How does output voltage of an electric guitar work?

[Averagesupernova]

Incidentally power would never swing positive and negative driving a resistive load. What you are looking at and where you got the images you posted I have no idea.
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They may be ok for showing the basics of how things cancel and add. I wouldn't trust them for absolute accuracy.

 

[sophiecentaur]

Doesn't the sound add up ? I read something about superposition of Sound

Absolutely But what "adds up" is the instantaneous volts (amplitudes) of each waveform. It's a linear system. At times, the voltages add in phase, which can give you a resultant value of up to 2v which corresponds to four times the instantaneous Power. But the mean power is just twice the Power.

Addition of Powers and Voltages is a constant source of confusion if we don't go back to basics.

 

[Xenon02]

I don't know what your orange line represents and I'm not going to bother trying to find out. This is your project and if you are unable to conclude what you are looking at then you have no chance of designing circuits to create guitar effects. I assume based on your first post that this is what you want to do.

What I tried to represent with my orange signal/line is that the signals add up like in the links I've provided :
https://nsinstruments.com/principles/linear.html , and from stackoverflow : https://physics.stackexchange.com/questions/495511/vibration-in-a-guitar-when-playing-two-strings in which you can see that the final signal looks like :

It is not voltage it is the vibration/sound wave. So This is what pickup receives and it doesn't calculate with the math you've said. Or as far I know. I'm not trying to the one who annoys everyone. I just see some conflicts in the logic of voltages and the input the pickup receives like the blue signal I sent now or my orange signal. The peak values where the thing that worried me because how a peak value from the sound is now received by pickup which maks voltage he can make is 1V ...

No one in the links says a word about what it is other than that is a sound/vibration wave/signal.

Dunno how these equations will help me or how to use it in practice.
I saw some guitar effects like : Distort and they just assumed that input is max 0.7V peak. So yea. I wanted to understand more because logically it didn't have any sense why 0.7V is max (from tutorials I took this value or from this website : https://sound-au.com/articles/guitar-voltage.htm), because the sound/vibration signal can exceed huge values so I didn't know how these two correlate.

Incidentally power would never swing positive and negative driving a resistive load. What you are looking at and where you got the images you posted I have no idea.

That's why I've sent links from where I've read it to make sure if I am right or not or to understand what is going on. Because my main knowledge comes from these websites and other websites says/shows the same graphs. So I tried to understand though.

So all the links are in the post # 26 check it up if it's possible.

Absolutely But what "adds up" is the instantaneous volts (amplitudes) of each waveform. It's a linear system. At times, the voltages add in phase, which can give you a resultant value of up to 2v which corresponds to four times the instantaneous Power. But the mean power is just twice the Power.

Addition of Powers and Voltages is a constant source of confusion if we don't go back to basics.

Yea instantaneous adds up so the final result is like here :

Well I guess something like that. The mean can be indeed the 2x and not 4x the power. But I don't know if this is the answer though. I don't know if this information resolves my questions about the what pickup will do with this orange final signal (orange signal is the sum of all 4 signals here).

 

[Averagesupernova]

I don't know if this information resolves my questions about the what pickup will do with this orange final signal (orange signal is the sum of all 4 signals here).

The pickup is what actually is summing the other signals to get the orange one.

 

[sophiecentaur]

How the pickup will interpret it ? As I said I just did what in other websites/videos did. So I am trying to use the example to understand it because without it I am lost.

If the pickup ( and the amplifier plus scope) has a fast response (wide bandwidth) then it will produce a single varying voltage (only one trace on a scope) which will correspond to the vibrations on the strings added together at each instant. If the pickup cannot respond fast, then (as when you hear the beats between two notes) you will see a wavy trace that changes in amplitude. The fast waves will be the pickup's attempt to chase both waveforms.

 

[Xenon02]

The pickup is what actually is summing the other signals to get the orange one.

But the input must be also a sine wave / waves am I wrong ? The pickup pick the vibration and the vibration itself must be sinus wave/waves. So I though from the link and they said that the sound/vibrations are these sinuses and they add up resulting in the single wiggly signal, which the orange signal was supposed to represent.
Hence the orange signal was supposed to be the vibration signal received by the pickup. So the output that is processed by the pickup with the sinus waves signals he produces the voltage equivalent. But still the input must be sinus waves or am I wrong ? If so is there any info about it somewhere ?

