[PD] RPI 3 USB audio performance?

[katja]

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 at 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 at 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 at 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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> --------
> Dan Wilcox
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> danomatika.com
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