Audio Interference on MS-100BT- troubleshooting log

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stubbsonic
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Audio Interference on MS-100BT- troubleshooting log

Post by stubbsonic » Sun Aug 13, 2017 11:23 am

[NEW EDITS; Mar 29, 2018]
[note: I'm updating this initial post and subject line as the issue and my understanding of it evolves.-- some posts below are related to my misunderstanding that the issue is entirely related to RF]

FINAL PROGNOSIS
I've had a persistent problem with stray signals from a sound system coming through my MS-100BT. The issue happens at a local dinner theater where I play most of my guitar gigs. I had originally thought this was related to RF and wireless signals. After a bit of trouble-shooting yesterday with the head sound guy, we determined that the sounds coming through my rig were not only from wireless mics, but pretty much everything in the mix. I later had an idea to ask if the theater had a secondary system for hearing impaired people. YES! The theater uses something called an "Induction Loop" or "Hearing Loop" to transmit, through magnetic inductance the entire mix. This signal can be picked up by many modern hearing aids, and also special boxes available to audience members.

I now suspect that the MS-100BT is somehow more susceptible to picking up these signals than all my other pedals. My guitar may also be a part of the "antenna". Though my bass has humbuckers, it also picks up this signal, so it is not merely a single coil pickup + MS100-BT.

When I thought it was RF (from the wireless mics), I had tried various ferrite beads, and isolation transformers, in various points in the signal path, but nothing worked. The Pyle PHE400 isolation transformer seemed to help (but it is difficult to say for sure, as I wasn't in a good testing situation). I placed it between my guitar and the MS-100BT. However, there was a severe loss in level and highs-- perhaps from loading/impedance issues. The next logical step should have been to try that unit with a buffer out front-- a step that I skipped -- but now wish I had tried. Instead, I returned the PHE400 (self-kick), and ordered a higher end isolation transformer (the Radial StageBug SB-6) however, this did nothing for the problem. Which made me question whether the PHE400 actually worked or not if I'd used it with a buffer. [UPDATE: I ordered another PHE400, and will try that one more time, but with a buffer.]

UPDATE: I tried the G3n on the gig last night. The sounds were different, but still very clear, very nice dynamics and good overall tone. The G3n did pick up the "bleed" but the level was comparable to the Pod and not problematic.]
Last edited by stubbsonic on Sun Apr 01, 2018 10:22 am, edited 7 times in total.
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Re: RF interference solutions? Ferrite bead?

Post by stubbsonic » Tue Aug 15, 2017 9:37 am

I ordered some clamp-on ferrites. Might try more than one to see if I can improve things.
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Re: RF interference solutions? Ferrite bead?

Post by Jim_Fogle » Tue Aug 15, 2017 1:25 pm

With ferrite beads, more is not better. Clamp on one bead to either side of the cable 1" to 3" from the cable connector. Follow the directions if any are included with the beads because different beads are installed different depending on the strength of the magnet.
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Re: RF interference solutions? Ferrite bead?

Post by stubbsonic » Tue Aug 15, 2017 5:36 pm

Thanks, Jim. Will post back results once I get them and try them out at the next tech rehearsal.
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Re: RF interference solutions? Ferrite bead?

Post by stubbsonic » Fri Aug 18, 2017 9:43 am

At a rehearsal, observed the wireless mics' signals appearing in my amp. I put a ferrite bead on the end of the instrument cable right as it enters the MS-100BT. No luck. I put another on the guitar end of the cable. No luck. I put another one near the output side of the MS-100BT. No luck. Put one right at the amp input, no luck. I would have tried putting one on the DC power near the input, but in the past, I've tried running the MS-100BT with batteries, which had no effect.

So, however that signal is getting into the amp, trying to block high frequency interference doesn't seem to help. FWIW, there is no problem when the MS-100BT is not in the signal path.

Any ideas?
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Re: RF interference solutions? Ferrite bead?

Post by Jim_Fogle » Sat Aug 19, 2017 2:25 pm

Where is the wireless microphone receiver physically located? What is the wireless microphone receiver audio output connected to? Perhaps the signal is escaping through the receiver power cable.
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Re: RF interference solutions? Ferrite bead?

Post by stubbsonic » Sun Aug 20, 2017 10:45 am

The receivers are all in the sound booth which is on the opposite side of the building 150-200 feet away. They outputs are plugged into a mixer in that same booth. However, there is a monitor feed that is coming up to the area where the band is (above the stage). The monitor signal includes the piano which does not bleed into my signal, but the mics do. And it doesn't seem to be all mics, but rather just some of them.

Something about the MS-100BT seems more susceptible to this interference.
Last edited by stubbsonic on Fri Mar 23, 2018 1:07 pm, edited 1 time in total.
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Re: RF interference solutions? Ferrite bead?

Post by stubbsonic » Mon Aug 21, 2017 8:26 pm

I'm about to play another show in the same venue and will be using a Pod HD500 instead of the MS-100BT. I will be curious to see how they might compare in terms of their tendancy to pick up these mics. I'll be in a tech on Wednesday, so I'll report back after I learn more. It won't be a fair comparison since the location of the band will be different, and the monitor set up with also be different, but still, I'll give it a whirl.
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Re: RF interference solutions? Ferrite bead?

Post by stubbsonic » Thu Aug 24, 2017 8:48 am

No problems with Pod HD500 & wireless mics. But, as I mentioned, it's not a one-to-one comparison. The band is in a different location, and the power set up is different.
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Re: RF interference solutions? Ferrite bead?

Post by stubbsonic » Fri Oct 06, 2017 8:35 am

The MS-100BT picks up strong signal from the wireless mics in this current set up, and the Pod HD500 does none.