You get it what I try to say here ? Like vibrations are also sinus waves if so I just made one with orange signal that has it's peaks without units because no one mentioned in the website about it.

But still interesting intel to get. But still want to confront what I read/understand/drawn with how other says, from websites as well. Because I guess my understanding isn't that incorrect but still doesn't make sense with the output max voltage value to the input values represented by my actual understanding which is the orange signal/function representing the sum of couple of the string vibrations.

 

[Xenon02]

PS.

The pickup is what actually is summing the other signals to get the orange one.

From what I understood from this is that my orange signal is not the input signal to the pickup but the output. Although what the input looks like as I mentioned in my post above.
Because in the website I understood that the sound/vibration are represented by the sum of all signals and that is what pickup receives. which made me confused, but it makes sense that vibration adds up, but it doesn't make sense when it comes to the peak values. Because it cannot exceed 1V peak.

 

[Xenon02]

@Averagesupernova

What do you think about what I've mentioned ?
I mean what I mentioned isn't wrong that much but still I wonder even if the sounds are like 300mV in peak voltage how is it that adding many voltage sinus waves with 10-300mV peaks doesn't exceed the 1V peak.

Well that and the thing I've mentioned in my posts. But still thanks for some info.

 

[Averagesupernova]

It is more of a question about magnetics. The experience I've had with this type of sensor is in tachometer pickup coils that never see anything except gear or sprocket teeth going past. Obviously slightly different than a guitar pickup. But it is the same principle. However, I did donate a speedometer sensor to a kid who made his own guitar for a science project. Didn't have all six strings but the speedo sensor was able to pickup both strings and demonstrate the principle. I never measured anything concerning the addition of several strings.
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My guess is that the magnetic field has to change faster to get more voltage. That can translate to several different things. Not just a string that is stretched tighter. The string will have to cover the same distance faster. This takes more energy. Split a string up into several strings and the net modification of the field has to reflect any increase or decrease in mechanical power applied to the strings. Keep in mind that a poor sensor will not necessarily reflect a change like this accurately.

 

[Xenon02]

It is more of a question about magnetics. The experience I've had with this type of sensor is in tachometer pickup coils that never see anything except gear or sprocket teeth going past. Obviously slightly different than a guitar pickup. But it is the same principle. However, I did donate a speedometer sensor to a kid who made his own guitar for a science project. Didn't have all six strings but the speedo sensor was able to pickup both strings and demonstrate the principle. I never measured anything concerning the addition of several strings.
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My guess is that the magnetic field has to change faster to get more voltage. That can translate to several different things. Not just a string that is stretched tighter. The string will have to cover the same distance faster. This takes more energy. Split a string up into several strings and the net modification of the field has to reflect any increase or decrease in mechanical power applied to the strings. Keep in mind that a poor sensor will not necessarily reflect a change like this accurately.

The faster the magnetic field changes the more voltage hmm
According to this : https://sound-au.com/articles/guitar-voltage.htm

E1 and E2 at bridge were very similar. Sometimes even E2 is smaller than E1.
At bridge the E2 has the same amplitude as chord which I guess consist of all 6 E sounds.

But I don't know if what you've said answered it. The vibration itself is also a sin wave as I understand. Many websites shows some sinuses adding up, and even in stackoverflow they've added 2 sinewaves with different frequences in result they've achieved value of "1.5" of something. I understood that this result is the input, and the output of the voltage is unknown.

How do the sounds mixs up so the amplitude doesn't skyrocket is weird, because in examples I see they do exceed that limit, still pickup somehow works IRL, dunno why.

I accepted what you've said about power and voltage but it somehow doesn't link with the information I've found so far or have missed somewhere that part in the websites/youtube videos.

So far what I understand is the following :

- Power =/= voltage
- Maybe the signals I see are the pickup ? Although the pickup maks amplitude is 1V or 0.7V.
- Signals/sounds do sum up, and can use superpositions.

