4 Cable Method Ground Loop Issues - Finally a good resolution!

[Leverage28]

I absolutely love the Helix and the 4CM with the exception of one major ground loop issue that I've experienced with 2 different 2 - Channel Amplifier's.  (Orange Rocker 15 and Freidman Runt 20)  I've searched and read many different forums where guitarists have battled this issue.  So, let me start at the beginning of what I've educated myself on from others who have shared their experience with this common grounding issue.  First off, I have used the HD500 and HD500X using the 4CM and did NOT have the extreme ground loop issues that I'm having with the Helix. From what I've read, it appears that the Line 6 Helix utilizes the same grounding points for all Outputs and Aux Send/Returns.  Had Line 6 isolated these different grounding points I don't believe that there would be the ground hum issues that exist.  I cannot verify this personally, but it's what I've read on other forum's who had looked at the schematic and does seem to make sense. 

 

So, in my personal experience there are two ground loop issues that I had to resolve to dramatically reduce the low end ground loop hum that I've fought with two different amplifiers.  In my situation I am not only running the 4CM, but also utilizing the Helix to switch my amp channels between clean and dirty channels.  When the amp switching 1/4" cable is NOT utilized, the ground hum issue is definitely still there, but dramatically less.  When you plug the 1/4" amp switching cable in, (in addition to the 4CM), it more than doubles the ground loop hum (on both amplifiers).  I had read on another forum that if you utilize a "ground loop isolator" on the effects loop send channel it would resolove the ground loop hum, which it does.  So, that is FIX # 1.  I bought a cheap Pyle 1/4" Gound Isolation box and also an expensive Lehle "P-Split" galvanic isolator.  I first bought the cheap Pyle box and it did reduce the hum, but not nearly enough, so I bought the Lehle P-Splitter hoping it would reduce the hum even more down to an acceptable level.  To the human ear I found that the dramatically more expensive Lehle P-Splitter ($180) did not provide any additional hum reduction over the less expensive Pyle box ($20).  If you are NOT utilizing the Helix Amp Channel switching, then this should dramatically reduce your "ground loop hum" and you should only read the next section for future reference.

 

Before I get to this next section which will reveal the fix that worked for my situation I wanted to make sure to share one other thing.  I did try and insert both the Pyle and the Lehle on my 1/4" amp switch output of the Helix, which did dramatically reduce the last part of ground hum, BUT it disabled the Helix from actually switching the amp channels back and forth.  

 

After realizing that I still had an issue after buying the more expensive Lehle P-Splitter with no improvements I then recruited the help of my good friend and sound technician for my band.  He's also has tremendous electronics background so I was hoping he might be able to help me resolve this grounding issue.  We started out with all the basic trouble shooting stuff like utilizing a ground lift, etc., to no prevail.  (I also have a high end ground ISO rack mount power supply in my rig.)  At that point he recommended that he build an ISO-Switch Box for me to insert right out of the Helix amp switch 1/4" output and then run the cable to my Amp's 1/4" channel switch input.  Well, IT WORKED!!!  After weeks of struggling to figure this out it was finally resolved.  So, I wanted to share my story with all of the other 4 Cable Method users and offer up a couple different options that my sound guy could help with.  Not looking to make big profit off this here, but do want to make it worth his time to build these units if anybody is interested.  He can build a 2 - channel ISO-Box (Clean/Dirty Switching) for $125 or he build a 3 -channel ISO-Box (Clean/Dirty/Reverb or Clean/Dirty/Lead - Tip/Ring/Sleeve) for $150.  Honestly, I would have paid $300 to get rid of the ANNOYING Ground Loop Hum as it was driving me absolutely nuts.  

 

So, for now I'll just say hit me up within this forum if you are interested and I'll connect you with my sound tech.  I'm going to put a YouTube video together at some point and I will update when I do.

 

Peace

[rd2rk]

If all you say is true, then this is the first serious and verified hardware design flaw that I've seen (apart from the funky USB connector).

