B How does output voltage of an electric guitar work?

[Drakkith]

RMS and peak voltage is listed. In the bracket (). It's even written Average RMS (Peak)

Ah, so it is. My mistake.

So my calculations where conflicting, peaks should add up at some point so E1 + E2 = 1V, the chord is 0.8V which doesn't make sense because the chord consist of E1 = 0.8V and E2 of 0.2V

How hard did the author strike the strings for each note and then the chord?

 

[Xenon02]

How hard did the author strike the strings for each note and then the chord?

That's a good point. Maybe you are right about that part that striking the chord results in smaller amplitude of each string. The question is, is it that radically reduced ? So that E1 from 0.8V will be smaller like 0.4V or 0.5V so that the rest strings will have like 0.1V

Although how much the amplitude changes. Author said he was striking them the same way repeatedly. So I assumed that E1 is equal 0.8V. But isn't the amplitude more dependent on the frequency like it was said before ? Like bridge E1 was 0.8V and E1 on neck is 0.45 V because of different frequencies than how hard it was stroke.

So let's say the chord that consist of E1 is 0.8V then the chord peak doesn't have any sense. If E1 on the bridge changes drastically from 0.8V to 0.6 V then it might be possible to have output of 0.8V when the rest of the strings have less than 0.1V if it makes any sense.

But yea did the E1 amplitude changed then the author played chord ? Single E1 is 0.8V then what is the value of E1 in chord of the bridge part ?

Interesting

 

[Drakkith]

That's a good point. Maybe you are right about that part that striking the chord results in smaller amplitude of each string.

My point is that the results in the article are from an almost entirely uncontrolled experiment. You would need to reliably strike the strings the same way each time to get an accurate comparison between the notes and chords. That's just not going to happen by hand. Amplitude, strike location, and strike direction will all vary with each strike by hand. Sometimes insignificantly, sometimes significantly. So trying to draw any conclusions from these numbers is problematic.

 

[sophiecentaur]

What is the flaw of superposition here ?

Superposition has no 'flaws' it's how you think of it and how you try to apply the principle to a particular situation. You have to distinguish between theory and practical results. As with money and heating the house, if you get an apparent disagreement then there's something you forgot.
I can't understand why you appear to be obsessed with what you see as anomalous behaviour. Precise values for pickup sensitivity are really not an issue, assuming you get enough out of it for your amp system. What is much more important is the relative sensitivity of the pickup to all six strings, As I mentioned before, the material and thickness of each string will affect this and many pickups have adjusting screws in an attempt to get balance. It's nigh on impossible to 'strum' all strings to achieve perfect balance.

You also keep talking in terms of 'sine waves' but the waveforms due to each string are far from sinusoidal - particularly on attack. The resultant voltage is the sum of those waveforms and not the sum of just six sine waves. If you want sine waves then you have to use a synthesiser.

 

[Averagesupernova]

@Xenon has it occurred to you to question why RMS and peak do not differ by a factor of 1.414 in the link in post #1. Does that not clue you in that the signal from each string is not a sine wave? You are missing so many things here and just choose to ignore what you don't want to see.

 

[sophiecentaur]

So let's say the chord that consist of E1 is 0.8V then the chord peak doesn't have any sense. If E1 on the bridge changes drastically from 0.8V to 0.6 V then it might be possible to have output of 0.8V when the rest of the strings have less than 0.1V if it makes any sense.

Actually, this comment makes 'no sense' because you refuse to change your opinion (and it's not a matter of personal opinion). The value of the voltage varies in time and is equal to the sum of all the instantaneous volts from the six strings. Statistically, they will add up to a high instantaneous value once in a while. At that time, there may be clipping / cracking due to the dynamic range of the amplification channel.

I have to ask whether you are just waiting for someone on PF to say "OK Xenon, you are right and we're all wrong"

 

[Xenon02]

I have to ask whether you are just waiting for someone on PF to say "OK Xenon, you are right and we're all wrong"

No I do not wait for this.
The answers I read seemed to me not to relate to example I tried to give and sources I used, so I kept asking again or the answer to the question was relating to a different part like power I didn't know why it was important.
I also asked to relate to my examples or so because it was a simplified version of what I tried to ask or give my idea how it would look like. But I see that I annoyed most of people here.

