I am hearing radio through my system... help!

[nck045]

Occasionally I can hear radio through my audio system, as in actual programs and/or songs from radio stations.

Not sure what is causing the interference. But the amplifier seems to be the culprit here, as I already tried turning off all other devices in the chain. The problem still occurs even when the amplifier volume is turned all the way down.

Anyone experienced this before? and any advice on the easiest and cheapest way to fix it?

 

[Doodski]

I had a system that picked up private aircraft chatter as they flew overhead. I bought a new amp and turntable and fixed that issue.

 

[Mart68]

Back when taxis used analogue radio I used to get this - I lived opposite a working man's club so late evening a lot of taxis would show up to take people home and their chatter was audible through my speakers. I think the speaker cables acted as an antennae, since it happened with a lot of different equipment, but I never got to the bottom of it and taxi radios went digital soon after.

 

[Apesbrain]

Some suggestions here. It can be a difficult thing to trace down. You may need a combination of remedies. If it is the circuitry inside your amp that is picking up the RF energy, you may need to move it or shield it.

Is the background radio audible only on one input? Sometimes, the "Phono" input is more sensitive to this. Is the noise there with everything except speakers completely disconnected from the rear of your amp?

 

[Talisman]

I imagine a lot of people listen to radio on their system, usually those people have a tuner though! Come on, you saved on the tuner!

 

[Speedskater]

a] plug everything into the same AC wall outlet.
b] braided shields on all interconnect cables.
c] try short twisted pair loudspeaker cables.
* * * * * * * * * * *
When all else fails, Jim Brown retired Audio Engineering Society interference expert, has several papers & Power Points on this problem on his page,

Audio Systems Group, Inc. Publications

 

[SteveC]

Back when taxis used analogue radio I used to get this - I lived opposite a working man's club so late evening a lot of taxis would show up to take people home and their chatter was audible through my speakers. I think the speaker cables acted as an antennae, since it happened with a lot of different equipment, but I never got to the bottom of it and taxi radios went digital soon after.

Me too. Years ago I had some funky speaker wires (don't remember who made them or what the design was) that seemed to love a Spanish language station somewhere in the area. I bought some Belden based cables from Blue Jeans Cable and that fixed the problem. For full disclosure I do confess to having had many years of audiophile addiction and bought or tried a lot of weird stuff. I'm MUCH better now!

 

[DVDdoug]

Yeah... Try some extra-short speaker wires. If it's "leaking-in" through the speaker wires using shielded (or twisted) cables should help. Not likely but worth a try. Otherwise the only solution may be a different amplifier.

I used to get that occasionally from the phono input back in the analog days. Then I thought it was happening again when played my new Pink Floyd album for the first time!

 

[Mr. Widget]

Anyone experienced this before? and any advice on the easiest and cheapest way to fix it?

I used to live down the hill from this tower... I picked up a radio station through my low output MC cartridge.
The only 100% effective fix I found was to move.

 

[egellings]

There are also ferrite cores that come in a plastic hinged snap on case that are made to be attached to power cords and audio cables in order to reduce RFI. You might try those.

 

[Timcognito]

Do you have a tuner in your system? Tune to an area on the band where there is to no station and no static. I used to do this with my Nakamichi 630 as the preamp was onboard.

 

[sergeauckland]

There are two main mechanisms for this to happen, from my experience.

For AM transmissions, RF gets into the electronics through interconnects, loudspeaker cables or (unlikely but possible) mains cables and gets demodulated by the non-linearity of the amplifier at RF. The problem there is the amplifier has been poorly designed and it's hard to do anything about that.

The second main mechanism is that the amplifier has a high frequency oscillation, also due to poor design, and this beats with the incoming RF and the result is audible radio breakthrough.

I had a friend who lived half-way between the Crystal Palace and Croydon TV masts in South London, in the days of VHF TV which had AM sound, and we could happily (actually not so happily) listen to TV sound at the same volume as the record playing. I tried pretty much everything, ferrite beads on all cables, capacitors across all inputs. Only thing that worked was for him to move house.

I had an amplifier that would demodulate Radio Moscow on shortwave to my great irritation. I couldn't find any way of stopping this in spite of ferrite beads everywhere. Eventually I got a 200MHz 'scope and found that the amp was hooting at HF frequencies, around 40MHz as I recall, and when I stopped that, Radio Moscow went away.

The moral of this story is that it's the very devil to fix, might not ever be fixable unless you get right into the amplifier circuit.

S.

 

[Speedskater]

If you do go with snap-on ferrite cores, place them as close to the chassis as practicable.
The molded one piece cores with a hole thru the center are better, but that ship as sailed.

 

[terryforsythe]

Occasionally I can hear radio through my audio system, as in actual programs and/or songs from radio stations.

Not sure what is causing the interference. But the amplifier seems to be the culprit here, as I already tried turning off all other devices in the chain. The problem still occurs even when the amplifier volume is turned all the way down.

Anyone experienced this before? and any advice on the easiest and cheapest way to fix it?

First, identify the culprit component for sure. Turning off other devices with their cables connected may not be sufficient.

1. Disconnect all cables from the amp except for the speaker cables and power cable. Does the problem go away? If not, then it likely is your amplifier. How long are your speaker cables?

2. If the problem did go away, next plugin your pre-amp, but with nothing else plugged into that. Did the problem come back?

3. If the problem did not come back, plug in one source at a time and identify the one that is the culprit.

Once you have identified the culprit, then you can start taking steps to address it. It may well be the amplifier, but do the above to make sure before you spend too much time/money on it.