I hope you've made L6 aware of this. There's no reason people should have to buy expensive add-ons to correct a design flaw in an advertised feature.

I would LOVE to hear what L6 has to say about this, so if you haven't contacted them yet, please do, and please post back with their response.

[scuccato]

Same problem with my setup using a real amp and it happens with other gear sometimes as well....but for the $2000 price tag you’d think this was something they would have just built into the unit. I put an isolation transformer before the input of my amp which fixes it, but just more stuff I did not want and should not have had to do. To be clear the amps I use are all high end and it’s not a power issue, it’s a ground loop. Wish I had tried this before buying the Helix.

[nhoven]

Running equipment in 4CM is a hit-and-miss concerning ground loops. It always depends on the grounding scheme of both the amp and the external gear. There is no design flaw, it's just the way it is. One could argue that Line 6 should have used potential free relay switching instead of transistor switching for the EXT AMP, but that how it is now.

 

I'm using the Helix in 4CM too, and there is one very easy solution: Isolate the redundant grounds so there's only one connection. In my case that's the cable running to my amp's input. The other two (FX send and return) are isolated via a bog standard iso transformer, in my case a Palmer PLI05, which is a dual 1/4" symmetric iso transfomer. The ghetto version is to cut the ground on the FX loop cables, but that can introduce other problems.

 

As for the EXT AMP, it cannot work with an iso inserted, as an iso completely breaks the physical connection, which is mandatory for the switching to work. The solution is simple: Either just disconnect the ground from the plug's sleeve of the cable or use an adapter to do it. On my board I have one such adapter with a stereo 1/4" plug going to a 1/4" stereo jack with only tip and ring connected, not the sleeve. Material cost about 10 bucks, assembly time around 10 minutes. $150 is a ripoff for a good friend.

[mtboydotcom]

I want one please let me know how i can obtain one

[rollylama]

I just got one of these and have a ground loop issue with a Dr Z Jetta with metro zero loss effects loop.  
 

Any ideas as to why I still get a hum when the grounds to both cables have been clipped at the HXFX end of them?  
 

I first tried running them normally with a clipped ground cable to the amp input and it didn’t work.

 

Next I mutilated 2 good cables for the loop and put a normal cable to the amp input.  Sounds exactly the same with a pretty bad hum.

 

Looking for some insight because I’d hate to send it back because of this but am also not willing to throw more money at it beyond the 2 cables I’ve ruined.

[rd2rk]

On 2/13/2020 at 5:14 AM, nhoven said:

Running equipment in 4CM is a hit-and-miss concerning ground loops. It always depends on the grounding scheme of both the amp and the external gear.

 

53 minutes ago, rollylama said:

Looking for some insight because I’d hate to send it back because of this but am also not willing to throw more money at it beyond the 2 cables I’ve ruined.

 

If you like your Helix AND your DrZ, then you do what you gotta do to fix the problem.

The Palmer mentioned above is $150. Ebtech Hum Eliminator is $72. The Pyle I mention below is $18.

Otherwise, you dump one or both and try something else.

Maybe you'll have better luck next time. Maybe no hum but crappy sound.

I don't mean to sound harsh (well, maybe a little), but welcome to the real world.

My Engl amp had horrible hum with my HD500X. A cheap Pyle "Hum Destroyer" got rid of most of it, enough to make it usable.

My Helix Floor with Egnator Tweaker has barely detectable hum, no gadgets required.

The Wizard of Oz knows why, but he's not talking.

Good Luck!

[rollylama]

3 hours ago, rd2rk said:

 

 

If you like your Helix AND your DrZ, then you do what you gotta do to fix the problem.

The Palmer mentioned above is $150. Ebtech Hum Eliminator is $72. The Pyle I mention below is $18.

Otherwise, you dump one or both and try something else.

Maybe you'll have better luck next time. Maybe no hum but crappy sound.

