Marantz SR7015 Radio Interference from Radio Station

Dem

Active Member
Just bought and installed a Marantz SR7015, replacing my Onkyo TX-NR616, with no other system set up changes. Immediately, during initial AVR setup, I could hear some kind of music coming through the speakers. I listened carefully to hear what it was and eventually worked out that it's "Lyca Radio on 1458AM and DAB".....(a London based radio station, I've since discovered). I never had this type of radio interference before on the old Onkyo AVR. Neither have I experienced this on an Onkyo TX-NR656 in another room in the house, nor with a DENON AVR in the cinema room.

For reference though, I have heard this same radio station being picked up on my PC Logitech speakers much more faintly, which are in a completely different part of the house.

I've disconnected all of the inputs to the Marantz AVR (HDMI) and the output to the TV (HDMI), but nothing stops this radio station coming through all 5 of the surround system speakers (my sub has stopped working, so can't judge if it's interfering with that). This radio station being picked up is loud enough to be heard even when playing an input source through the speakers, to the point where I can't use this AVR.

Ordinarily, I wouldn't blame the amp, but given the previous one (Onkyo) didn't suffer from this, nor the other two AVRs in the house, I am wondering if it could be faulty?

I moved the mains plug to a different wall socket about a meter away from the original, but no change. Only powering off the AVR stops the radio station playing through the speakers.

I could buy a ferrite core to put around the mains lead, but is that really likely to be effective?

Appreciate any thoughts on this.
 

jwlawler

Active Member
This is a familiar problem from the old days but quite surprising today. I have more often heard guitarists complaining that their amps were picking up radio stations. It will be the AM broadcast that you are picking up. Your amp won't be inadvertently decoding a DAB broadcast but AM decoding is simple and sometimes occurs inadvertently. Tracking it down and solving it can be a challenge. The first step is to try to determine which component or stage is responsible. Does the selected input affect it? In particular, is it worse when an analogue input is selected? Does the volume affect it? Do you have a turntable? These are more likely to accidentally pick up radio.

Here's an odd thing to try. Are your cables longer than they need to be? Is the spare length neatly coiled up? If so, it might be inadvertently acting as an aerial. Oddly, a random mess is better or, of course, trim them so there is no excess length.

Also, check that your connections are clean and firm. Are any of your plugs, particularly analogue source inputs, loose, dirty, or corroded? Try unplugging and replugging. Try swapping inputs around (be careful if you have a turntable).

Try moving house. Of course, that's a joke but if you could move the amp, it might help diagnose the problem. Another room if possible, better still another floor. Many houses use one mains ring per floor. Even better bring it to a friend's house (a problem during lock down).
 

jwlawler

Active Member
Reading your post again, I see that you have tried disconnecting all inputs. Unfortunately, this pretty much rules out the most likely and most easily fixed explanations. It's still worth trying playing with the inputs as an empty analogue socket could pick up a strong signal. Select a digital input, e.g. a BluRay player, with a connected but inactive device.

If the explanation is not in a source then it may be inside the AVR. I can think of two possible explanations. A bad connection within the amp. Similar to but not as easily fixable as a bad external connection. Another is that an internal component is inadvertently acting as an aerial. Similar to my coiled spare cable idea but, again, not so easily fixable. You may be able to diagnose this by rotating the amp. Put it on the floor and rotate it by 30, 60, and 90 degrees. For the loose connection, you could pick it and shake it but that is more likely to make things worse so I do not recommend that.

If it is new from a reputable dealer then I would talk to them. If the dealer is local then they may know of the issue.
 

CaptainJames

Well-known Member
OP also said that he picks up this radio station on his PC speakers elsewhere in the house. In which case, why assume the AVR is faulty? It has no bearing on your PC speakers!

Sounds more like either a mains problem or possibly a speaker cable issue. What speaker cables are you using, how old, and how long are they? Could you test a neighbour's mains perhaps by running an extension cable into their house?
 

Rodders53

Distinguished Member
Where are you located? Lyca 1458 kHz is transmitted from Brookmans Park at 125 kW effective maximum radiated power.

If close enough to an AM transmitter things can be difficult to eradicate. Back in the days when BBC owned/operated that site the maintenance engineers would occasionally go out, locally, to resolve interference as a 'good neighbour' thing.

