radio interference in studio monitors

[styphon]

In advance, I have already read searched and read threads about this topic.

Problem: While using a used set of KRK VXT8's with a Presonus Firestudio, I have very heavy static and a radio station in the background. The radio station is FM, 103.3 to be exact. It is not related to changing the volume of the monitors

What I have tried: I have read many threads about this problem and have tried various solutions. I tried unplugging everything electric in the room, no change in the noise or radio station interference. I tried moving to different rooms, no change in noise or radio station. I had an electrician check the sockets, all sockets are correctly grounded. I tried ferrite rings, on the cable and on the power cable, no change. When I unplug the monitors from the audio interface at the monitor end, nothing changes. I have noticed slight change when using a thicker power cable I had with my mpc1000.

What's left: I am thinking about trying monster cable power cables or some other similar item that claims to have great shielding. Another option is a voltage regulator/power conditioner. Another option is having an electrician check the actual grounding of the electrical system. Another option, send in the monitors to KRK to have them checked.

Short of moving out, or making a faraday cage, what do I have left? Is it even worth it to try to better shielded cables?

[Radioman]

take a look a this thread

Mexican Radio whoa-oh, (RFI before our preamp)

[styphon]

This is driving me crazy, the radio station comes in so clearly and loud. So will attempt monster powercord, then monster powerconditioner, if neither work...Repair or sell speakers

[Radioman]

Try to cover the cables with aluminium foils connected to ground, instead to buy very expensive grounded cables.

[JohnRoberts]

#1- do both monitors act exactly the same?
#2- Does the radio pickup change when you move the boxes around the room?
#3- Does radio pickup change when you move the line cords.
#4 does it matter if you plug a shorted jack into inputs
#5- does it matter if you wrap tin foil around the speaker box?

I am reluctant to advise messing with power, but depending on vector that RF is getting into your speaker, the solution may be to add filtering somewhere.

There are always two parts to this problem.. First RF gets to sensitive circuitry, and circuitry is not fast enough, or filtered properly to ignore RF.

Multiple possible solutions... maybe ask KRK for advice. Surely if they are susceptible, they have encountered this before.

JR

[styphon]

Originally Posted by JohnRoberts

#1- do both monitors act exactly the same?
#2- Does the radio pickup change when you move the boxes around the room?
#3- Does radio pickup change when you move the line cords.
#4 does it matter if you plug a shorted jack into inputs
#5- does it matter if you wrap tin foil around the speaker box?

I am reluctant to advise messing with power, but depending on vector that RF is getting into your speaker, the solution may be to add filtering somewhere.

There are always two parts to this problem.. First RF gets to sensitive circuitry, and circuitry is not fast enough, or filtered properly to ignore RF.

1# Monitor seem to sound the same, sometimes I think its more in one monitor, than the next day it seems to be more in the other monitor.
2# The radio stations are just as loud/clear no matter what the monitor's position is in the room
3# I have gotten the radio stations to soften a little by moving the cords around.
4# Not sure how to do that? I have unplugged the incoming cable from the monitor end, no difference in the radio interference.
5# I have not tried to wrap tin foil around the mintors yet.

I just bought a monster power conditioner, lets see how this goes.

[James S]

I have a pair of the VXT6's in my studio that exhibit all of the same problems you are experiencing. The only thing that seemed to work (somewhat) was to put ferrite rings on the audio cables. With the ferrite rings, I was able to tame it to the point where it couldn't be heard from mix position. This was definitely a compromise and not a solution.

During my troubleshooting process, I was able to try multiple pairs on loan from a local dealer.
I tried the VXT6's and the VXT8's. All had the same problem. I tried different power conditioners including the Monster conditioners. None of those made any difference.

Over the course of several days, I randomly took the monitors to different locations and simply plugged them in. Some places they were whisper quiet, and some places they were single channel radio receivers. Chances are, they will either work as advertised or they won't, in any given room.

At the time when I was testing the KRK's, they were sitting next to monitors that were quadruple their price and monitors that were downright crappy. Only the KRK's had this problem.

