nhoven

I removed the rubber feet from the bottom panel and applied copious amounts of the velcro that came with the pedalboard. I used four strips, one for each pedalboard bar, over the whole width of the Helix. That's alot of velcro, but the fluffy part of the velcro is very well applied to the metal bars of the spaceship, so unless you tend to remove the Helix from the board on a daily basis there is no danger of ripping it off, and the Helix is secured very firmly to the pedalboard. To remove the Helix from the board I need some help from a largeish screwdriver, though :-)

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. 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.

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.

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.

I doubt that there is anything wrong. I might have missed it, but which speaker / microphone combination are you using? In the real world, depending on the amp, speaker type, the microphone used and the mic placement you will not find any content above 7k either. I would say the Helix correctly models the realy world behaviour of guitar speakers. Starting with the speaker: Take a look at the frequency response of a guitar speaker like the Vintage 30: you can see that the speaker itself does not produce much content above 4k and does attenuate higher frequencies drastically. Many modern amps also attenuate high frequencies to get rid of fizz and achieve their smooth, "buttery" distortion. Not sure about the Engl Amps, I'd be pretty sure the Überschall falls into that category. A dimed Plexi does not have any high frequency attenuation to speak of and gives much more high frequency sizzle. The chosen mic type and its position also plays into that. A Royer or similar mic placed at the cone edge produces hardly any high frequency content, a 414 placed at the cap will fry your ears. Long story short, I'd say what you see is perfectly normal. If you still suspect your Helix is faulty, take an empty patch, feed something like a white noise signal into it and compare input and output.

I've mounted my Helix on a Thomann pedalboard together with a few other gadgets, see the attached pics - sorry for the dirt and the loose cables, need to clean up. Had the pedalboard home for maintainance (I needed to cut a few calbe ties to get the Helix off the board as I had to lubricate the expression pedal), usually it sits in our rehearsal space where the pedalboard tends to get a bit dusty. The board is the Harley Benton Spaceship 80, which is a tilted metal frame with velcro covering. The board area is 800 mm by 390 mm, sturdy contruction, the bar spacing is variable, it comes with a soft carrying case and is really affordable. With everything on it it is pretty heavy (my scales say 16,5 kg), but managable. As you can see, to the right I have the Mission Engineering SP1-L6H, which is the version for the Helix Rack, i.e. the one with the toe switch. The pedal is connected to exp 2 (pedal) and 3 (toe switch). I had to modify the pedal's toe switch circuit, I don't really remember too clearly - I think the toe switch switches between closed contacts and a 47k resistor. Next to the ME pedal is my old trusty wah, which I didn't want to give up, as I built and tweaked it myself and it sounds great. I use all four FX loops on the Helix, the first of course for the 4CM. The white pedal at the top is a small linear boost that allows me programming-independant on-the-fly volume correction for different guitars - I needed this before the snapshot bypass feature introduced in 2.8. But also I don't have to waste a Helix footswitch for that feature. The grey pedal is a Foxx Tone Machine clone that I prefer to the one offered by Helix. Lastly I use the Mini Vent II for rotary sounds as the Helix rotary sucks through a guitar amp. On the underside of the board I have mounted a Palmer power supply that powers the pedals. It's a bit overkill concerning the power and connectors, but the footprint fit well under the board. Below the palmer is a Rockboard MOD 2, which is a small interface box designed for the rockboard boards. The MOD 2 passes four symmetrical 1/4", MIDI in/out, USB and power to the board. The four 1/4" are the three connections the the amp's in/send/return plus the channel switching. The MIDI out is used alternatively to the EXT AMP on one of my heads. I have a cable snake with four 1/4"-cables, one midi and an IEC cable in a mesh sleeve. The blue box in the center is a Palmer PLI-05 dual isolation transformer needed for the 4CM-connection. At the top right of the picture you can see a small power strip diverting the incoming 230V to the Palmer PSU's power adapter and the Helix. Hope you can get some inspiration from my board. Even with some DIY it wasn't the cheapest solution (PSU, Mini Vent II and the ISO in particular), but especially the HB Spaceship is very good value for the money and a good fit for the Helix plus some extras.

I've opened a support ticket about that CC toggle bug almost two years ago. Got closed with "we'll get back on that". If I was a cynic I would say someting like "shows how much Line 6 care about users interfacing with non-L6 gear"... at least the EXT control doesn't do the inverting thing like the CC toggle.

It's still a useless, broken, buggy design. No sugarcoating around that. Might sound harsh, but that's the truth as I (and probably others battling with those kinds of issues controling external amps battle with) see it. If you want it the way it is now, remove the ability to change the contact state between snapshots. This is inconsistent and spells out trouble for the user.

Well then it's a broken design. Call it a kitchen appliance if you will... still something that needs fixing. In the context of the "discard snapshot edit" this is totally broken. If I set my Helix to discard I expect it to recall the snapshot as it was saved, including the states of external controls. Honestly, there isn't a single use case I can imagine that would require JUST the ext amp to behave differently from everything else. The LED turning off but the switch contact not following is a dead giveaway that this can't be the intended behaviour.

