Some megabus action to Chicago from Detroit to see my kiwi mate Alex. While we were there, we slightly abused some Divvy bikes (and took them out of state!).
Over the last few months I’ve been working on a small electronics workbench and shelving system that can fit into my bedroom. I started out with a floor plan in inkscape until I rearranged all of the furniture to maximize space and then designed everything in CAD. Everything is made out of plywood and assembled with a brad nailer and glue, the supports for the shelves are made from 1.5″ aluminum angle stock with holes drilled every 3″.
The desk height adjustable and appropriate for standing and has a self-closing drawer for hand tool storage. There is an integrated shelf for test equipment and this also holds a rackmount power bar that powers everything on the bench. The surface of the desk is covered with an ESD mat with attachments for grounding straps.
Underneath the desk fits a storage cart that holds 6 divider bins and also has a drawer for more hand tools. The cart is on industrial locking casters to be pulled out as a second work surface. After my first late-night stubbed toe I added glow-in-the-dark markers to the corners as well. The shelves are 1/2″ plywood and held together with t-nuts and bolts. I also used 1/16″ stainless steel aircraft cable and turnbuckles for stability and casters for easy moving.
So far I’ve been very happy with the setup and so has nin and bubs.
I’m currently taking a business course online through MITx, and if you have a few minutes to fill out my little survey on gaming it would help with the final assignment!
My pono player arrived yesterday, time to take it apart!
The Pono Player is using ESS’s ES9018K2M 32-bit Sabre reference DAC to convert the digital to analog audio, which can handle up to 384kHz sample rates. This chip looks like it is already finding it’s way into some DIY projects as well.
On the front-side of the pono PCB, the output section looks to be made up of discrete transistors laid out very symmetrically (I like that). Near the output is also a OPA4376 precision, low noise, low quiescent current operational amplifier.
The rear side of the circuit board has two 1000uF 6.3V thru-hole capacitors near the output as well that are part of the audio amplifier section. The board itself is nicely laid out and it looks like each section is separate from the others. It’s also worth noting that the silkscreen layer on the circuit board is very informative with every component and signal line clearly labelled which is very nice.
The battery is very easy to replace and disconnects from the circuit board with a 3-pin connector, and is press-fit into the rear of the case. This battery is a 3.78V 2950mAh Lithium-Ion battery made by McNair New Power Co. in China. This appears to be a standard 18650 size battery. The pono player uses Texas Instruments’ TPS65921B1 power management and USB chip to regulate the voltages, manage charging and do USB stuff. On the rear of the PCB is an LM26 chip, which looks to be for thermal management of the battery since it is placed to be very close to the battery.
On the rear of the PCB is Micron’s JW734 NAND-based multi-chip-package. I don’t know if this is the main processor of the pono player as well, maybe someone knows this chip. The memory chip is mounted opposite to the micro-SD slot and is a Samsung KLMCG8WEBC-BB31 which is a 64GB NAND memory chip with built-in controller it looks like. Sadly, it looks like there is a 128GB version of the chip available that Pono chose to not use. With the size of high-definition lossless audio files, I’m already wishing they would have opted for the larger chip here. But hey, the fact that they included a micro-SD card slot is nice. Update: I received an email from one of the guys at Pono and they said that the 128GB chip was “much, much more expensive and would have put the price point well above $399” – Thanks for the clarification guys!
At the end of the day, being able to carry around hundreds of albums in your pocket is amazing full-stop. The build of the Pono Player is very simple, no nonsense. Where there is compromise, it isn’t with any part of the player that is responsible for music production. The build quality looks nice, very simple and repairable and it looks like a lot of care went into the actual circuit board layout. The enclosure is simple and cost effective, but I can’t help thinking that the toblerone-shaped case that a lot of people seem to dislike could have been avoided completely. Maybe it was an aesthetic decision, because the triangle shape is iconic. But it seems if the battery and 1000uF capacitors are what dicated the triangle shape, they could have used a flat battery pack and laid the caps sideways or used multiple smaller caps to acheive the same 1000uF. But it fits in my pocket fine, and spends most of it’s time on a flat surface anyways.
How does it sound?
It came pre-loaded with Neil Young’s “There’s a World” in 24/192 and I think it sounds great with headphones. The mix sounded more dynamic than I was used to, but that’s more about the mastering and not necessary about the high definition of the audio file. In the next few weeks I hope to be running a few tests on the sound quality though to see I feel a difference. I’ve been listening to FLAC files on my old iPod video running RockBox for years. I can tell the difference between badly encoded MP3’s and FLAC files no problem, but I’m not entirely convinced that “high resolution audio” is something I can distinguish compared to CD-quality FLAC files from the same source. But I’m open minded and I have a decent set of headphones, so I’m looking forward to posting more tests soon.
I finally got a chance to test out this little invention I call the “Stuffomatic”. It is used for stuffing circuit boards with components by lighting up the correct part bin. It is activated by a footswich, and uses a Teensy 2.0, buzzer, OLED 2×16 character display and a MAX7219.
While manually stuffing and hand-soldering Therevox circuit boards, I wanted something that would speed up the process and cut down on errors. On first test, the stuffomatic seems to speed up the “stuffing” process by close to 30%. Grabbing a component directly out of the lit bin is also a lot less prone to errors, compared to the normal way (reading the reference off the board, cross referencing it with the Bill of Materials to get the part value, find the right value part bin, grab the part).
The stuffomatic advances to the next part when a footswitch is pressed. I used a buzzer to make a small “click” noise when the footswitch is pressed for some audio feedback. There is also an “up” and “down” switch on the stuffomatic to quickly go through the list of parts.
The only problem with this project was that the Teensy couldn’t store the entire BOM (bill of materials) in memory. Instead, larger amounts of data need to be stored in PROGMEM which requires very messy code to declare the variables. To get around this, I wrote a PHP script that reads a CSV file and outputs the PROGMEM variable declarations as a 2 dimensional array. This also makes it easier to recompile the stuffomatic code for different projects.
On the front of the stuffomatic is a “note” LED to draw attention to the display if there is a special note or instruction being displayed. The stuffomatic can show messages like “flip board over” or “solder”, or a specific component might have a note with it.
So far I’m happy with the stuffomatic, it did take a lot longer to finish than I expected, but building it was more fun than stuffing circuit boards.