Crackly distortion when I play multiple notes?

Peanut posted Jan 15 '20, 01:31:

I’m using SamplerBox on a Raspberry Pi 3 But whether I use the built in audio or a USB DAC I still get weird crackles/distortion when I play more than one note at once. I’ve tried messing around with the volume settings, which alleviates the problem a little bit, but the fact that it happens more prevalently with multiple notes is making me wonder whether it’s a performance issue rather than an audio issue.

I tested this theory somewhat by using a class 10 SD card instead, but the problem persisted. Before I try my next theory and try a better USB sound card, I’m wondering if anyone else has had this problem or could suggest what might be going wrong here?

HansEhv posted Jan 15 '20, 10:34:

The volume of the wav's is too high, so the sound is distorted before the volume adaptions you tried come in.
Either use a sound editor to normalize them to at least half or 1/3 of the volume or reduce the input volume via %gain of %%gain (if you use an image that supports those parameters).

Peanut posted Jan 16 '20, 00:28:

Thanks, I'll try that. Hopefully after reducing that volume I'll be able to increase the master volume in order to not have it be too quiet for my headphones... Is this usually the case with all of the samples provided on the SamplerBox website? What's the best place to find properly normalised samples??

Georg Vietor posted Jan 17 '20, 19:56:

Hi, I have experienced the same. After having installed all the bits and pieces, and now that SamplerBox is running on my RB 3B+ I also wonder why there is the distorted sound. If I play all the 12 wave-files e.g. from Chorus Key on my Mac/Digital Performer at the same time there is a clean and un-distorted sound. Loading the wave files into an audio editor (DSP-Quattro) shows that the files are already normalized.

What I experience is that if I have a strong attack on my keyboard then there is this distortion. If I softly push the keys then the sound is clean. This suggests to me this is a velocity issue.

Any idea/comment?

HansEhv posted Jan 17 '20, 23:48:

Yes, see my message above and/or read the "Controlling the Volume" on the "More info" tab on the site where you retrieved the 3B+ image.
Samplerbox is DIY and not a Mac. Luckily prices also differ :-)

Georg Vietor posted Jan 18 '20, 09:28:

Thanks Hans,

I may have solved the issue by adding (where not already included) the %%gain parameter. Adjusting gain for e.g. Grand Piano to 0.3 results in no audible distortion. One will have to experiment with each song, but for my Rhodes Piano I ended up at gain=0.2.

HansEhv posted Jan 19 '20, 02:33:

Exactly, glad it's solved & thanks for your feedback :-)


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