FWIW, not considering this a bug would be very ignorant towards the people using the Helix with an external amp. One could argue that it's not very logical that the external control commands behave different from internal bypass states. If I assign a footswitch to an FX block and save it as "off" in two snapshots, the bypass state of the block correctly turns off if I engage it manually between snapshot changes (I use the Helix in the same way with snapshot edits to discard). Everybody and his mother would call it a bug if the block bypass state would behave like it does on the EXT controls. I really wish Line 6 would be taking bugs interfacing with external gear much more seriously - see the desaster with CC toggles, which is a two year old bug. I work my way around the EXT switching issue by never never ever ever touching the EXT AMP state between snapshot, but this really sucks.

Well, let's agree to disagree :). I didn't mean to start an argument or something. I can't back this up with measurements, but with my Helix unit and my amps, I can hear a clear difference in the noise level between the two output types (I bypass the volume knob). I wouldn't be surprised if this was subject to variation from unit to unit - with a S/N ratio in the 140 dB range I'd say there's room for a variance of a few dB. Not to forget, with an amplifier where the gain stages usually have a µ of 80 to 100 every dB difference in noise will be audible. I just wanted to offer another way of doing it. I also do the 4CM thing different from the templates because my amps' loops operate a line level and it makes more sense to me to use the ins and outs as I described above.

Sorry to repeat myself here, but that's not always true. In front of a high gain tube amp there can be a noticable difference. It's not huge, but you can hear it. Both the main outs and the sends have pretty low noise floor (and there's no audible difference) in front of a clean amp or a FRFR rig, but with some high gain tube amps both output types can exibit quite some hiss, and the main outs do that just this little noticable bit less.

A few more details: Matching the loops is only neccessary if you want to use an FX loop block. There are possible reasons not to do so; for example if your amp's FX loop operates at line level it would make sense to use e.g. send 1 set to intrument level to feed the amp's input and to use return 2 set to line level to receive the signal from the amp's send. Be aware you'd have to use the single send/return blocks instead of the FX loop blocks, and that there's a chance you're wasting (in the above case) return 1 and send 2. I'm using a setup different from the provided 4CM templates, because I found it to be less noisy: I use path 1 as pre-amp path, set the output of path 1 to be the 1/4" jacks set to instrument level. The amp's send goes to receive 1 (set to line) which is fed into path 2, which is my post-amp path. The output of path 2 is sent send 1 feeding the amp's return. You cannot switch between the amp's preamp and a modeled one on the fly within a preset with that setup, but especially with (my) high gain amps I'm getting a little less noise. I've found the fx loop's send to be quite a bit noisier before a high gain amp than the 1/4" outs and I never ever use modelled amps.

To offer another perspective: From a performer's and pedal lover's point of view I disagree. My Helix serves pretty much als a big pedalboard for my tube amps, having replaced a 12HE rack with loads of pedals, two TC 19" units and a midi looper/switcher - I don't use any amp modeling or speaker simulation. Never. For someone who wants six pedals to start with the HXFX might be too small too soon - it is limited to a maximum of 9 DSP blocks, and in the worst case that would include the FX loop for the 4CM, right? Also (and that's the performer's view) the HXFX might have too few footswitches if you want to use it in stomp mode and want/need to control a multichannel amp as well as the effects. Also for me the 4 stomp / 4 snapshots mode is the best marriage between controlling stomps and playing preset (or in this case snapshot) based. The Helix offers enough DSP power to be a really nice, big pedalboard, and enough stomp switches to enjoy that, too. Things you need to consider before you "settle" for the HXFX. Getting the Helix is not wasting money just because you don't use the amp modeling. It's much more than "just" amp modeling and well worth it for the other stuff.

I've made the same experience with my tube amps - the sends of the Helix are very (VERY) noisy. Using a second Helix loop with a gainy pedal only makes things worse, as there's two noisy sends being amplified by two gainy amplification stages. There's really not much you can do. I made the 4CM work well enough for me by not following the standard 4CM method (Helix send to amp input, receive send from amp to Helix return, Helix output to amp return). I'm using the main output (I use the output of path 1B) of the Helix to feed my amp's input, feed the amp's send into path 2A via a Helix return, and output path 2B to the amp's return via Helix send. As I'm using the path ins and outs I don't need to "waste" DSP path space with send and return blocks. The main output is a little less noisy than the sends, but using the high gain channel of my amp is only tolerable for me by paring it with a noise gate after the amp's preamp (which is totally not neccessary without the Helix). The downside is loosing the ability to switch between the tube preamp and a Helix preamp on the fly (within a preset). As for dealing with the noise, there's not much to choose from: You can always ditch the Tentacle for the Helix Octave Fuzz. Of course the sound is different; not too bad, but a less pronounced octave effect - I used a Foxx Tone Machine before moveing to the Helix (which had a much more pronounced bite) and am actually considering putting it back in a loop. If using the Helix Octave Fuzz is no option, you can only live with the noise or add a noise gate. I don't see any other choice. Hope this helps.