Portable All-in-one/DAP with Chord Mojo

[Staxton]

Since I received the Chord Mojo, I have been working on all-in-one/semi-portable digital audio player/server enclosures for the Mojo with lots of on-board storage and some kind of low power PC, such as the Banana Pro, Raspberry Pi 2 and 3, and the Cubietruck. This thread is a follow-up to my earlier post in the Chord Mojo thread (http://www.head-fi.org/t/784602/chord-mojo-the-official-thread-please-read-the-3rd-post/12105#post_12381029), which contains some background and my first attempt at an enclosure.

Here is the latest, and more or less final, version of the Banana Pro enclosure:





It is 152 x 130 x 36 mm, roughly the same length and a bit wider than an Amazon Kindle Voyage, but of course far thicker.

This is what is included:

Banana Pro Mainboard
5" Lemaker TFT Screen
8000 mAh Lithium Battery (eBay) (to power Banana Pro)
Pololu 5V Step-Up Voltage Regulator U3V50F5
Adafruit USB LiIon/LiPoly charger (to charge Lithium Battery)
On-Off Switch (for Battery Power to Polulu regulator)
On-Off-On Switch (for Battery/AC Power)
Adafruit Panel Mount Ethernet Extension Cable
Female USB 2.0 Port (for AC Power to Banana Pro)
USB 2.0 Micro-B Male to Micro-AB Female Adapter, Black, Manhattan 308755 (to enable charging the Mojo)
Homemade short USB A Male to USB A Female cable (to connect Anker SD Card Reader to Banana Pro)
NTJ Short Flat Thin Noodle (20cm) USB 2.0 Male A to Male Micro-B Cable (to connect Mojo to Banana Pro)
Adafruit Panel Mount Ethernet Extension Cable (Modified)
Monoprice 3.5mm Stereo Plug to 3.5mm Stereo Jack Adaptor 7130 (to connect to headphone out port on Mojo)
Samsung 2TB SSD (removed from case; connected via on-board SATA port on Banana Pro)
Anker USB SD/MicroSD Card Reader
SD to Micro SD FPC Extender
2 PNY 512GB SD cards (1TB)
Chord Mojo
3D Printed Enclosure made from nGen filament

It has Ethernet and wireless network access, and up to 3TB on-board storage. The 3TB maximum is possible by using a 2TB SSD, removed from its 2.5" enclosure, and 2 full size 512 GB SD cards, one of which is directly inserted in the Anker reader's SD slot, and the second is inserted in the SD to microSD card extension, which is then inserted in the Anker reader's microSD card slot.

It takes a while to boot because there is a lot of unnecessary junk being loaded, since the Raspbian Wheezy distribution I am using is not dedicated to audio. Unfortunately, there is no Rune Audio or Volumio distribution for the Banana Pro, and I don't know enough about Linux to strip out the unnecessary stuff. Also, I can't scroll with the touch of a finger just anywhere on the screen; instead I have to touch scroll bars. Fortunately, I was able to make the scroll bars very large, so scrolling is not much of a problem.

The multiple switches are the result of my limited knowledge about electronics generally. One switch turns power on and off between the battery and the 5V step-up regulator. The second switch allows current to flow from either the 5V step-up regulator or from AC current to the Banana Pro. The reason I didn't just use that switch alone is because if there was no separate switch between the battery and the Step-up regulator, the regulator would constantly draw power from the battery, even when AC was being used or the unit was off entirely. Also, I can't seamlessly switch between battery and AC power because, frankly, I don't know how to do it. I guess there should be a capacitor or some such thing to keep the current going to the Banana Pro when the power source switch is changed between battery and AC.

My connections between the switches, battery chargers, boosters, and batteries are pretty crude, and the USB connection between the Banana Pro and the Mojo is just a cheap USB cable. (It's not an accident that I don't show any pictures of the internals.) Surprisingly, though, the sound is very clean. There's also a fair amount of heat generated by the power booster, battery charger, and the Mojo itself, but I haven't caught on fire yet. I have used this both as a portable/battery-powered digital audio player playing music stored on-board through Sennheiser HD800s, and as a desk-top All-in-one playing music from on-board storage or from a Synology NAS via Ethernet to headphones or via line-out to a separate pre-amp/amplifier to speakers. I can access the player through the touch screen or remotely through VNC.

Hopefully my next post will be about one or more enclosures using the Raspberry Pi 3 with Rune Audio (based on Arch Linux). A headless version I have been working on is 125 x 115 x 38 mm, weighs 480g, and has USB attached SD card readers instead of an SATA SSD. It might conceivably take up to 6 SD cards, making for a 3TB capacity using currently available cards, although the most I have used is 4 SD cards. The battery is 5000 mAh and lasts up to 7 hours (about as long as the Mojo on a good day.) It has WiFi, and also a built-in bluetooth module, but I don't believe that is currently operational with Rune Audio. It boots quickly, and can be controlled via any web interface (phone, pc, ipad, etc.) located on the same network.

