SunVox and Raspberry Pi 3 HiFiBerry DAC+ Terrible?

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danzigism
Posts: 2
Joined: Sun Sep 17, 2017 11:42 pm

SunVox and Raspberry Pi 3 HiFiBerry DAC+ Terrible?

Post by danzigism » Sun Sep 17, 2017 11:52 pm

Hey there folks. I've been doing some testing with USB Audio vs. a HiFiBerry DAC+ which is basically a GPIO HAT for the Raspberry Pi 3 and SunVox. Needless to say I've had some interesting results that I've documented in this video https://www.youtube.com/watch?v=qK-BuYLYi10

I'm just curious to hear from other MIDI people in here and if they've had any success with the GPIO based DACs for the Raspberry Pi?

When I first tried the Behringer UCA202 for Raspbian Jessie, I finally managed to get the latency working at a reasonable rate (after compiling RT support and getting JACK setup correctly) but it still was laggy enough to annoy me. I thought a DAC+ might be the solution, and simultaneously, Raspbian Stretch now became available as well.

I got the DAC+ and tested it with a fresh install of Raspbian Stretch, and to no surprise, the default ALSA settings were horrible sounding, no matter what buffer rate I used. So I went down the JACK path and had very hit or miss results, including extremely low output levels, requiring you to turn up the volume very loud and getting lots of crackling and distortion, sometimes no audio at all, terrible latency, the whole gamut. I tested every buffer setting I can, tried another RT kernel, and it just plain sucks with a DAC.

The curious thing I found out with Raspbian Stretch, is that USB Audio on the otherhand, worked flawlessly with JACK. Much better than Jessie Lite for some reason. I can actually play this thing now with 256 frames no problem. 128 is pushing it, and you can still hear some cracks, but wow what an improvement. So I've determined in my testing at least, that USB Audio is considerably better for the Raspberry Pi.

I'm just wondering if anyone else out there has had success with GPIO based DACs/HATs and MIDI latency?

danzigism
Posts: 2
Joined: Sun Sep 17, 2017 11:42 pm

Re: SunVox and Raspberry Pi 3 HiFiBerry DAC+ Terrible?

Post by danzigism » Wed Sep 27, 2017 8:54 am

Just a quick update that I found another annoying feature of the DAC+ called "Auto Mute". It creates a little popping noise every time the sound stops. This is super troublesome when using SunVox and MIDI in general, especially when trying to record the output on an external device. The alsamixer allows you to change the mute period in seconds, but that's it. No way to disable it.

Is it just me or is this a cheapskate way for a software developer to eliminate line noise from a not-so-great piece of hardware?

In addition to testing on the Pi 3, I tried it on a Pi 2 as well with the same identical results.

On another note, the Behringer USB Audio is still working fantastically.

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