What I still don't understand is :

- What is this unit in diagrams of summed sinewaves, is it an input or and output, if an output why it exceeds 1V, if input why it exceeds value "1", hence how will the pickup respond to high pick from multiple sinuses.


For example :

So for the sake I am not taking this out of nowhere :

Looks to me like input, because the output cannot be more than 1V, so pickup somehow must work on it ? How ? I don't know, but somehow the input signal is the same as output in volts so it is magic. It somehow scales it or something, dunno.

 

[Averagesupernova]

The faster the magnetic field changes the more voltage hmm

So are you disputing my claim that a faster field change generates a higher voltage based on the difference between E1 and E2 in what you linked to? I know very little about the musical notes and scales, etc.
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I never said a higher note will generate a higher voltage compared to a lower note. I said the vibrating string has to cover the same distance for this to be true when they are compared.

 

[Xenon02]

So are you disputing my claim that a faster field change generates a higher voltage based on the difference between E1 and E2 in what you linked to? I know very little about the musical notes and scales, etc.
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I never said a higher note will generate a higher voltage compared to a lower note. I said the vibrating string has to cover the same distance for this to be true when they are compared.

Just trying to put on some ideas.
I just deduced that higher frequency means different sound. I also don't know much about musical notes etc. I am simply just comparing what was written here.

also trying to understand the graphs I also linked that has some Y-axis without units. Sinuses have max "1" which is of course true, but how does the input to the pickup looks like and how does the output looks like.

In my example I've shown my "theory". In which the input was the orange one (what pick up receives) and the output (voltage from pick up). The orange one has a peak of "3", and the output has the similar shape but the peak is now 0.6V and not 3V because it is somehow scaled ? Dunno, just some random guesses so far. What is input peaks where higher etc.
There is a power you've mentioned but I don't know how to link that info to the graphs.

Like I said random guesses. Maybe somebody know maybe not. But I wondered a lot because people creates these guitar effects but the voltage each sound makes and making all sounds at the same time without loosing it while the amplitude didn't change much was weird for me.
Weirder it goes when I saw this one : https://physics.stackexchange.com/questions/495511/vibration-in-a-guitar-when-playing-two-strings here they've added two sounds waves and the result was a peak pretty big, hence what will the pickup do ? "Reduce the peak" ? What rule is behind of it ?

Maybe my question is stupid and I should look at it like that but I don't know sounds like a good way to understand what pickup is receiving, and how to prepare op amp for the output voltage.

But also when reading I only see images with graphs of added signals but having high peaks, so there was only a question how pickup works with this then. or any other electric Device. If that makes sense.

 

[Baluncore]

Because it cannot exceed 1V peak.

You appear to be wrongly assuming, that all sine waves have an amplitude of ±1 volt, and that when several waves are added, they must exceed the dynamic limit of ±1 volt.

If one guitar string could produce a signal with a maximum amplitude of ±100 mV, then it would need 10 strings, played to the maximum, all at the same time, to make the maximum ±1 volt signal.

 

[Drakkith]

How do the sounds mixs up so the amplitude doesn't skyrocket is weird, because in examples I see they do exceed that limit, still pickup somehow works IRL, dunno why.

What limit? I keep seeing you talk about some 1 volt limit. Where did you get such a number?

 

[Drakkith]

Weirder it goes when I saw this one : https://physics.stackexchange.com/questions/495511/vibration-in-a-guitar-when-playing-two-strings here they've added two sounds waves and the result was a peak pretty big, hence what will the pickup do ? "Reduce the peak" ? What rule is behind of it ?

The pickup will detect the motion of one section of the strings and output a voltage profile that is the sum of both strings. It might be similar to the 3rd graph if the pickup is located at the same place along the string that the 3rd graph is, but it doesn't have to be. If, for example, the pickup was located in the direct middle of both of the example strings, it would output a simple sine wave since there is a node at that location on the first string.

 

[Baluncore]

What limit? I keep seeing you talk about some 1 volt limit.

There was a standard for telemetry signals that were to be recorded on multichannel tape recorders, and plotted on polygraphs, that set a maximum voltage of 1 Vrms. That range would be limited to ±1.4142 volts peak.

