TOPIC:

Hi.

Made my first measurements and filters, and they seem to cause clipping distortions. It seems worse from volumio than from usb.


I cant see the attenuation settings any where, is there a hidden setting or are you supposed to put -10 db on the outputs in the dsp app?

Thanks!

@ Jonbon

Without seeing the setup, hard to say but it's most likely the way the Dirac measurement was done.
Make sure to not run the setup at 0dB for max volume control. Keep about -10dB headroom or so on the master volume control.

How did you run your measurement? Microphone level should be raised, then master volume should also be slowly raised.

DevTeam

Hi!

Did some more research and it is not dirac that does it, its on certain tones in tracks, i get a crackle, sort of like vinyl.

Guitar intro to Jeff Buckley - Hallelujah has it, if somebody else could check if they can hear it, it would be great.

It might be inherent to the airplay protocol, as get similar issues via a airport express, on another network and from both an iphone and mac.
Although, i would think there would be more reports of this.

USB cable from mac has no issues, and usb drive playback in volumio is also fine.

This looks similar:
volumio.org/forum/airplay-problems-t1796.html

So, I found this thread on shairplay-sync, the project that volumio airplay is based on:

github.com/mikebrady/shairport-sync/issues/459

Basicly, the noise I hear is interpolation noise.

If i set disable_synchronization option in shairport-sync.conf.tmpl to

alsa =
{
output_device = "${device}";
disable_synchronization = "yes";
};

The problem is gone, but i get stutters every few minutes. That is complete hickups, and NOT the interpolation noise.

According to the thread, setting drift_tolerance_in_seconds to a larger number, like 0.010 should solve it.
I tested .010, .015 and .050. At .050 it sounds good but i get 2 second resyncs about every minute.

Maybe the latest version of volumio and shairport would solve it?

@Jonbon

Mmmh, that's an Airplay setup... we've never done any testing with Airplay to be honest..
There is a new build of Volumio coming up soon.. Worth to see if that does the trick...

Devteam

.

Hello!
It´s a known issue, that the latest version of airport express (the one with the power cable) is bad. I had distortions and hickups.
So I bought the older version of airport express The one with the "integrated" power plug) and everything´s fine.