Dan, the reason I focused on small devices is that RPi is still prone to loose USB connection in cases of short voltage dip. The larger pro-sumer audio interfaces draw a lot of current which adds to the risk of those dreaded brown out moments. That is why I discarded the idea of using my favorite interface, Mackie Onyx Black Jack, in a wearable RPi setup. From the top of my head: the Mackie draws some 500 mA, an iMic ~45 mA and a cheap skype dongle ~10 mA.
Katja
On Tue, Oct 10, 2017 at 6:51 PM, Dan Wilcox danomatika@gmail.com wrote:
Katja, that's some good research especially considering the size of those interfaces. I'm mainly sticking with larger boxes which have XLR and jack inputs.
How is the performance overall ala dropouts, latency, etc?
I ran into issues with RPIs before that simply could not handle asynchronous with a more pro-sumer USB audio interface, leading to constant dropouts when running full duplex. I'm mainly using older but very solid Roland boxes (UA-25 and UA-25EX) which are stereo duplex USB 1.1, fully standard USB audio compliant, and work with pretty much anything including my iPhone.
I'm asking as I'd rather not go through the process of setting up a new system on yet another embedded device and get *less* performance than with my 500 Mhz wearable 10 years ago. :)
On Oct 10, 2017, at 5:49 PM, katja katjavetter@gmail.com wrote:
What I found is, small USB audio dongles don't process low frequencies well because they use too small capacitors. This can be improved by DIY soldering. Also some of them do a bad job in noise shaping, leaving quantization noise in audible range. That is something you can't improve. Here is a page describing some of my findings:
http://www.katjaas.nl/audiodongle/audiodongle.html
Good old Griffin iMic is better than the dongles I tried. But it is nice to hack a dongle and make it a tiny bit better. Maybe it's time to design our own audio dongle.
Katja
On Tue, Oct 10, 2017 at 3:41 PM, Dan Wilcox danomatika@gmail.com wrote:
For those of you using RPI 3s with Pd, how is the audio performance using a standard stereo USB audio interface?
I'm talking simple, USB 1.1 full duplex at 16 bit, nothing fancy. No special RPI-only backpack boards or GPIO audio debs, just regular usb audio devices.
Dan Wilcox @danomatika danomatika.com robotcowboy.com
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