 

[sam_adams]

You could, as some have already suggested, place ferrites on the input and output cabling of the amplifier to suppress the RFI. However, the "mix" of the compound that the ferrite is made of will determine how well it works at the frequencies that you wish to suppress. Most of the snap-on ferrites that are sold on Amazon and Ali-Express are of unknown composition and there is no way to know how effective they would be at solving your problem with low-frequency RFI.

Ferrites made by Fair-Rite that use their 75 material are designed to suppress frequencies in the 100 KHz to 10 MHz range. They are available from the following known suppliers:

Fair-Rite 75 material ferrites at Digi-Key

Fair-Rite 75 material ferrites at Mouser

You may be able to use the snap-on types for your interconnects and speaker cables. More difficult problems may require the toroidal type ferrites.

Some technical explanations of how this particular mix compound works:

Fair-Rite 75-material for Low-Frequency EMI Suppression Demystified (PDF)

Fair-Rite 75 Material for Low Frequency Suppression - HF Technology (PDF)

The one con in using these ferrites—they are not cheap.

 

[kyuu]

The one con in using these ferrites—they are not cheap.

Seems pretty cheap? Of course a lot cheaper (per unit) if you order 100, or 1000...

Should work well if it's AM radio that's being picked up, which seems likely.

 

[Holmz]

If you do go with snap-on ferrite cores, place them as close to the chassis as practicable.
The molded one piece cores with a hole thru the center are better, but that ship as sailed.

One can put one on both the plug and the chassis side.
I got the ones that the local electronics place had and they were something $10 for two.

Occasionally I can hear radio through my audio system, as in actual programs and/or songs from radio stations.

Not sure what is causing the interference. But the amplifier seems to be the culprit here, as I already tried turning off all other devices in the chain.

Now… unplug the from the wall… and unplug the RCAs…

The problem still occurs even when the amplifier volume is turned all the way down.

Anyone experienced this before? and any advice on the easiest and cheapest way to fix it?

The ferrites on the amp and maybe the try the speaker cables. You’ll need 3 to start.

If those ameliorate the RF, then start hooking up the rest of the gear..
like plugging in the RCAs first…
Then the power last…
And, do one component at a time…

 

[terryforsythe]

You could, as some have already suggested, place ferrites on the input and output cabling of the amplifier to suppress the RFI. However, the "mix" of the compound that the ferrite is made of will determine how well it works at the frequencies that you wish to suppress. Most of the snap-on ferrites that are sold on Amazon and Ali-Express are of unknown composition and there is no way to know how effective they would be at solving your problem with low-frequency RFI.

Ferrites made by Fair-Rite that use their 75 material are designed to suppress frequencies in the 100 KHz to 10 MHz range. They are available from the following known suppliers:

Fair-Rite 75 material ferrites at Digi-Key

Fair-Rite 75 material ferrites at Mouser

You may be able to use the snap-on types for your interconnects and speaker cables. More difficult problems may require the toroidal type ferrites.

Some technical explanations of how this particular mix compound works:

Fair-Rite 75-material for Low-Frequency EMI Suppression Demystified (PDF)

Fair-Rite 75 Material for Low Frequency Suppression - HF Technology (PDF)

The one con in using these ferrites—they are not cheap.

Snap on ferrites result in a commond mode inductor with a single turn. Depending on how bad is the problem, that may or may not be sufficient. If not, winding the power cord arround a torroidal ferrite core would provide much higher common mode inductance.

Nonetheless, the above potential solution assumes the RFI is coming over the power line directly into the amplifier. It very well may be doing so, but I would first confirm that is the case before spending money.

Also, if the RFI is coming directly into the amplifier over the power line, the next question to ask is why the amplifier's power supply capacitors are not suppressing the noise. It may be the case that the power supply has one or more bad capacitors and/or bad connections. If that is the case, the proper solution would be to fix the amplifier.

 

[Speedskater]

Some Jim Brown (see post #6) papers on chokes & ferrites:

RFI, Ferrites, and Common Mode Chokes For Hams

http://www.audiosystemsgroup.com/RFI-Ham.pdf

RF Interference in Audio Systems

http://www.audiosystemsgroup.com/AES-RFI-SF08.pdf

Understanding How Ferrites Can Prevent and Eliminate RF Interference to Audio Systems (2005)

http://www.audiosystemsgroup.com/SAC0305Ferrites.pdf

Measured Data For HF Ferrite Chokes

http://www.audiosystemsgroup.com/FerriteDataHF.pdf

Coax Chokes on Low Loss Toroids

http://www.audiosystemsgroup.com/Toroid61Data-2.pdf

New Understandings of the Use of Ferrites in the Prevention and Suppression of RF Interference to Audio Systems (2005)

http://www.audiosystemsgroup.com/AESPaperFerritesASGWeb.pdf

 

[Holmz]

Snap on ferrites result in a commond mode inductor with a single turn. Depending on how bad is the problem, that may or may not be sufficient. If not, winding the power cord arround a torroidal ferrite core would provide much higher common mode inductance.

Nonetheless, the above potential solution assumes the RFI is coming over the power line directly into the amplifier. It very well may be doing so, but I would first confirm that is the case before spending money.

How does one confirm that?
It seems like they need a couple of the ferrites or an o-scope to start.

Also, if the RFI is coming directly into the amplifier over the power line, the next question to ask is why the amplifier's power supply capacitors are not suppressing the noise. It may be the case that the power supply has one or more bad capacitors and/or bad connections. If that is the case, the proper solution would be to fix the amplifier.

The power cord, the speaker cord, and all the other source cables.
If we unplug all the sources then we have speaker and power cables.
If there is no RF coming through, then plugging in the sources one by one might shed some light on the subject.

Once one knows where the noise is happening, then the why and the how can be noodled out.