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Post by aceinc on May 3, 2021 22:12:43 GMT
I have watched Ethan's video on his Null Tester. It all seems reasonable to me. During the video Ethan was quite careful not to have the wires come close to any source of EMI. This then begs the question "How much of an impact does EMI have on various interconnects?"
For example, running a 50' standard unbalanced cable inside a conduit with a 240v pair used to power an A/C unit may be expected to "inject" a signal into the unbalanced cable which is audible. I realize this is an extreme example, but it illustrates a point.
My question becomes can induced signal issues be ameliorated by the design of the cable?
Is this required? I saw a video where a person demonstrated how "zip" cord makes a good antenna for FM radio as proof that zip cord does not make good speaker cable. Yes I know FM is outside of the audible range, but other EMI which may be present is not.
For example, for a speaker cable, could I take two 23 awg CAT 6 wires (tightly twisted) connect all of the white/color wires together and all of the solid color wires together and end up with a cable which would filter out most audible EMI?
Or am I chasing down the wrong rabbit hole?
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Post by rock on May 4, 2021 0:09:07 GMT
No, You're not "chasing down the wrong rabbit hole", you're just learning the reality of EMI interference. This is really basic stuff we all learn one way or the other. I studied electronics after high school to get a job but lots of people learn by doing or trial and error... that's OK too. You wrote "My question becomes can induced signal issues be ameliorated by the design of the cable?" The short answer is YES but there's more to it. It's kind of a big subject so I'll look for a link for you...OK I'm back... here's the first link I stumbled across: www.dataforth.com/protecting-signal-lines-against-electromagnetic-interference.aspxHere's another: www.analog.com/media/en/training-seminars/tutorials/MT-095.pdfRead these and if you have more questions, please ask. Cheers, Rock |
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Post by aceinc on May 4, 2021 2:09:58 GMT
No, You're not "chasing down the wrong rabbit hole", you're just learning the reality of EMI interference. This is really basic stuff we all learn one way or the other. I studied electronics after high school to get a job but lots of people learn by doing or trial and error... that's OK too. You wrote "My question becomes can induced signal issues be ameliorated by the design of the cable?" The short answer is YES but there's more to it. It's kind of a big subject so I'll look for a link for you...OK I'm back... here's the first link I stumbled across: www.dataforth.com/protecting-signal-lines-against-electromagnetic-interference.aspxHere's another: www.analog.com/media/en/training-seminars/tutorials/MT-095.pdfRead these and if you have more questions, please ask. Cheers, Rock Rock: I read portions of both articles. Based on what I read the approach I mentioned in my original post, to use CAT 6 cable and fabricate my own speaker wires would have a benefit in regards to magnetic EMI, due to the high number of twists per foot in CAT 6 cable. Shielding and grounding seems to be the preferred method to filter capacitive EMI/RFI. Does twisted pairs provide any benefit in regards to capacitive interference? Is capacitive interference something I need to be concerned about in a 30' speaker run? One scenario I have is in my living/listening room I have wall plates behind my equipment cabinet. These wall plates have 12 gauge zip cord running behind the shoe molding along the floor to wall plates for my rear and surround speakers which range in length from 30'-40'. Additionally My fronts use the same approach with 8'-10' distance. For varying distances all of these wires run parallel to each other and are touching. I also have low cost 12 gauge Monoprice "speaker wire" running to my height speakers in the ceiling. At some point in the not too distant future I may have the opportunity to replace this wiring during a remodel and I am curious as to what benefits I may be able to gain. |
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Post by rock on May 4, 2021 3:31:16 GMT
One thing we need to clarify: Are the cables you are interested in and talking about just speaker cables? If not, what other audio signal levels are you running through your cables. The type of signal (level and impedance) and length of run will determine the type of cable that will work satisfactorily. (note I did not say "work best" as that could lead us down the proverbial "rabbit hole"  |
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Post by aceinc on May 4, 2021 20:26:15 GMT
My interconnects at present are 1 meter XLR between the sound processor/Amplifiers, RCA to 1/8" jack -> wireless for subs and between the other devices everything is HDMI. Generally I am a digital kind of guy.
I do need to clean up a rats nest behind my equipment and route all the HV wires away from the LV wires. Make sure all my speaker patch cables are appropriately sized, and perhaps fabricate new ones if there would be an advantage to a different wire topology.
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Post by Hexspa on May 4, 2021 21:16:11 GMT
I'm not sure I fully understand what you two are discussing. In any case, make sure audio cables are perpendicular to other cables and your problems should be minimal. Also, I think star quad cables offer better rejection for long runs.
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Post by rock on May 4, 2021 21:35:08 GMT
I'm not sure I fully understand what you two are discussing. Actually, that's what I'm trying to figure out myself! If I had to guess, it's seems like the OP want's to discuss hypothetical scenarios which may cause specific problems. If that's the case, but they don't have any actual interference problems, I say: If it ain't broke, don't fix it. On the other hand, if you do have actual problems, we'll try to help. |
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Post by aceinc on May 4, 2021 21:57:43 GMT
I'm not sure I fully understand what you two are discussing. In any case, make sure audio cables are perpendicular to other cables and your problems should be minimal. Also, I think star quad cables offer better rejection for long runs. It started off hypothetical and Rock had me read some technical links which I briefed. The hypothetical question when distilled is, "How much attention needs to be paid to protecting cables from signal injection?" The follow on is, "What are the best designs to reject signal injection?" I then went from the hypothetical to some of the cabling issues I have which, if you ignore my rats nest of interconnects, are mainly long "in wall" speaker cable runs. |
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Post by rock on May 5, 2021 0:21:29 GMT
OK, here are the basic things you need to consider: Shielding and balanced line or even Star Quad (as Hexspa mentioned), especially for mic and line level signals. Also like Hexspa said: If cables need to cross each other, do it on the perpendicular and keep physical distance as much as possible from power lines and high level from low level. Keep distance from "Wall Wort" transformers or other gear with power transformers. Physical distance and direction orientation can solve lots of problems. Speaker cables are usually the least of your problems; 12 ga zip cord should be fine, I don't see any need for twisted pair or star quad schemes for speaker runs.
If you're in doubt about your "In Wall" plan or just want to verify your plan, test your plan out of the wall located physically as close as you can to your in-wall design; if your test is quiet, good chance it will be quiet in the wall.
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Post by mickey242 on May 10, 2021 7:12:16 GMT
One anecdote. Buy pre made Star Quade cables so you don't go insane trying to solder the wire to the XLR connectors. Ha Ha.
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Post by rock on May 10, 2021 12:52:25 GMT
I never soldered Star Quad to xlr so I wondered what problems you ran into. I found this you tube: www.youtube.com/watch?v=xT4ITP1yjgI I think the trick is to listen to soothing acoustic guitar music |
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Post by Hexspa on May 10, 2021 17:36:17 GMT
It's not the Star Quad that keeps me up at night - it's the db25!
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