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RF Interference in Speaker Cables??? (video)
- Thread starter amirm
- Start date
solderdude
Grand Contributor
If and when an amplifier can be susceptible to RF depends very much on:
A: frequency of the RF station in question
B: Transmitted power/distance
C: Concrete or wooden house structure
D: modulation type of the RF station
E: speaker cable length and direction it is pointing at.
F: (above all) circuit used
G: Inductor placement in the amp (when present) and Boucherot filtering
H: immunity to RF on all its ports (mains, speaker and inputs)
AFAIK by law the one transmitting is responsible for counter measures against this.
RF chokes can help, some are more efficient in specific frequency ranges.
No more than about 5 'windings' in chokes otherwise capacitive coupling may lower attenuation again.
I don't think a different speaker cable will help, perhaps it can when it is screened or twisted.
all one needs to do in such is a case is lower the RF entering the amplifier far enough so 'AM detection' doesn't happen. It doesn't have to be completely eliminated.
Yes, it does happen that speaker cables can pick up RF and this can lead to hum, noises, radio reception.
Relatively very, very few people will actually have an situation where this happens.
Instruments and vinyl carts will be more susceptible. Back in the days when it was popular to have an electronic organ in the home this was a very common nuisance with all the long wires and inductors inside.
A: frequency of the RF station in question
B: Transmitted power/distance
C: Concrete or wooden house structure
D: modulation type of the RF station
E: speaker cable length and direction it is pointing at.
F: (above all) circuit used
G: Inductor placement in the amp (when present) and Boucherot filtering
H: immunity to RF on all its ports (mains, speaker and inputs)
AFAIK by law the one transmitting is responsible for counter measures against this.
RF chokes can help, some are more efficient in specific frequency ranges.
No more than about 5 'windings' in chokes otherwise capacitive coupling may lower attenuation again.
I don't think a different speaker cable will help, perhaps it can when it is screened or twisted.
all one needs to do in such is a case is lower the RF entering the amplifier far enough so 'AM detection' doesn't happen. It doesn't have to be completely eliminated.
Yes, it does happen that speaker cables can pick up RF and this can lead to hum, noises, radio reception.
Relatively very, very few people will actually have an situation where this happens.
Instruments and vinyl carts will be more susceptible. Back in the days when it was popular to have an electronic organ in the home this was a very common nuisance with all the long wires and inductors inside.
I never made that claim... I'm simply saying that most loyal ASR readers are not the main audience of these videos.
Amir is not attacking Danny, the context is the other way around, Amir is politely responding to an attack by Danny (check out the two videos by Danny). And Amir is forced to answer, because otherwise it would be interpreted that Danny is right with his "theory" (lack of knowledge on the part of ASR and influence of RF on audio reproduction, <20kHz, with normal LS cable).
You can't leave people who want to be informed with the raw measurements, to understand them most lack the basics.
Therefore, it is important that the measured data is also interpreted - in this case by Amir.
The point is to prevent the average Joe from spending his hard earned money on crap due to lack of information and tricky advertising - with the proper information, everyone can decide for themselves.
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From what i've read on this forum, Amir is the type of guy that would make people have multiple seats if they were out of line. hahahahaha
For the first time in my life I feel very lucky, and not in a good way lol.
What would you recommend for people dealing with this issue? Other than to seek out over-priced snake oil.
I've experienced aircraft radio chatter being picked up by a old 1970's Sears Stereo amplifier and when I replaced that with a Technics SU-V303 integrated amplifier the issue went away. We had a ASR member with radio reception occurring with a amplifier he bought new and when he returned that amp and bought a different unit that issue went away. Some amps are susceptible to radio interference and others have a better design and don't. I don't think you have speaker wire issues. I don't think you have RCA wire issues.
The problem disappeared when the cables where 'tucked in' close to the concrete wall behind a bookcase. So it's definitely because my speaker cables are not braided.