I don't mean to sound harsh (well, maybe a little), but welcome to the real world.

My Engl amp had horrible hum with my HD500X. A cheap Pyle "Hum Destroyer" got rid of most of it, enough to make it usable.

My Helix Floor with Egnator Tweaker has barely detectable hum, no gadgets required.

The Wizard of Oz knows why, but he's not talking.

Good Luck!

It does it with another amp that has a passive insert loop.  
 

I’m curious as to why it’s still happening since the cables have been ground-lifted and am hesitant to try anything else if this is going to end up being a rabbit hole.

Not the end of the world since I can return it.  May end up with a Stomp, anyways

[BlueD]

On 2/12/2020 at 3:49 PM, scuccato said:

Same problem with my setup using a real amp and it happens with other gear sometimes as well....but for the $2000 price tag you’d think this was something they would have just built into the unit. I put an isolation transformer before the input of my amp which fixes it, but just more stuff I did not want and should not have had to do. To be clear the amps I use are all high end and it’s not a power issue, it’s a ground loop. Wish I had tried this before buying the Helix.

 

You're 100% correct, I had the same issue with a Mark V that ultimately led me to selling the amp because I got tired of having spaghetti all over to include hum-buster in the 4CM setup. This is a pretty serious flaw considering 4 cable setups are a key thing the Helix is supposedly designed for.

[BlueD]

On 2/13/2020 at 4:14 AM, nhoven said:

Running equipment in 4CM is a hit-and-miss concerning ground loops. It always depends on the grounding scheme of both the amp and the external gear. There is no design flaw, it's just the way it is. One could argue that Line 6 should have used potential free relay switching instead of transistor switching for the EXT AMP, but that how it is now.

 

I'm using the Helix in 4CM too, and there is one very easy solution: Isolate the redundant grounds so there's only one connection. In my case that's the cable running to my amp's input. The other two (FX send and return) are isolated via a bog standard iso transformer, in my case a Palmer PLI05, which is a dual 1/4" symmetric iso transfomer. The ghetto version is to cut the ground on the FX loop cables, but that can introduce other problems.

 

As for the EXT AMP, it cannot work with an iso inserted, as an iso completely breaks the physical connection, which is mandatory for the switching to work. The solution is simple: Either just disconnect the ground from the plug's sleeve of the cable or use an adapter to do it. On my board I have one such adapter with a stereo 1/4" plug going to a 1/4" stereo jack with only tip and ring connected, not the sleeve. Material cost about 10 bucks, assembly time around 10 minutes. $150 is a ripoff for a good friend.

 

That's an absurd amount of work and knowledge required to make something work that should just work out of the box. I call that a design flaw no question about it. The Axe FX 3 doesn't have any of those issues.

[nhoven]

17 hours ago, BlueD said:

 

That's an absurd amount of work and knowledge required to make something work that should just work out of the box. I call that a design flaw no question about it. The Axe FX 3 doesn't have any of those issues.

 

Sorry you feel that way. I tend to disagree (which is totally fine). It's not an absurd amount of work and knowledge required. It's called evolution. It has become an accepted standard that guitar rigs have become much more complicated, including 4CM-setups. With development and evolution comes an increased learning / knowledge curve, unfortunately.

 

Back in the old days we replaced batteries with a daisy chain to power multiple pedals, and we fought with ground loops. The first isloated power supplies cost a fortune, were hard to find, and as a result you had to deal with a more complicated pedalboard setup if you wanted a hum free experience. It's always been like that. Plus, back in the dino age a little bit of hum and noise was perfectly acceptable. These days, people freak out about the most minimal amounts of noise (including me, I'm guilty as charged as well!).

