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Post about any product in the Audio category on the SparkFun website: https://www.sparkfun.com/categories/273
By amongstmyselves
#201791
Howdy all,

The problem is that when a sample is played there is a background noise also. This noise is still heard for about 30 seconds after the sample has finished playing. This is something I had mentioned to Jamie the creator of the unit back a year or so (or two maybe) which I did resolve at the time but clearly the resolution was not completely fixed.

Quick background on the project. This is a large project which is using the Tsunami as a sample player controlled via a MIDI keyboard. The four stereo outputs have their own VCA modules which are controlled via individual stereo LFOs. The signal then gets mixed to another stereo VCA. This is followed by a stereo VCF module, Effects unit, valve distortion etc etc. A big project.

If I have the board simply connected to my audio system there is no noise when a sample is playing. But the instance that I connect it through a VCA or any other audio device on the same power supply the noise appears during playback. This noise comes out of all the Tsunami outputs regardless of where the played sample has been routed. Which makes the noise level quite loud. If I have the Tsunami connected to its own supply there isn't a problem. The noise is only present via other modules but it originates from the Tsunami ?

Here's a voice sample played along with the noise until it stops.

https://www.dropbox.com/s/1nzj5haa5fxfv ... 1.mp3?dl=0

Any help would be greatly appreciated.

Regards,

Steve
By Creepy
#202213
Hey there.
Totes speaking out of turn. I don't 'know' and there's a lot of 'assume' in my response, but:

I noticed the same noise when I powered my Tsunami from my laptop. Using a power supply resolved that noise issue for me.
Ground loop perhaps?
#202222
It's an odd one. I think I have a solution which is an isolated DC to DC converter module. I've not tried it as yet. It is certainly related to grounding I think. The odd thing though is that the noise disappears a few seconds after all samples have finished playing. I would have thought your "standard" ground loop would have the noise there the whole time.
By Creepy
#202235
You are correct, I believe.
I think when I had the Tsunami plugged into the laptop for power, the whine was constant.

Unless the audio file you posted is subject to the VCA and if there is any gating on that side of things...?
#202238
That's the giveaway that it's not ground loops I think because the noise never changes. In fact it will multiply as you use more of the outputs from the Tsunami. No the VCAs were totally open the whole time. Still to try out the DC to DC isolator which I might do today or tomorrow.
User avatar
By DSp
#202416
This may not be much help, but I can at least confirm that we've had this issue with Tsunami as well - noise keeps playing for some time after samples were either stopped or muted (memory fails me as to which one).

Our "solution" was:

* Optimize WAV file volume by multiband dynamic range compression
* Maximize sample gain while avoiding clipping (we were using Tsunami-Arduino-Serial-Library for control)
* Attenuate analog output using a potentiometer

While this masked the noise well enough for our application, it's still very much there.

Best regards