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Re: Humming noise

Posted: Sun Jul 24, 2011 12:57 am
by Stew
That IS noisy!

So when it was cutting in and out, is that you taking your fingers on and off the strings? And when it was going from quite subtle to quite loud, was that you egtting closer to the SoftStep?

Re: Humming noise

Posted: Sun Jul 24, 2011 1:13 pm
by NoFi
I have the same problem with all my different guitars when using the softstep (PC windows 7 with usb soundcard), so i don't think it is really a grounding issue with guitars.
The funny thing is the squealing get slouder whenever my foot gets closer to the softstep and my hand touches the strings...
I don't mind just turning the lights of.
To cure the problem, i would probably first try to use a DI with a transformer between the guitar and the soundcard.
Then maybe a separate USB power supply for the softstep (then there's the switched mode VS linear regulated power supply issue).
I'll try to use the softstep with my batttery powered laptop in the next few days, i'll let you know if i get the same problem with my laptop.

Re: Humming noise

Posted: Sun Jul 24, 2011 3:20 pm
by Stew
I'd tend to agree NoFi, that it's not related to bad earthing of a guitar, given your experiences.

It sounds like interference from the lights is coming through the guitar electronics VIA your body ... that is dodgy!

I mean our bodies have electrical potential, you can see that when you zap someone after dragging your feet on the carpet. But this is another level! The SoftStep is effecting the electric field of the body and then being transmitted into the guitar. Funny thing is the only way it can get into the guitar is by the same earth that the KMI team were saying was not working correctly in Mr G's case, ie. the interference from the SoftStep is passing from the players body, through the strings and via the earth connection (normally connected to the bridge) to the pickups/electronics and then being sent to the computer interface.

... and yes, a transformer isolated DI may help, although this is so weird I really have no idea what may help.

It would be good if anyone else who is having problems like this could post their experiences to try and help the folks at KMI understand what is going wrong. I'd also be interested to see if the KMI team could replicate these experiences or whether there is something 'unusual' about the setups in which this is an issue.

Re: Humming noise

Posted: Mon Jul 25, 2011 10:37 am
by NoFi
I made a mistake in my previous statement : the softstep squeals in my monitoring system when my feet get closer to it, but it squeals less when i touch the guitar strings or the chassis of my mixer.

Also i noticed the softstep itself emits an "insect noise" with the EL turned on if i put my ear close to the 4 red digit display.

Re: Humming noise

Posted: Mon Jul 25, 2011 11:06 am
by Stew
Ok, so maybe there is some kind of earthing issue going on.

So when you touch the strings or the chassis of your mixer does the noise go away completely NoFi, or is it just less?

... and just to fully understand the situation, if you turn the lights off ( and by this you mean the lights that surround each pedal) the noise is completely gone?

Would anyone from KMI like to comment on this issue?

Re: Humming noise

Posted: Mon Jul 25, 2011 11:28 am
by NoFi
This happens only with a guitar plugged in the soundcard so i guess the guitar picks up the interference from the lights or something...
When i touch the strings of the guitar, the chassis of the mixer or the chassis of my soundcard the noise lessens, for instance if i step on the softstep really hard and take a huge grip on my mixer with all my hand then it goes away completely. If i only touch the mixer with one finger then the noise just lessens.
And yes, when i turn off all the blue lighting (EL ON/OFF in the software editor), there is no more noise problem.

Now if i remove the guitar from the equation, with all my equipment of, just the softstep powered via usb from my computer, i can still hear the noise in the softstep itself it i put it close to my ear. And the noise stops when i turn off the lights.

Re: Humming noise

Posted: Mon Jul 25, 2011 11:37 am
by SarahKMI
One customer discovered that plugging one end of a 1/4in cable into his audio interface and putting the other end in his sock made the noise go away. We believe what's happening is that your guitar strings are ungrounded which is why when you get close to the SoftStep you begin to pick up the energy from the EL Lights and then your body acts as a conductor for when you touch the ungrounded guitar strings which then act as an antenna, and this is why it is picked up in your audio. This is why it worked for the customer to plug in a cable to his interface and then put it in his sock, because by doing that he was essentially grounding himself and then by touching his guitar strings he grounded them too. This is also why it works to turn off the EL backlighting.

Not all guitars have ungrounded strings so you could experience this using one guitar but not another.

It is completely understandable that people would not want to put an audio cable in your sock during a performance so perhaps this solution might be better (this was the suggestion Mr. Gorilla referred to earlier that we told him about): first, try the sock experiment and then touch the ground part of the extra cable (from the end that would have been in your sock) to one or more of the guitar strings, then touch those strings yourself, does this also solve the noise problem when you get near the SoftStep? If so try putting some copper foil under the bridge of your guitar so that it is touching the ball end of the strings, then connect a wire from the foil to the grounding output of your guitar, making sure that it's touching the metal of the output. This should ground your guitar strings and make the humming go away.

Hope this helps!

-Sarah Howe

Re: Humming noise

Posted: Mon Jul 25, 2011 1:39 pm
by NoFi
Well, I know for a fact that my guitar strings are connected to ground (i checked to make sure).
And when i touch the strings, the noise goes down (which proves the strings are grounded), but it does not disappear completely especially when i have my foot on the softstep : the noise is then quite loud.

I just did another experiment, with my feet not touching the softstep, the closer i bring the guitar to the softstep, the louder it hums.
Anyway, i don't care that much, it is just fine with the lights off.

Re: Humming noise

Posted: Mon Jul 25, 2011 3:17 pm
by Stew
Hi Sarah ... appreciate your input into this situation.

It sounds however that there is an issue beyond the guitar grounding (note NoFi's last post). Is this something that the KMI team could investigate to determine whether there is a problem with SoftStep that needs to be addressed?

At the moment it appears you are assuming the problem is with one or two particular user's setups. This may be the case but is it also possible that this 'issue' is inherant in the unit itself and it happens to be something that you guys just have come across yet?

Re: Humming noise

Posted: Mon Jul 25, 2011 4:26 pm
by mrgorilla
Sarah did ask me to try putting the copper foil in my guitar. I have attempted a couple times, but I am an idiot and I haven't gotten the copper foil to stay proper. I'm going to keep trying, and i'll let you guys know.

I will be out of town for a couple weeks though, but I will try to do it before I leave.

Sarah, could you recommend a guitar you guys have tested it out on? I could probably even just take the soft step with me (and my computer/interface) to a guitar store and try out a handful of different types too.

just so we can rule it out as the guitar or not being the issue.