RFI (Radio Frequency Interference)

  • Thread starter Thread starter eurke
  • Start date Start date
E

eurke

New member
Hello All!

I recently purchased a JDX48 (Radial JDX 48? Reactor? - Guitar Amp Direct Box) from Radial Engineering. When I connect it to my Focusrite Scarlett 2i2 (https://us.focusrite.com/usb-audio-interfaces/scarlett-2i2); I get a lot of clear RFI (Radio Frequency Interference). Every cord is new and balanced.

MY SET UP:
• Line 6 Spider II Head HD
• Line 6 4x12 Cab
• JDX48 DI
• Focusrite Scarlett 2i2
• iMac

CABLES USED FOR CONNECTIVITY:
• 3 Speaker Cables
• ¼” Guitar Patch Cord
• XLR to XLR
• USB (Focusrite to iMac)

HOW I CONNECT:
• Back of speaker has two Left/Right 8ohms /150 watt connections
• Back of the head has two Left/Right 8ohms /150 watt connections
oBoth connected with speaker cables
• ¼” Patch cable inserted, tested, great connection

AT THIS POINT THERE IS NO RFI.

• I connect that set up to my Focusrite from my Direct Out on my Spider II Head and I have a great connection, no RFI.

WHERE THE PROBLEM STARTS:
• I remove the direct out connection from the amp and the Focusrite
• I connect one cable from the speaker to the “From speaker” connection on the JDX48
• I connect one cable from the amp head to the “From amplifier” connection on the JDX48
• The I use another speaker cable to connect the head to the speaker.
• I use an XLR to XLR from the “Balanced output” on the JDX48 to the Input on my Focusrite Interface
• THIS IS WHEN THE RFI STARTS​
oIf I push the phantom power on the Focusrite interface, the RFI of course gets stronger.

MENTIONS:
1. On the JDX48 there are a GND Lift, BASS Ext, and 300W Amp buttons
2. I tried a completely different amp, same issues

I can record with it, however the RFI is present and it very annoying!

Any help/feedback is appreciated!

Thanks,
-Alexander
 
eurke said:
WHERE THE PROBLEM STARTS:
• I remove the direct out connection from the amp and the Focusrite
• I connect one cable from the speaker to the “From speaker” connection on the JDX48
• I connect one cable from the amp head to the “From amplifier” connection on the JDX48
• The I use another speaker cable to connect the head to the speaker.
• I use an XLR to XLR from the “Balanced output” on the JDX48 to the Input on my Focusrite Interface
• THIS IS WHEN THE RFI STARTS​
oIf I push the phantom power on the Focusrite interface, the RFI of course gets stronger.

MENTIONS:
1. On the JDX48 there are a GND Lift, BASS Ext, and 300W Amp buttons
2. I tried a completely different amp, same issues
Click to expand...

Just to be clear about the direction of signal flow, it's from the amp's speaker output into the JDX 48's FROM AMP, from the JDX 48's TO SPEAKER output to the the speaker. There is no FROM SPEAKER connection on the JDX 48. Both of those connections require speaker cables. Also:


eurke said:
• The I use another speaker cable to connect the head to the speaker.
Click to expand...

Does that mean the amplifier is connected through the direct box and directly to the speaker? If so I would double check the manual to be sure that's correct.
 
This part confuses me.

• Back of speaker has two Left/Right 8ohms /150 watt connections
• Back of the head has two Left/Right 8ohms /150 watt connections
• Both connected with speaker cables
Click to expand...

I never used Line 6 stuff. Why do you need to go from the head to the speaker twice? You should probably use just one cable.

• I connect one cable from the amp head to the “From amplifier” connection on the JDX48
• The I use another speaker cable to connect the head to the speaker.
Click to expand...

Same thing here. remove the cable that goes directly from the head to the speaker.

[Edit: I see BSG posted the same time and said the same thing]
 
When you say RFI, do you really mean mains hum? RFI is higher in frequency (because, you know, it's radio frequency). As the other guys pointed out, I think you're creating a ground loop with the second speaker connection.
 
To "JMac52, Chili, bouldersoundguy",

You all nailed it! I removed the "From speaker" connection and only connected, "From amplifier" to the Focusrite and I there is no feedback now.

The engineer from Radial was the one who told me to set up my gear that way, he was beyond helpful, but perhaps I didn't fully explain myself?

Regardless, the problem so far is fixed!

Thank you again, you have no idea how excited I am now hahaha
 
eurke said:
The engineer from Radial was the one who told me to set up my gear that way, he was beyond helpful, but perhaps I didn't fully explain myself?
Click to expand...

Most likely a communications breakdown, which can happen when you're trying to describe your entire setup to someone. I doubt they would tell you to do that type of hook-up, as it's not normal....but all's well that ends well. :)
 
eurke said:
The engineer from Radial was the one who told me....
Click to expand...

