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cletcher1

XLR Hiss (Phantom Power and Helix)

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I think this has been mentioned elsewhere, but felt it was important enough to share again.  Unplugged the HD500 from our M20 mixer system and plugged in the Helix (XLR outputs) and started getting a snowstorm of hiss.  Plugged back into the HD500, quiet as a mouse. Turns out that the phantom power was accidentally turned on those channels.  When shut off everything was fine.  Why this has never impacted the HD500 I don't know.  I've really never seen this occur with any other device either.  I'm assuming this could be fixed with a software update.  However be aware, because it could be a gig killer if your not aware. 

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I'm assuming this could be fixed with a software update.

 

It would be nice to get a confirmation of that from L6 to set our minds at ease. L6?

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Do you have the phantom power turned on in the Helix? Also, did you have the XLR outs on the Helix set to line or mic?

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It would be a problem expecially if you don't have a mixer with separate phantom switch per channel.. I once had a problem, never solved, with a keyboard of a well known japanese brand.. if phantom power was on the xlr channels of the keyboard you could hear horrifying rhythmic bangs on the speakers that could have easily damaged them .. the assistance said that it was a professional keyboard so it's expected separate phantom power switches on the mixer :lol: :lol: :lol: :lol: .. pity that the top of the line keyboard of the same brand did not have the problem.. and the problem is still there.  :angry: :angry:  I am sure Line 6 has a totally different approach with customers

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I have never changed the default phantom power settings in my Helix.  Wouldn't that only correspond to input XLR anyway?  I did switch back and forth between mic and line on the XLR outputs, neither changed the noise problem.  I'm not saying this happens in every case, but it seems to be happening to others as well.  In my case we use the Line 6 M20 board, which doesn't have individual channel phantom power switching, but 2 banks of inputs.  It also has auto sensing inputs, which may play into this.  I guess until this issue can be pinned down, I think those who haven't gone out and plugged into a board yet with XLR might need to know of this issue, just in case the sound guy isn't aware either.  It's a loud enough hiss that it takes over the mix and can't be compensated for other than switching to 1/4" outs...

 

Thanks for responding...

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I have never changed the default phantom power settings in my Helix.  Wouldn't that only correspond to input XLR anyway?  I did switch back and forth between mic and line on the XLR outputs, neither changed the noise problem.  I'm not saying this happens in every case, but it seems to be happening to others as well.  In my case we use the Line 6 M20 board, which doesn't have individual channel phantom power switching, but 2 banks of inputs.  It also has auto sensing inputs, which may play into this.  I guess until this issue can be pinned down, I think those who haven't gone out and plugged into a board yet with XLR might need to know of this issue, just in case the sound guy isn't aware either.  It's a loud enough hiss that it takes over the mix and can't be compensated for other than switching to 1/4" outs...

 

Thanks for responding...

 

The reason I asked about the whether the phantom power was on on the Helix was that there was another post here where someone mentioned they had hiss on the XLR outputs when it was on.

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Nope appreciate it...however in every case I found the issue was with the phantom power provided from the board.  Sounds like it's not playing well with some mixers, especially the newer advanced ones.

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Doubting a firmware update will fix this one, as the normal way to be insensitive to phantom power for XLR devices is an isolation transformer stage of circuitry -- physical connections, in other words, not programmed responses, just like you can't program your way out of a ground loop, you need physical circuitry to isolate the problem. Make a note -- turn off phantom power on the device you're plugging into (the "Phantom Menace") - it should be the normal state of a mixing board, and be a simple push button on the channel you're plugging into...

 

Dave

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IF it is like davidb said, it would be a serious problem; most of the 16 or 24 ch mixers don't feature individual phantom power switching. So if you are in a gig with such mixer and you need phantom power for microphones (just think of the drum kit) you cannot use your XLR outputs on Helix. Or you would have to buy a line isolation box, and that would be expensive and a bit silly as none of the previous line 6 products had this problem.

