I’ve managed to get Pd patches running on my Seed board, which is great.
One thing I’m not sure about: when I listen to the audio output on headphones there’s always a consistent quiet but noticeable high pitched whine/noise.
At first I thought it was interference noise from the USB bus when I was programming, but the sound is still there when battery powered.
The Seed is still on a breadboard at the moment, so there are lots of exposed non-shielded wires, so perhaps that’s the cause? However that doesn’t seem right to me because it’s so flat and consistent, it seems more like a DAC type noise.
Has anyone else noticed and/or fixed this?
I can make a recording later today if that’s helpful.
See the topic: Questions about digital noise and grounding which has entries from Aug 2020 to Sep 2021 for discussion on the various digital and analog issues that may cause this and ways to minimize each. I do think a recording would be interesting.
an update on this - today I recorded the output from my test patch. You can download the audio file and the Pd patch here.
This gave me a few clues. The first was that the output gain was very very low - it barely registered on the meters of my sound card when using line-in.
Here’s a spectrogram of the (normalised) sound file.
I guess what I’m hearing at the buzzing noise is those very clear lines going all the way up the spectrum!
This therefore feels to me like I’m simply hearing the digital noise floor, because for some reason the output gain from my Seed is very high.
This also may relate to another issue I’ve had, where my Pd patches need their output gain reduced much more than I would expect before they can sound good running off the Daisy.
Perhaps I’m completely misunderstanding how the output gain stage works on Seed, or pd2dsy?
I want to shorty weigh in on the question. I have the same experience. First blamed my psu/breadboard. But there is no difference with usb or battery power or double isolated and filtered power input.
I did some tests and the culprit seems to be in the actual code (I am also using pd/plugdata at the moment).
Running a sine through the dac~ sounds fine. No noise. But if I passthrough the adc~ to the dac~ i get a terrible whine. The frequency of which changes with different block sizes and sample rates.
Even with no actual sound input the noise is terrible. I will do some more testing to see if this can be omitted or filtered some how (in software).