Just the fact that you got support like that is awesome in this day and time... and industry.
Yeah, he may not have completely understood your set up, but very cool he was there to help.
 
Radial kit has a reputation for BSH build and high quality over here. It is, like so much US audio gear also expensive. I wonder therefore if the technical support to UK users would be as forthcoming?

I has been my experience however that many companies DO give good support and have good people on board very willing to help. The snag is the morass of obstacles that the website designers put in one's way to GET to the good folks!

Two companies come to mind, Magix and ESI. Both very helpful ONCE you get an electronic "foot" in the door!

Dave.
 
Oh, absolutely!

I was throwing no blame! :D Mike @Radial was fantastic at prioritizing my concerns and sticking with me while I work it out.

Big ups to this forum as well for sorting out what I couldn't!

Thanks again to all :thumbs up:
 
I totally agree with your frustration in regards to support with some companies, within or outside of the music industry.

Ignore me if you've done this; but I've found reaching out via private message on Twitter has rendered quick results.
 
Do you have both the left and right 'speaker out' from the amp connected to the radial? If not, you are unbalancing the amp and will eventually burn something out in it. This is well documented on the Line 6 site.
 
mjbphotos said:
Do you have both the left and right 'speaker out' from the amp connected to the radial? If not, you are unbalancing the amp and will eventually burn something out in it. This is well documented on the Line 6 site.
Click to expand...

Won't that require two of the Radial units?
 
RFI and ground loops are very different sounding phenomena. I suspect here we were all thinking different noises. Glad it's sorted, but I wish we'd heard the noise. The term RFI is usually only used to denote interference that is wireless in origin, and as this was clearly a cable based issue, it's probably circulating ground currents that was the cause, but we will never know.
 
rob aylestone said:
RFI and ground loops are very different sounding phenomena. I suspect here we were all thinking different noises. Glad it's sorted, but I wish we'd heard the noise. The term RFI is usually only used to denote interference that is wireless in origin, and as this was clearly a cable based issue, it's probably circulating ground currents that was the cause, but we will never know.
Click to expand...

Yes Rob and it is only to be expected that peeps posting in the noob section will have their terminology a bit mixed up!

RFI is indeed the breakthrough of radio transmissions and manifests itself as the actual programme, clear and distinct or can be any degree of distorted. There can be several stations crashing in together.

TVI will usually be a harsh buzz, the field sync pulses (50Hz here, 60Hz over the Pond) and maybe some sound.

Eliminating R/TVI can be simple and just need some cheap external components or it can involve some serious work inside the actual kit. In some cases it is incurable. Quality gear is generally better protected than budget stuff.

"Static" is an umbrella term used in the States to characterize any form of noise or interference. It derives from the radio industry and should really NOT be used in an audio context.

"Hum" is a noise derived from the mains supply and is usually 50/60, 100/120 or 150/180 Hz but can extend throughout the audio spectrum and thus is termed a "buzz" . We old valve farts have a term for "buzz" we call it a "griddy" hum!

"Hiss" is noise of high frequency content and has no defined frequency (tho' it might have a "colour" as you get from sea shells) and is largely caused by the random motion of electrons in a conductor. Good design and intelligent gain staging can make hiss a non issue. Again, quality will out!

"Digital" noise (also Googe "zipper" noise) can be the result of ground loops (especially Firewire) and can be a combination of hums, hisses and buzzes.

Dave.
 
rob aylestone said:
RFI and ground loops are very different sounding phenomena. I suspect here we were all thinking different noises. Glad it's sorted, but I wish we'd heard the noise. The term RFI is usually only used to denote interference that is wireless in origin, and as this was clearly a cable based issue, it's probably circulating ground currents that was the cause, but we will never know.
Click to expand...

I took the term RFI with a grain of salt and just looked for generic wiring issues. I bet it was a hum from a ground loop rather than radio reception from an accidental detector circuit.
 
So, UPDATE: The Interference is back.

It only seems to occur when I activate the preamp on the Focusrite.

:cursing:
 
eurke said:
So, UPDATE: The Interference is back.

It only seems to occur when I activate the preamp on the Focusrite.

:cursing:
Click to expand...

It would be nice to have a more accurate description of the noise, and an audio sample would be extremely helpful. Have you tried the ground lift? Is it patched correctly? Amp out to Radial, Radial out to speaker, no direct amp-to-speaker connection.
 
bouldersoundguy said:
It would be nice to have a more accurate description of the noise, and an audio sample would be extremely helpful. Have you tried the ground lift? Is it patched correctly? Amp out to Radial, Radial out to speaker, no direct amp-to-speaker connection.
Click to expand...

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