Sorry to hear about the issues you have encountered.
boondlux If this is such a common problem, and a known limitation of the BB boards then please someone tell me why this is not mentioned as a warning on the product page?
The main reasoning behind this is that Bela is designed for embedded use: once you are done programming it, you put it in a box and run it without having a USB cable connected. Using it as a sort of "outboard FX unit" permanently connected to your computer is also not a common use case: the overall system latency of your computer would dominate the latency figure and then the modest CPU capabilities of the board compared to the host would give such a small incremental advantage that it's probably not worth the effort. Even with this setup, once the code on Bela is finalised and the USB connection is removed (powering Bela from a separate PSU), the ground loop issue is resolved.
Therefore, the only use case I see for having Bela connected via USB and at the same time processing live sound from a host computer is for prototyping purposes: you need some input test sound for your signal processing and so you play some sound out of the host computer. Makes sense, we have all been there and I understand that even in this configuration the noise induced by the ground loop can be annoying. I have gotten around this occasionally using a DI box with ground lift, or recording a sample of the type of sound I want to process from live input (e.g.: a guitar) on the board itself and then using that recording for further prototyping, till I am ready to go back to live input again.
I understand there may be some more complex setups not covered above where this issue could also emerge and I am sorry you encountered one of those. Luckily the type of use cases where this is an actual problem are not very frequent (I guess we could get a sense of that by looking at how many ground loop issues have been reported on this forum since foundation out of 2200 posts).
boondlux Now all I have left is to say, please can you put a notice UPFRONT somewhere in the network or connectivity section on the bela website,
That's something we could look into. Where would you think it would be best to put such notice? Where did you go looking for it?
boondlux The fact that the use cases involving connecting to the a computer with supercollider (remote mode, hosted mode) is presented
We present live coding from the Sc IDE running on the host computer for prototyping purposes and this has also be done for live performance, where Bela's I/O and low-level connectivity were useful, but I am not aware of a place in our documentation where we recommend such a setup while processing live sound from the host computer, or to otherwise connect sound from the host computer to Bela alongside a USB connection.
I should also say that if you are unsatisfied with your purchase and would like to return your boards, all you have to do is contacting orders@bela.io.
ryjobil I haven't tried it, but I wonder if something like this would help:
www.amazon.com/Isolator-Protection-Isolation-ADUM3160-Module/dp/B08HHW4DXY/ref=sr_1_11?keywords=usb+isolator&qid=1650138646&sr=8-11
Good question. This is Full-Speed only, while the USB connection to Bela is normally High-Speed, however high-speed isolators are much more expensive. I investigated a bit in the kernel and it seems like there is no straightforward way to set it to run at full speed by default, but if negotiating with a host which is only full speed-capable, it should gracefully fall back to full speed. If anyone has such a host around, and/or a USB 1.1 or USB2.0 FS only hub around, it would be worth trying out whether Bela connects fine through it, then we could try a Full-Speed isolator as the one you recommend.