And no it is not about the refusal of changing the opinion rather I see couple of answers, which I take those from websites as a point of reference because people there know what they are saying and some part of the information kept repeating but at some examples I've seen seemed to be conflicting to the theory that was repeating.

@Xenon has it occurred to you to question why RMS and peak do not differ by a factor of 1.414 in the link in post #1. Does that not clue you in that the signal from each string is not a sine wave? You are missing so many things here and just choose to ignore what you don't want to see.

Yes each string is not a sine wave, sorry for this part, but still the sum of peaks was incorrect. I haven't checked the difference between RMS and peak.
Instead of ignoring I rather expected to relate to my answers like "this diagram doesn't make sense because", "the diagram can look similar but", "the values from the website E1 and E2 vs chord with E1 and E2 sum aren't equal because" "in theory adding peaks like you've said would indeed give 1V but in the picture it is 0.85V because ... " so on and so on, I don't know how to describe it better. But I saw something about something about Power which I didn't know what it has to the amplitude of the voltage when I strike the string, because it is about vibration or when I gave diagram I had an answer like where is the math, in which I used the values from the website, or why do peaks must exceed 1V, or my geogebra example where I proved that no matter the phase shift the sum of all signals their peak must sum at some point : https://www.geogebra.org/graphing/merap3ws. I also expected some answers like "this part is correct but this not of your post" etc.

If it's alot then I am sorry for asking much.

Statistically, they will add up to a high instantaneous value once in a while. At that time, there may be clipping / cracking due to the dynamic range of the amplification channel.

Perhaps they clip, I thought it does not because playing the chord or something the same time usually or practically sounded the same without a bit of distortion. But I can imagine it. So what I said about that the sum will result in high peak which is the sum of all peaks of the sounds once in a while so my geogebra thing wasn't incorrect as I assume.

My point is that the results in the article are from an almost entirely uncontrolled experiment. You would need to reliably strike the strings the same way each time to get an accurate comparison between the notes and chords. That's just not going to happen by hand. Amplitude, strike location, and strike direction will all vary with each strike by hand. Sometimes insignificantly, sometimes significantly. So trying to draw any conclusions from these numbers is problematic.

Makes sense, though it is possible that from 0.8V E1 to reduce drastically when E1 is in chord so that the max is 0.85V ? Hence the E1 when is in chord must reduce from 0.8V to smaller like 0.6V so that the rest of the strings will add up if their amplitude is smaller than 0.1V. I guess ? If some part what I said makes sense then let me know.

 

[Averagesupernova]

All this discussion and have yet to hook a guitar up to a laptop and look at some signals in audacity or something similar. There is only so much this thread will take until you come with better info than a bunch of stuff collected from the web and wrong assumptions made by you. Geogebra appears to be a website that can add some sine waves. Big deal. As said before that can be done on your favorite spreadsheet. It's simple addition. How multiple strings react with each other in the field of the sensor generating signals that are not pure sine waves is reality.

 

[Xenon02]

All this discussion and have yet to hook a guitar up to a laptop and look at some signals in audacity or something similar. There is only so much this thread will take until you come with better info than a bunch of stuff collected from the web and wrong assumptions made by you. Geogebra appears to be a website that can add some sine waves. Big deal. As said before that can be done on your favorite spreadsheet. It's simple addition. How multiple strings react with each other in the field of the sensor generating signals that are not pure sine waves is reality.

Pure sin waves or not, even if a string generates non sin wave signal which will for sure, that waveform is constructed with a bunch of sinwaves, and my geogebra was only supposed to prove that the sum of all signals there is one moment that the peaks adds up no matter what ... That's all. But I see some irony from you.

So that's why this question came :

Makes sense, though it is possible that from 0.8V E1 to reduce drastically when E1 is in chord so that the max is 0.85V ? Hence the E1 when is in chord must reduce from 0.8V to smaller like 0.6V so that the rest of the strings will add up if their amplitude is smaller than 0.1V. I guess ? If some part what I said makes sense then let me know.

