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Microphone audio interference - EMI?

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Microphone audio interference - EMI?

Postby itipturtles » Tue Aug 06, 2019 9:28 am

I have been getting very large amount of EMI and fan noise with my current setup, I am using a Rode Procaster, connected to a Focusrite solo.
Spent some time trying to figure it out with a friend and seems like just very high levels of interference.
I have turned the Solo up to max gain, and Windows to 100 to showcase the problem, which does occur at all audo levels but the louder the settings are the more prominent it is, so might be easier to diagnose this way.
https://vocaroo.com/i/s0LZ61JDEFhn
In the first 5 seconds of the clip the microphone is in the location it would normally be in for me, and then after that I move it closer to the PC which amplifies the interference. Some of that is fan noise (generally my fans are quiet but mic seems to pick them up a lot) and then the rest is just awful static.
Here is a recording when I set the focusrite to 5/10 on the gain. https://vocaroo.com/i/s11BHm9rE4Ch
Connected everything to my macbook and switch the PC off. Midway through here I flick the switch the PC PSU is connected to at the wall off, and the squeel goes away as heard here https://vocaroo.com/i/s0ar0n8M4nbZ Though I am struggling to consistantly replicate that.
To make everything more confusing, I turned all power switches off, and PC off. Using macbook with battery only I used a Blue Snowball connected via USB and the issue of the high pitch squeel still occurs. https://vocaroo.com/i/s0HnrHwg1iPT.
So pretty much, whether I have any other electrical stuff turned on in the room or not, the issue occurs. Mic picks up a lot of noise from my PC fans (which arent very loud really) which doesn't help, but can manage that at least.

What steps can I take to improve this?
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Re: Microphone audio interference - EMI?

Postby Mike Stranks » Tue Aug 06, 2019 11:37 am

Not yet listened to your clips...

Have you tried using a different mic cable? Have you tried the audio interface with phantom on and off?

Where are you based? Are you aware of any radio/TV transmitters close by?
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Re: Microphone audio interference - EMI?

Postby itipturtles » Tue Aug 06, 2019 1:32 pm

I haven't tried a different XLR but one is on order (currently working away from home).
I have tried with phantom power on and off, no noticeable change.
There are no radio/tv transmitters nearby
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Re: Microphone audio interference - EMI?

Postby N i g e l » Wed Aug 07, 2019 9:06 pm

The fan noise seems a bit dull to be electronic.

How is your Rode mounted ?

If its not in an elastic cradle then the fan noise will vibrate through the various solid objects and arrive on the microphone body.
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Re: Microphone audio interference - EMI?

Postby Sam Spoons » Wed Aug 07, 2019 10:42 pm

How far from the mic were you speaking?
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Re: Microphone audio interference - EMI?

Postby ef37a » Wed Aug 07, 2019 11:56 pm

I don't see how to play or download the clips? Is this a Firefox problem?

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Re: Microphone audio interference - EMI?

Postby Mike Stranks » Thu Aug 08, 2019 9:23 am

ef37a wrote:I don't see how to play or download the clips? Is this a Firefox problem?

Dave.

I'm on Firefox too, Dave. Went to to the site and, as you say, it isn't a self-evident thing to access the sound. Tried a few things and no joy... Walked away.

FWIW I don't think it's Firefox-related... just not a site best-suited to hosting sound-clips for others to access in the way the OP intended.

OP: can you put the clips into something like Dropbox, Googledrive or Souncloud? Ta!
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Re: Microphone audio interference - EMI?

Postby ef37a » Thu Aug 08, 2019 9:45 am

Thanks Mike, not me being my usual IT numpty then!

My policy is always NOT to do anything other than "press play" when presented with such clips. I am cerainly not going to subscibe to anything.

In fact there are two rules I would like to see in all forums?

1) The poster's country must be given. Makes things SO tricky with mains supplies e.g. otherwise.
2) The forum gives a (SHORT!) list of ways to post sound examples.

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Re: Microphone audio interference - EMI?

Postby Mike Stranks » Thu Aug 08, 2019 9:52 am

Good points Dave, but not sure how practical either is....

People can say anything about where they are... only two people here could actually state categorically that I'm in the Cirencester area!

Suggestions about how to post sound-clips and images are fine, but no guarantees that anyone would read them before posting! Of course, if there were guidelines us pedants could always then refer posters to them!

Too many exclamation marks! :D
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Re: Microphone audio interference - EMI?

Postby Wonks » Thu Aug 08, 2019 1:33 pm

You need to allow flash to run. Works fine for me on Firefox once I clicked on the film projector icon and allowed flash to run for that site.

I know Mike (and his evil twin) is in the Cirencester area, so is there only one other?
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Re: Microphone audio interference - EMI?

Postby Wonks » Thu Aug 08, 2019 1:35 pm

It must be a very high pitched noise as I couldn't hear it with my old abused ears (though I could hear the general rumble in the first clip).
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Re: Microphone audio interference - EMI?

Postby Mike Stranks » Thu Aug 08, 2019 2:53 pm

Wonks wrote:You need to allow flash to run. Works fine for me on Firefox once I clicked on the film projector icon and allowed flash to run for that site.

I know Mike (and his evil twin) is in the Cirencester area, so is there only one other?

Ah! Thanks Wonks...

As for knowing I'm where I say I am the only two people who know for sure that I live here are the two forum members who've visited mon repos :)

Anyways... airy persiflage... back to the problem... any noise in a quiet(ish) recording area is always going to result in the need for careful thought or compromises. That's why when mics are in use here I record to standalone recorders. Not suitable for everyone of course, but in my situation... pin drop...
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Re: Microphone audio interference - EMI?

Postby ef37a » Thu Aug 08, 2019 3:37 pm

Mike Stranks wrote:Good points Dave, but not sure how practical either is....

People can say anything about where they are... only two people here could actually state categorically that I'm in the Cirencester area!

Suggestions about how to post sound-clips and images are fine, but no guarantees that anyone would read them before posting! Of course, if there were guidelines us pedants could always then refer posters to them!

Too many exclamation marks! :D

Oh!! I am not saying we need to be draconian or snotty but if people do not get the help they seek because we are unable (or unwilling) to decode their sample, more fool them if the rule is there.
Similarly, their 10/20 is their business but then it can be said "you should have TOLD us you were in the States/100V Japan... whatever!!

Oh!! and thought I would chuck a few more !!! in for luck!

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Re: Microphone audio interference - EMI?

Postby Mike Stranks » Thu Aug 08, 2019 4:44 pm

Just to be clear... the 'exclamation marks' comment was directed at me... but thanks for yours Dave. I'll add them to my collection. :lol:
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Re: Microphone audio interference - EMI?

Postby ef37a » Thu Aug 08, 2019 5:21 pm

Mike Stranks wrote:Just to be clear... the 'exclamation marks' comment was directed at me... but thanks for yours Dave. I'll add them to my collection. :lol:

Yes, I got that. Just being silly!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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