SET-UP: Low Power Linux Audio Player (ODROID-C2 & Volumio 2)

As you know from a few weeks back, I got myself one of these little single-board computers (SBC) - the Hardkernel ODROID-C2 - and posted a PREVIEW on it. As described in that article, I had flashed a copy of Volumio 2 "Release Candidate" (0.861RC1) to my SDHC card and have been streaming music to my TEAC UD-501 DAC in the music room for the last while.

Originally, I was going to publish both the contents in this post as well as measurements but it quickly became obvious that this was going to be too unwieldy (plus the day job got very busy)! As such, let me talk about the basics of the setup here today along with a few changes you might want to try if you're streaming from one of these Linux-based network machines. Then later, we'll get to the measurements...

Note that although I'll obviously be specifically addressing the ODROID-C2 I have here, the software is portable and at present, the good folks at Volumio have software images for many low-power computers including: Raspberry Pi, Beaglebone Black, Cubox, ODROID-C1+, etc... Just check their site to see if your machine is supported with a ready-to-use OS/app image. I've been informed that RuneAudio will also have ODROID-C2 support ahead (maybe as early as this weekend), so keep an eye on that one as well!

RETRO-MEASURE: 1994 Sony MDP-750 LaserDisc / CD Player [and further thoughts on the importance of objectivity]

Okay everyone... For this week, let's go old skool! Feast your eyes on this baby:

Notice the microphone input to the right - karaoke, of course...

That, friends, is the Sony MDP-750, a "vintage" LaserDisc (LD) player manufactured in February 1994 "Made in Japan" according to the label on the back. My dad bought this unit when I was still in university.

In 1994, S. Africa held interracial elections and Mandela won. The IRA declared a cease-fire in Northern Ireland. Kurt Cobain committed suicide. ER and Friends debuts on TV. Doom became a hit videogame launching many future FPS's. W3C (World Wide Web Consortium) was founded. Netscape was founded. Yahoo was launched. The Pentium was found to have some flaws in math calculations! Of course, who can forget? O.J. Simpson gets arrested for murder charges after driving around L.A. in his white Bronco. My, how time flies!

Although my family had owned a couple other CD players before this device, all the previous optical media machines have since died. This machine is built like a tank (weighing in at >21lbs) and still plays LaserDiscs like a champ! I opened it up to check on the gears and cleaned up some dust accumulated over the years.

PREVIEW: ODROID-C2 Single-Board Computer... [And an obligatory MQA addendum.]

Over the last year, every once awhile someone will come and ask me when I was going to try out a Raspberry Pi as a streaming replacement for my Squeezebox systems... Certainly I've been looking around and while I was relaxing in Puerto Vallarta a few weeks back, I decided to leisurely check online the varieties of these low-cost single-board computers (SBCs). Here's a pretty good list of recent SBCs on the market to get a feel of what's out there in early 2016.

Without a doubt, the Raspberry Pi computers are the current reigning champions in popularity. They announced 5 million units sold back in early 2015. The recently released Raspberry Pi 3 looks excellent. Plenty of support, reasonably fast quad-core Broadcom BCM2837 64-bit ARMv8 1.2GHz, decent but not impressive 1GB RAM, OK 10/100Mbps ethernet, and convenient wireless 802.11n WiFi with Bluetooth 4.1. The list price should only be about US$35 for one of these but due to worldwide shortage, there's a bit of a markup currently (very common supply-demand issue of course).

But looking around, another little computer caught my attention - the US$40 ODROID-C2 from Hardkernel, a South Korean company. This was just released in March 2016. I was able to get it here in Canada from Diigiit Robotics but I see that they're now out of stock and like the Pi 3, prices have become elevated. Here's the block diagram for the C2:

All technical details including schematics can be found here.

As you can see, it's a reasonably powerful little unit which easily can outrace the Pi 3 computationally (some benchmarks here compared to Pi 3). Quad-core Amlogic S905 CPU with 64-bit Cortex-A53's running at 2GHz, 2GB of DDR3 RAM, Gigabit ethernet, and a video subsystem capable of HDMI 2.0 4K/60fps output and hardware decoding for H.265 (750MHz Mali-450 "pentacore" GPU). Unlike the Pi 3, this unit does not have built-in wireless communications. Micro-SD card (supports UHS-1 speed) can be used or faster e.MMC 5.0 (400MB/s interface) module for flash storage. There's also an IR receiver built-in for remote control of features like volume adjustment.

So I figured... Why not? Let's get one of these little guys with the goal being to run a simple Volumio streamer out of it (I think we'll be seeing RuneAudio on this device soon also). Here's what I got:

The ODROID-C2 with clear plastic case. Note how small this computer is - about the form factor of my Costco card :-). Around the same size for the Raspberry Pi...

MUSINGS: USB Audio Gremlins Exposed: Beyond 1s and 0s? - Analysis of Industry Content

Fear, Uncertainty and Doubt in digital audio...

[This article has been modified over the years with reduction in the quotes from an article that appeared back in 2016! Even though AudioStream has been dead for years, I suspect iFi really doesn't like this article. I've received a number of claims that this article has been in "violation" of some kind of terms reported to Google. To be honest, I'm not sure what's the problem since free speech does allow me to quote from published articles and ads for the sake of voicing my own commentary. --- December 2023]

Oh my... Run for the hills folks! Didn't you hear? USB is a horrible interface for audio purposes!

Hmmm... At least that's the kind of interpretation one might be tempted to consider after reading this "truthy scientific" article on AudioStream ("USB Audio Gremlins Exposed: Beyond 1s and 0s, by iFi Audio")! What can I say? Brutal! Nice example of content from Industry to instill some measure of concern among susceptible audiophiles.

Okay, let me first say that I'm not claiming that USB is perfect - nothing is... You could run into issues. But the fact really is that these days, with a decent asynchronous DAC (what decent audiophile USB DAC these days isn't asynchronous?), one should not be concerned with data errors, jitter issues, and I have yet to come across noise pollution from a computer other than atypical situations like what I demonstrated a year back.

A typical $10 USB cable made to appropriate specifications by a reputable brand is fine.

With that said, let's delve into this short "article" and consider truth and fiction (delusion?)...