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[HELIX] - Noise with using Power Station for recording/re-amping

Discussion in 'Digital & Modeling Gear' started by dirtyfunkg, Mar 4, 2020.

  1. dirtyfunkg

    dirtyfunkg Member

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    Hey everyone. I'm hoping you will be able to help me, as this is about as good as it gets for all things Helix.

    Use case:
    I want to be able to track a DI guitar track AND track my amp simultaneously.

    The gear in question:
    2010 iMac running Logic X
    Helix Floor
    Fryette Power Station PS-2 (running as a silent reactive load, not connected to a speaker)
    VHT Pittbull CLX Head
    Kit-build Les Paul clone with Graph Tech Ghost piezo system, Duncan JB in bridge, P-Rail in neck.

    Hardware Signal routing:
    Guitar-->Helix Guitar In
    Send 1 (Instrument Level)-->Pittbull Hi Input
    Pittbull Speaker Out-->PS-2 Amp In
    PS-2 Line Out-->Helix Return 4 (Line Level)

    Internal routing within Helix:
    Path 1: Input: Guitar --> Output: Send 1
    Path 2: Input (Return 4) --> Helix Cab emulation --> Output (USB 3/4 panned hard left)

    The problem:
    Lots of noise. I haven't been able to diagnose the frequency, but it's a higher pitched whirring type of noise.

    Diagnostic Steps Taken:
    I've swapped all of the cables and toggled the ground lift switches on the Helix, Pittbull, and PS-2. None of these trials made any impact.

    I do NOT experience the issue if I plug straight into the Pittbull, which then, via the PS-2 is feeding Return 4 in signal path 2 on the Helix. Then it sounds great, but precludes me from being able to do a DI take with the amp affected take.

    Preliminary Conclusion:
    I believe I have narrowed the issue down to something related to the Helix's Send 1.

    I appreciate any help/pointers that you can provide.
     
  2. LaXu

    LaXu Member

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    Try going direct into the amp for the guitar instead of passing it through Helix guitar input. If this works, then you most likely have a ground loop between the Fryette and Helix.
     
  3. dirtyfunkg

    dirtyfunkg Member

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    I did try this and the noise did go away. What would be the best suggestion on fixing this ground loop issue?
     
  4. LaXu

    LaXu Member

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    It might get complex as my understanding is that to get around this would require severing the ground somewhere between the Helix fx loops and the Fryette fx loops. I would suggest contacting Fryette about it. Just using the ground lift buttons on either device don't seem to do the job and you might need some custom cables or something instead.

    When I had the Fryette I had this issue when trying to run in 4 cable method, it would get noisy and prone to feedback. This isn't a defect or anything but just a thing that happens with this attenuator.
     
  5. Aquinas

    Aquinas Silver Supporting Member

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    This is a known issue with the way the load in the PS2 works, causing a partial ground loop. It often manifests as a high-end "whistling" sound through the speaker, but there are a number of other possible outcomes - and some amps don't do it at all. It is just the interaction of several products with different ground planes, along with a bit of oscillation of the windings of the output transformer...

    I have the same issue when trying to use the Helix and PS2 in the same way!

    There will [almost certainly] be a fix on the next major revision of the PS2 and PS100 (at least two years away, gotta run through existing stock), as it wasn't something Steve noticed in testing and honestly hasn't come up much in more "conventional" use because of electrical isolation in power supplies. Pretty much just Helix/Axe users have had the issue, and only when trying to use the Helix/Axe both before the amp and in the PS2/100 loop (not the amp loop). To put it in perspective, you are only the 5th or so person, including myself, to have had the issue, at least as of about a month ago when I was talking to Steve about it. Just isn't a common use case, but it is becoming more so, hence working in a fix when he can.

    The current "best" fix is to use an isolation transformer before the input of the amp. There are plenty of products that do this - any transformer-based passive DI works well, for instance - but this is the cheapest option and works great. The Ebtech works great, too, but is three times the price for essentially the same product (B-loves-to-copy). The transformer isolates out the issue, and very transparently.
     
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  6. dirtyfunkg

    dirtyfunkg Member

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    Y'all are the best. Thank you kindly. Now I've got a Behringer piece of gear set to be delivered tomorrow.

    I had always hoped my next (only) Behringer kit would end up being an X series console. Oh well...
     
    FlyingsCool and Aquinas like this.
  7. Razor

    Razor Silver Supporting Member

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    Mine was a different application, but when I tried to use the Helix in the 4-cable method, I experienced unwanted noise. I tried several solutions, some of which helped a little, but I was never able to solve the problem to my liking.
     
  8. dirtyfunkg

    dirtyfunkg Member

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    UPDATE: I received the HD400 yesterday evening and tried it out.

    Night and day difference. The noise is gone.

    Thanks @Aquinas !
     
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  9. marshall2553

    marshall2553 Supporting Member

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    Man, I wish I had known this when I tried the PS2 a while back. I was using it with my amp and a Fractal Audio FX8 with the 4 cable method and ended up returning the PS2 due to terrible noise/squealing issues.
     