I have also been working on a Raspberry Pi version with a 3.5" screen. Unfortunately, the only screen of that size that I can find that works with Rune Audio has resistive touch. There is a 7" touch screen that works great, and also permits full touch scrolling, but it is far too large for a semi-portable application. I wish I could find a capacitive 3.5" or 5" touch screen that attaches directly to the Pi (not through HDMI) and works with Rune Audio or some other dedicated audio distribution. In the meantime, I will be experimenting with the 3.5" version with a touch pad. The sound from the Raspberry Pi 3 with Rune Audio might, if anything, be even better than from the Banana Pro. However, with the Raspberry Pi there are some issues with interference from the poor wiring, the design of the Pi itself, or lack of power that may introduce some faint crackling now and then.

In any event, the size of the Mojo (in its case it is about 83 x 62 x 22 mm), the screen, the battery, and the space needed for the USB connection between the Mojo and the front-end pretty much set the limits on how small I can make any of these players. I would love to make a smaller unit in a sturdy metal or plastic case with a dedicated SoC and OS dedicated to transporting bit perfect audio to the Mojo, with SD card readers or an SSD attached directly to the PCB, a direct connection between the Mojo and the front-end, with one battery for both the Mojo and the front-end. But all that is far beyond my current skills. Here's hoping that someone who knows what they're doing will try.

And please post any suggestions or ideas on how to improve on any of this!

Cheers.
Rod

 

[masterpfa]

I'm impressed.

Wish I had the time to devout to something similar, but I'll be sure to use this as a guideline

 

 

[warrior1975]

Well done. Very impressive.

 

[Staxton]

Thanks!

 

[west0ne]

It's good to see people tinkering with things like this to get what they want. It's certainly more interesting than just stacking an amp with a phone or attaching a DAC with velcro.
 
How about a Windows/Foobar based system using one of those cheap Chinese no-name Atom based PC's that are designed as TV set-top boxes. I have found that provided you don't want to do any complex DSP the Atom based tablet connected to an external DAC/AMP works fine with Foobar and with streaming services so the set-top box types should be the same. Many of them are about the same size as the Pi and have similar power requirements, in fact you could probably just swap you Pi out for one, some even have a built-in battery.

 

[Staxton]

How about a Windows/Foobar based system using one of those cheap Chinese no-name Atom based PC's that are designed as TV set-top boxes. I have found that provided you don't want to do any complex DSP the Atom based tablet connected to an external DAC/AMP works fine with Foobar and with streaming services so the set-top box types should be the same. Many of them are about the same size as the Pi and have similar power requirements, in fact you could probably just swap you Pi out for one, some even have a built-in battery.

 



I actually tried one of those PCs - it was an Ainol Mini PC for about a $100. It had a built-in battery and I ran foobar. It worked pretty well, and certainly required a lot less fiddling that the Raspberry Pi, both software and hardware-wise.

The problem for me was I wanted to attach a screen and the only way to do that with the miniPC's was through HDMI; on the other hand, I could attach a screen directly to the Pis, so it was a bit more compact.

The other thing is Windows has a lot of stuff going on that goes beyond audio and to my ears at least, the Pis with Rune Audio sound just a tiny bit cleaner than the Windows PC.

But there's no doubt that these tiny PCs, whether Windows or Linux-based, are a great way to put together an economical, great-sounding system.

 

[Staxton]

This looks interesting as a Windows 10 miniPC front end for a DAC like the MOJO. https://www.indiegogo.com/projects/gole1-cheapest-windows10-intel-touch-mini-pc#/

 

[Currawong]

You should definitely re-post your Mojo thread post about the mod here with the latest pictures. 

 

[Staxton]

Here is my latest (and most likely final) all-in-one portable transport enclosure for the Mojo: the "MojoPi".








Size comparison with iPhone 6s


It consists of:

Raspberry Pi 3 Mainboard with built-in WiFi, but with the LAN, USB, HDMI, and audio ports removed.
Waveshare Spotpear 3.5" Resistive Touch Screen or equivalent (see http://www.ebay.com/itm/291722114342?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
Adafruit 2500 mAh Lithium battery to power the RPi3 (at least 3hrs play time)
Adafruit Powerboost 1000c (to convert the 2500 mAh 3.7 volt battery to 5 volts and to charge the battery)
Anker USB Dual SD/MicroSD reader removed from shell
SD to Micro SD FPC Extender
2 PNY 512GB SD cards
200GB Sandisk MicroSD card (OS + Music) inserted in RPi3 microSD card slot
Adafruit Switch
Chord Mojo
3D Print Enclosure

Its dimensions are 125mm long x 98.2mm wide x 26mm high and it weighs 358g. The Mojo is connected to the RPi3 via a DIY microUSB cable soldered directly to the RPi3. The dual USB SD/MicroSD card reader is also soldered directly to the RPi3. The MojoPi can hold up to 1.2 TB of music on 2 full-size SD cards and a 200 GB microSD card. The interface is Rune Audio (based on Arch Linux). I can access Rune Audio through the screen or remotely via WiFi on a web browser using the IP address of the MojoPi.