Arqiva now own and operate the transmitter site but any help would need to be requested via the radio station Lyca Lyca Radio | Home i.e. complain to them about the problem.

Both the Onkyo and Marantz units are 'double insulated' and have no 'ground/earth' to the metal case screening.

It might be worth trying a wire from a known good earth point on to the AVR case to see if that helps?

AM transmissions just need a simple rectifier (e.g. a diode or dry solder joint) to be decoded; so can be difficult to track down where and why it's happening in strong signal areas.

Ultimately the RTIS The Investigation Process | RTIS and/or Ofcom Troubleshooting interference may get involved, if the issue is widespread locally? Certainly check if your neighbours are having problems.
 

jwlawler

Active Member
OP also said that he picks up this radio station on his PC speakers elsewhere in the house. In which case, why assume the AVR is faulty? It has no bearing on your PC speakers!

Sounds more like either a mains problem or possibly a speaker cable issue. What speaker cables are you using, how old, and how long are they? Could you test a neighbour's mains perhaps by running an extension cable into their house?

Not necessarily faulty but sensitive to interference. Swapping the Onkyo with the Marantz introduced the problem which points a finger at the Marantz.

Either problem, the Marantz or the PC speakers, indicates that this radio signal is particularly strong in his area. I guess that he is near the transmitter or some odd quirk is concentrating the signal near him. That the PC speakers pick up the interference, particularly if they are active ones, is less surprising. That a good AVR is picking it up is more surprising and disappointing.

I suggested checking his cables. Indeed the speakers cables are a candidate but, supposing that the speakers connected to his Marantz are quite large, it is more surprising that the interference is strong enough to pick up an audible signal.
 

jwlawler

Active Member
Where are you located? Lyca 1458 kHz is transmitted from Brookmans Park at 125 kW effective maximum radiated power.

If close enough to an AM transmitter things can be difficult to eradicate. Back in the days when BBC owned/operated that site the maintenance engineers would occasionally go out, locally, to resolve interference as a 'good neighbour' thing.

Arqiva now own and operate the transmitter site but any help would need to be requested via the radio station Lyca Lyca Radio | Home i.e. complain to them about the problem.

Both the Onkyo and Marantz units are 'double insulated' and have no 'ground/earth' to the metal case screening.

It might be worth trying a wire from a known good earth point on to the AVR case to see if that helps?

AM transmissions just need a simple rectifier (e.g. a diode or dry solder joint) to be decoded; so can be difficult to track down where and why it's happening in strong signal areas.

Ultimately the RTIS The Investigation Process | RTIS and/or Ofcom Troubleshooting interference may get involved, if the issue is widespread locally? Certainly check if your neighbours are having problems.

Good advice.
 

Dem

Active Member
Thanks for everyone's replies; much appreciated!
@Rodders53 You're spot on with that information. I live across the road from the Brookmans Park transmitter unfortunately, about 400m as the crow flies. Really appreciate your points about options to complain. In terms of grounding, I do wonder if there is a problem in the house as from some power sockets, capacitive features of devices can be sketchy. i.e. if a mobile phone is plugged in, the screen is less reactive, similarly with a laptop scratch pad if plugged into the mains (but this is not in all cases). In terms of improving grounding for the mains, is there anything I can do at least for the power to the Marantz AVR? Would a ferrite core around the mains lead (or a different mains lead?) make any difference?

@jwlawler As you mentioned, straight swap for the Onkyo unit, so does suggest that the Marantz is substantially less resilient to RFI than that 10 year old AVR! Also, the other Onkyo AVR and a Denon AVR still running in the house do not suffer with this.

The speaker cables are buried in the wall (except for the centre speaker one). They were installed when the room (part of an extension) was built, and they are 'builder spec' cables......so nothing fancy. Also, there are no analogue inputs (no turntable etc.), just a Sky Minibox, PS4 and a Samsung Blu-Ray player.

I will try to move the AVR to another room and attach only the centre speaker to see if it picks up anything. Will let you know what this does.

Overall though, I can't help but think that this new Marantz amp isn't robust enough when the previous amp was fine! So, is it worth calling Richer Sounds up and telling them that it may be faulty?
 