 

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Good points and yes I agree you shouldn't have phantom power running to the helix outputs anyway if possible. It's strange they would have included the correct hardware on the hd500 and not the helix. I'm only trying to help raise awareness as many mixers don't have individual channel phantom power selection. Even so how many experiencing this issue for the first time would even think to attribute it to phantom power from the board? Especially if your dealing with an inexperienced sound crew.

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I just tested this with my Helix, and yes, with the phantom power on my mixer on, there was a lot of hiss. However, the hiss cleared up completely if I hit the ground lift button on the back of the Helix (while the phantom power on my mixer was still on). So I believe there is a simple solution even if phantom power is on at the board.

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And there was no hum with ground lift on? If so that's good news as the problem is solved.. :) :)

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And there was no hum with ground lift on? If so that's good news as the problem is solved.. :) :)

 

Yep, no hum with the ground lift engaged even with phantom power coming from the board.

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Interesting. Ran the same test with 2 different boards...had hiss regardless of ground lift switch position on both. Turned phantom off and of course no noise.

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I have been out of pro sound too long. You guys are telling me they make boards with no on or off for phantom power on channels? That sounds absurd to me as there was always an odd device or two that didn't play well with phantom power. Back when I did sound for a living (granted it was 25 years ago) even a cheap 8 or 16 channel board with a single button for phantom power only engaged it on a couple channels. Not every one. I would never buy a board if it was like that.

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I just tested this with my Helix, and yes, with the phantom power on my mixer on, there was a lot of hiss. However, the hiss cleared up completely if I hit the ground lift button on the back of the Helix (while the phantom power on my mixer was still on). So I believe there is a simple solution even if phantom power is on at the board.

That is some good information as I did not try doing that. I simply had FOH turn the phantom power off. At lest now if play where turning it off is not a option I have a possible work around. Also wonder about the combo with line vs mic as well.

 

Thanks, phil_m

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I have not run my Helix with our normal sound guy, yet. Will tomorrow night. The bar where I used the Helix first a couple of weeks ago had their own sound system, and I had no problems with his setup, but I do always run with my ground lift on, as I use a stage amp (Quilter Tone Block 200) that provides the local ground via the 1/4" I run to it. I do it as habit. You do have to have a local ground reference, and ground loops are a lollipop, but have not run into the phantom voltage issue -- or the ground lift took care of it, and I was not aware of it. Some mics are sensitive to it, and can be damaged, so I would be really surprised if it could not be switched off.

 

I just took a look at the manual for the Soundcraft digital soundboard and digital stage box or snake our sound man uses, and the 48V phantom power is assignable on a per channel basis. I know he uses some condensers on the drummer, but the wireless and wired vocal mics are dynamic, so don't use phantom. The guitars and the bass all go direct, so do not need and should not have phantom on those runs. each channel XLR input on the stage box has an indicator light on when 48V is present.

 

Like I said, it was not an issue with the HD500X, and should not be an issue with the Helix with our set-up, but it will be interesting, and I will keep an eye out for it....

 

I'm an electrical engineer, and so is our sound man, so we have good communication between us and can usually troubleshoot situations fairly fast together.

 

Dave

 

Had my first lollipop replacement in this post.... :lol:

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I read somewhere the helix master volume should be turned up to 10 which is essentially unity gain.  When I first plugged Helix into a board, I had a lot of hiss.  I had the volume about 50% and consequently, the board's gain was turned way up to get a usable signal - thus a lot of hiss.  So then I turned the Helix to 100% and the board's gain way down to compensate.  Hiss gone.  Here's what I've noticed though, I'm running into a Mackie DL1608.  When the phantom power is on, it attenuates my Helix's sound by -10 to -20 and I have to increase the gain to compensate.  Turn the phantom power off, and I get a great, strong signal to the board.  Apparently the Helix doesn't play well with phantom power.

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Last night's gig with our own soundman went great. I asked him about the phantom power, and it is as I read in the manual for his board & stage box -- the phantom power is assignable on a per channel basis, and he only turns it on the channels he has condenser mics on, for the drummer. The place was small and he didn't mic the drummer, except for the kick. I noticed 2 phantom indicator lights on on the stage box, but he had no XLR's plugged into those, they were just on in his preset for the board.