 

[Xenon02]

You appear to be wrongly assuming, that all sine waves have an amplitude of ±1 volt, and that when several waves are added, they must exceed the dynamic limit of ±1 volt.

If one guitar string could produce a signal with a maximum amplitude of ±100 mV, then it would need 10 strings, played to the maximum, all at the same time, to make the maximum ±1 volt signal.

Perhaps, but looking at this site again :

So if 2 strings can generate 300mV like in the Bridge part, then 6 strings can exceed 1V for sure. If course they are phase shifter and have different frequency but at some point all peaks must meet somewhere and then all peaks add up which will result in high peak.

The pickup will detect the motion of one section of the strings and output a voltage profile that is the sum of both strings. It might be similar to the 3rd graph if the pickup is located at the same place along the string that the 3rd graph is, but it doesn't have to be. If, for example, the pickup was located in the direct middle of both of the example strings, it would output a simple sine wave since there is a node at that location on the first string.

simple sine wave in the middle of both strings, node at the location of first string even though the pickup is right in the middle of 2 strings ?

 

[Averagesupernova]

Well it may be stupid to someone but I wouldn't say from my perspective or yours it's a stupid question. Do you have a guitar? If so, do some experiments.

 

[Averagesupernova]

So if 2 strings can generate 300mV like in the Bridge part, then 6 strings can exceed 1V for sure.

Where is your math for this and are you assuming peak amplitude or RMS?

 

[Baluncore]

So if 2 strings can generate 300mV like in the Bridge part, then 6 strings can exceed 1V for sure.

That is irrational. If two produce 300 mV peak, then one produces 150 mV peak and six produce 900 mV peak. That is less than one volt peak, not more.

If course they are phase shifter and have different frequency but at some point all peaks must meet somewhere and then all peaks add up which will result in high peak.

This is an electric guitar. If you hit every string at once, you would complain if it did not clip and distort.

 

[Xenon02]

Well it may be stupid to someone but I wouldn't say from my perspective or yours it's a stupid question. Do you have a guitar? If so, do some experiments.

I don't have the guitar but if I had I don't have anything good to church the voltages etc.

Where is your math for this and are you assuming peak amplitude or RMS?

The number comes from the link from the first post so I used them as a reference to my geogebra version of these graphs.

What I took out of this lesson is that no matter the phase shift or the frequency. All signals with different frequencies while adding up will meet at some point where all peaks will add up resulting in high peak.

So I research a lot and many sites shows the same graphs as mine which is the orange one. They did not use units so I interpreted them as an input signal. So input signal had peak of "4" what will the pickup do to this signal ? It won't cut it creating distortion so ??? Input is signal like my orange signal what is the output ? Reduced to 0.6V peak version ?

If yes then there is no logic in between input signal peaks with output voltage because the peak could have value "10" so what pickup will do ? What value he will give to this peak ?

BUT look at the table I gave in post #47 the higher notes we get from the guitar the bigger the amplitude or maybe the lower notes ?? I dunno the sound on the bridge. But yea, so there is some conclusion I can take from this picture BUT how does the input to the guitar looks like ? Why if I have 6 signals with 0.3V adding up did not exceed 1V ? Dunno. There is in the table that possibility and the chord gave only 0.3V output having individual strings with 0.3V peak. And we know signal with different frequencies all meet their peaks at some point so 0.3*6. Why am I confident they must meet ? My geogebra example.

That is irrational. If two produce 300 mV peak, then one produces 150 mV peak and six produce 900 mV peak. That is less than one volt peak, not more.

Individual string have this much the table I've provided doesn't lie. Plus what if you pull the string harder then maybe the amplitude rises. But maybe not because the frequency of the sound is the same just how high the bouncing is increased. So it should have any impact. I think so reading what Averagesuperman has said in post #41

This is an electric guitar. If you hit every string at once, you would complain if it did not clip and distort.

Clipping and distortion should the circuit do and not the pickup I assume.
And if randomly pulling the string makes distortion then playing on the guitar the same way will result randomly in distortion which doesn't make sense.