Dem

Active Member
OP also said that he picks up this radio station on his PC speakers elsewhere in the house. In which case, why assume the AVR is faulty? It has no bearing on your PC speakers!

Sounds more like either a mains problem or possibly a speaker cable issue. What speaker cables are you using, how old, and how long are they? Could you test a neighbour's mains perhaps by running an extension cable into their house?
Well, we can't deny that the old Onkyo and two other AVRs in the house don't suffer from this problem; only this new Marantz. It's a question of what is a reasonable level of RFI protection? Of course, can always go round in circles on the topic of reasonable robustness...) For the PC Speakers, I wouldn't expect too much, but for this specification of new AVR? I'd expect better.....
 

CaptainJames

Well-known Member
Thanks for everyone's replies; much appreciated!
@Rodders53 You're spot on with that information. I live across the road from the Brookmans Park transmitter unfortunately, about 400m as the crow flies.
You might have mentioned that in your original post.... :p
 

jwlawler

Active Member
400m is very close to a powerful transmitter. I am now less surprised that the Marantz and your PC speakers are affected than that the others aren't. It is certainly worth talking to Richer Sounds but you might need to rely on good will for a refund or exchange than a claim that it is faulty. I don't know whether there is a standard for resistance to external interference but, even if it there was, it would not prove that then Marantz is faulty; you would need some expert advice. Maybe the Marantz just about qualifies but the others more than qualify. Think of cars, all should pass standardized safety tests but that does not mean that all are equally safe.

If a refund or exchange is not possible then you could continue to experiment with shielding or playing with the location. You could research Faraday cages. Also, try my suggestion of rotating it. If some internal component is acting as an aerial then it may pick up more in some orientations than others.

If you can't beat them then join them. Deliberately tune in and listen the station. When you want a specific piece of music, call them and request it. It might not work for movies though: please play the complete soundtrack to The Matrix.

There are other solutions but not all are legal.
 

jwlawler

Active Member
One more question. Is the Marantz considerably lighter than the Onkyo? I don't know either model. I used to have an Onkyo 605 and it was a big heavy beast. My current Denon X3200W is a little smaller and lighter but not much. Maybe newer models are even lighter.

In many ways, lighter is good but a good heavy case could be an effective shield.
 

CaptainJames

Well-known Member
I would also be a bit concerned about what those speaker cables are picking up - if they were chosen by a builder, chances are that the shielding is pretty ropey..........
 

Dem

Active Member
You might have mentioned that in your original post.... :p
I know what you mean, but given that no other AVR in the house has suffered....
400m is very close to a powerful transmitter. I am now less surprised that the Marantz and your PC speakers are affected than that the others aren't. It is certainly worth talking to Richer Sounds but you might need to rely on good will for a refund or exchange than a claim that it is faulty. I don't know whether there is a standard for resistance to external interference but, even if it there was, it would not prove that then Marantz is faulty; you would need some expert advice. Maybe the Marantz just about qualifies but the others more than qualify. Think of cars, all should pass standardized safety tests but that does not mean that all are equally safe.

If a refund or exchange is not possible then you could continue to experiment with shielding or playing with the location. You could research Faraday cages. Also, try my suggestion of rotating it. If some internal component is acting as an aerial then it may pick up more in some orientations than others.

If you can't beat them then join them. Deliberately tune in and listen the station. When you want a specific piece of music, call them and request it. It might not work for movies though: please play the complete soundtrack to The Matrix.

There are other solutions but not all are legal.

400m is very close to a powerful transmitter. I am now less surprised that the Marantz and your PC speakers are affected than that the others aren't. It is certainly worth talking to Richer Sounds but you might need to rely on good will for a refund or exchange than a claim that it is faulty. I don't know whether there is a standard for resistance to external interference but, even if it there was, it would not prove that then Marantz is faulty; you would need some expert advice. Maybe the Marantz just about qualifies but the others more than qualify. Think of cars, all should pass standardized safety tests but that does not mean that all are equally safe.

If a refund or exchange is not possible then you could continue to experiment with shielding or playing with the location. You could research Faraday cages. Also, try my suggestion of rotating it. If some internal component is acting as an aerial then it may pick up more in some orientations than others.

