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How To Reduce Noise
by sxross on 2010-12-27 13:35:22

I'm experiencing quite a bit of noise (hum) with the HD500 (love the tones).

I am using it in three configurations:

1. Guitar -> HD500 / HD500 Out L/MONO -> Input on Peavey Delta Blues

2. Guitar -> HD500 / HD500 Out L/MONO -> Effects Return on Peavey Delta Blues

3. Guitar -> HD500 / HD500 USB -> Mac

I've tried it with a Fender Strat, an Epi Les Paul, and no guitar at all and all three exhibit the same characteristics: Excessive hum even on a new preset with no amp. Adding an amp or any FX makes it worse. Noise Gates do nothing to reduce the hum. I've tried every cable I have -- some quite expensive -- and tested them direct from guitar -> amp. Guitar -> amp produces minimal hum, whereas running through the HD500 produces very noticeable hum.

The amp and HD500 are plugged into the same power strip, and there is no other electronic equipment nearby except the computer which is about 6-8 feet away.

Any thought on how to reduce the hum are most appreciated.



Re: How To Reduce Noise
by cGil on 2010-12-27 13:45:22

Try setting your secondary input to "None", instead of "Same".   It not only killed a lot of hum for me, but it killed a whole lot of uneccessary hiss when the amp model I was using at the time was dimed, too.  Gotta be RF sneaking in through the aux and mic inputs somehow.   There's a drawback in that "Same" is required on the second input setup to send the one input (guitar or whatever) to both parallel paths before the mixer.  See Advanced Guide section 2-5 for detailed info on input routing, etc.

Gil...



Re: How To Reduce Noise
by sxross on 2010-12-27 22:29:29

@cGil-- Makes all the sense in the world, but I don't have an option of "none". Only same, guitar, variax, mic, aux, and combinations of these. Am I missing something obvious or did I misread your answer?

Thanks



Re: How To Reduce Noise
by cGil on 2010-12-27 22:39:43

Could've sworn there was a "none" option!  Nope. Neither in HDedit or the system menu.  Weird.  Okay, set the first input to Guitar, and try setting the second input to Aux or Mic and see what happens to the hiss and buzz factor.  Actually, it doesn't seem to matter if input #1 is set to Guitar or everything, it appears that merely selecting "Same" for the second input is what causes me grief.

Gil...



Re: How To Reduce Noise
by Seppi on 2010-12-28 07:31:35

I'm also experiencing hearing noices from my HD500. Its not hum in my case. I think its like a fizz. Its like distorted reverb. I hear it when I use high gain settings.



Re: How To Reduce Noise
by sxross on 2010-12-28 09:21:33

If it's ok with you, I won't mark your post as "correct answer" because I'd like to hear any hints other people have. One thing I've noticed in the meantime is that the HD500 does "hear" bluetooth (ackkk!). It's unlikely I can eliminate all bluetooth noise but maybe bluetooth mice aren't the best idea near the device.

Not to completely take this OT, but here is a patch I was working on that actually got me listening to the amount of noise. It's a very loose interpretation of tones used in Cream's "Badge". I admit not to understanding all about how best to construct a tone, but wondered if there was something I could have done better to reduce the amount of hum.



RE: How To Reduce Noise
by ricksox on 2010-12-29 16:05:30

Hello,

I downloaded your patch and synced it up with our POD HD500 here.

I was playing an Ibanez RG with Active EMG pickups so they're fairly hot. Came 1/4" out of the POD into the front of a DT50 212.

The DT50's are a bit noisy inherently. Bogner's amps typically all are to some extent but other than the noise floor hiss I was getting from the amp I felt your patch wasn't all that noisy.

If you're getting a humming maybe the power strip isn't cleaning up your power enough? Maybe try a power conditioner? Just my thought.

Line6Miller



Re: RE: How To Reduce Noise
by McBarry on 2010-12-29 19:45:16

not to hijack this thread,

but speaking of power supplies.. does anyone know if Line6 ever offerred a multi-output isolated pedal power supply - same idea as the Brick, Voodoolabs, T-Rex fuel tank etc..

I've seen the Line 6 part no of 35-00-00225 but can't find any info..

Trying to even find where to ask this Q is a nightmare..

Res, Dave



Re: RE: How To Reduce Noise
by sxross on 2010-12-31 09:28:35

Ok, I have more information: The hum is very noticeable when the USB cable is hooked up and nearly disappears when I unplug it. The computer is currently on a different circuit, although I doubt the polarity is different. I've tried a couple of different USB cables but I need an 8' run, which USB is fully capable of. Also, I would expect USB to experience data loss if there were attenuation, not noise induction. Anybody have any thoughts on this?

Thanks and Happy New Year!



Re: RE: How To Reduce Noise
by Seppi on 2010-12-31 09:40:44

WOW!!! I will try this now!!! Thanks for the info sir!!! Happy new year!!!



Re: RE: How To Reduce Noise
by Nick_Mattocks on 2010-12-31 10:37:24

Hi

You appear to have a ground loop issue which is causing your problem.  If you are using a laptop, a temporary workaround is to use the computer on battery power.  A more permananent fix would be to use a different laptop PSU that does not require a ground connection.  You may also consider using an isolating device between the audio outputs of your computer's audio interface and your monitoring system.  In this case you will almost certainly be using the POD HD  as your audio interface, so you may want to look at something like the Behringer Hum Destroyer between the unbalanced audio outputs and the monitor system.  If using an HD500 and the XLR outputs to supply a monitoring system (either powered monitors or a mixing desk > amp > monitor speakers) switching the Ground Lift switch on the HD500 to Lift might help.

Don't whatever you do be tempted to remove the ground wire from the mains plug for any device as this is potentially a killer (I mean there's a possibility you could be killed if there is a malfunction in the mains circuits which causes the mains Live connection to short to the chassis connection of any of your devices)

Nick



Re: RE: How To Reduce Noise
by sxross on 2010-12-31 13:17:28

I think you may be right about the ground loop issue, but here's the really weird part: The hum occurs when the USB cable is plugged into the iMac I7 even if the computer isn't on. Of course, unplugging the computer makes the hum disappear. Replacing the iMac with a MacBook Pro gives me zero hum, but the MBP won't really help if I'm recording... I mean, like I'm reaaalllly that good anyone would want to hear what I record? But I like to be able to hook the whole rig together and keep presets and stuff on my computer. For not, the MBP buried under a bunch of stuff is ok. But how to isolate...



Re: RE: How To Reduce Noise
by Nick_Mattocks on 2010-12-31 13:25:18

Well I can't be 100% sure as I don't have access to your equipment, but I am certain that with two different laptops I have (one has a two core mains lead to its PSU with no ground and the other has a three core mains lead to its PSU which is grounded) that the one with no ground produces no buzz and the other one does.

If your iMac has a PSU with a three core mains lead that is connected to the computer even though the computer itself is not powered on, you will have the ground loop issue.  Also if your iMac has USB connections to anything else that might be grounded, you will experience the ground loop issue.

Happy New Year

Nick



Re: RE: How To Reduce Noise
by sxross on 2010-12-31 13:52:33

I think this is the correct answer. I'm going to keep poking away at this. FWIW, Mac desktops like the iMac have grounded power supplies and the Mac laptops have ungrounded ones. I'm going to pull all the other USB devices out of the iMac and see if it calms things down ... I wonder if there is an in-line noise filter that can be placed on a USB cable to eliminate that hum. Unplugging all the other USB devices reduces the desktop Mac to a high priced toaster




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