I just wondered if the chord could just make the E1 reduced from 0.8V to smaller like 0.6V, It's just a guess of why the chord could have the same value as single E1 sound. And to add to this I proved before and it was said that all the peaks should add up at some point so peak should be bigger and it wasn't. So I just thought

"hmmm then maybe if single E1 was 0.8V, E2 was 0.2V and chord which consist of E1 and E2 has 0.85V something doesn't add up, maybe E1 amplitude as well as E2 etc are reduced when played at the same time ??? because now they interact with each other or something if so then can E1 from single strike 0.8V can now be smaller like 0.6V or smaller because other strings are now vibrating as well"

Process of thinking of what other people said here ...

 

[sophiecentaur]

The answers I read seemed to me not to relate to example I tried to give and sources I used, so I kept asking again or the answer to the question was relating to a different part like power I didn't know why it was important.

You have, as I mentioned above, asked a question that really doesn't mean a lot. You are trying to run this process on your own terms, leaping in, half way through without taking on board the basics. Why do you think the answers you've been getting are not satisfying you? It's because you are trying to run before you can walk. You should try some other, very fundamental sources, like the basics of signals that can be found in a decent EE text book. Not the style of many, these days, I know; there are a lot of newbies who seem to think that the basics don't count. There are other forums that are chock full of nonsensical ideas about musical signals and processing. Very entertaining but not good sourses for getting a proper understanding.

Perhaps they clip, I thought it does not because playing the chord or something the same time usually or practically sounded the same without a bit of distortion.

You cannot trust your ears by listening to non-critical material. Experienced guitar players can spot things that you would never do, at this stage. Guitars are so far from ideal sound sources that you need to switch to an analysis using more straightforward, theoretical signals.

 

[Averagesupernova]

I just wondered if the chord could just make the E1 reduced from 0.8V to smaller like 0.6V

If you actually did something besides pick stuff from the net that you really don't know what the signal is you would understand this. If you concern yourself with peak without considering RMS in this you will not get very far. Yes, adding a second signal from a different string could reduce the peak of the signal while increasing the RMS voltage.
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You need to study up on signals and systems to fully understand this. It's apparent that you don't. Yet you think you do.

If the above can be believed as accurate then the fact the RMS is higher with the chord vs E2 and the peak remained unchanged (20 mV to 36 mV RMS and 300 to 300 peak) should have answered your question, yet you asked. So that implies you don't trust the source of this info.
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It's really difficult to get anything meaningful about the behavior of the pickup just thumbing it. A constant vibration of the string(s) will tell you something. This has to be controlled and the travel of the string measured. This takes patience and a well fixtured setup.

 

[Drakkith]

It's really difficult to get anything meaningful about the behavior of the pickup just thumbing it. A constant vibration of the string(s) will tell you something. This has to be controlled and the travel of the string measured. This takes patience and a well fixtured setup.

Indeed. I've brought this up at least twice now and I would be very surprised if the numbers listed could be reliably replicated when playing by hand.

 

[Xenon02]

If the above can be believed as accurate then the fact the RMS is higher with the chord vs E2 and the peak remained unchanged (20 mV to 36 mV RMS and 300 to 300 peak) should have answered your question, yet you asked. So that implies you don't trust the source of this info.

Aha so indeed I was partly correct that the E2 was reduced because of the chord like you have said here (20mV to 36 mV RMS and peaks are the same 300mV) so the E2 peak had to be reduced then. But yea the RMS changed which I didn't give much thought. Well not always the peak was reduced but I get the idea.

Oke I think now I know what I wanted to know, now I can go back to the stuff that really matters ;>
I know this knowledge might be not useful but now knowing a bit how it looks like, satisfies my reptilian cerebellum.

Of course the source info isn't very accurate like it was said before, still thanks for patience. I'll just go back learn basics I guess ;>

You have, as I mentioned above, asked a question that really doesn't mean a lot. You are trying to run this process on your own terms, leaping in, half way through without taking on board the basics. Why do you think the answers you've been getting are not satisfying you? It's because you are trying to run before you can walk. You should try some other, very fundamental sources, like the basics of signals that can be found in a decent EE text book. Not the style of many, these days, I know; there are a lot of newbies who seem to think that the basics don't count. There are other forums that are chock full of nonsensical ideas about musical signals and processing. Very entertaining but not good sourses for getting a proper understanding

I mean learning from text books won't be something new to me ;>
But I will do what you've said. I've had before lessons about signals etc (hamm windows, white noise etc.), tbh I couldn't understand a thing ;>

So for this discussion I just researched how to analyse output music signals and it was mentioned the superposition. That every weird looking signal can be deconstructed into bunch of sine signals. So I used it in this case after some reading.

