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Posted

Android 5 finally allows USB audio out.  It was available in various forms on Samsung products, but is now baked directly in to Lollipop.  

 

In attempting to connect my Pico dac/amp directly (no hub) to my Lollipopped Galaxy S5, I am unable to send the digital audio out to the dac.  The Onkyo app actually has a setting for USB Audio, but the phone just hangs and shows no love.  I've had my Pico for years now, so maybe I need a newer version?

 

Most googling sends me to the other site or to Korean sites with posts about other dacs.  Google is not my friend.

 

Justin - is this something you are familiar with?  Is there a way to update my beloved Pico?

 

Posted (edited)

one thing i've found is that the phones can be extremely picky about the amount of capacitance on the 5V line. USB spec is supposed to limit this capacitance to 10uF. but in the era that the Pico was designed, nobody really cared, and more capacitance was usually added in order to filter the noisy computer power supply. So what happens is when you plug in the cable, the 5V is momentarily shorted by the capacitor and it messes up the handshaking. I've never used a computer that had a problem with this, so my guess is the phones are either more susceptible to this capacitive load or they aren't attempting to handshake again.  I found that a small resistor such as 2.2-ohms in series with the 5V can fix this problem. If the resistor is too large it would no longer handshake correctly with my computer 100% of the time. This could be built into a custom USB cable, or the Pico could be hacked to add it. Earlier Picos had a resettable fuse in series with the 5V which had enough built-in resistance on its own. This fuse was later removed because it was never useful. 

 

You may be able to get it to work sometimes with repeated connection attempts or very quickly reconnecting the cable after a failed attempt

 

this is what i found testing with Samsung phones pre-Lollipop, so i don't know if it all still applies. Never had an issue with the iPad/iPhone using the Apple CCK.

Edited by justin
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