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RF Interference in Speaker Cables??? (video)

Francis Vaughan

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One error I noticed, maybe someone already pointed it out, but any voltage applied to the output of an amp is reduced by the feedback divider the same amount as the gain of the amp,before it reaches the negative input so you dont need to add that 27db? of gain
I noticed I had quoted this earlier, and somehow forgot to put my commentary in after, as I was replying to more than one post at once. Sorry about that.
What happens with the feedback divider is interesting. At low radio frequencies indeed, the divider will attenuate the signal. But a feedback loop in a conventional power amplifier isn't usually a simple resistive potential divider. It is usual to bypass the resistor between the output and the negative feedback input with a small value capacitor. This helps manage loop stability. Also, unless a DC offset servo is used, the leg of the divider to common will be run though a large value DC blocking capacitor. So, as the frequency increases the first resistor reduces in value as the bypass capacitor starts to dominate (this is why it is there) and the DC blocking capacitor - typically an electrolytic - will start to become inductive. The entire loop will look more and more like a direct connection from output to negative input. Eventually, as the frequency rises even higher nothing looks like what it says on the label, and the most important aspects are just the layout of PC traces. By then most audio use active components will have ceased useful operation anyway, so it won't matter.
 

dreite

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There's nothing wrong with a little RC shunt on the far end of speaker cable to terminate it for above-audio frequencies.
If this sort of RF interference is an issue, that will solve it in most cases.

The hand-waving from folks like Danny Richie on a topic like this is disgusting. But, this is the world of audiophiles.

Dave.
 

Bruce Morgen

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Tinned wire ends should not be used with screw terminals. The soft solder deforms over time, leaving a loose connection
That doesn't happen to any significant extent -- at least in my experience -- with modern lead-free solder, which is why I recommend it rather than the traditional and easier-to-work-with 60/40 stuff for this particular application.
 
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amirm

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Thread Starter #187
Anyone ever measure the effectiveness of all the various speaker cables connectors?
I have to limited extent. When I was testing the Benchmark AHB2 amplifier, it is so low in distortion that the connector made a difference. Best was SpeakOn because internally it had the shortest path. Next was locking, solid bras banana plugs which I use to this day. Others cost a bit in distortion (nothing audible though).
 

B4ICU

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It seems that some smart (alike) site users tend to lean on breadcrumbs, at the time they have no idea what the bread dough is made from.
Nutrik plugs (how many speakers or Amps can use it?) or crimping over soldering the wire ends...
What about the cable?
You got a speaker, and Amp. and it need a distance to be placed at. What #AWG should that cable be?
Most doesn't get down to this resolution. A speaker cable is picked randomly, with no particular "know how". Says as: "Get me 20' of that wire pool at home depot", or I'll knock myself out with a "branded extra expensive" cable. Like stating, if they are branded and cost that much, it must be good.
Well, none of that is the reason to pick this cable over another.
What you should be looking at, is the cross section, that should be meticulously calculated vs. DF and length.
Any other method is a long shot in the dark. You spend "Big" money in the system and than go so wrong with the speaker cable, just because
of ignorance? Would you do the same with an eye or heart surgery?
Unfortunately, the cables industry is happy to keep things going as they do now. They enjoy nice profit and plenty of ignorance.
Go play the game and open your wallets. You do not buy good cables, but donate your hard earned coins to a "Mafia like" industry.
 

respice finem

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Cable choices for the amateur are different, and not really based on any technical parameters. Some of my friends have hardly chosen their speaker cables at all (just took what the salesman recommended / had in stock) or chose by... looks. Somehow, a big fat cable looks more "serious" than a "doorbell wire". That said, for home use, with 2-3 m distance from the amp, anything will do. The popular 4mm2 are "overkill" already, I'm still using my old stuff from the 80s and 90s (because why not). For my living room "cinema" I needed 15m extra and bought this https://www.amazon.de/gp/product/B01LFAAI00/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 but not because of "needing" 4mm2, but because this fits the bananas. :D
 

mansr

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I have to limited extent. When I was testing the Benchmark AHB2 amplifier, it is so low in distortion that the connector made a difference. Best was SpeakOn because internally it had the shortest path. Next was locking, solid bras banana plugs which I use to this day. Others cost a bit in distortion (nothing audible though).
How does a connector cause distortion?
 

ezra_s

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Let me say it again, great video. For me to watch an educational video twice, knowing how lazy I am... then it must be good.
 

tomchr

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How does a connector cause distortion?
In case of the AHB-2, it may not be the connector that causes the distortion. It is more likely to be the PCB routing to the connector that adds distortion.

I've only ever had connectors cause distortion when they don't make good contact. I've seen that quite a bit with banana connectors, actually. I use some low-cost banana jacks for prototypes and they do sometimes oxidize enough that the distortion rises by as much as 20 dB. I then grumble, twist the banana plugs in their sockets, and remeasure. That said, I'm building amps at the same performance level as the AHB-2, so these things start to matter.
I've never seen a speakON connector cause distortion.

I don't know the specific distortion mechanism in crappy connectors, but I suspect it has to do with the spreading resistance from a limited number of good connection points to the connector terminal or wire.

Tom
 
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amirm

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Thread Starter #195
How does a connector cause distortion?
I haven't examined the mechanism but I am assuming its resistance is modulating with voltage and that caused distortion (at these very small levels). I have often found distortion changing by rotating cheaper banana plugs.
 

amm

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I haven't examined the mechanism but I am assuming its resistance is modulating with voltage and that caused distortion (at these very small levels). I have often found distortion changing by rotating cheaper banana plugs.
Hello, my first post here. You are correct, the phenomena is likely due to passive intermodulation (PIM)
For example please see "passive inermodulation causes" in:
https://www.electronics-notes.com/a...rmodulation-pim/what-is-pim-basics-primer.php
and on the nonlinear analysis of PIM:
http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1210&context=nanopub

My name is also Amir!
 

chris719

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Hello, my first post here. You are correct, the phenomena is likely due to passive intermodulation (PIM)
For example please see "passive inermodulation causes" in:
https://www.electronics-notes.com/a...rmodulation-pim/what-is-pim-basics-primer.php
and on the nonlinear analysis of PIM:
http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1210&context=nanopub

My name is also Amir!
I have seen this happen firsthand at RF, but I'm not sure this is what's going on at audio frequencies.
 

solderdude

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I haven't examined the mechanism but I am assuming its resistance is modulating with voltage and that caused distortion (at these very small levels). I have often found distortion changing by rotating cheaper banana plugs.
I have some older banana plugs with some measuring cords running to a Fluke for measuring DC values of a specific product (not audio) and have found that you can get substantially different voltages (and there isn't even a load by the Fluke) up to 50%.
This is annoying when you are measuring small voltage differences. Tapping or rotating the banana plug makes it go away.
Replacing it or (for temp solution) flooding it with deoxit solves the issue.
Banana plugs can be a crapshoot.
 
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