My speakers are also a bit more sensitive (93 dB/W) than average.
That does not disprove that the amplifier may have a issue. The symptom being the noise and the apparent cause being the wires when the actual problem is probably the amplifier.
Can you elaborate further on that? Because the amplifier hasn't changed.
Do you mean you changed the amplifier and the issue did not go away?
Another great video. I share a link to these videos in a Facebook group where I am a member.
No, I meant that the issue went away without changing the amplifier.
The moment the cables weren't flailing around in the room like an antenna the issue disappeared, you claimed it could still be the amplifier. How did you arrive to that conclusion?
The amplifier may have poor RF interference rejection capability. By moving the wires you reduced the RF pickup but the issue with the amp is possibly still present. I suggest try a different amp and move your wires about and then you will know if the amp has poor RF rejection. It's the only way you can find out.
So the cables are picking the signals, they're going against the 'flow' to the amplifier, they're getting transformed into the audible range and amplified and back into the speakers?
Wow.
RF energy is pretty neat in it's energy transformations and how it can be filtered out too. Try another amp. It's not magical. With some electron flow principles training and some basic RF fundamentals it becomes more practical and less magical and the wowzer factor is gone. Most situations like yours end with the amplifier being swapped out for something with better RF rejection circuitry. It's really that simple. The wires being part of the symptoms and not part of the cure.
I can imagine a conducted rf susceptibility test on audio equipment where, as one example, you might inject onto the I/O under test (through a line impedance stabilization network) a switched rf signal burst repeating at 1 kHz...and measure the level that burst needs to achieve to start degrading measured SINAD?
That could provide a ‘figure of merit’ in what appears to be an unquantified performance parameter of audio equipment. That said, the test would require very well controlled conditions to be repeatable, and might not be directly comparable for that reason.
It could be an important factor for some, who live in a generally noisier environment, or who have had such problems in the past?
That could provide a ‘figure of merit’ in what appears to be an unquantified performance parameter of audio equipment. That said, the test would require very well controlled conditions to be repeatable, and might not be directly comparable for that reason.
It could be an important factor for some, who live in a generally noisier environment, or who have had such problems in the past?
XGEOX
Member
Please correct me if wrong, but my understanding of Amir's explanation and members' follow-up comments is that speaker cables (when used for their intended purpose) _can_ experience RF noise, but...
- The power is so low as to have zero mechanical effect on the speaker drivers
- The frequencies of any significant RF signals (such as radio stations) are so high as to be far outside of our hearing range (and the speaker driver's range)
- The mobile phone speaker-buzzing phenomenon is a result of a much stronger/closer RF source directly affecting poorly-shielded amplifier components, not RF being 'collected' by the speaker cables
Is that the gist of it?
- The power is so low as to have zero mechanical effect on the speaker drivers
- The frequencies of any significant RF signals (such as radio stations) are so high as to be far outside of our hearing range (and the speaker driver's range)
- The mobile phone speaker-buzzing phenomenon is a result of a much stronger/closer RF source directly affecting poorly-shielded amplifier components, not RF being 'collected' by the speaker cables
Is that the gist of it?
Yes, yes and yes. Correct on all accounts.
Pick up some ferrite cores that either clamp on the speaker lines, or a "donut" ring that you loop the speaker wires through once or twice. That will help suppress RFI from hitting the amplifier's output.
Aside: For power amplifiers, the most common RFI path I have seen is through the speaker cables hitting the internal feedback and bias circuits to be rectified and re-appear as audible noise in the speakers. The output impedance of an audio amplifier is typically high at RF frequencies, not low. The input cables are usually shielded and many (most?) inputs include RFI suppression (often in the form of small capacitors if the input stage itself does not reject it). I have not seen this often, at least not in recent times, but back in the CB craze of the 70's and 80's it was not uncommon to hear "good buddies" coming through the speakers (often due to lousy illegal sweep-tube power amplifiers spraying crap everywhere).
