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Ground buzzzzz

mojave

Inspired
Anyone ever have a buzzzz when using 1/4 outputs on back going into a lil mixer.Its the Axe-Fx as soon as i unplug jack stops,, XLR outs work fine.I know its not my cables tried ground switch no change.Id just use XLR but if it needs to be fixed like to get it taken care of. any ideas thxs
 

mojave

Inspired
Its like you wana smash it kinda loud and so the the units is worth less,, it buzzes is very loud when your playing ?
 
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Cron

Inspired
I have the same problem when hooking my axefx up in front of an amp. Ive looked at the humx and it seems perfect but they dont seem to make a euro/aus voltage one.

Anyone have any ideas? How bout a schematic to build something similar?

Sorry for the threadjack but im desperate.
 

Rex

Legend!
The Hum X is essentially a pass-through power connector. The exception is the ground connection. Instead of passing the ground straight through from one connector to the other, it passes through the following three devices, all connected in parallel:

  • Two back-to-back 6 amp, 1 KV diodes;
  • One 1 KOhm, 1/2 watt resistor (I haven't done the conversion math, but I think a 1KOhm, 1 watt resistor might (*MIGHT!...no guarantees) work for Euro/Aussie voltages).
Alternatively, you could just buy an isolation transformer.
 

dodo

Inspired
Behringer HD400 Ultra Compact 2 CH Hum Destroyer works (for a lot of people, in certain set ups) if you have 1/4 jacks and you need the hum removing.
 

Cron

Inspired
The Hum X is essentially a pass-through power connector. The exception is the ground connection. Instead of passing the ground straight through from one connector to the other, it passes through the following three devices, all connected in parallel:

  • Two back-to-back 6 amp, 1 KV diodes;
  • One 1 KOhm, 1/2 watt resistor (I haven't done the conversion math, but I think a 1KOhm, 1 watt resistor might (*MIGHT!...no guarantees) work for Euro/Aussie voltages).
Alternatively, you could just buy an isolation transformer.

Thanks!

Can anyone else confirm this? I just want to be sure :)
 

mojave

Inspired
Not sure if this matters when I run the 1/4 to RCA to my sound card it don`t do it ? Why would it do it on the 1/4 outs not the XLR out ??
 
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LMO

Fractal Fanatic
The Hum X just uses the two diodes--no resistor. I'm guilty of using one without thinking about it, but now that I have I'm concerned that the diodes used are too small to handle the amount of ground current required for UL certification.

I'll probably just build my own, either with some hefty power diodes, or perhaps using a 20 amp bridge, depending on parts availability.
 

Rex

Legend!
NotWhy would it do it on the 1/4 outs not the XLR out ??
The Axe's 1/4-inch outputs are unbalanced — the ground connection is part of the audio circuit. The XLR output is balanced — its ground connection is provided by a thrd wire that's not part of the audio circuit.
 

Rex

Legend!
The Hum X just uses the two diodes--no resistor.
Maybe there are different revisions. The information about the resistor comes from someone who opened one up and unpotted it to see what he cold see.


...I'm concerned that the diodes used are too small to handle the amount of ground current required for UL certification.
What current capacity does UL require? The full rating of the branch circuit, or something else?
 

LMO

Fractal Fanatic
Maybe there are different revisions. The information about the resistor comes from someone who opened one up and unpotted it to see what he cold see.
I also got the information from someone who opened one up, so there may be different versions. I haven't found it, but a patent application supposedly references just the two diodes; that sounds shaky to me, so I don't entirely credit that information. Pure speculation building on that shaky foundation: it's possible the resistor disappeared when a prior art search turned up the identical circuit in a galvanic isolator. ;)

What current capacity does UL require? The full rating of the branch circuit, or something else?
It must be able to trip the breaker repeatedly. I suspect the diodes will fail to a short circuit, so it may well trip the breaker the first time or two. A small plastic package in potting compound would be subject to heat build up, so it probably wouldn't take long to burn the junction through and open the circuit. :cry
 

Dpoirier

Power User
The Hum-X is rated for 6 amps... the Axe-fx draws a small fraction of that, hell even and a Verve 12mA blasting at ear-shattering levels draws less than that... so why is everyone worried about current capacity? The Hum-x is not intended as protection against current spikes (that's what your power conditioner is for), but rather to eliminate ground loops. A judicious combination of both should provide some users with usable solutions to audio problems they are facing.

Why the worry?
 

LMO

Fractal Fanatic
The issue is the integrity of the ground wire connection. If you have a failure that shorts AC directly to the case, then the ground leg has to be able to carry that current until the breaker trips.

A standard household circuit is usually 15 or 20 amps, plus whatever the tolerance is for the breaker.
 
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