I am a fan of the older, much more expensive, and now discontinued KRK monitors. I do like the way the VXT's sound and translate, but I wouldn't recommend if they are your only choice of monitors. In my opinion, they have a flaw in their design or manufacturing. There is a definite problem in how they handle RF suppression. Seeing as these are marketed to prosumers and
home studios, this just seems like a recipe for disaster.

I hope some of this helps you sort it out.

[Engr]

had the same problem with a pair of cheap monitors...(same radio station too)

I had some one help me modify them but it wasn't good enough.

My solution was to buy adam a7's. Absolutely no problems.

Hope that helps

[styphon]

Originally Posted by James S

I have a pair of the VXT6's in my studio that exhibit all of the same problems you are experiencing. The only thing that seemed to work (somewhat) was to put ferrite rings on the audio cables. With the ferrite rings, I was able to tame it to the point where it couldn't be heard from mix position. This was definitely a compromise and not a solution.

During my troubleshooting process, I was able to try multiple pairs on loan from a local dealer.
I tried the VXT6's and the VXT8's. All had the same problem. I tried different power conditioners including the Monster conditioners. None of those made any difference.

Over the course of several days, I randomly took the monitors to different locations and simply plugged them in. Some places they were whisper quiet, and some places they were single channel radio receivers. Chances are, they will either work as advertised or they won't, in any given room.

At the time when I was testing the KRK's, they were sitting next to monitors that were quadruple their price and monitors that were downright crappy. Only the KRK's had this problem.

I am a fan of the older, much more expensive, and now discontinued KRK monitors. I do like the way the VXT's sound and translate, but I wouldn't recommend if they are your only choice of monitors. In my opinion, they have a flaw in their design or manufacturing. There is a definite problem in how they handle RF suppression. Seeing as these are marketed to prosumers and
home studios, this just seems like a recipe for disaster.

I hope some of this helps you sort it out.

Helpful, but you just crushed my spirits.. Now I am doubting if it is worth it to even send these to KRK to be checked out.

[drewharris]

I've just glanced over this thread, but to throw in a quick two cents just in case, what mic do you have hooked up? We got radio interference on a Microtech Gefell M71 (I think it was an M71 at least if I recall correctly) and came to find out its apparently a known problem with the mic?

Now, that having been said, it sounds like other people have had a similar problem with your monitors, but nonetheless, something to consider.

-drew

[styphon]

I think? I have mostly fixed it.

I took one of the monitors apart, haphazardly put aluminum foil on the sides and some near the subwoofers. Now, the monitor I did that to does not recieve ANY radio interference, but does have lots of the static in the background. The unshielded monitor still CLEARLY gets the radio station interference...

Interesting.. I wonder how much of a difference the thicker copper foil I use to shield guitars would make. I also wonder, if I solder the different pieces together and rim the foil around the edge so the metal backing makes contact, if that would improve the reduction of static.

[Radioman]

Originally Posted by styphon

I also wonder, if I solder the different pieces together and rim the foil around the edge so the metal backing makes contact, if that would improve the reduction of static.

Aluminim can't be soldered, you must use copper foils if you want to solder them. Obviously you can join together some aluminium foils extremes.

[JohnRoberts]

There are electrically conductive coatings that can be used to treat the inside of the box, or perhaps a fine metallic screen. For best results that shield should be grounded.

Of course be careful about using conductive shielding inside the box as it could get loose and short circuit something.

JR

[Milesy303]

you could turn your mixing space into a small faraday cage by covering the walls with a fine metal meshing.

[cleartrueblue]

Googled and found this apropos thread. Glad I did as I thought I was just stuck with my problem, and now I have some things to try.

I'm down in Buenos Aires (from California) with a pair of VXT4's. Daytime I get from two to four stations (different on each monitor). At night (when I'm working alot) it is mostly dance ("electronico"). Especially this one track which this guy sometimes plays over and over.

Going out for aluminum foil now; wanted to acknowledge and thank the contributors to this thread.