Still thanks for the help.

 

[Drakkith]

Aha so indeed I was partly correct that the E2 was reduced because of the chord like you have said here (20mV to 36 mV RMS and peaks are the same 300mV) so the E2 peak had to be reduced then.

I'm not sure that's what Averagesupernova meant.

 

[sophiecentaur]

Aha so indeed I was partly correct

Avoid being complacent about this. You have a long way to go still; as @Drakkith says, you may only 'feel' you are right.

 

[Xenon02]

I'm not sure that's what Averagesupernova meant.

Ok maybe yea it could be the possibility, but it's still a good thing to know this could be the thing.

Avoid being complacent about this. You have a long way to go still; as @Drakkith says, you may only 'feel' you are right.

I mean, I tried to link this with the theory I've read, and if it wasn't then the question was why focusing on mainly that point of where the math didn't math. So Hence I understood from Averagesupernova post that E2 having peak 300mV and the chord that consist of E2 + ther sounds also have 300mV could be like that because the chord (other sounds) could reduce the E2 peak voltage. There might be other reasons like maybe E2 that time was hit lighter than before or the string was further from pickup, or other factors you've guys provided.

So being complacent about something that was partly right is a good thing I guess ... Because the part about peak not adding up to the result and some speculations weren't wrong or atleast could be the thing why E2 and chord had the same amplitude while chord has E2 in him as well as other sounds that should add up. So this possibility is fine by me that could be possible.

Still thanks for the help and patience, but I felt unwelcome here at some point, so I'll just leave it this way. If again post 103 wrongly interpreted post 102 then I don't know what is true then ;> Because I really tried to show some stuff I found and focus on factors that didn't match but I felt like when I asked a question the answers where about something else ;D

 

[bobob]

Here is a great article that derives explains how a guitar pickup works in great detail.

http://kirkmcd.princeton.edu/examples/guitar.pdf

 

[sophiecentaur]

So being complacent about something that was partly right is a good thing I guess ... Because the part about peak not adding up to the result and some speculations weren't wrong or atleast could be the thing why E2 and chord had the same amplitude while chord has E2 in him as well as other sounds that should add up. So this possibility is fine by me that could be possible.

IF you have a hand-waving reason for thinking that your thoughts are in tune with reality then you may be allowing yourself to suspect that your 'understanding' is good. Using an arbitrary set of numbers for an argument doesn't get us anywhere because that can easily mask what could happen with different values. It would instantly destroy the possibility that 'understanding has occurred'.

could be like that because the chord (other sounds) could reduce the E2 peak voltage.

That doesn't make sense. The peak in one signal can always add (at a certain time)directly to the peak of a second signal. That doesn't necessarily apply for some combinations of signals that are harmonically related and with a constant phase relationship but no musical instrument behaves like that. Of course, those resulting peaks may not occur very frequently but you'd need to look at the statistics of any particular combination of signals.
Without some attention to the maths involved then all you can do (and it might be enough for many situations and satisfy you, personally) would be to read about other people's experiences, measurements and opinions. But don't be surprised when your own experience goes against what you thought you 'knew'. And don't be surprised when boring old nerds (PF members etc., like me) don't take you seriously because they learned it the 'proper way'.

They didn't manage to get the James Webb Space Telescope to work, a million miles from Earth, by not being rigorous in their theory.

 

[Xenon02]

That doesn't make sense. The peak in one signal can always add (at a certain time)directly to the peak of a second signal. That doesn't necessarily apply for some combinations of signals that are harmonically related and with a constant phase relationship but no musical instrument behaves like that. Of course, those resulting peaks may not occur very frequently but you'd need to look at the statistics of any particular combination of signals.

Sorry for long wait.
Then why peaks don't add this is still a mystery for me. Why superposition doesn't work ? The peaks of two sounds must add up at some point... If possible could you give me an example I can relate to then ?

I just see not much logic in it.
Yes I don't know what the input looks like. I only know some output example from the web. Yet I still got interested because the thought of "How people making sounds mixing know what will be the amplitude or if the instrument won't surpass that voltage and make it distorted". I know how distorted signal looks like so the sound is really different.

