I have just begun my journey on learning about electronics, so please pardon me if this questions sounds ridiculous.
To my understanding, AC signals require two leads, one hot and one cold. So that when the sine wave drops below positive, the cold end instead transmits the negative signal. Now, audio signals to my understanding is also an AC signal, but inside IEM and ear buds cables, there aren't two leads per channel, instead, the usual configuration is TRS, in which tip carries right, ring left, and sleeve a common ground.
This leaves me with the question, how come one cable is able to carry an AC signal?
Thank you for reading my question.
To my understanding, AC signals require two leads, one hot and one cold. So that when the sine wave drops below positive, the cold end instead transmits the negative signal. Now, audio signals to my understanding is also an AC signal, but inside IEM and ear buds cables, there aren't two leads per channel, instead, the usual configuration is TRS, in which tip carries right, ring left, and sleeve a common ground.
This leaves me with the question, how come one cable is able to carry an AC signal?
Thank you for reading my question.
The common ground carries both signals. An analogy is the US mains house wiring with two 120 VAC lines and a common ground, which has the same issues of ground integrity.
All good fortune,
Chris
All good fortune,
Chris
Yes, and this type of signal is also called "single-ended" or "unbalanced" because there is only one hot signal and the ground is a zero-reference point that never changes.
There is another audio signal type called "differential" or "balanced" where there is a +hot and a -hot and the ground is not used for signal transmission. Typically XLR connectors are used for balanced signals.
You will eventually come across this on your journey.
And welcome to the forum!
There is another audio signal type called "differential" or "balanced" where there is a +hot and a -hot and the ground is not used for signal transmission. Typically XLR connectors are used for balanced signals.
You will eventually come across this on your journey.
And welcome to the forum!
Thank you for your answers. Now I remember that amplification circuits produce a balanced cable naturally, and SE is merely that same signal but only the +hot signal.
Sorry but no, wrong explanation.
Transmitting any voltage, signal or DC requires 2 conductors in total.
Polarity is irrelevant.
Again wrong.
Historically, since the very first tube on Earth, signal was created in an unbalanced way.
Yes, the reason two conductors are required is that current (either AC or DC) must always flow in a loop,
because charge is conserved.
https://www.khanacademy.org/science/physics/circuits-topic/circuits-resistance/a/ee-kirchhoffs-laws
The three wire headphone's "ground" wire shares the left and right return paths for simplicity and cost.
This is not necessary, and some headphones do have two wires per side, with the left and right "grounds"
connected together at the typical three terminal stereo plug end.
because charge is conserved.
https://www.khanacademy.org/science/physics/circuits-topic/circuits-resistance/a/ee-kirchhoffs-laws
The three wire headphone's "ground" wire shares the left and right return paths for simplicity and cost.
This is not necessary, and some headphones do have two wires per side, with the left and right "grounds"
connected together at the typical three terminal stereo plug end.
Apologies for my typo above, the reply should have been "amplifiers naturally produce a balanced signal." But that statement is also inadequate.
My question is how some audio signals can be carried by a TRS connector, forcing Left and Right channels to share a common ground. The answer is, that common ground serves as the 0-reference that was not necessary in the balanced configuration.
So in the end of the day, the signal does still rise and dip below 0, but a balanced signal does that by using two signal carrying conductors, and single ended signals does that by referencing against a 0 point defined by the ground signal.
Thank you everyone for the help correcting my understanding of electrical signals.
P.S.
Which raises some questions involving amp design along the lines of: how to best amplify the signal to a desired output format so that no energy is wasted. E.g. amplifying a signal so that the output is naturally single ended, or an output that does both balanced and single ended and the method to convert between those two.
Revising my understanding: 2 conductors are necessary to transfer both AC and DC signals. For an AC signal, a positive voltage is transmitted by the first conductor, once the sine wave dips below 0 (negative), current flows from the second conductor to the load and back to the first. When the sine wave goes back above 0 (positive), the signal switches to flow from the first conductor to the load and to the second conductor etc.
My question is how some audio signals can be carried by a TRS connector, forcing Left and Right channels to share a common ground. The answer is, that common ground serves as the 0-reference that was not necessary in the balanced configuration.
So in the end of the day, the signal does still rise and dip below 0, but a balanced signal does that by using two signal carrying conductors, and single ended signals does that by referencing against a 0 point defined by the ground signal.
Thank you everyone for the help correcting my understanding of electrical signals.
P.S.
Which raises some questions involving amp design along the lines of: how to best amplify the signal to a desired output format so that no energy is wasted. E.g. amplifying a signal so that the output is naturally single ended, or an output that does both balanced and single ended and the method to convert between those two.
