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mmarino426

Help with loud Ground Hum when using Helix LT and the 4-Cable Method

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I've just been using the LT in the Effects Loop of my Friedman Runt 50, but today decided to try the 4CM to have some effects hit the front of the amp. When I hooked it up per the Line 6 Youtube video, I had a horrible (presumably ground) hum come through my speakers. I also hear what I would describe as a "Dry Signal" coming through the speaker as well when I switch to my distortion channel on the head at the same time.

 

Here is my layout:

 

See picture of the layout: I have Volume, Wah, Compressor, and OD before it goes to "Send 1", which then after that has Delay 1, Delay 2, Flanger, Boost, and Reverb inside the Effects Loop, then going to Return 1, then to 1/4" out.

 

My connections are as follows:

Guitar (Gibson Les Paul) -> Helix LT Guitar Input

Helix LT Send 1 -> Friedman input (front)

Helix LT Return -> Friedman Effects Loop Send

Helix LT 1/4" Out -> Friedman Effects Loop Return

 

All power cables are plugged into the same Furman power conditioner, and those are the only things being plugged into it. This is a closed loop system.

 

Any help or advice would be appreciated!

Screen Shot 2019-01-17 at 3.52.02 PM 1.png

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You are sending signal to your pre-amp via the Send block.  If this is set to send 100%, there is no signal at all going through the subsequent effects before the signal from the pre-amp comes back via the Return block.  If there is a mix both ways in the Send, then this will cause the dry signal to come through as well.  The Send and Return blocks have some odd settings that you need to check carefully.  Rather than using separate Send and Return blocks, you are better to just use a combined FX Loop block at the point you send to the pre-amp (i.e. where your send block is now).  The signal goes through the pre-amp, and then comes back into the same FX loop block.  The subsequent effects are "in the loop" and add to your pre-amp sound before the signal goes back out to the amp's power section. 

This is unlikely to be the cause of the hum, but it may not be a ground loop. There can be all sorts of causes for this, and it is nearly always external.  One that nearly drove me mad was interference to the effects loop only of a Blackstar Artist 15 (didn't happen when just going in the front end).  It turned out to be a ripple on the power supply caused by power-line networking.  Subsequently I had a similar problem caused by an electric reclining chair - it had always been there, but it had just got plugged into a different electric wall outlet in the same room!  If possible, turn off and unplug all electrical appliances on the same circuit, one by one.  And I do mean all appliances - lights, TV, TV cable and satellite, clocks, fridges, heating timers, sound systems, alarm systems, - I even turned off the fountain in my garden pond!  Chances are it will abruptly go quiet just as you turn off some seemingly innocuous bit of equipment.

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Same problem with my Engl Rockmaster. Channel switching by Hx. 4CM humming increases drastically when I plug the stereo cable into the Amps Insert for Channelswitching. Could Midiswitching help e.g. with a Voodoo Lab Control Switcher MIDI Amp Channel Switcher?
Thanx

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I'm having this problem with my M13 and a Vox AV60. When I use the dirty channel, the hum gets worse. Or if I place a distrotion(metal zone model, on the M13) on the effect loop.

The M13 manual says that this may be resolved by adding a ground lift box. So, it seems that I need to get a "ART Cleanbox II Earth Loop Eliminator" to try to resolve this.

https://line6.com/data/l/0a0600729b4f4af8b8d2e9557/application/pdf/M13 Advanced Users Guide (Rev A) - English.pdf . (Page 2*4)

 

I had a quick look at the helix manual and they don't mention anything about Hum on the effect loop, but it might be worth trying the earth loop eliminator... the question is... Where in the chain do you put it :-)

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As I suggested above, these are not necessarily ground loop problems, particularly if it only occurs when using the effects loop but not straight in the front of the amp.  Methodically eliminate anything else first.  Eliminate interference to the guitar by turning the guitar's volume pot to zero.  Try the Ground Lift button on the Helix, if there is one (there is on my Helix Floor, though it has never solved anything).  Noise will always get worse with gain - gain amplifies everything - not just your guitar signal, and that is not indicative of a ground loop.

Try removing the Helix from the loop - replace it with just a single ordinary pedal, or just with a patch lead across the amp's effect loop.  It is also well worth while testing the rig in another house - if the problem does not occur there, you can be sure that the cause is EM interference in your own house.  Then you just have to find the cause.  

 

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On 1/19/2019 at 6:43 PM, latus said:

Same problem with my Engl Rockmaster. Channel switching by Hx. 4CM humming increases drastically when I plug the stereo cable into the Amps Insert for Channelswitching. Could Midiswitching help e.g. with a Voodoo Lab Control Switcher MIDI Amp Channel Switcher?
Thanx

 

This is most likely a different problem - Helix's EXT Amp switch socket is not Relay isolated (like most other devices are) - and because it's not isolated there can be a ground loop created.  So with a lot of traditional tube amps plugging in the EXT amp when in 4cm either does not function properly at all, or causes hum. or both.  There are many threads about this - Yes you need a MIDI amp switcher - or to build a relay isolation module to go into the EXT amp socket.

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