The touchscreen is resistive, not capacitive, and so requires a fingernail or a stylus; it is not very easy to scroll. There doesn't seem to be a readily-available 3.5" or smaller capacitive touch screen that works with both the RPi3 and Rune Audio.

I think this is as small an enclosure as possible that contains both a 3.5" screen and a Mojo without removing the Mojo board from its case and connecting the Mojo directly to the RPi instead of using the Mojo's microUSB port. That would potentially narrow the unit by about 10 mm. A smaller board (One example is the Odroid C0), containing just a SOC for the operating system, an on-board battery booster/charger, and USB connections to SD cards, could provide for either more storage or a larger battery, but wouldn't change the overall size very much, since the Mojo and the screen pretty much determine the minimum dimensions of the enclosure. The plastic enclosure is fairly sturdy, but a harder plastic or metal enclosure would clearly be preferable.

I haven't done any kind of real comparison between the MojoPi and a more traditional phone/Mojo or PC/Mojo setup, but to me it sounds great. Despite the slapdash internal wiring, I haven't had any noticeable clicks or interference. I've played 44.1/16 up to 192/24 PCM without any problem. DSD64 seems to work well enough, although I have had the occasional drop-out.

Is it just me or does anyone else think it would be cool if Chord came out with something like this?

Cheers,

Rod

 

[reubanski]

Hi Rod,
I'm very impressed with your DAP/Mojo creation and attempting to replicate your work. I wondered about your 3d printed enclosure. Did you create your own design for this? Would you be willing to share your design? Anyway great work.
Cheers
Eric 

 

[Staxton]

​Hi Eric,
 
I'd be glad to share my design with you. Actually, I've been using a slightly different design over the past few weeks; I found a better, although smaller), touch-friendly screen (the Adafruit 2.8" capacitive) and I am using a larger battery (5000 mAh) from eBay. I also managed to squeeze in another SD card, so the total capacity can reach 1.7GB with 3 Full Size 500 GB SD cards and a 200 GB microSD. However, the newer model is 7mm taller and weighs about 50 g more than the first MojoPi, so it is not quite as compact.
 
I can send you one or both designs in either Sketchup format or .stl. Just let me know.
 
Rod

 

[reubanski]

Hi Rod,
I've started on your first design but I'd be grateful if you sent both designs. Installing a lot of memory is important to me also. I want to be able to sore my music library on the device.
Cheers
Eric 

 

[Staxton]

Hi Eric,
I am unable to load the files, either on the thread or as a private message. Perhaps you could PM your email address and I could try to send the files directly. I will be sending you the Sketchup files if that is O.K.
 
Best,
Rod

 

[NaiveSound]

Since I received the Chord Mojo, I have been working on all-in-one/semi-portable digital audio player/server enclosures for the Mojo with lots of on-board storage and some kind of low power PC, such as the Banana Pro, Raspberry Pi 2 and 3, and the Cubietruck. This thread is a follow-up to my earlier post in the Chord Mojo thread (http://www.head-fi.org/t/784602/chord-mojo-the-official-thread-please-read-the-3rd-post/12105#post_12381029), which contains some background and my first attempt at an enclosure.

Here is the latest, and more or less final, version of the Banana Pro enclosure:





It is 152 x 130 x 36 mm, roughly the same length and a bit wider than an Amazon Kindle Voyage, but of course far thicker.

This is what is included:

Banana Pro Mainboard
5" Lemaker TFT Screen
8000 mAh Lithium Battery (eBay) (to power Banana Pro)
Pololu 5V Step-Up Voltage Regulator U3V50F5
Adafruit USB LiIon/LiPoly charger (to charge Lithium Battery)
On-Off Switch (for Battery Power to Polulu regulator)
On-Off-On Switch (for Battery/AC Power)
Adafruit Panel Mount Ethernet Extension Cable
Female USB 2.0 Port (for AC Power to Banana Pro)
USB 2.0 Micro-B Male to Micro-AB Female Adapter, Black, Manhattan 308755 (to enable charging the Mojo)
Homemade short USB A Male to USB A Female cable (to connect Anker SD Card Reader to Banana Pro)
NTJ Short Flat Thin Noodle (20cm) USB 2.0 Male A to Male Micro-B Cable (to connect Mojo to Banana Pro)
Adafruit Panel Mount Ethernet Extension Cable (Modified)
Monoprice 3.5mm Stereo Plug to 3.5mm Stereo Jack Adaptor 7130 (to connect to headphone out port on Mojo)
Samsung 2TB SSD (removed from case; connected via on-board SATA port on Banana Pro)
Anker USB SD/MicroSD Card Reader
SD to Micro SD FPC Extender
2 PNY 512GB SD cards (1TB)
Chord Mojo
3D Printed Enclosure made from nGen filament

