Midihub creating a tempo buzz

I am running my Midihub between a Keystep Pro and a 1010Music Blackbox plus some semi-modular gear - all on 5-pin DIN except the Blackbox. The Midihub is powered from the Blackbox, which has a USB Host powered connection. All works fine (actually brilliantly) except that I get a noticeable tempo-related buzz from the Blackbox when I start the sequencer on the Keystep. Connecting the Keystep and Blackbox directly (USB to USB) does not do this so the buzz is coming from the Midihub. It is NOT mains-related. Filtering in Midihub does not make it go away.

How can I kill this off? It is making this setup unusable and I don’t have enough 5-pin connectors out of the Midihub to link the Blackbox up that way (would be good to be able to configure the 5-pin ins & outs as say 2 in and 6 out…)

Hey, what do you mean by tempo buzz? Is it audible, or the tempo is stuttering?

It is a very obvious audible buzz which increases and decreases in pitch as I change the tempo on the sequencer. It is there whether or not anything is playing on the Blackbox.
I have actually been able to get around it in my setup now as there are two midi outs on the Keystep - one of which I am now taking directly to the Blackbox. But I would like to sort this as I now can’t use filtering (and all the other wonderful properties of Midihub) on the midi feed to the Blackbox.

Which audio output is producing the buzz sound? The Blackbox itself?

Yes it is the Blackbox audio output. There is no “noise” from this at any other time, just when the sequencer is linked to the Midihub and the Midhub is running off the host USB connection on the Blackbox.

That’s very strange - I can’t think of anything in Midihub itself that would make Blackbox produce any noise.

What is producing the MIDI clock when Midihub is connected to Blackbox?

Could you upload the preset you currently have on Midihub for us to take a look?

The Keystep Pro is producing the midi clock. The noise happens just the same with any Midihub preset including completely blank.
BUT I have just been experimenting and it is linked to the other 5-pin outs. Three are plugged into 2 Moog units (Subharmonicon and Mother-32) and to a MakeNoise 0-Coast. If I unplug all these then the buzz from the Blackbox stops! I don’t understand this as there are no other connections into these other units and it is not a ground loop type problem as it only appears when I switch the sequencer on and the frequency of the buzz is related to the tempo. Trying each DIN connector separately gives a little noise from plugging in each. Weird.
I have managed to work around my problem as I described earlier so I quite understand if you want to take this one away and think about it!

Does it happen when you runt Blackbox from a Powerbank aswell? I hade a hum (before I got a midihub) from the BB that disappeared when I used a power bank instead of the wall socket.

Run not runt. Sorry. Using Swedish auto correct in the phone…

Thanks but that would be due to a mains / power issue into the Blackbox. I have a very specific oddity where I am powering Midihub from the Blackbox and it is a sequencer-tempo buzz that is coming through, not mains frequency. You are certainly right that the Blackbox (and other gear) can suffer from mains hum if several bits of gear are run off a single power supply and using a power bank can help.

Yes your right. That sounds like something different. I haven’t tried power the midihub via the bb host. I remember I hade some problems when I powered My Beatstep pro with it, but I don’t think it was THE same issue you’re having. More like a memory lack in the BB.