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dfennessey1122

Helix USB / Audio output noisy

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Hello everyone,

 

I solved a big mystery today...i have a Helix LT as some of you may know from my previous posts. I also have a rack of preamps and a pedal board that i use as well as the LT depending on what sound i am after. I have been chasing this really nasty hum / signal noise problem when i was using my rack preamps in Lead CH overdrive mode in particular. I went though all kinds of hoops to check for ground noise, ground loop, bad signal / power cables, noisy pedals, patch cords, etc...this has been going on for several months...in fact, ever since i got my Helix LT...hmmmm....well, i don't turn on the LT when i use the other preamps....so i did not suspect that it was part of the problem...not to mention it is not in the guitar signal path when i use the external preamps.

 

But the LT unit does sit next to my external pedal board.....so after exhausting everything else...i had to consider that i may have an X-File case here.... :) So i first i unplugged the USB cable on the LT....the noise level dropped significantly....then i unplugged the output cables on the LT...noise gone!! ....or at least back to normal acceptable levels. Wow! this really had me going for several months...so glad i solved this killer noise problem finally...the Helix LT is a digital noise blasting machine....so i just leave it unplugged unless i plan to use it.

 

The funny part is that the LT does not seem to be susceptible to the noise it creates...that is the good news for those of you that don't have any other gear you are interfacing with. I am amazed that this thing passed EMC certification testing (radiated electrical emissions testing to ensure that it does not do things like this). 

 

Enjoy...Dan

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I don't own an LT - I've got the full floor unit - but I seriously doubt you have correctly sorted the problem.

It's a batch of electronics in a metal box - so it should be totally shielded.

Just because you unplug some cables and remove hum does not mean the thing you unplugged was faulty or extremely noisy, just that the other devices don't have a ground relationship until you introduce that piece of kit.  Somewhere recently someone discussed noise and how to deal with it - they actually suggested disconnecting the earth wire on some leads.  Which can work, but you really need to know what you are doing if you go down that road. If the eathing were to not ground everything somewhere in the path, you could zap yourself.  Why don't you try to borrow some isolation units and see if that also solves your problem? (try it on your amp or other gear - not just the Helix) Or better still, take your stuff to an audio expert - preferably one with musical equipment experience?

You must know that plenty of people are running rigs with some similarity to yours without problem?

Some examples - 

or in the studio - 

in the studio.

Now it's not the LT, but it is the same electronics inside that box.........so very unlikely to be different.

You might find a ground lift for your amp solves everything?  Unless your particular unit is faulty.........it's not the Helix.

I assume you have tried the ground lift on the Helix itself?

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Hello rvroberts,

 

Thanks for the insight....i tried the Hum-X approach on isolating the grounds on all preamps as well as the LT...no difference....i know all the AC electrical wiring in my studio that my system is connected to runs off the same breaker loop...checked that yesterday....no ground loop opportunities. I have read that other people complained on the forum about how noisy the effects sends are...i have also experienced that but not the kind of  radiated noise i was getting ( i did mention that this problem is radiated, not conducted)...i do not have this problem with any other gear in my studio...and i have  a lot of gear in my studio....i hear what you are saying about the ground relationship...but i am not sure what else i can do about it...i tried both grounded/ground lift on the preamps and the LT....made no difference...and this is the really strange part.....just connecting the USB cable and the output cables to the Helix without powering the Helix creates this problem....very strange...perhaps it is just my Helix LT that is having a problem...i have followed all the correct grounding procedures i can think of....it's not a big deal for me to unplug the Helix when not in use and plug it in when i need it....i am just happy i found a solution to the problem.

 

Thanks, Dan

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It’s not just you. I got a helix LT 2 week starts ago and have been experiencing similar problems when running 4cm with my Mesa Mark V. I get a ton of hum on channels 2&3. that drops if I unplug the usb but there’s still enough to be annoying. Running direct guitar to amp with no helix is dead silent on all channels. I’ve not had problems previously with just pedals powered by a one spot (which is used on pedals before I put and in the loop).

I was trying to diagnose with a 2 to 3 prong adapter but that made no difference when trying on both the helix and the Mesa. However, while trying that I noticed that the hum is there even with the helix off and unplugged from an outlet if the cables are still connected. Weird. Pulling the USB did help a lot but it’s still a problem. Channel 1 is quiet but I think the noise is still there, it’s just not gained up like 2 & 3.

Would like to know if you’ve figured it out.

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