 

As usual, I ran with my Helix ground lifted to his equipment. No problems. He said on the XLR's pin 1 is +, pin 2 is -, and pin 3 is the ground. When phantom is on, it puts voltage across pin 1 and pin 3, so phil_m saying the ground lift cured it for him is most logical, as it broke the 48V DC path.

 

Cletcher1 may have an issue with his mixing board possibly using the case ground of the board or snake XLR as the ground path for the phantom, so a ground lift at the Helix would not necessarily have broken the DC Voltage path. Just a thought...

 

Dave

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Thanks Dave for reporting your results. 

 

I guess to summarize would be to say that depending on the board your connected to, the Heilx can and will have phantom power issues (mainly hiss) that can possibly be corrected by the ground lift switch.  Obviously disengaging phantom power is the preferred method, however this might not be an option on boards with shared power switching (including Line 6's flagship M20). Furthermore this issue never existed to my knowledge on the HD500 for either software and/or hardware design.  So the minimum thing Line 6 would need to do is at least make sure users are aware of this in the manual.  I could see the less tech savvy users and sound guys scratching their heads in frustration trying to figure this out right before a possible gig.

 

Thanks everyone....

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Can we get some input from L6 on this? Do they see it as a problem? If so, is it a hardware problem? Will they need to change the circuit for future builds to fix this problem?

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My Helix manual warns me not to use phantom power connected to its XLR outputs. This must be why.

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Sorry Peter, I can't find where the manual says it. Can you tell where in the manual it's mentioned?

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As already said, some input from L6 would be appreciated... What's the problem here? We would like to know.

None of previous L6 products had this problem, so what are we going to do now?

Last night the sound tech had to disconnect pin 1 of the xlr cable just to be able to use Helix.. Is it solvable or do we have to get a line isolator for gigs where mixers with individual channel phantom switching is not available? :(

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Good points Brainbug....that's why I started the thread.  I too could find no warnings of this issue in the manual.  I almost left practice and boxed the thing up to send back out of frustration because I thought it was defective.  Thankfully others had posted something.  Even if it's only a manual statement "don't accidentally use phantom power dummy, you'll get massive hiss", at least users will be aware.  Especially considering lesser models have never done this...I would think this board is the first place to look for oversights discovered by customers given that it's a brand new product.

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Sorry Peter, I can't find where the manual says it. Can you tell where in the manual it's mentioned?

 

It is not in your manual as I see it now. It IS, however in the manual for the Rack version.

 

I wonder if it wasn't discovered to be such an issue right away before the manual for the floorboard was printed, or if it's only an issue with the rack version and your problem still needs to be addressed. I'm guessing the former.

 

I am actually using a DI on the output because it's simpler for me to avoid feeding phantom to this unit (as I apparently have to). I always liked the sound of the 1/4" outputs on the HD 500 BETTER through a DI box than the XLRs. 

 

I will compare them at some point, but so far, using the DI sounds so great I am not that concerned. Don't know if that helps YOU though...

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Thank you.  I guess I wasn't aware of the knowledge base page (my bad) and it didn't come up when googled.  My opinion would be that this explanation is still vague and doesn't communicate the issue of noise as well.  I'm assuming this is not going to be addressed in some sort of fix anytime soon, as it's probably hardware related.  I personally find the 1/4" output to be sonically inferior, at least with my initial test.  As far as I'm concerned I can deal with the issue, however I do view it as an unfortunate downside especially since it wasn't an issue with the HD500. As I and others have said, many boards, including the Line 6 M20, do not offer individual phantom power switching forcing you to choose 1/4' outs if you need to share with condensers. 

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In other words this is a mistake in the electronics project. The use of 1/4" is not a workaround, is a second-best expedient. 1) The use of  1/4" means you need a DI.  2) The use of 1/4" means you can't use XLR for foh  AND  1/4" for monitoring.  3) One of the strong points of Helix was the possibility of having 2 separate outputs for 2 different paths (another guitar? another instrument? whatever) now you tell me we can't.