 

Again, this is not a design flaw, it's a limitation of physics. Every bit of kit (can't stress that enough: EVERY!) that can be used with multiple ground referenced connections suffers from this problem, not only guitar setups (think recording studios and such - buying an iso transformer or two is a cakewalk compared to that). A ground loop is a physical, electrical limitation. Sure, there are things you can implement to prevent them, and it would be peachy if every manufacturer implemented every possible measure without raising the price tag; but, unless I missed it, not even the AxeFX III (which costs twice the price of the Helix) offers transformer isolated outputs; they sell you special cables as solution for that problem (sell being the keyword here). If you don't buy the Humbuster cables or isolate your output, you will have an increaded chance run into a ground loop in 4CM, as with every piece of equipment.

 

Almost no amp with an FX loop has integrated iso transformers, no matter how high end it is, even though it's practically guaranteed to have issues with ground loops. There's maybe a handful of amps (if even that) that have them, and these amps cost more than my car. If you're lucky, they MIGHT have a ground lift. Most don't.

 

So yeah... you want a more complicated setup, be prepared for issues. Otherwise stick to easy setups. Applies to life in general, I guess.

[Wolfster]

So how is this dudes iso box different from a 2 channel ebtech hum eliminator? Isn't the circuitry pretty simple? 

 

Fwiw regarding the friedman runt, I've heard and read posts (including from friedman himself) that the effects loop on that thing is pretty noisy, and if you put an hx effects near one side of the amp it picks up lots of noise. That most definitely is an acknowledged design flaw. There was talk of it being addressed, with new parts to be sent out for owners to do skne DIY and fix it. Not sure what happened to that tbh. 

[nhoven]

Interesting issue, do you have any links to read? This sounds more like an EMC issue though and is different from the inherent ground loop problem.

 

1 hour ago, Wolfster said:

So how is this dudes iso box different from a 2 channel ebtech hum eliminator? Isn't the circuitry pretty simple?

 

it is. It is nothing more than two isolation transformers in a box. Prices of these vary alot because the transformers used vary alot in quality and thus have different influence on the sound.

[ColonelForbin]

Yeah; I've got a Runt 50 and eventually gave up on using Helix with it in 4CM. Especially with the amp channel changer connected to Helix.

 

The irony; is now I use an HX Stomp on my pedalboard with the Runt, in the FX loop, in 4CM; but with the HX just in the FX loop for comp/gate/mod/delay/verb.

 

Actually, at the moment my buddy is using my HX Stomp because, quarantined.. I'm using my Helix at home; and the Runt rig went back to using Nemesis and Ventris; though it;s not getting played much, because it's at the jam spot, and also, friggin quarantined...

 

May the Fourth Be With Us All!.....

[wesstore]

Hi,

I had this problem and I use the loop in a 4cm method with a Marshall VM, wanted to just add 2 quick solutions. 

1. Sticky tape your cables outer jacks ring (thin layer of tape obviously so cable can still go into socket) thats going to your amps fx send and return.

2. More permanent pro solution is get a 4cm junction box for your pedal board. These usually separate and disconnect the grounds from the fx send and return part of the circuit.
(this also has the benefit of switching to regular 2cm if you dont want to use 4cm by just pulling out a cable and then internal switching runs all pedals now before your preamp)

best solutions i found:

https://brightonion.co.uk/products/shifter-switch-patchbox-v2

and vertex has a version with and without buffers (but they stupidly expensive for they are but yeah he has a video on how to make one yourself)

 

Hope this helps someone.

[peterwoodward]

I have been struggling with this with an 7CM set up with my helix rack and two Mesa combos.  One combo has simple single channel switching so I was able to use the CV output jack and transistor gate as mentioned in a number of other threads here. 

 

The other combo has 3 channels toggled by the connection of Tip or Ring to ground, and this was the source of the ground loop issue.  I built a pass through box with an isolated stereo jack on either side and then wired tip to tip and ring to ring from one jack to the other but I did not connect the sleeve terminals.  The input came from the Ext Amp 1/2 jack and the output went to the combo channel switching jack.  Once I put this box in the channel switching path, it complete resolve the sound loop issue and I can run both amps (and control them) from the helix with no issues.