Zoom F8 digital or RFI noise problem

[Tomás Mulcahy]

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.

[Mike Stranks]

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.

[Hugh Robjohns]

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 mics and/or cables than the recorder itself.

Interested to know what you find...

H

[Tomás Mulcahy]

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?

[Bob Bickerton]

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

Bob

[Tomás Mulcahy]

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)?

[Mike Stranks]

... 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?

[Tomás Mulcahy]

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

[Mike Stranks]

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

Aren't we all!

... 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...

[Hugh Robjohns]

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!

H

[Tomás Mulcahy]

OK thanks Hugh for those very useful suggestions!

[markvonreddy]

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.

[markvonreddy]

I've had some horrible experiences since January this year with some sort of RF bursts when I hit the record button on the F8. F8 is running the latest firmware (V6.10). My wireless setup consists of the Sennheiser ew500 G4 series. 1 x SKP 500 transmitter and 3x SK 500 lav transmitters on the Aw+ band (470 to 558Mhz).

The receivers are the EK500 G4 receivers.

I get these RF hits as soon as I hit the record button. Otherwise it's practically noise free. Initially I thought it was an issue with the Sennheisers and then had them replaced. I still face the same issue with the new set.

I am yet to try this wireless setup with sound devices recorders.

[Hugh Robjohns]

Digital audio equipment inherently generates a lot of very high frequency -- into RF -- signals, so it's quite possible that the Zoom is actually causing interference with the radio mic receivers and/or their cabling.

I'd try separating the recorder and receivers as a first experiment to overcoming the problem...

[Benoit.GRIESBACH]

I stumbled across this thread when I was also searching for interferences on F8 and Wireless system.
I have a similar setup with 2 G3 receivers on the bag, and the sound is fine when it's monitored in idle state. Once record has been pushed it's a nightmare like you with intermittent bursts that are actually recorded on the tracks and the ISOs as well, which make the whole tracks pretty unusable.
I saw someone having the exact same problem. He said that when Sample rate frequency increased from 48kHz to 96kHz, the problem was actually occuring twice faster. So it really seems it comes from the SD card writer.
However, when he tried to unarm SD Slot 1, and rec only on SD Slot 2, the problem disappeared.

As the problem is not that much frequent and it's not easily reproductible as it appears only when Card is Recording it's a nightmare to troubleshoot it. Most of the times it's in the middle of a hurry on a shooting durint a take and we can't take the appropriate amount of time to debug and test solutions.

Hint 0 : as one said, it could be because the external battery is floating and doesn't connect the ground with the shield and during Recording we would need that, so try to see if it does the same on internal AA batteries.
Hint 1 : try to not write on SD1 as problem seems to stop
Hint 2 : the SD card is too "fragmented" and SD writer is struggling so maybe before shooting we should do a complete bit by bit erase (software) and not just a quick format.
Hint 3 : as the Zoom F8 is getting older, maybe the new SD Cards are too complex for it, maybe downgrade to good old SDHC 16Gb with lower speeds (class 2, class 4) and not SDXC like 128Gb for camera V10 (170Mb/s).
Hint 4 : what if a small piece of aluminium tape would be sufficient around the SD slot to prevent it from spreading ?

[Tomás Mulcahy]

That's a good tip about SD1, I will try that with the problematic machine here.

I can only guess as to the cause, perhaps a weak or unmade joint to a screen somewhere on the board. But as you say it is from the SD card, so if we could find where that bus is on the board... or get Zoom to do a recall!

[markvonreddy]

I've had the same issue for a while now and only today saw a reply on here that seems to have sorted out my issue. The SD Card slot 1 seems to be the culprit. I've been trying to figure out what the problem is on multiple shoots and have spent countless hours with iZotope RX to remove the RF hits that have been recorded due to the card writing RF burstsfrom the F8. I have been using the Sennheiser 500 G4 units that don't have great RF filters.

Now that I'm recording only onto slot 2, it's a scary place to be in since I know I don't have a backup. For tomorrow's shoot, I'm going to try using a much older 16GB SD Card to see if it makes a difference.

Another thought: what If the receivers were placed outside the audio bag far away from the recorder itself. Would a set of ferrite cores on the mini TRS to XLR cable halp absorb the RFI? And if so would it also affect the Signal itself since the cable itself acts as a second antenna for the Sennheiser G4?
I will post the results on here.

My Zoom F8 was purchased directly from the B&H superstore in NYC back in March of 2016. It also runs the latest firmware V6.10E . I am hoping a firmware fix would resolve this. Otherwise it would have mean I have to send this to an authorised service centre in an another city altogether.

[Tomás Mulcahy]

The RFI is from inside the Zoom, so changing anything outside it won't help unfortunately.

[markvonreddy]

That just sucks. What would be a possible solution to this?

I tried using a different SD card with a slower writing speed but that didn't help. I noticed some mild RFI while recording onto slot 2 as well. I hope someone from Zoom chimes in on this to sort this out. Could this also be firmware related as this problem has seemed to have cropped up at the start of 2020. It ran flawlessly from 2016 to 2020 though.

I am upgrading to a wisycom system in the next few months so I'm hoping that the front end filtering will help filter this RFI out. I really love the zoom except for this annoyance. A friend of mine who uses the F8n and hasn't had any issues with it. I hope Zoom either does a recall or issues a firmware update to fix this.

[Tomás Mulcahy]

Again, external filtering won't work. It's happening inside the Zoom itself.

Ya we have 4 here, and 2 of them do it consistently. The F4 (we have 3) don't do it at all.

It's an internal shielding or grounding issue. I've an old H2 that does it when held sideways!

[markvonreddy]

What leaves me confused is that it doesn't happen with wired mics (only wired microphones and no wireless in the rig). I should send this unit for service.

[markvonreddy]

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.

Hi Tom,

Were you able to get this issue sorted at any of the Zoom service centers?

[Tomás Mulcahy]

For various reasons, Zoom were not contacted. It happens with wired mics here!

[markvonreddy]

Hi Tom.

I recently received a reply from Zoom North America and they have offered to replace my faulty F8 with an F8n at a cost of $450 plus shipping since my F8 is now out of warranty thanks to the 'plandemic'!! The local authorised service centre in India had never repaired one of these units so they were quite unsure whether they'd be able to put it back together once they opened it up. They were also too lazy to replicate the setup to asses the problem correctly. I had to resort to writing in to Zoom North America to have this problem addressed! Now that IM stuck in India, sending the unit back to the US would be a logistical problem. I may end up paying a hefty customs duty when they ship a replacement unit.

I hope your faulty units were replaced!

Best

Mark

[Mike Stranks]

As we're revisiting this thread...

My F4 does seem unaffected by this 'F8' problem... although these days it's only used for non-field work - in part because getting out and about during Covid-times has proved more problematic with events cancelled etc.

But I did have one occasion on location when it got very upset. I was recording old, static petrol engines that were designed to power pumps, generators, small log-saws etc. Some were connected to said generators - also of a certain age - to demonstrate their capabilities. It was clear on listening to playback that some of these setups were generating significant amounts of RFI - think spark-gap transmitters - which was presumably being picked up on the mic cables...

... but apart from that, zilch.