If you can't beat them then join them. Deliberately tune in and listen the station. When you want a specific piece of music, call them and request it. It might not work for movies though: please play the complete soundtrack to The Matrix.

There are other solutions but not all are legal.
Ref the car analogy, I work in the automotive industry so agree with you on this. I won't mention the number of times an OEM will eventually get to a "well, it's clearly not robust enough, even if it meets our specification....." argument..... I'm really not looking to get a refund as prefer for to find a way to make it work. I just can't avoid the normal problem solving technique of "what's changed?". Oh, that'll be the amp..... Question is, i it a faulty unit or, is it just less robust to RFI than other brands. I'll keep playing about to see if I can narrow down the biggest influence to it. Strangely, the radio station interfernce noise last night was much louder than today; wonder if they'd cranked the Bhangra up for Saturday night? I would tune into it except this AVR doesn't have a tuner! (well, not specified one.... 🤣).
 

CaptainJames

Well-known Member
I know what you mean, but given that no other AVR in the house has suffered....
I'm only surprised your brain isn't fried to be honest......I'm not one for 5G mast conspiracy theories, but I wouldn't fancy living that close to a transmitter!
 

Dem

Active Member
I would also be a bit concerned about what those speaker cables are picking up - if they were chosen by a builder, chances are that the shielding is pretty ropey..........
No doubt its not the best, but again, absolutely fine with the Onkyo. Plus, when I only have the centre speaker connected with 30cm of speaker cable, the intereterfere is there.

Wait a minute though, the cable is branded. Never heard of "+0 26M" though.... 😜
P_20210131_164435.jpg
 

jwlawler

Active Member
I think that we can rule out the speaker cable now. You are just too close to the transmitter and you have been lucky that some of your devices have managed to cope.
 

Rodders53

Distinguished Member
I'd suggest that the
I'm only surprised your brain isn't fried to be honest.....
This is MF radio we're talking about. The dangerous areas are securely fenced off and have warning signs on them.

The mobile in your hand next to your ear is more dangerous to your health than anything emitted from a transmitter in areas that the public can access.

Speaker wires are rarely (if ever?) shielded / screened and amplifiers have no means of dealing with a braided screen, do they?

Well, we can't deny that the old Onkyo and two other AVRs in the house don't suffer from this problem; only this new Marantz.
Yep. A lack of Electromagnetic Compatibility (EMC) is the issue with the Marantz.

I'd try adding a single core wire to the 'signal ground' screw on the rear and touching that to a know earth (e.g. a screw on a mains socket faceplate) to see if that helps at all? Also try a different mains cable from the supplied? A 3-core IEC lead as used for a computer will fit (although only L & N are used, of course).

AM interference correction isn't my speciality, I'm afraid (we left that to the transmitting team engineers). Inductors on the cables, by making coils through a ferrite core, might help or do nothing useful.

I'd certainly talk to Richer Sounds to see what they can offer in the way of help on this unusual problem. They have a presence on the forum.

It may be worth asking Lyca Radio if their engineers could talk to Arqiva's engineers to provide some suggestions to remedy the issue?
 

Dem

Active Member
I think that we can rule out the speaker cable now. You are just too close to the transmitter and you have been lucky that some of your devices have managed to cope.
Bizarrely, my crappy PC Logitech speakers are not picking up Radio Lyca right now, but the Marantz is. What ever happened to "you buy cheap, you buy twice....."? lol
 

Dem

Active Member
I'd suggest that the

This is MF radio we're talking about. The dangerous areas are securely fenced off and have warning signs on them.

The mobile in your hand next to your ear is more dangerous to your health than anything emitted from a transmitter in areas that the public can access.

Speaker wires are rarely (if ever?) shielded / screened and amplifiers have no means of dealing with a braided screen, do they?


Yep. A lack of Electromagnetic Compatibility (EMC) is the issue with the Marantz.

I'd try adding a single core wire to the 'signal ground' screw on the rear and touching that to a know earth (e.g. a screw on a mains socket faceplate) to see if that helps at all? Also try a different mains cable from the supplied? A 3-core IEC lead as used for a computer will fit (although only L & N are used, of course).