I like the sounds in the MS-100BT more than I do the Pod HD500, but for some reason, the Zoom is vulnerable to this specific set of circumstances. Otherwise, it's a dream box. Fortunately, it works well In my home studio.
Last edited by stubbsonic on Fri Mar 23, 2018 1:09 pm, edited 1 time in total.
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Re: RF interference solutions? Ferrite bead?

Post by stubbsonic » Wed Mar 14, 2018 10:46 am

I was wrong when I said the Pod HD500 didn't pick up the wireless mics. It does, but to a much lesser degree-- (i.e., not problematic). For my current show, I'm not liking the sound of the Pod and can't get a good clean sound. The dynamic response is all wrong, the clarity is gone. In fact, for dynamics, the MS-100BT is WAY better than the pod or the boss GT-1, or the RP-255 (I was able A-B those three). I tried an RP360 in a store, but could not A/B it with the MS. It might have been better, but I'm not sure, since it uses similar hardware to the rp-255, and perhaps similar models.

As I mentioned in another thread, I'm considering a G3n. I will post back here in this thread if it works acceptably well in the theater.
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Re: RF interference solutions? Ferrite bead?

Post by NucleusX » Wed Mar 14, 2018 11:09 am

The POD HD has ALWAYS been a difficult beast to tame, requires a lot of tweaking to make it sound right.
This possibly smells like a bad power supply setup, ground loop, or signal cable. Have you somehow
eliminated all those possibilities ? RF can be induced into almost every point in your hardware.
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Re: RF interference solutions? Ferrite bead?

Post by stubbsonic » Wed Mar 14, 2018 11:36 am

The Pod HD500 does some things well, no amount of tweaking affects the lost dynamics, messed up attack, and loss of clarity of high-end in clean sounds. Will sell.

The RFI with the MS-100BT has shown up with 4 different amps, with all different cables, both my bass guitar and my electric guitar, whether I use batteries or AC adapter, whether I used a buffered pedal in front, or with the aforementioned ferrite beads.

I just saw your other posts (THANKS!)

I have a Radial Big Shot ((true bypass send/return loop switcher) sitting right in front of me. I'll try using it tonight to see if that makes an improvement. I also just ordered a PylePro PHE400 isolation transformer (1:1) perhaps that will do something useful.
Last edited by stubbsonic on Fri Mar 23, 2018 1:11 pm, edited 1 time in total.
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Re: RF interference solutions? Ferrite bead?

Post by NucleusX » Wed Mar 14, 2018 12:20 pm

stubbsonic wrote:
Wed Mar 14, 2018 11:36 am
The Pod HD500 does some things well, no amount of tweaking affects the lost dynamics, messed up attack, and loss of clarity of high-end in clean sounds. Will sell.

The RFI shows up in 4 different amps, with all different cables, both my bass guitar and my electric guitar, whether I use batteries or AC adapter, whether I used a buffered pedal in front, or with the aforementioned ferrite beads. It might be on the ground in the theater, and somehow the MS-100 just amplifies it.

I just saw your other posts (THANKS!)

I have a Radial Big Shot ((true bypass send/return loop switcher) sitting right in front of me. I'll try using it tonight to see if that makes an improvement. I also just ordered a PylePro PHE400 isolation transformer (1:1) perhaps that will do something useful.
I've just recently done away with the Radial in favor of a Boss LS-2 and TU-3W combo. The TU-3W handles all the
possible input impedance senario's with the ability to function as a true bypass, or buffered pedal, and the LS-2
follows that to function as a buffered pedal to the rest of the pedalboard, with the added benefits of gain control,
and retaining the A/B function of the Radial. One downside, the LS-2 doesn't do A/B/Y :( Maybe the LS-3 will get it.
Keep in mind, this is setup for active pickups right now, the settings could change once i start playing on passives.
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Re: RF interference solutions? Ferrite bead?

Post by stubbsonic » Wed Mar 14, 2018 10:57 pm

I tried the Radial BigShot EFX switcher with the MS-100BT at the show tonight. Having the loop 1 ground-lifted had no effect. The wireless mic signal was the same. PylePro PHE400 1:1 isolation transformer arrives tomorrow, so I'll try that tomorrow night-even along with the lifted ground-- to see if that gets me anywhere.

Would there be any benefit to trying to put either the ground lift or the transformer after the pedal? The mics are only audible when the guitar is turned up.
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Re: RF interference solutions? Ferrite bead?

Post by NucleusX » Thu Mar 15, 2018 11:15 am

This is the one i got http://www.tonebone.com/re-bigshot-aby.htm

When i bought this pedal initially, i didn't have noise issues to address. I bought it primarily for the fact it
could do ABY, but also having ground lifts and phase reversal, i thought it was wise to have it for when i do
run into those kinda issues. Nice to know its there if i need it. I think Radial make some very interesting
units, and tailor well to the routing nut. Whether or not it helps you any is anyone's guess, but I'm going to
guess no, but you'll never know unless you try right ? There's a good chance you'll never get to fix it if the
problem resides all in the MS-100BT. Might just be an inherent weakness that would take nothing short of
modding it internally with a soldering iron. As for placement, where to place it mostly depends on where
the issue is in your chain. Trial and error, that's all i can say for now. Either way, let us know your results !
Just out of curiosity, and if possible, have you tried changing channels on the wireless unit ? Any changes ?
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Re: RF interference solutions? Ferrite bead?

Post by stubbsonic » Thu Mar 15, 2018 1:31 pm

I will try putting the isolation transformer and the groundlift both pre- and post- the MS-100BT.
If the wireless noise is on the ground (shield) of the MS-100BT's output, then lifting the ground at the output side might work. If it's getting into the signal inside the unit, neither will work.
Last edited by stubbsonic on Fri Mar 23, 2018 1:12 pm, edited 1 time in total.
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