But you can agree that signal with different frequencies must meet at some point all their peaks must add up at some point like in my orange graph example right ? Resulting in high peak moment. So like how does the input looks like. Why the 6 string sound peak wasn't above 1V knowing from the table that strings have 0.3V or even 0.8V at some example.

So how does the input look like and why pickup with these signals amplitude didn't exceed 1V. Weird and interesting

 

[Xenon02]

PS

If pickup output can be max 1V and the input vibration signal it's peak can be "3", "10" etc. Then pick up must reduce it into 1V so hard clipping resulting in distortion. Which doesn't make sense because randomly playing will give distortion.

So how the Input looks like ? What is the unit of those input peaks because websites only shows the graphs with high peaks. Check them out. I am just recreating a simple example to them. So pickup receives these "4","10" etc peaks.

Lastly, the table it shows how big are the amplitudes for specific Playstyle ? Dunno. But it shows that strings can have 0.3 or even 0.8V while pickup can have max 1V so what if I add all 6 strings ? It must exceed 1 V because different frequencies peaks must all add up at some point

0.8V in all Strings will result in like more than 4V
... But that's how the table says so I believe it that individual string can have 0.8V because pickup can make maks 1V

 

[Baluncore]

If pickup output can be max 1V and the input vibration signal it's peak can be "3", "10" etc. Then pick up must reduce it into 1V so hard clipping resulting in distortion. Which doesn't make sense because randomly playing will give distortion.

What do you mean by "which doesn't make sense"? Randomly playing a few strings will not give distortion.

If you want loud and perfect sound without distortion, you will be playing more gently, but turning up the gain of the amplifier. If you put all your energy into shredding your fingers, you deserve all the distortion you can get. It is not the pickup, but the input to the amplifier, that will distort when exceeding the one volt envelope.

The player knows, and is in control of, their equipment. They know what they are doing, and how to stay within the one volt envelope, when that is wanted.

 

[Xenon02]

What do you mean by "which doesn't make sense"? Randomly playing a few strings will not give distortion.

If you want loud and perfect sound without distortion, you will be playing more gently, but turning up the gain of the amplifier. If you put all your energy into shredding your fingers, you deserve all the distortion you can get. It is not the pickup, but the input to the amplifier, that will distort when exceeding the one volt envelope.

The player knows, and is in control of, their equipment. They know what they are doing, and how to stay within the one volt envelope, when that is wanted.

But here I was talking about pick up and not what op amp amplifies. Op amp amplifies what he gets from the pickup.

The website showed the sound amplitude which you've said yourself amplitude of 0.8V is a lot and if all 6 strings or more had 0.8V then peak can be even 4 V on the pickup itself although the pickup cannot exceed 1.4V as you mentioned.


I've used a bit of chatgpt he showed me some ideas and had some sense. Like if the vibration amplitude exceed the peak value "1" then the overall amplitude is reduced by the pickup.

It said that :

• Generating Input Signals: Each string generates a signal with a specific amplitude and frequency.
• Summing the Signals: These signals are summed, which can lead to very high amplitude values at certain moments.
• Clipping the Signal by the Pickup: The pickup applies a nonlinear function, such as tanh⁡\tanhtanh, to limit the summed signal to a maximum value, e.g., 1V.
  
  
• Nonlinear Summation of Input Signals: The pickup processes input signals nonlinearly, preventing simple linear addition of amplitudes.
• Signal Clipping: The pickup uses a soft clipping function (tanh⁡\tanhtanh) to avoid distortion and provide a stable output signal.
  

So yea, but this nonlinear part is the black line, although it is just linear sum of all signals and reduced to be max 1V, maybe it has some sense.
But someone mentioned that pickup doesn't reduce the input signals so I don't know now how the pickup works with high peaks. Also chatgpt told me that these vibrations are :

Vibration signal units:

The value "3" on the graph is the amplitude of the signal, which is a dimensionless unit in the mathematical context (it simply shows the maximum value of the vibration).
In a real-world context, signals from a pickup truck are measured in volts (V). The pickup converts the amplitude of the string vibrations into a corresponding electrical signal, which can have different voltages depending on the design of the pickup and the strength of the string vibrations.