Without some attention to the maths involved then all you can do (and it might be enough for many situations and satisfy you, personally) would be to read about other people's experiences, measurements and opinions. But don't be surprised when your own experience goes against what you thought you 'knew'. And don't be surprised when boring old nerds (PF members etc., like me) don't take you seriously because they learned it the 'proper way'.

What is a proper way then ?
I just found something confusing and wondered how it was resolved.
Is it because I tried to learn it from websites ?

I've used stuff I learned like superposition, interference etc. And tried to apply to this example. I learned here that interference isn't applied to two different frequency signals but superposition yes. So I used a graphical website to see how it is. And I proved that peaks at some point must to add up. So adding all sounds should surpass the voltage yet it didn't. Hence it was weird for me.

PS.
As one person said that in example E2 and chord had two different RMS but the same peak should answer my question yet I tried to deduce something and I was incorrect so what is the correct answer I should take as a fact ? Why is it not distorted ? Why it doesn't add up ? Why it doesn't surpass a certain voltage level ? Why it is not necessary to understand not knowing the output of something that changes the input ? Same shape but different units. Why making a guitar effect its said that pickup is 0.7V peak so they make circuit around this value.
While single strings makes this huge of a peak and somehow never exceeds this peak value ...

Maybe some wicked math is behind of it, and my physics knowledge is 0, yet trying to understand it. Maybe I take some stuff happens at instant.

 

[sophiecentaur]

What is a proper way then ?

It should involve a text book or the equivalent on-line source. If you are relying on casual, ill informed remarks then don't be surprised when you get it wrong. If you are finding 'contradictions' in what you are taking on board, it's because you are either not reading good stuff properly or reading dodgy sources. None of what you are claiming to be inconsistent is actually not consistent. You have to be prepared to learn stuff and not to jump to your own conclusions after minimal reading. Don't expect any of this to be 'obvious'.

Then why peaks don't add this is still a mystery for me. Why superposition doesn't work ? The peaks of two sounds must add up at some point...

Of course "peaks add" but only when they coincide in time. No one has claimed that superposition doesn't work; it has to, in a linear medium.
If you are trying to relate the addition of non-related signals to Interference, (which is between coherent signals) then you will always be confused.
Your "PS" implies that you have not actually been reading what's in this thread. Peak and RMS values of two signals are not automatically tied together except when you are discussing the same signal (e.g. sine wave).

 

[Xenon02]

Of course "peaks add" but only when they coincide in time. No one has claimed that superposition doesn't work; it has to, in a linear medium.
If you are trying to relate the addition of non-related signals to Interference, (which is between coherent signals) then you will always be confused.

This is what I tried to say by using a two signals with different frequency that at some point the peaks must add up. If the two signals were the same frequency and had a small phase shift then their peaks won't add up ever, but this is a different story with two signals with different frequency.
But yea it is still confusing, looking at certain real values.

Your "PS" implies that you have not actually been reading what's in this thread. Peak and RMS values of two signals are not automatically tied together except when you are discussing the same signal (e.g. sine wave).

What do you mean by not tied together ? Chord consists of these two signals. So there were 2 signals separate and 2 signals together at the same time. Yes they are not sinusoidal, but these signals consist of many sinusoidal signals. Hmm how to describe it so it won't sound stupid from me, any sound can be made adding up many sinusoidal signals so in fact even if the input is not sinusoidal it consist of many sinusoidal signals with different frequencies so they add up.
It's hard to imagine to be honest, is there any picture that could better describe what you've tried to tell me ? Sorry if I am asking alot.

I just see it in the way I saw in lessons like sinuses adding up or that every signal is like a bunch of sinuses added up to create a unique shape of a signal.

So I gave my thoughts and it was confusing in many ways, such as why 0.7 was max value (more renowned circuit designer in music assumed this in circuits I have seen made by him), if the strength of the strum can make the amplitude bigger then what is the limit ? why it doesn't distort ? Can strumming the string has a limit ?

