of course, I didn't want to embed my NI ELVIS III into MegaDot. And so once I had all of the logic working, I deployed the terminal solution to a myRIO. The myRIO is meant for embedded applications and runs the same LabVIEW FPGA diagrams, and then it was a trivial thing to motility over.

three.) Programming the LED Strip

The LED strip I chose has individually programmable RGB LEDs based on the WS2812B driver IC. Each RGB LED is programmed with a 24-bit word, with eight bits for each colour. It is programmed with a uncomplicated ane-wire protocol. Each driver IC has one data line in and a data line out. The output of one is continued to the input of the next one in the strip. You lot shift the data ane scrap at a time. In one case you shift 24 $.25, whatsoever additional $.25 cause data to exist shifted into the adjacent LED. And then if you shift out 72 bits, you would be programming 3 RGB LEDs. For MegaDot, I take to shift out iii,072 bits in order to program all 128 RGB LEDs.

You lot have to generate a pulse for every fleck, and the width of the pulse determines if information technology is a 0 or 1. A short pulse corresponds to a 0 and a long pulse corresponds to a 1. Afterward shifting out all of the $.25, yous bulldoze the line low for an extended menstruum to employ the shifted information to the actual LEDs. It is easy to run into the timing requirements with LabVIEW FPGA, which allows you lot to create hardware timed custom digital protocols. I verified the signal beliefs with the oscilloscope. The LED strip is powered from three.3V, so I bought a 12V to 3.3V converter to go with the 12V supply I already had on hand.

Making Giant Buttons

The Echo Dot has four buttons for volume up, volume downwardly, pairing, and disabling the microphones. In guild to continue the right scale, these have to be a little over 4.v" in bore. For some odd reason, I couldn't detect anyone that sold buttons in this size—let solitary with the right symbols on them. So I had to make my own. My solution consisted of four parts: a round piece of MDF for the push button face up, attached to a hinged slice of MDF to allow information technology move up and downward; a 3D printed frame to human activity every bit a end and hold a compression spring; and finally a microswitch mounted to the 3D printed frame.

Pressing the push face swings the arm down. Information technology stops confronting the frame and, when yous release the button, the spring returns information technology to the original position. The location of the microswitch is fix and then that it activates near the end of the button travel. The microswitches get wired to the screw concluding previously attached to the Echo Dot.

Amplifiers and Speakers

I took autonomously an older 15" 250W Cerwin Vega subwoofer that I had. While 250W might not sound like a lot of power for a fifteen" subwoofer, this speaker was from a fourth dimension when that was a quality 250W. Internally, there was a sizeable ability transformer, extensive heatsinking, and an all effectually robust implementation. I had to cutting and extend some of the wires, as I didn't have a unproblematic place to locate the components in the new circular enclosure. I then disassembled a pair of speakers I had to scavenge the mid-range speakers, the crossovers, and the tweeters. These weren't powered, so I ordered a elementary stereo amplifier lath to drive those. I had a 12V power supply hanging around and dedicated that to power this amplifier.

Mechanical

I had really expected hacking into the Echo Dot, figuring out the protocols, and implementing the FPGA controller to be the most time-consuming part of this project. Still, I spent just as much, if non more than time, working on the mechanical construction. I really wanted to go on the scale accurate, but optimize the size to just fit the speakers. This made it pretty tricky to pack everything into the circular enclosure.

Base and Speaker Enclosures

I started with the base of operations that would hold the five speakers. I decided to create iii sealed chambers. In lodge to fit these, they couldn't be unproblematic squared-off boxes. In gild to make the curved chambers, I took autonomously an old bookshelf. I kerfed the pieces with a radial arm saw so that I could bend them. Using shelf pieces was peachy, because the plastic laminate helped foreclose the pieces from snapping at the sharper bends. I used a combination of hot mucilage and screws to hold all of the pieces together.

One time the base of operations was assembled, I could mount the speakers and amplifiers. The speakers dropped correct into the holes and were screwed in. The amplifiers, power supplies, and cross overs were harder, as they had to be fit into the odd shapes left around the speaker enclosures.

Outer Skin

I had debated how to make the outer cylindrical skin. I was originally going to kerf a long piece of MDF, but decided that I didn't have a great manner of supporting it while making all the kerfs. The next thought was to effort wrapping it with a thin piece of plywood. I built a bones frame to back up the skin, then tried bending a sample piece of plywood around it. As information technology got to most twice the radius, information technology needed to exist snapped in half. And then next, I tried soaking a piece in h2o for well-nigh xx minutes. It didn't start to snap until it was really close. My final effort (which was practiced that information technology was last, because it was my last piece of plywood) involved soaking the wood for an hour, and so trying. Success! I bent information technology fully around the frame and clamped and screwed it in place. I let it set overnight to dry in that position, and so redid the screws and epoxied the small gap where the ends met.

Meridian Surface and Buttons

In that location was no applied style to make the top portion by manus and have information technology come out looking correct. Information technology needed the 4 big holes for the buttons, 84 ellipsoidal holes on the perimeter, and a series of small-scale holes in the centre to provide access to the Echo Dot microphones and light sensor. Fortunately, I was able to borrow fourth dimension on a CNC machine and accept these all carved out for me.

All of the not-speaker-related electronics were mounted to the underside of the top surface, along with the button assemblies. A multifariousness of fiddling wooden brackets and mounts were fabricated to concord it all together.

Terminal Assembly

Hither is an image of the first fourth dimension information technology was all put together:

[All images courtesy Joe Peck]

Source: https://www.designnews.com/gadget-freak/megadot-how-give-your-amazon-echo-dot-bass-boost

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