I think this oversight (and your answers) makes Helix less professional than I thought it was

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My initial tests have indicated that the 1/4" output through a decent direct box is identical, or even a tiny bit more "present" sounding (I DEFINITELY found this --more-- with HD 500), than the XLR... but you have a point.

Then again, I've seen loads of gear that needs special stuff to get it to go to outputs you want, and most of that is pretty pro gear.

 

It really stuck out to me when I was reading the rack manual, and to be safe, I felt I would avoid using that output just in case. My board lets me turn it off per channel, but I don't want to risk damage for sure.

I think Whirlwind or somebody makes a 1:1 XLR isolator that removes phantom power.

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Sescom SES-IL-PPB XLR Inline Phantom Power Blocker

The SES-IL-PPB removes harmful phantom power from energized microphone inputs when phantom power isn't required. The SES-IL-PPB protects expensive and sensitive ribbon mics, dynamic mics, direct boxes, splitters and other devices not compatible with phantom power. It features complete passive circuitry to keep your audio signals distortion & noise free. A perfect addition to any audio run bag.

 

SES-IL-PPB.JPG

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But still.................................  <_<

 

Yeah, I agree brainbug. It looks like a design flaw to me, and L6 is now in damage control, mostly by not talking about this problem too much. If they have no plans to fix the hardware, they need to update the manuals to specifically note this issue. Maybe they do plan to fix it, but don't want to tell people not to buy Helixes now. Either way, L6 needs to tell customers what they are planning to do, since if they do change the hardware, they will have to offer a warranty fix for existing units or lollipop off a whole lot of early adopters. And if they don't plan to change the hardware, they need to update the manuals ASAP to highlight this issue. So, what are your plans L6/Yamaha?

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"Design flaw?" "Damage control?" I think that's overstating. There are loads of products that don't play nice with phantom power and there are loads of products whose original documentation has to be revised.

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I guess it depends on your opinion.  Does the Kemper, Axe Fx do the same thing?  We know the HD500 doesn't, which is not even in the same class now.  This is suppose to be a rugged/tour ready piece of gear, but yet you have to baby it when it comes to phantom power.  I would agree it appears to be an afterthought they just discovered based on the manual and knowledge network statement.  Coming out and saying oops, we owe you 1st gen guys a fix would be too expensive.  So ya I expect them to lay low, act like it's intentional, maybe fix really angry customers units at some point, but mainly address it with an engineering change in future models.

 

Fortunately for Line6 there are clearly customers that this is not a big deal do to their mixers or the way they choose to connect to the Helix, but it's fair to say others that this issue affects directly should have the right to be unhappy.  Let's face it, early adopters are really beta testers anyway.

 

Having said all that, it still is an amazing piece. Kudos to the design team...

 

Just my opinion...and I'm a longtime Line6 customer:

M13

M9

2- HD500

1- X3 Live

2- M20 boards

Relay 60

Helix

Original Bean

Various other....

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...So ya I expect them to lay low, act like it's intentional, maybe fix really angry customers units at some point, but mainly address it with an engineering change in future models...

 

It will be interesting to see what they do. Keep in mind that it may be as new an issue to them as it is to you. They may be having meetings right now (well not right now, because it's 6:00 in the morning in California) about this.

 

And yes, it's an amazing unit. The sound improvement is noticeable, the flexibility improvement, for me, is revolutionary. I would need 3 or 4 HD 500s to do what I'm doing with this unit now that I couldn't do before.

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I agree Peter, it's hard to be flawless out of the gate.  I'm sure they are having discussions about this.  If not, that would be very concerning. Opinions are going to very on how much of a buzkill this issue is.  I'm a little disappointed, but not going to return the unit over this...others may.

 

My main point in starting the thread was issue awareness, as I was very frustrated at the time this happened, almost embarrassed, as the band guys were laughing my expensive new toy was making all kinds of noise.  Had it been an actual gig I would have been seriously angry.  Almost came home and boxed it up for a return to MF.

 

I can't imagine this not happening to others as this roles out with the backorders continuing, communication will save new users the frustration and Line 6 from returned units to retailers because users think it's defective.  Hard not think that when you unplug from the Helix back into the HD500 and it sounds fine, back to Helix..hiss.

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