Powered USB-hubs: a friendly word of warning

Hey folks.
Today at work I managed to accidentally plug in the wrong PSU in my 7-port USB hub after rearranging my desk. The hub needs +5V and I accidentally grabbed the +12V PSU from the APC40. I immediately realized the error – but 3 seconds was enough to fry my keyboard, the hub, and my graphics tablet. 500€ down the drain – not too bad for one day.

Back at home I’m using the same USB hub. It is connected to a lot of my gear.
Pyramid, ICM4+, PreenFM2, Micromonsta, DoubleDrummer, Nanokontrol, LXR, Padkontrol.
While I’ve really loved the no frill setup and the convenience of having a combined power/midi connection I’m realizing how super easy it is to get PSU connectors mixed up, especially on dark stages. On a powered hub, this error will get passed on to all the gear that’s connected to it. That’s when I realized how happy I am that my synths still live.

The bottom line: no more powered hub, no more power over USB.
Also saves me the ground loops I’ve occasionally had.

Maybe this advice will save synths in the future!


I bought a powered Anker 40W USB charger. Doesn’t connect to my PC, but with the “figure-8” style connector, it’s pretty impossible to mix it up.

But yeah, I did the same thing: fried a Small Stone phaser pedal, brand-new, with a 9V PSU, but got it mixed up with my MidiREX which uses Center-Positive vs. Center-Negative polarity on a guitar pedal.

Easy to do under a dark desk.

Noise used to be my big reason for avoiding USB power, now I have a second much more scary reason. And a very good reason to continue to label every single lead I have with their source destination sockets, audio, MIDI and power, I’m about to embark on rearranging my studio space so this warning has come at a good time. Cheers for the heads-up.

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yeah, i label my PSUs , and on the generic ones make voltage and polarity.
(fortunately, i only have one device that’s centre -ve)

@maximee what usb hub was it…
I’m really surprised it didn’t have some kind of voltage protection… definitely a sobering thought!

It was a D-Link DUB-H7 7-Port USB. Always liked it so far, but will definitely get rid of my other one I have.

Really annoys me to no end that a $0.02 and 0.2mm zener-diode they ommitted is responsible for such a hefty bill. I too label my PSUs, but so far only on the PSU itself. Thinking about labelling the actual connector, although it won’t look pretty.

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i just started labeling everything and putting veclro ties on everything, it’s so good and nice to have done

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I’ve got to the point of labelling my leads with what they are going into, eg MIDI cable ends are labelled where they are headed to or coming from, not what that end is plugging into, same with audio. It’s not so bad with audio and power, but due to the nature MIDI there is more of a need to know where they are coming and going from and once the setup is done, as you know where the lead has come from when you pull it out but may not know where it’s going, Oh I should mention the current count is 28 MIDI devices I’m linking, including 3 MIDI routers. Such measures to maintain a smaller rig may seem a little OCD, but my advice is it’s best to start good habits early.