Having a very odd experience tonight with different combinations of USB hubs and power supplies with my Digitone, Digitakt, iPad, and an Anker USB hub.
I have this unpowered USB hub, which Anker said supports MTT. I have that plugged into an iPad Air 4 with the official Apple USB/HDMI/Charging dongle and official Apple PSU. I have the Digitone and Digitakt both plugged into the hub running into AUM on the iPad to control some synths and receive program/pattern change messages. The DN is my master clock, transport, and audio mixer. It sends MIDIUSB to the iPad, and MIDI DIN to the DT. The DT sends audio and MIDI DIN to the DN, and the DT receives MIDIUSB from the iPad. The iPad is sequenced by the DN, and sends audio to the DN via USB. I also have a powered UGreen USB hub that I use in my studio with everything routed the same way, and it works flawlessly. I also have some 3rd party PSUs for the Elektron devices so that I don’t need to crawl under my desk and unhook stuff when I want to work outside the studio.
Tonight, I was setting up everything for the first time with the new Anker hub and 3rd party PSUs, and ran into an issue where the audio from the iPad into the DN would drop out regularly. After some extensive (and extremely scientific) testing, I came upon the following combinations of what works and what does not work. Note that I tested all 4 scenarios using both the DT and the DN as the midi/audio usb brains to see if it was the DN itself. Also, everything works normal if I plug one of the units directly into the iPad.
- If I use the Anker hub and both 3rd party power supplies, the audio drops out.
- If I use the UGreen powered hub and both 3rd party power supplies, the audio does NOT drop out.
- If I use the Anker hub and one 3rd party power supply and one Elektron power supply (it does not matter which machine has which) OR both Elektron power supplies only, the audio does NOT drop out.
- If I use the Anker hub with the Elektron PSUs but do NOT power the iPad, the audio does NOT drop out.
This implies to me that there is something going on with the power between the 3rd party plugs and the Anker. Since the Anker is unpowered, does it draw its current from all of the devices plugged in, or only the host device would deliver power?
I’m assuming that the 3rd party PSUs are to blame, somehow, but I can’t for the life of my figure out why. It’s so hard to justify spending $100 on a pair of extra PSUs, but I probably need something better than what I got from eBay. Even though they work totally fine with powered hubs, I would reckon that since they aren’t working fine with unpowered, they’re also probably not necessarily “healthy” for my gear.