It has Ethernet and wireless network access, and up to 3TB on-board storage. The 3TB maximum is possible by using a 2TB SSD, removed from its 2.5" enclosure, and 2 full size 512 GB SD cards, one of which is directly inserted in the Anker reader's SD slot, and the second is inserted in the SD to microSD card extension, which is then inserted in the Anker reader's microSD card slot.

It takes a while to boot because there is a lot of unnecessary junk being loaded, since the Raspbian Wheezy distribution I am using is not dedicated to audio. Unfortunately, there is no Rune Audio or Volumio distribution for the Banana Pro, and I don't know enough about Linux to strip out the unnecessary stuff. Also, I can't scroll with the touch of a finger just anywhere on the screen; instead I have to touch scroll bars. Fortunately, I was able to make the scroll bars very large, so scrolling is not much of a problem.

The multiple switches are the result of my limited knowledge about electronics generally. One switch turns power on and off between the battery and the 5V step-up regulator. The second switch allows current to flow from either the 5V step-up regulator or from AC current to the Banana Pro. The reason I didn't just use that switch alone is because if there was no separate switch between the battery and the Step-up regulator, the regulator would constantly draw power from the battery, even when AC was being used or the unit was off entirely. Also, I can't seamlessly switch between battery and AC power because, frankly, I don't know how to do it. I guess there should be a capacitor or some such thing to keep the current going to the Banana Pro when the power source switch is changed between battery and AC.

My connections between the switches, battery chargers, boosters, and batteries are pretty crude, and the USB connection between the Banana Pro and the Mojo is just a cheap USB cable. (It's not an accident that I don't show any pictures of the internals.) Surprisingly, though, the sound is very clean. There's also a fair amount of heat generated by the power booster, battery charger, and the Mojo itself, but I haven't caught on fire yet. I have used this both as a portable/battery-powered digital audio player playing music stored on-board through Sennheiser HD800s, and as a desk-top All-in-one playing music from on-board storage or from a Synology NAS via Ethernet to headphones or via line-out to a separate pre-amp/amplifier to speakers. I can access the player through the touch screen or remotely through VNC.

Hopefully my next post will be about one or more enclosures using the Raspberry Pi 3 with Rune Audio (based on Arch Linux). A headless version I have been working on is 125 x 115 x 38 mm, weighs 480g, and has USB attached SD card readers instead of an SATA SSD. It might conceivably take up to 6 SD cards, making for a 3TB capacity using currently available cards, although the most I have used is 4 SD cards. The battery is 5000 mAh and lasts up to 7 hours (about as long as the Mojo on a good day.) It has WiFi, and also a built-in bluetooth module, but I don't believe that is currently operational with Rune Audio. It boots quickly, and can be controlled via any web interface (phone, pc, ipad, etc.) located on the same network.

I have also been working on a Raspberry Pi version with a 3.5" screen. Unfortunately, the only screen of that size that I can find that works with Rune Audio has resistive touch. There is a 7" touch screen that works great, and also permits full touch scrolling, but it is far too large for a semi-portable application. I wish I could find a capacitive 3.5" or 5" touch screen that attaches directly to the Pi (not through HDMI) and works with Rune Audio or some other dedicated audio distribution. In the meantime, I will be experimenting with the 3.5" version with a touch pad. The sound from the Raspberry Pi 3 with Rune Audio might, if anything, be even better than from the Banana Pro. However, with the Raspberry Pi there are some issues with interference from the poor wiring, the design of the Pi itself, or lack of power that may introduce some faint crackling now and then.

In any event, the size of the Mojo (in its case it is about 83 x 62 x 22 mm), the screen, the battery, and the space needed for the USB connection between the Mojo and the front-end pretty much set the limits on how small I can make any of these players. I would love to make a smaller unit in a sturdy metal or plastic case with a dedicated SoC and OS dedicated to transporting bit perfect audio to the Mojo, with SD card readers or an SSD attached directly to the PCB, a direct connection between the Mojo and the front-end, with one battery for both the Mojo and the front-end. But all that is far beyond my current skills. Here's hoping that someone who knows what they're doing will try.

And please post any suggestions or ideas on how to improve on any of this!

Cheers.
Rod

U should make and sell these seriously

 

[serman005]

This thing is supercool!!! Bravo! (no pun intended)