RF interference solutions? Ferrite bead?

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stubbsonic
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RF interference solutions? Ferrite bead?

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

I'm getting some loud interference from wireless mics through my MS-100BT. Somehow the MS-100BT is demodulating it into audio and passing it to the amp. I can gate it, but the threshold is so high that it is making the sound not very good.

I had someone install a small ferrite bead into my guitar cable, but its not really working I think part of the problem is that it is soldered onto the center wire and not the shield.

One of my searches showed an audio cable that was wrapped around a ferrite donut. I wondered if something like that would filter out the UHF (or whatever range it is) from my signal.
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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 to receive those signals and demodulate them. I wondered if the Bluetooth hardware might be related.
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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 "demodulations" (?) lots of sound from 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 I wish Zoom had done a better job with the hardware to make it a more resilient, hi-fi unit. It's a dream box, except for that. In my home studio, it works very well.
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