RFI (Radio Frequency Interference)

  • Thread starter Thread starter eurke
  • Start date Start date
eurke said:
Not a problem, I will provide one in about an hour or so!

My temp solution before I stepped out was to turn the focusrite volume lower and turn up my amp. Seems to make the interference much less noticeable
Click to expand...

Is everything connected to the same power outlet, or at least the same circuit? Sometimes when gear is on different power but connected by audio there can be power ground loops that cause hum.
 
Yep, that would be RFI. Something is behaving like a detector circuit. You probably don't have any others but it would be interesting to try some other DI boxes, at least one active and one passive.

Have you tried the ground lift? I doubt that would solve it but it's worth a shot.
 
So, on the JDX48, there is a ground lift you can activate and deactivate. Currently it is activated.

To answer your question, I have tried plugging the amp and the iMac into dedicated separate plugs.

Still the same problem.
 
Ferrite Clip On HEM3012 | Maplin
I am sure you will find the above from RadShak or similar? I would wind as much of the 2i2 USB cable around one for starters (and see if you can source an old USB cable? Thicker, probably better shielding and a ferrite lump, often each end) Then do the XLR cables and finally the speaker lines. Buy quite a few of the absorbers since one each end is best.

If you can identify the station(s) I am sure there must be a gvmnt department that investigates RFI? Our long gone GPO engineers USED to do it, all privatized now so might as well call Mother Care!

If you can pin down the 2i2 as the culprit contact Focusrite. I have never read of any RFI problems there but it IS possible that the vital filters never got fitted!

Lastly, there are outboard filter boxes you can build to go in speaker and mic lines if you are handy with a solder iron. Do NOT buy anything online that claims to fix RFI issues. Probably won't and might bugger an amplifier.

Dave.
 
Thanks all, and my apologies for the "terminology", not entirely knowledgable about specifics. Either way I think we're on the same page.

I will definitely try these suggestions soon, be out of town.

Will let you know how it works out when I return!
 
Snap on RFI chokes which snap on OVER the cord (no soldering, no risk of hurting anything)

Hole sizes vary so take the cord with you that you want to put it on if you can.
Has no effect on audio signals at all.

https://www.radioshack.com/products/radioshack-snap-together-ferrite-choke-core?variant=5717359621

https://www.radioshack.com/products/radioshack-snap-choke-core?variant=5717355973

https://www.radioshack.com/products/radioshack-snap-choke-core-1?variant=5717356421

I was having issues with my wireless mouse acting weird whenever I had headphones plugged into my computer.
Rearranging the headphone cord changed the symptoms so I put one of these on the cord. It blocks wireless signal from getting into the headphone jack from the cord (acting as antenna) and blocked RF from getting out the headphone jack and being radiated from the inside of the computer via the headphone cord (acting as antenna)

(suggestion from an electrical engineer and ham radio guy - me)
 
Thanks all,

I have ordered some from Amazon and will try them out.

I saw on my USB from the Focusrite to my Mac, there was a Ferrite choke on it, but I'll try different variations to see if anything helps!
 
I am experiencing the same issue with my JDX. I pick up clear radio transmissions. Seems to happen more on a old tube amp than a newer amp (unsure if this one is tube or solid state, its not mine and I only see it every few weeks doing sound)

I have not contacted Radial nor taken time to debug, so i'm not much help, but more letting you know that you are not alone.
 
Skeyelab said:
I am experiencing the same issue with my JDX. I pick up clear radio transmissions. Seems to happen more on a old tube amp than a newer amp (unsure if this one is tube or solid state, its not mine and I only see it every few weeks doing sound)

I have not contacted Radial nor taken time to debug, so i'm not much help, but more letting you know that you are not alone.
Click to expand...

Odd that a device from such a well respected manufacturer should suffer RFI? Odder still since the manual shows a transformer in the input circuit and they are usually very efficient as an RF stop (look for traffs with an interwinding electrostatic shield ) .

Some things to try.
1) Found out if you can the FREQUENCY of the interfering station. Dividing this into 300 gives the wavelength in metres. Check that none of your leads are multiple of that frequency or worse half or a quarter wavelength or multiple thereof. The logical conclusion of that is that making a lead longer could help and that is exactly so.

2) Buy some clip on ferrite absorbers and wind cables on those. Often one each end. Input cables are obvious to start with but speaker leads, mains leads and data cables can all cause problems.

3) Make an input cable up as "shielded return". This is done with 2 core "mic" cable. One end tie screen and "cold" core together but at the other end insulate the screen from the jack sleeve and just connect the cold core to sleeve. Hot of course to hot.

But at the end of the day decent gear REALLY should not suffer this problem!

Dave.
 
You must log in or register to reply here.
Back
Top