AM interference correction isn't my speciality, I'm afraid (we left that to the transmitting team engineers). Inductors on the cables, by making coils through a ferrite core, might help or do nothing useful.

I'd certainly talk to Richer Sounds to see what they can offer in the way of help on this unusual problem. They have a presence on the forum.

It may be worth asking Lyca Radio if their engineers could talk to Arqiva's engineers to provide some suggestions to remedy the issue?
Thanks again for your input on this. I actually tried the 3 pin lead from my Mordaunt-Short subwoofer, but that made no difference. I'll look for that signal ground screw on the rear of the AVR and see if I can attach it to the mains socket faceplate cover screw.

I will also give Richer Sounds a call, but I would imagine they are likely to blame the transmitter....

Is where I've highlighted on the picture attached the correct place to connect to? It states "SIGNAL GND"
Marantz SR7015 - Rear View.jpg


Cheers,

Dem
 

jwlawler

Active Member
Thanks again for your input on this. I actually tried the 3 pin lead from my Mordaunt-Short subwoofer, but that made no difference. I'll look for that signal ground screw on the rear of the AVR and see if I can attach it to the mains socket faceplate cover screw.

I will also give Richer Sounds a call, but I would imagine they are likely to blame the transmitter....

Is where I've highlighted on the picture attached the correct place to connect to? It states "SIGNAL GND"View attachment 1452193

Cheers,

Dem

Advice from Marantz or Richer Sounds would best but, in the absence of another ground connection, this is worth trying. You do not want to doubly earth audio equipment or you might get a dreaded earth / ground look and pick up a main frequency hum.
 

jwlawler

Active Member
Bizarrely, my crappy PC Logitech speakers are not picking up Radio Lyca right now, but the Marantz is. What ever happened to "you buy cheap, you buy twice....."? lol

Have you moved them? This type of interference can be quite sensitive to location and orientation. Are you old enough to remember playing around with old transistor radios trying to pick up a weak station? This is similar except that you are trying to avoid picking up the station.

Are they active speakers, are they powered? I guess so as active speakers will be more susceptible. See below.
Speaker wires are rarely (if ever?) shielded / screened and amplifiers have no means of dealing with a braided screen, do they?

Speaker wires don't normally require shielding. 8 Ohms is a very low impedance for an RF signal, pretty much a short circuit. If the speaker is being fed 8W then the amp will be outputting 8V and 1A RMS. It would be a heck of a radio signal to show up against that. Of course, the OP might have that heck of a radio signal.

On the contrary, an analogue line level signal might be only 0.5V and the amplifier's input will be very high impedance and will only need a tiny current. Radio interference can be significant hence the universal shielding of analogue line level signals. Phono stages for turntables will be even more sensitive and the cartridge's coil can pick up interference,

If the OP could find or jury rig some shielded cable for his centre speaker then it would be interesting. If this solved the problem then it would confirm the problem. I would not bet on this though.

Now that we know how close the transmitter is, I am betting on some internal component picking up the interference, It is just luck that the Onkyo did not.
 
Last edited:

gibbsy

Moderator
I'm only surprised your brain isn't fried to be honest......I'm not one for 5G mast conspiracy theories, but I wouldn't fancy living that close to a transmitter!
Ha ha! I've got that one covered.

signs_foil_hat-thumb-550x373-179961.jpg
 

Rodders53

Distinguished Member
Yes that's the ground terminal I was suggesting you use.

Metalwork on a double-insulated item is not connected to a proper ground/earth is it? So temporarily connecting it to the home earth may prove (or disprove) something wrt the screening effect with a 'proper earth'?

Only if it 'fixes' the pickup issue will it need considering as a permanent solution. Even then the dreaded earth loop hum may not happen.

My gut is saying that the AM transmitter is getting in at around the DSP-analogue output stage, or power amp inputs... especially if Lyca is a fixed level as I'm inferring from the first post description.
So something is getting past the chassis/case screening and into the box?
It may be the AVR is faulty (mis-assembled) or just poorly designed and not immune enough to the legal transmitted signal?

The 1458 kHz transmitter wavelength is roughly 205 metres, 1/2 wave 102 m, 1/4 51 m so bits of wire need to be long to be a proper match (or coils of wire around a magnetic core as in AM radios).
 

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