MIDI noise

A

Alexander

Well-Known Member
One thing I have never been able to solve is MIDI noise (ticking) from the Tempo LED on my Axe-Fx.
Disabling Poll State on the GT, which makes the MIDI LED blink less often, makes it less apparent.

It happens with every MIDI cable I use, even high quality ones. Also with the 6-pin XLR, and with or without the phantom power box in-between.

It goes away when I disconnect the cable between MIDI OUT on the Axe-Fx and MIDI IN on the GT.

Disabling real-time sysex on the Axe-Fx doesn't solve it.
Disabling the Tempo action on GT buttons doesn't solve it.

Strangely it's more apparent at home than at rehearsals and gigs.
 
That's odd, typically changing cables is enough... So, you're saying that disabling Poll State and tempo flash on the GT and turning off Send Realtime System on the Axe-Fx at the same time still results in the noise? Do you have the looper block active in your Axe-Fx preset(s)?
 
That's correct.

No looper in the presets.

But I did a little more investigation and it is not the GT hardware. Because just holding the tip of the GT's power plug (not connected to the GT) already makes the tick audible.

It some kind of bleed-through from the Axe-Fx. Maybe something in the wiring of that specific wall socket, maybe EMI or whatever. So I'll take the issue elsewhere. :)
 
Definitely check the ground situation on those wall outlets, and if you're using a power strip or rack-mounted power distro, check those outlets too. Make sure the GT power supply is plugged into the same power strip / power distro as the AxeFX, to avoid any ground potential between those feeds.

Esoteric, but possible culprit: clocks in educational facilities and large business buildings receive a timing pulse via the power line. It's done to keep all of the clocks in sync. Many modern clocks receive their time via WiFi and are synced to the second. But older systems inject the time sync into the power feed for the building, and that often leaks out into adjacent power feeds. I used to live about a block from a middle school, and I could never keep my studio timeclock stable. Eventually we had an Engineer friend come and analyze the power with a scope, and sure enough, there it was. We got a fancy power conditioner / line stabilizer (TrippLite LCR 2400) and it corrected the issue.
 
Further investigations: the noise synced to the Tempo LED disappears when I disable real-time sysex on the Axe-Fx.

But the noise synced to the MIDI LED stays, and only disappears when disabling Poll State on the GT.

I suspect that the instrument input (small pcb board inside the Axe-Fx) isn't shielded as it should be.
 
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