Also why this question is also irrelevant ? I know in practical use designing a circuit probably I just need to know max value and that's it. But there are tools to reduce some specific frequency so it is known the value. These frequency has to be somehow picked and reduced. Or making a sound effect that affect I guess specific frequencies so I must to know how much to reduce etc. So it's cool that superposition works but somehow seeing real values it is just incorrect. I can't picture it why though. And what if I just strum to hard ? The amplitude could make the circuit just distort, or if even pickup can distort stuff. If only pickup distort before giving the signal to the circuit then it should be hearable even small cut will lead to distortion. Playing the same chord should lead to distort to if the sum is just to big.

It should involve a text book or the equivalent on-line source. If you are relying on casual, ill informed remarks then don't be surprised when you get it wrong. If you are finding 'contradictions' in what you are taking on board, it's because you are either not reading good stuff properly or reading dodgy sources. None of what you are claiming to be inconsistent is actually not consistent. You have to be prepared to learn stuff and not to jump to your own conclusions after minimal reading. Don't expect any of this to be 'obvious'.

The sources aren't that ill informed, I've gained some of these sources from people that tried to get me into it. But after learning or rather

 

[sophiecentaur]

What do you mean by not tied together ?

= low coherence

So there were 2 signals separate and 2 signals together at the same time. Yes they are not sinusoidal, but these signals consist of many sinusoidal signals

Describing the signals from the two strings as "many sinusoidal signals" is only describing them in the frequency domain, rather than in the time domain. The two descriptions are entirely equivalent. Neither is more correct than the other. If you are concerned with ampl.idier 'headroom' then the time domain description is more informative and relevant because it's when peaks on each signal happen to coincide in time that the cracking is heard.

So it's cool that superposition works

It's a fact that superposition is what happens in a linear system. That's hardly "cool"; it just is.

 

[Xenon02]

= low coherence

I still don't get this part or perhaps I don't know what coherence is or looks like in this situation.

something like this ? I mean yea it looks like they are of different frequencies so because of that the peaks must add at some point in time. All peaks visible in the incoherent part will add up at some point no matter what creating really big value of that peak.

So still I don't know what this has to this

Your "PS" implies that you have not actually been reading what's in this thread. Peak and RMS values of two signals are not automatically tied together except when you are discussing the same signal (e.g. sine wave).

So it still suits the idea, many signals with different frequencies adds up at some point all their peaks. In the reality it does not, question is why. If they do add up like with E1 and E2 it can exceed this 0.7V said while constructing a circuit. And why pickup doesn't distort it ? Or can pickup distort it/cut the signal or it will just give in the output 2V instead of 0.7V max.

If you are concerned with ampl.idier 'headroom' then the time domain description is more informative and relevant because it's when peaks on each signal happen to coincide in time that the cracking is heard.

Is it heard ? When you play many time the same chord or the same note, you won't hear the crack, when the smallest distortion happens (peak is just cut and flattened) then you hear the crack. Or at least that what I felt listening to many kinds of music and in real life as well.

So that's why I asked for any visualization. Because I see you understand my question and you know what it looks like so maybe you know an image or something that could show more. A picture is worth of a thousand words. Also tried to emphasize it or visualize my confusion at any point so far.

It's a fact that superposition is what happens in a linear system. That's hardly "cool"; it just is.

I just said that (it's nice that what others think is also correct to what I thought as well), nothing more behind of that "cool". And I don't know what you've tried to imply here. I was just glad that my part of thought was correct with others, I need to also emphasize that it is a part not the whole thing I wrote.

 

[Tom.G]

I don't play guitar, or any musical instrument for that matter, My background is mainly in electronics (with bits from other technical fields). I'll likely get a few details 'not quite right' but most of it should be close.
That said, lets try this.

"Why doesn't it distort?"

A)
As I understand a guitar pickup, it is a coil of wire wound around a permanent magnet. A wire will have a voltage induced in it if it is in a changing magnetic field. A coil of wire will have that voltage induced into each turn; with the induced voltages from each turn adding to each other.

Even though it isn't a magnet, the string of an electric guitar is made of a material that is magnetic; that means it can be magnetized and will also be attracted to a magnet.

When that guitar string is near a magnet it distorts the magnetic field around the magnet. If the string is vibrating, the magnetic field around the magnet will change with the vibration. For a given motion the amount the field changes depends on how close the string is to the magnet.