That's what I've found so far but are conflicting with what you've guys said

 

[sophiecentaur]

Also, when you are adding multiple sine waves of different frequencies, it is usually the RMS values that you add, not the peak values.

If you are estimating power supply requirements or thermal effects in the output stages or in the speaker coil then RMS addition will be relevant. If you are trying to maintain headroom, to avoid clipping then you have to involve individual signal peak volts as they will add at some point, which is where clipping will occur.
Audio amps are always specified 'optimistically' so as to give the impression that 100W means 100W of sinewave supplied to the speaker. Something will over-heat or the volts from the supply will dip.

But I still wonder how pickup works when the sum of all amplitudes from sound or vibration exceeds this value "1". Like the sum of all signals is "100" and what pickup will do with this peak.

There is nothing in a normal pickup that will 'run out of range' so your "100" is an arbitrary number of mV. It's amplifiers that will limit the total excursion of the signal. Somewhere in the amplifier chain there will be an adjustable attenuator to take care of this.

Microphones can run out of headroom and you can get limiting with excess sound level. You can get rugged mikes for use with drums etc.

 

[Xenon02]

There is nothing in a normal pickup that will 'run out of range' so your "100" is an arbitrary number of mV. It's amplifiers that will limit the total excursion of the signal. Somewhere in the amplifier chain there will be an adjustable attenuator to take care of this.

Microphones can run out of headroom and you can get limiting with excess sound level. You can get rugged mikes for use with drums etc.

Do you have any information from websites/videos etc about it that pickup doesn't run out of range ? How input signal looks like and how to interpret the peak value of that input signal ? Does the value of peak equal to mV ? Because the input signal doesn't have unit or so I couldn't find on websites whole Output signal is in V or mV. Any source ???

If this diagram is incorrect.

Then what does the real diagram of input signal and output signal.

Like I said I couldn't find any example of vibrations signal which unit I don't know and the equivelant pickup signal on mV

 

[sophiecentaur]

Because the input signal doesn't have unit or so I couldn't find on websites whole Output signal is in V or mV. Any source ???

For the purpose of the theory, it doesn't matter what the actual voltage output is. It will depend on the thickness of the strings, the number of turns on the pickup coil and the geometry of the magnetic core. The Physics will be exactly the same. There is a limit to the amplitude of the string vibration and a few other things, which is ultimately a non-linearity.
You must remember, though, that all musical instruments are inherently nonlinear and strings on the same neck will interact mechanically through the wood and by altering the tension in the bridge etc.. There is little point in trying to talk of sine waves because nothing from a musical instrument (except maybe a quiet flute) is anything like pure, A waveform is just a waveform so analysing it in terms of sinusoids is not always helpful.

Do you have any information from websites/videos etc about it that pickup doesn't run out of range ?

Any non linearity due to the string's motion through the magnetic field is inconsequential compared with the way the string itself behaves. Why would you be so interested in that aspect of the guitar?

 

[Averagesupernova]

@Xenon02 you have plenty of misconceptions. The pickup does not run out of headroom. Clipping is done in the amp, not the pickup as long as the pickup is passive meaning it doesn't contain its own preamp. Your diagram in post #56 is wrong. The black line is a summation of the 6 signals and I would say linear. The dotted yellow is a soft clipped signal. Why it is soft clipped I have no idea. There is no reference to anything in an amplifier which would cause this clipping.
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@sophiecentaur is correct in that the signal from each string will not be a pure sine wave to begin with.
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I don't understand why all this is so important to you when you don't even have a guitar. And then you want to build circuits to produce effects? Makes no sense to me.

 

[sophiecentaur]

I don't understand why all this is so important to you when you don't even have a guitar. And then you want to build circuits to produce effects? Makes no sense to me.

The OP may just want a way into circuit design and building. He has ended up down a rabbit hole, involving many more factors than are involved in making a low power amplifier.

 

[Baluncore]

I've used a bit of chatgpt he showed me some ideas and had some sense.

Chatgpt is an idiot. It has collected garbage for you from the web.
You need a better crap detector.

The pickup is linear, it does not limit the output.
The amplifier is non-linear, it does limit the signal at its input.