RF Interference in Speaker Cables??? (video)

[uwotm8]

We won't hear 100 MHz, but RF can enter audio circuits via cables and get demodulated. It can result in offset shifts in opamps, for example

Well, this is too hard for majority of audience, way more complicated than just UHH DUMB PHILES WE DON'T HEAR 100Ghz.
(Btw, I can't remind any shielded "audiophile" speaker cable - there's no need of shielding on that end as you mentioned).

 

[phoenixsong]

When I rest my handphone directly on a cheap mic cable, there was a buzzing sound picked up. However, there was absolutely no detectable noise when I tried the same with a balanced starquad cable I had at that time

 

[GGroch]

....I'm sorry to say I see no point in those videos.
..... What's the use ?

The use is quite clear: reaching out to an audience that would not otherwise be exposed to ASR's scientific perspective. There is considerable discussion of the efficacy of this on the ASR thread concerning Danny's video that inspired Amir's video. Some posters questioned whether Danny's video should be a thread topic here. Others whether it is worthy of response.

My view: One of the biggest problems with determining truth today is that the vast majority of us live in information silos. People only see information from sources that they already agree with. The ASR YouTube channel reaches a new audience most of whom either do not know we exist, or would never normally visit a text intensive forum.

I further feel that posting Danny Et Al. audio influencer video threads here is a good thing. They can challenge ASR members to re-examine our beliefs, sharpen our arguments, and gain insight into what YouTube audio influencers are saying outside of ASR.

Danny may have felt safe in attacking ASR as "Flat Earthers" who ....."do no real science over there. They are just a propaganda machine for their belief system." because he did not expect a YouTube response from ASR. I am glad he got one that was reasoned, not an attack.

 

[GGroch]

When I rest my handphone directly on a cheap mic cable, there was a buzzing sound picked up. However, there was absolutely no detectable noise when I tried the same with a balanced starquad cable I had at that time

In the video Amir points out that RF interference is indeed a concern with mic cables.

 

[solderdude]

What would you recommend for people dealing with this issue?

Find out if the radio station coming through is nearby.
Disconnect all devices from the amplifier and connect 1 speaker.
Then add another speaker.
Find out if this is what's causing it if it starts to happen when connecting another device to the amp.
Maybe loan/borrow another amplifier see if that helps.
Then resort to cable clamp ferrites (with big hole so the cable can be run through a few times), locate that as close as possible to the amp output.
When that doesn't help you can put a common mode choke (2x 1uH) in series with the cable.
When that doesn't help connect 1nF capacitors in series with a 4.7 Ohm between the + output to the metal chassis and - output to the metal chassis (also when the - is connected to ground) combined with the common mode choke.
When this doesn't help use a screened cable and connect the screen to the amp chassis.
When all of this fails try to route cables and locate the amp at a different spot.
After that buy another amp, one that can be returned if that too doesn't help.

Be methodical.

 

[Vini darko]

The video seems to clearly show rf being picked up by speaker wires. Danny's primary claim that braided speaker wire will reject this and make for more robost transmission isn't even tested in your measuing setup. I get the feeling this video may have the opposite of intended effect. Never mind that voice coil inductance and massive heat sinking combined with suspension resistance means rf just evaporates like a tear in a firestorm. Fortunately all my gear has cap coupled inputs anayway and all my wires are shielded too.

 

[Doodski]

Never mind that voice coil inductance and massive heat sinking combined with suspension resistance means rf just evaporates like a tear in a firestorm.

Yes, I was thinking this is part of the actual circuit versus the virtual circuit. The speaker load needed to be represented too. That should further shunt RF energy.

 

[milosz]

#23: But, even in that extreme scenario, would a different speaker cable have saved the woofer?

Yes- one that did not conduct any electricity.

My point had nothing to do with the nonsense about RF on speaker cables but I wanted to raise the point that RFI IS a real thing under certain conditions.

 

[pma]

Local AM radio stations measured on a connected speaker cable, voltage axis calibrated.

 

[Klint]

Thanks @amirm
Keep on educating me so that i know where to put my money and enjoy music listening.
The main thing is the measurements and the conclusion.

 

[respice finem]

Local AM radio stations measured on a connected speaker cable, voltage axis calibrated.

View attachment 113535

Not surprising, but "miles" above hearing range / speaker FR, unless demodulated in the amp somehow.

 

[eddantes]

I used to have hedges. I would trim said hedges. Occasionally, I'd also trim the extension cord. I'd then add banana plugs to said extension cord and use it as speaker wire. <kidding> Am I unwittingly injecting 60hz tones into my music? </kidding>

 

[KMN]

RFI energy injected in through speaker cables terminated by normal audio gear....probably not so interesting in most cases.

Unwanted audible band noise problems, due to EMI, such as that annoying humming sound? ....Now there is an interesting topic. Who hasn't battled that demon at some point?

 

[mansr]

I don't know how I got dragged into this but thought I do a video showing the proper effects of RF on speaker cables and what it takes to demonstrate audibility. I thought it needed to be done even though I did not want to engage in any tit for tat type of videos.

Nice scope, looks just like mine. I've found the spectrum analyser a bit limited, however. To get better resolution (and generally more choices), I've captured the sample buffer from the normal inputs into Matlab and processed it there. That way it's also possible to use any TekVPI probe without needing the ridiculously expensive TPA-N-VPI adapter.

 

[Deleted member 2944]

Amir,

You can't get anywhere with this guy.....nor his followers.
You've now played into his hands and he'll co-opt your effort and integrate it into his selling shtick.

Very disappointing.

Dave.

 

[jbrown]

@amirm Have you ever thought of trying to quantify if any aspects of speaker cable design DO make a difference? AWG? Capacitance? Inductance? Length? Twisted conductors vs parallel? Maybe measure the same speaker/amp combo multiple different ways with only the speaker cable changing?

 

[the_brunx]

Great Video, Great explanation.

 

[KTN46]

Local AM radio stations measured on a connected speaker cable, voltage axis calibrated.

You've just made me spend 10 minutes sticking my ear up to my speaker. I live really close to an AM radio station. My friend had an issue with his Schiit Fulla where the amp was playing the signal through his microphone, but through my mic and speakers I hear nothing. I use rando cables too. I wonder what the physical difference is that makes some gear more susceptible to demodulating AM signals than others.

 

[kejar31]

Great video and very well explained!

 

[PeteL]

When I rest my handphone directly on a cheap mic cable, there was a buzzing sound picked up. However, there was absolutely no detectable noise when I tried the same with a balanced starquad cable I had at that time

Is there such thing as an unbalanced mic cable? Define cheap?