[styphon]

Tell me if it works for you also

[SoundWeavers]

Hello. For eliminating RF/RFI, you can try building a Faraday cage around your room (and there are different ways of doing it)... info on Faraday cage

Hope this helps.

Gerry

[bace]

Its a very common problem with KRK's. At least rokit powerd and VXT, they all are very sensitive about radio waves. And that not strange at all. The amplifier is totally free from sheilding! It pickups my neigbours cellular and some times I can hear some AM stations. And the amps are very noicy.

[styphon]

Originally Posted by bace

Its a very common problem with KRK's. At least rokit powerd and VXT, they all are very sensitive about radio waves. And that not strange at all. The amplifier is totally free from sheilding! It pickups my neigbours cellular and some times I can hear some AM stations. And the amps are very noicy.

With the foil lining there is *no* noise at all.

[bace]

Originally Posted by styphon

With the foil lining there is *no* noise at all.

Where? Have you put foil around the speakers?

[bace]

Originally Posted by James S

I have a pair of the VXT6's in my studio that exhibit all of the same problems you are experiencing. The only thing that seemed to work (somewhat) was to put ferrite rings on the audio cables. With the ferrite rings, I was able to tame it to the point where it couldn't be heard from mix position. This was definitely a compromise and not a solution.

During my troubleshooting process, I was able to try multiple pairs on loan from a local dealer.
I tried the VXT6's and the VXT8's. All had the same problem. I tried different power conditioners including the Monster conditioners. None of those made any difference.

Over the course of several days, I randomly took the monitors to different locations and simply plugged them in. Some places they were whisper quiet, and some places they were single channel radio receivers. Chances are, they will either work as advertised or they won't, in any given room.

At the time when I was testing the KRK's, they were sitting next to monitors that were quadruple their price and monitors that were downright crappy. Only the KRK's had this problem.

I am a fan of the older, much more expensive, and now discontinued KRK monitors. I do like the way the VXT's sound and translate, but I wouldn't recommend if they are your only choice of monitors. In my opinion, they have a flaw in their design or manufacturing. There is a definite problem in how they handle RF suppression. Seeing as these are marketed to prosumers and
home studios, this just seems like a recipe for disaster.

I hope some of this helps you sort it out.

I have the problems with out any audio cables, so I dont think any ferrite will help.

[styphon]

Originally Posted by bace

Where? Have you put foil around the speakers?

I opened up the speaker (voids the warranty if you have one) and then lined the sides with foil, making sure it made contact with the back plate i removed.

[mmcfarlane]

Originally Posted by styphon

This is driving me crazy, the radio station comes in so clearly and loud. So will attempt monster powercord, ...

I never understood how changing the last 3 feet of a powercord could significantly change the electrical characteristics of an AC feed.

You probably have 100 feet of "cheap wire" in your wall and ceiling (effectively a long antennae) connecting the outlet to your breaker box. How can upgrading the last 3 feet of wire have a significant impact?

Am I missing something meaningful with all these magical power cords? I understand the wire and insulation need to handle the devices current load, but beyond that...

[styphon]

Originally Posted by mmcfarlane

I never understood how changing the last 3 feet of a powercord could significantly change the electrical characteristics of an AC feed.

You probably have 100 feet of "cheap wire" in your wall and ceiling (effectively a long antennae) connecting the outlet to your breaker box. How can upgrading the last 3 feet of wire have a significant impact?

Am I missing something meaningful with all these magical power cords? I understand the wire and insulation need to handle the devices current load, but beyond that...

Try to read the rest of the thread.

[bace]

Originally Posted by mmcfarlane

I never understood how changing the last 3 feet of a powercord could significantly change the electrical characteristics of an AC feed.

You probably have 100 feet of "cheap wire" in your wall and ceiling (effectively a long antennae) connecting the outlet to your breaker box. How can upgrading the last 3 feet of wire have a significant impact?

Am I missing something meaningful with all these magical power cords? I understand the wire and insulation need to handle the devices current load, but beyond that...