  10. Guitardave

    Guitardave Supporting Member

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  11. Aquinas

    Aquinas Silver Supporting Member

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    You're welcome!

    Here's the thing, it isn't really a "problem" with the PS2, per se, but with the method and how you in particular are implementing it - if you tried the same thing with a standalone power amp, load, and the AX8 or Helix you'd very likely have the same issue. It has to do with the device in 4cm sharing a single ground plane between multiple inputs and outputs, which is pretty much the only practical way to do it in a device like that, and in fact has other advantages in the vast majority of applications.

    It isn't all that obvious that it would happen, either, because it isn't a "typical" power-related ground loop. The loop is through the audio chain, not through the power supplies - which is why the ground lifts don't work, because they are lifting/shifting grounds on the power supply. Since that is where ground loops almost always happen in typical rigs, that makes sense.

    There is an easy enough fix to that, which is to isolate either the send or return on the power amp itself through a 1:1 transformer - something that would be prohibitively expensive to implement on the 4cm device, but is pretty easy to pull off on the PS2/100 itself. This was an unforeseen issue, as a "traditional" rig with pedals and rack gear doesn't typically run into the issue at all - though it is theoretically possible with some effects loop devices, the big commercial ones (Voodoo and RJM) don't display this behavior due to the way they are designed - so it wasn't so much a "design flaw" as a lack of future sight in the rise of standalone, high-quality 4cm solutions...

    But like I said, Steve is aware of the issue and has a fix planned. It isn't something worth modding existing units for (because the 3rd party fix is so easy, cheap, and available), but it is something that should go into the next major revision. At least that's the plan, last time I spoke to him about it!
     
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  12. tech21nyc

    tech21nyc Member

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    My experience as someone that represents a manufacturer is that the end user will sometimes attribute an issue with a single component (usually ours) in a signal chain without troubleshooting properly. The title of this thread bears that out. There are 4 pieces of gear mentioned in the first post but the assumption was that the Power Station was the issue. Whenever gear is combined the potential for problems is multiplied. Bob Bradshaw has made a living solving these issues for many top players.

    Grounding issues are common whenever two or more pieces of gear are hooked together. I always bring an Ebtech Hum Eliminator to gigs for that very reason. One thing to be aware of with ISO transformers, they will create hum with switching power supplies. The transformer becomes an antenna for the switching power supply. It's always something...
     
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  13. Aquinas

    Aquinas Silver Supporting Member

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    Yup, but in this case I have to at least give @dirtyfunkg some credit - it isn't an issue many guitarists run into, a ground loop through the audio path, and it is actually kinda hard to "place blame" with this particular problem. You could blame the Helix for sharing all those ground points - but as I said in one of my posts, that is an advantage in many use cases. You could blame the PS2, but it isn't an issue in its primary intended use case and wasn't even discovered to be an issue until well after the second revision's release (just isn't that common of an issue)!

    In this particular case, it isn't really anyone's "fault". That being said, now that the issue is known, it isn't to hard to integrate a solution into the more "esoteric" piece of gear. Might end up adding $20 to the overall price of the revision, but there was going to have to either be a price bump or major cost-cutting in the production process on the next revision anyway (not a reflection on Fryette, just a reality of doing business, and the costs of certain components has been, shall we say, "less than stable" this last year), so not really a big deal.

    The product I linked to above is pretty much identical to the Ebtech/Morley, just cheaper. Not a huge fan of that particular company, but in this instance there really isn't a reason to spend more unless you have a moral issue with them or something like that.

    As far as the hum problem with switching supplies, that is an easy enough issue to solve (just as information to those reading this thread in the future) - just move the transformer! I've seen that problem in rack rigs and pedalboards, but only if the iso transformer is far too close to the power supply. Given that the iso will do its job in several places in the signal path, some of which are quite distant (physically) from any potential switching supplies, it is a pretty easy thing to troubleshoot. Just don't stick it on your pedalboard if it has switching supplies! Stick it on top of your amp, or the PS2 (uses a standard transformer-based supply), or behind your amp, or somewhere no where near a power strip. Velcro it to the side of the cab if you have to (I've actually seen that solution in action for a touring rig)!

    And yes, with more complexity comes more chances for malfunction. It is always something!
     
  14. dirtyfunkg

    dirtyfunkg Member

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    I think @Aquinas has it right here. This was an issue report, and there was never intent of blame assignment. I tried to represent as much information as possible to this community because my initial expectation was that I was doing something wrong or overlooking something. I thought I had isolated the issue down to something related to the Helix because when the Helix was not in the chain, the noise went away.

    I am (relatively) new to the world of digital modeling, so I wasn't sure if there was something I needed to do in the Helix itself to fix the issue. Paul was very helpful in a) letting me know that he has experienced the exact same issue with the same gear, and b) providing the solution (and where to place it within the chain), all while providing an informative explanation of the problem.
     
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  15. tech21nyc

    tech21nyc Member

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    It would happen with our original powered speaker the Power Engine. In that case the iso-Xformer is in the amp and even a pedal on the floor away from the amp would cause this issue. We developed a grounding plug to disable the iso-xformer on the input so devices like modelers could be used without the issue.
     
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