B)
That coil of wire around the magnet will have a voltage induced in it by the changing magnetic field. The amount of voltage will depend an the field strength, how close the string is to the magnet/coil, and how fast the string is vibrating (what note it is playing). WIth this setup, the only way to get distortion is if the string contacts the pickup. If the string hits the pickup, it is not moving for an instant, no changing field, no output voltage (in other words, the output waveform would have a notch in it.)

C)
This is where I make the assumptions that:

1) the 'nominal' output voltage from the pickup coil would be measured at a 'standard' distance between the pickup and string,
2) while playing a specific note,
3) and that the string is made with a 'standard' material.
​

D)
Given the above assumptions, the pickup could be designed to give a specific output voltage at 'standard' conditions; perhaps 0.7V.

Now none of the above says anything about the maximum input voltage the amplifier can handle without distortion. Since amplifiers do have volume controls, their gain can readily be adjusted to handle a wide range of input voltages without distortion. If you want distortion, use a Fuzz Box.

Hope this helps!

Cheers,
Tom

ADDENDUM: That "coil in a changing magnetic field" is the the basis for power at the wall outlet at home, and the alternator in a car that keeps the battery charged.

 

[sophiecentaur]

@Xenon02
You will have seen many different pictures of waveforms. The 'spikey' sounds from a guitar string have a waveform with distinct peaks - unlike all your smooth, sinusoidal examples. Two similar waveforms of that sort of shape will clearly only cause an audible crack then the peaks occur at the same time and add together. That is far more obvious than the subtle changes

in 'roughly sinusoidal' waves. An amp may produce very little distortion except where the spikes on two waveforms occur at the same time.

it's nice that what others think is also correct to what I thought as well)

Don't assume that this is anything more than chance - if you don't understand the theory. Theory is not 'thinking'.

When you play many time the same chord or the same note, you won't hear the crack

How would you actually identify the 'crack'? The distortion will be more audible as the amplitude is increased but you can only be sure of detecting it if you subtract the original waveform from the new one (suitably scaled). Your ear can't do that but distortion measuring equipment effectively does just that.
But I have already remarked that all musical instruments produce distortion all the time so you cannot be certain of what you are hearing.

And why pickup doesn't distort it ?

What evidence do you have? Theory will predict distortion but that doesn't mean you will hear it in mild cases.

A)
As I understand a guitar pickup, it is a coil of wire wound around a permanent magnet. A wire will have a voltage induced in it if it is in a changing magnetic field. A coil of wire will have that voltage induced into each turn; with the induced voltages from each turn adding to each other.

Unfortunately there is another can of worms here. It could further confuse the OP.
1.The induced voltage will be proportional to the rate of change of flux. So it's already differentiating the position of the string related to the pole.
2. The fields around the pickup are not uniform where the string is moving about, by any means, so large displacement of the string will take it through a range of magnetic field values (and directions).

I was hoping to avoid these extra complications which tell us that the 'transducer' is not actually linear. That will mean the signal from each string is a 'version' of the basic note (distortion of the individual signals).
However, inside the pickup, the system is linear so the individual emfs will add in a well behaved fashion so there would be little cross-modulation between the individual signals.

 

[Xenon02]

You will have seen many different pictures of waveforms. The 'spikey' sounds from a guitar string have a waveform with distinct peaks - unlike all your smooth, sinusoidal examples. Two similar waveforms of that sort of shape will clearly only cause an audible crack then the peaks occur at the same time and add together. That is far more obvious than the subtle changes

in 'roughly sinusoidal' waves. An amp may produce very little distortion except where the spikes on two waveforms occur at the same time.

May I ask if I can.
So I understand that this picture is like a single string sound. I can imagine it is like that. This can be also analyzed as many sinusoidal signal added up into this red signal.

Also my signal I know it was clear sinusoidal but the sum was not. So my point was that the peaks should add up.

So I understand that the peak of red signal and the second signal very similar to the red signal must add up at some time, hence the time is small that even if the distortion happens we don't hear it ?

That's how I understood the text

How would you actually identify the 'crack'? The distortion will be more audible as the amplitude is increased but you can only be sure of detecting it if you subtract the original waveform from the new one (suitably scaled). Your ear can't do that but distortion measuring equipment effectively does just that.
But I have already remarked that all musical instruments produce distortion all the time so you cannot be certain of what you are hearing.

Okey that's how I understood the text :

- the sum of peaks happens
- these peaks will produce the distortion but it is not hearable
- it is hearable if it more distorted or longer ?