It's about rejecting radio frequency. TH power is about 50-60 Hz. Radio is about 1MHz and above. You try to increase the HF-impedance near the monitor without increasing it for the power freq. See it as an EQ, but for radio trying to stop the signal geting into the monitor. Radio works with short wavelengths about few meter. And you need to fix the EQ in about 1/2 wavelength from the monitor otheriwise it acts as a antenna picking up more RF.

[bace]

They krk are very very sensitive! I have now found one source for the buzz in the speakers. Its my SIP box for telephone over internet. About 75 cm from the speaker. And the shielding are ridiculously poor. Half a meter of aluminum foil without any grounding can take the buzz away. Wrapped on the outside of the monitor. And that on a $1000 monitor.

Originally Posted by krksys web

For over 20 years, KRK has mastered the art of recording monitors, and the VXT is the culmination of this art. Listen for yourself, and believe!

The have building monitors for 20 years have not learned the basic concepts of electronic design? Mastered, not yet...

[overbias]

How close to you is the station's transmitter? Keep in mind most stations use an RF link from the studio to the transmitter, so even though the studio is across town, the transmitter may be in your back yard.......

Not for the timid, but try using a "ground lift" adapter on the power cords...

Try using a different length power cord....

Let us know.....

Jack

[mmcfarlane]

...Not for the timid, but try using a "ground lift" adapter on the power cords...

Being somewhat of a safety nut (ask my kids) I reocommend you don't ever remove/disable the high-voltage safety ground from any equipment. If the equipment was designed to operate safely without a safety ground (e.g. double insulated) it would come from the manufacturer with a 2 prong plug without the safety ground.

Don't risk electrocuting yourself or someone else visiting your studio, there are safe ways to fix the problem.

Lifting ground or a shield on audio level voltages running between gear is an acceptable way to resolve noise problems but just say no to disabling safety grounds on high-voltage gear. If you decide anyway to do it as a test, make sure you re-enable the safety ground immediately after the test is completed and fix the problem in a manner that wont risk the life of you or a customer

This public service annuncement was brought to you by an anal retentive guy.

[cleartrueblue]

Originally Posted by cleartrueblue

Googled and found this apropos thread. Glad I did as I thought I was just stuck with my problem, and now I have some things to try.

I'm down in Buenos Aires (from California) with a pair of VXT4's. Daytime I get from two to four stations (different on each monitor). At night (when I'm working alot) it is mostly dance ("electronico"). Especially this one track which this guy sometimes plays over and over.

Going out for aluminum foil now; wanted to acknowledge and thank the contributors to this thread.

Follow-up: The foil wrapping made a dramatic difference. I wrapped the audio, a.c., and the monitors themselves, with all the shielding connected. Still had to futz a bit with where the cables lay/crossed, but after that nearly silent! What a relief. Thanks again.

I should mention Buenos Aires has numerous pirate stations and, pirate or not, I could look across the skyline and count several broadcast antennas just in my site line. And, I was running unbalanced output from the iMac's internal converter. Here in the California 'burbs fed by balanced ouput I've had no trouble at all with the VXT-4's (which are for sale...check the classifieds!).

Cheers.

[styphon]

Originally Posted by cleartrueblue

Follow-up: The foil wrapping made a dramatic difference. I wrapped the audio, a.c., and the monitors themselves, with all the shielding connected. Still had to futz a bit with where the cables lay/crossed, but after that nearly silent! What a relief. Thanks again.

I should mention Buenos Aires has numerous pirate stations and, pirate or not, I could look across the skyline and count several broadcast antennas just in my site line. And, I was running unbalanced output from the iMac's internal converter. Here in the California 'burbs fed by balanced ouput I've had no trouble at all with the VXT-4's (which are for sale...check the classifieds!).

Cheers.

Ah ha, my warranty-voiding solution has now worked for you and me...
Very interesting that people making plus $1000+ monitors can't afford 25 cents of shielding.

Wait, never mind. Its called the "american way". I have bought $1500 guitars that lack cavity shielding. Showing even higher priced companies will do anything to cut down the "low end"