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Zoom F8 digital or RFI noise problem

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Zoom F8 digital or RFI noise problem

Postby Tomás Mulcahy » Wed Nov 23, 2016 10:05 pm

Anyone experienced noise with the F8? It sounds like the digital bus (writing to the card) is getting on to the analogue line. Or it might be RFI from wi-fi or something like that? Did a field test yesterday and had the noise on 4 different recorders all jam-synched to timecode. Two with Zoom stereo mics and two with Rode NTG-2. I am going to try some more testing tomorrow because we may have been in an area with a lot of RFI, and the machines have not had the latest firmware update installed.
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Re: Zoom F8 digital or RFI noise problem

Postby Mike Stranks » Wed Nov 23, 2016 10:37 pm

Bob Bickerton has an F8 - maybe he can give some input on this.

I have an F4, but haven't given it a detailed workout yet. That said, what stuff I have done - with an NTG1 and adjacent to a router - has been clean as a whistle.
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Re: Zoom F8 digital or RFI noise problem

Postby Hugh Robjohns » Wed Nov 23, 2016 11:00 pm

I didn't notice any problems when I reviewed it, and card-writing noises would be pretty obvious.

External RFI is always a possibility, but I would think more likely to be a problem with the mcs and/or cables than the recorder itself.

Interested to know what you find...

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Re: Zoom F8 digital or RFI noise problem

Postby Tomás Mulcahy » Thu Nov 24, 2016 7:56 pm

This is what worries me. The interference was present with the Zoom clip on stereo mics. So in that case it definitely is not the cables. Ill test a machine at home, out in the sticks where there is less RFI. On the location above there is a microwave link between two buildings, but my understanding is this is a very focussed signal that doesnt radiste outside of the dishes. Is that correct? Could that be a source of RFI?
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Re: Zoom F8 digital or RFI noise problem

Postby Bob Bickerton » Thu Nov 24, 2016 8:25 pm

Haven't noticed any issues with the Zoom F8 here.

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Re: Zoom F8 digital or RFI noise problem

Postby Tomás Mulcahy » Mon Dec 05, 2016 2:35 pm

OK, tests in an actual field (i.e. in the country side) with the same set up show no RFI. A student recently demonstrated exactly the same noise issue with the NTG-1 connected directly to a camera. So if it's happening with other gear the fault is not with the Zoom F8. Next step is to see if someone in the engineering or IT department has portable test gear so we can see what RF is flying around the area.

I guess we'd need a spectrum analyser and an aerial (i.e. long wire)?
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Re: Zoom F8 digital or RFI noise problem

Postby Mike Stranks » Mon Dec 05, 2016 3:52 pm

Tomás Mulcahy wrote:... A student recently demonstrated exactly the same noise issue with the NTG-1 connected directly to a camera....

Asking the obvious I know... Is it the same with balanced and unbalanced cables/inputs? I'm sure a person of your calibre has that angle covered, but with the above quote I just wondered... Presumably that was a balanced input on the camera?
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Re: Zoom F8 digital or RFI noise problem

Postby Tomás Mulcahy » Mon Dec 05, 2016 8:47 pm

Hi Mike, yes it was a balanced input. And calibre? What are you talking about?!? I'm still waiting to be found out! :lol:
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Re: Zoom F8 digital or RFI noise problem

Postby Mike Stranks » Mon Dec 05, 2016 11:25 pm

Tomás Mulcahy wrote:Hi Mike, yes it was a balanced input. And calibre? What are you talking about?!? I'm still waiting to be found out! :lol:

Aren't we all! :P

... and just to add that I spent a morning doing field-recording (literally!) last week with the F4 and an NTG-1. Not a squeak or splutter of anything unexpected or unwanted...
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Re: Zoom F8 digital or RFI noise problem

Postby Hugh Robjohns » Tue Dec 06, 2016 11:55 am

Tomás Mulcahy wrote:OK, tests in an actual field (i.e. in the country side) with the same set up show no RFI.

Okay... so that suggests the problem is external interference... so the task now is to figure out where it's getting in.

A student recently demonstrated exactly the same noise issue with the NTG-1 connected directly to a camera. So if it's happening with other gear the fault is not with the Zoom F8.


Not necessarily. It could be that the camera and F8 both have the same degree of susceptibility to external interference... but given that these two devices will almost certainly have very different mic preamp designs and constructions, the chances are that the interference is actually getting in to the mic itself, or the mic cable.

Next step is to see if someone in the engineering or IT department has portable test gear so we can see what RF is flying around the area.

Actually, I'd say the next step would be to swap out the mic, and then the cable. Can you borrow another NTG1 from somewhere? Try a cable with Neutrik's EMC connectors on each end, for example.

Also, because I presume this problem occurs with entirely battery-operated gear, try connecting a solid earth to the equipment ground and see if that helps. battery-gear inherently 'floats' and the whole lot acts as its own aerial. Stick a metal spike into the wet soil, with a wire running up to a ground connection on the equipment somewhere (the sleeve of the heaphone socket, for example). See if that helps...

I guess we'd need a spectrum analyser and an aerial (i.e. long wire)?

Aerials are designed to capture specific bandwidths centred on specific frequencies. A ''long wire" is a bit too random to be a lot of use... but if you can find someone with an RF spectrum analyser the chances are they'll also know how best to set up an aerial system to work with it! ;-)

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Re: Zoom F8 digital or RFI noise problem

Postby Tomás Mulcahy » Tue Dec 06, 2016 2:41 pm

OK thanks Hugh for those very useful suggestions!
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Re: Zoom F8 digital or RFI noise problem

Postby markvonreddy » Sun Feb 16, 2020 1:04 am

I recently started experiencing this problem on my F8 which is about 4 years old now. I have a strong suspicion that is a card writing induced RF spikes in my wireless system. I'm using the Sennheiser Ew 500 G4 sytems connected into the F8. My theory is that high operating temperatures, outdoor may have caused the RF copper shielding inside the F8 to somehow get disconnected. I'm still trying to find a service center in India that can help.
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