The problem I also have is how big value can the input give and how the pickup produces the output (I know changed in magnetic field) but how strong the vibration must be to achieve 0.7V peak etc. The distance matters etc as I read.
Maybe I slowly get it I dunno for now I am said to "have" a feeling of understanding then I don't know what is learning when I ask questions, try to use my own words to confirm if this is what you meant :D

Still thanks.

 

[Averagesupernova]

@Xenon02 you are assuming that the signals that make up the complex waveform are all as large as the signals in your sine wave example. This is not the case.
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Yes, signals add. Yes, the amplifier will clip if the signal gets large enough. No, you cannot always hear this and if you do it might not sound like something you think is wrong.

 

[sophiecentaur]

@Xenon02
You will have seen many different pictures of waveforms. The 'spikey' sounds from a guitar string have a waveform with distinct peaks - unlike all your smooth, sinusoidal examples. Two similar waveforms of that sort of shape will clearly only cause an audible crack then the peaks occur at the same time and add together. That is far more obvious than the subtle changes
View attachment 350636
in 'roughly sinusoidal' waves. An amp may produce very little distortion except where the spikes on two waveforms occur at the same time.

it's nice that what others think is also correct to what I thought as well)

Don't assume that this is anything more than chance - if you don't understand the theory. Theory is not 'thinking'.

When you play many time the same chord or the same note, you won't hear the crack

How would you actually identify the 'crack'? The distortion will be more audible as the amplitude is increased but you can only be sure of detecting it if you subtract the original waveform from the new one (suitably scaled). Your ear can't do that but distortion measuring equipment effectively does just that.
But I have already remarked that all musical instruments produce distortion all the time so you cannot be certain of what you are hearing.

And why pickup doesn't distort it ?

What evidence do you have? Theory will predict distortion but that doesn't mean you will hear it in mild cases.

So my point was that the peaks should add up.

The values of both signals at any one time will add to produce a resultant. As one set of peaks runs through the other set of peaks, there will be instants when the two peaks add together. The rest of the time they do not coincide so the resultant will be less than 'cracking level'. The subjective effect will be the result over time of the signal addition.

Maybe I slowly get it I dunno for now I am said to "have" a feeling of understanding then I don't know what is learning when I ask questions, try to use my own words to confirm if this is what you meant :D

The best level of understanding is when you can predict what will happen in a particular situation and it turns out that way. In this sort of subject it has to involve some formal maths and is verified by an experimental result. (Alternatively you can deal with 'set' questions in the book and get the 'correct' answers.) That avoids the risk of a false feeling of understanding. None of this stuff is a matter of opinion - any more than your three times table.

 

[Xenon02]

@Xenon02 you are assuming that the signals that make up the complex waveform are all as large as the signals in your sine wave example. This is not the case.
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Yes, signals add. Yes, the amplifier will clip if the signal gets large enough. No, you cannot always hear this and if you do it might not sound like something you think is wrong.

Yea you are right. I just assumed that signals can be large from the website I was referring to so that's why I think I asked how input looks like or how big it can be so that pickup changes this input into equivalent voltage output. And I thought pickup only makes 0.7V but it can make more if the peak of two signals is big.

It's a shame that peaks in the website I've provided their sum didn't match up with my expectations for some reasons. Maybe the peak wasn't "visible" at that vast time.

And ok so the do clip but it is not hearable, for it to be hearable probably the distortion has to occur more often or something or last longer.

 

[Averagesupernova]

Yea you are right. I just assumed that signals can be large from the website I was referring to so that's why I think I asked how input looks like or how big it can be so that pickup changes this input into equivalent voltage output. And I thought pickup only makes 0.7V but it can make more if the peak of two signals is big.

It's a shame that peaks in the website I've provided their sum didn't match up with my expectations for some reasons. Maybe the peak wasn't "visible" at that vast time.

And ok so the do clip but it is not hearable, for it to be hearable probably the distortion has to occur more often or something or last longer.

Sometimes it may clip, others not.
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Concerning what I put in italics: Get over yourself. It's a shame that things aren't the way I think they should be or would be, and everyone should accept that things are way I say they are, etc. Get over it and learn to accept that nature works the way it does and not how you think it should.