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Unless you have a specific reason you should probably leave alone the questions of balanced operation and of amplifier efficiency for another time, and focus on learning to design a simple stage of amplification.
Indeed, those are just something I thought would have to be considered in an amplifier design due to the nature of balanced/single ended signals. I am currently working on a simple ESL speaker. I will be making a post very soon!
NO NO NO.That is a horrible "explanation", not sure where you pulled that from.
No positive (or negative or AC) voltage is transmitted by one conductor.
Read this 10 times until it clicks.
No.
No conductor switching at any moment.
Stop using this "explanation"
Read a book on basic Electricity, not even Electronics.
Which balanced configuration?
Irrelevant if you don't know conduction along a wire.
You skip chapters so your knowledge is incomplete and full of holes.
Start at chapter 1 and read books page by page until the end.
And then reread it many times.
Every time you will understand more and more and parts will begin to join and make sense.
You are obsessed with balanced signals which are 0.1% of what's available in the real world. .
Go step by step and read all preceding chapters.
The reason that multimeters have two probes is that any signal on a wire is always with reference to another wire.
So if you have two wires you can measure the voltage difference between them, but whether one or the other is 'ground' is irrelevant for the signal.
The important take-home is that you cannot talk about 'a voltage' on a point - it's always the voltage on a point referred to some other point - hence the need for two probes!
In a balanced signal each signal is the reference for the nother, again, it's the difference between the two wires that determines the signal. Whether one or the other or none is ground is irrelevant for the signal.
Once you grok these concepts, your understanding makes a quantum leap.
Jan
So if you have two wires you can measure the voltage difference between them, but whether one or the other is 'ground' is irrelevant for the signal.
The important take-home is that you cannot talk about 'a voltage' on a point - it's always the voltage on a point referred to some other point - hence the need for two probes!
In a balanced signal each signal is the reference for the nother, again, it's the difference between the two wires that determines the signal. Whether one or the other or none is ground is irrelevant for the signal.
Once you grok these concepts, your understanding makes a quantum leap.
Jan
Thank you everyone for your tolerance. I will pick an electronics book to read from and report back then.
You'll be fine. Nobody is born knowing anything. You have Le Gai Savoir, and that's all that matters.
All good fortune,
Chris
All good fortune,
Chris
Broadtalk,
The US Navy Electricity and Electronics Training (NEETS) books are a bit old, but still a good introduction. They were intended to bring recruits up to speed quickly from basic electricity to using and maintaining Navy gear. They are about tubes mostly, but the basics apply to all electronics. They are available to read or download online.
Doug
The US Navy Electricity and Electronics Training (NEETS) books are a bit old, but still a good introduction. They were intended to bring recruits up to speed quickly from basic electricity to using and maintaining Navy gear. They are about tubes mostly, but the basics apply to all electronics. They are available to read or download online.
Doug
I don’t want to muddy the waters but as you learn more you might enjoy using this highly visual (and free) online circuit simulator. I use it all the time for quick things. https://www.falstad.com/circuit/ it animates current so I hope it builds up your intuition.
A teacher for physics told me once criticizing that students at universities are often misleaded to be trained to calculate formulas without really understanding them.
For making them learn in depth he recapitulated the very first experiments in history with electricity where you had to struggle to understand electric phenomenons.
This usually is so palpable and interesting for the students as it can be.
For making them learn in depth he recapitulated the very first experiments in history with electricity where you had to struggle to understand electric phenomenons.
This usually is so palpable and interesting for the students as it can be.
To add some fuel,
To make any speaker diaphragm move in and out two wires are necessary. That’s why audio circuits are all AC. One wire makes the diaphragm move OUT, the other makes it move IN. That’s why if you switched the wires the speaker would be out of polarity, the diaphragm would move IN when it should move OUT, and vice versa. Moving electric fields and all that jazz. The AC signal alternates direction 🔛 on both wires at the instantaneous audio frequency everywhere in the signal path. 🤗
To make any speaker diaphragm move in and out two wires are necessary. That’s why audio circuits are all AC. One wire makes the diaphragm move OUT, the other makes it move IN. That’s why if you switched the wires the speaker would be out of polarity, the diaphragm would move IN when it should move OUT, and vice versa. Moving electric fields and all that jazz. The AC signal alternates direction 🔛 on both wires at the instantaneous audio frequency everywhere in the signal path. 🤗
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WRONG
Both wires work all the time, at the same time.
Exact same current on both, at the same time.
Only polarity differs.
You’re close, very close. When the signal travels to the speaker on one wire it travels in the opposite direction on the other wire. And vice versa. And so on and so on. That‘s why they call it alternating current. 😬
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