Hi, I am new to modular and my first purchase has been an Arturia RackBrute 6U housing. Even with just a single module installed the unit is creating an annoying 1.5kHz tone, which is clearly apparent when monitoring and in audio recordings. I suspect that this is being generated by the Arturia power supply unit and must surely be a hardware fault. Has anyone else come across this? I have seen one or two comments on the Arturia forum about this and wondered if it was a well known problem in this community. Thanks!

If it's the line supply (they're usually switching types, and this sort of crap is indicative of a low-quality switching power supply), then you might want to consider adding another ferrite to the DC line to the RackBrute. Mouser has a good selection of clamp-ons at https://www.mouser.com/Passive-Components/EMI-Filters-EMI-Suppression/Ferrites/Ferrite-Clamp-On-Cores Also, try adding an inline EMI filter to the AC side, as the AC supply might also be sending the 1.5k crud back down the AC line and from there it's getting into other components. Mouser has these at "https://www.mouser.com/Passive-Components/EMI-Filters-EMI-Suppression/EMI-Feedthrough-Filters (edit: the forum's formatting is screwing with these URLs, but they should give you a good idea of where to look on Mouser's site)

And if all else fails, dump the Arturia AC supply altogether. Personally, I really don't think a lot of switching-type supplies in audio-critical or RF-critical applications unless they're specifically engineered for them. Changing to a linear supply might be a bit inconvenient, but the stability of linear supplies plus their working method ensures not only much lower noise figures but also better stability. Plenty of suitable linear supplies from the likes of Tektronix, Hewlett-Packard, et al can be found on eBay...just make sure to overspec the current capacity by at least 1/3rd (if not more) to deal with inrush currents on switch-on, and choose something that's in good, calibrated working order.

Thanks Lugia, that's very helpful.