Exactly!Or if a player decides to plug in a booster or tube screamer and dime the amp...
I still remember buying a Boss Blues Driver that I really couldn't afford (still living on a tiny scholarship). I bought it because supposedly it was wonderful-sounding and made your amp sound better.
Well, when plugged into my already harsh-sounding solid state guitar amps, they didn't sound better. They sounded even worse.
And now we finally know why!
-Gnobuddy
I forgot to mention the role of V5/R11.
LTSpice doesn't include a TL072 model. I found one on the 'Web, and used it for this sim. This particular model seems to have some DC offset voltage built in. (A bit of additional realism I would be quite happy not to have. )
I DC-coupled the entire circuit to avoid false results due to phase-shifts in coupling capacitors potentially confusing the differential amplifier stage. That in turn meant that any offset voltage from U1 or U2 was amplified by every subsequent stage.
And that DC offset voltage also confused the differential amplifier (U3), causing non-zero Vout even if the incoming guitar signal wasn't clipped.
So I temporarily replaced the guitar signal with a single small-amplitude sine wave, added R11 and V5, and tweaked them until I got good-enough cancellation of signals A and B. Basically, I nulled out the DC offset voltage as best I could.
In case anyone wants to tinker with them, I'm attaching both the TL072 LTSpice model, and the full clipping detector circuit I used.
Drop the TL072.txt file in the same folder as GuitarClipDetector022.asc, and you should be good to go.
-Gnobuddy
LTSpice doesn't include a TL072 model. I found one on the 'Web, and used it for this sim. This particular model seems to have some DC offset voltage built in. (A bit of additional realism I would be quite happy not to have.
)I DC-coupled the entire circuit to avoid false results due to phase-shifts in coupling capacitors potentially confusing the differential amplifier stage. That in turn meant that any offset voltage from U1 or U2 was amplified by every subsequent stage.
And that DC offset voltage also confused the differential amplifier (U3), causing non-zero Vout even if the incoming guitar signal wasn't clipped.
So I temporarily replaced the guitar signal with a single small-amplitude sine wave, added R11 and V5, and tweaked them until I got good-enough cancellation of signals A and B. Basically, I nulled out the DC offset voltage as best I could.
In case anyone wants to tinker with them, I'm attaching both the TL072 LTSpice model, and the full clipping detector circuit I used.
Drop the TL072.txt file in the same folder as GuitarClipDetector022.asc, and you should be good to go.
-Gnobuddy
Not really, unless the pedal is set extremely conservatively, or a clean booster Most drive pedals clip the signal to some extent. Tube screamers certainly do.Or if a player decides to plug in a booster or tube screamer and dime the amp...
Cheers, and regards,
Ant
Thanks for chiming in! I remember previous posts on diyAudio where you mentioned seeing 5 Vpp from your guitar, and I was hoping you would confirm that here.
I think a lot of people would agree with you.
Statista.com claims that nearly 700,000 "instrument amplifiers" were sold in the USA alone, in the year 2021, down from 1.24 million in 2005: https://www.statista.com/statistics/448472/number-of-instrument-amplifiers-sold-in-the-us/
It's probably a safe bet that most of those "instrument amplifiers" were in fact guitar amplifiers (though some were probably keyboard amps or amps for electronic drums, and so on).
It's probably also a safe bet that most of those guitar amps were solid-state. And the vast majority - particularly in 2005 - were almost certainly analogue, built around op-amps in the preamp, and a power amp IC for the output.
In other words, guitar amp manufacturers have been successfully selling literally hundreds of thousands of amplifiers per year in the USA alone - surely that would be millions per year if we had statistics for the entire planet.
And we can guess that most of these amplifiers are of the type that sound harsh and unpleasant to me.
Evidently, they don't sound bad to the hundreds of thousands of people who bought them. Or at least, those buyers consider them good enough for their purposes.
(Many will be beginner amplifiers, many will be bundled with a starter guitar, sold as a pack at Walmart or Target or Best Buy in the months leading up to Christmas and New Year.)
Until recently, I tended to play with only clean tone 99% of the time. (The reasons are too long to go into here.)
That might actually be one of the reasons why I could hear that initial "gritty" distortion at the start of each note; if I had been playing with a heavier overdriven sound, the initial clipping would have been buried under all the other layers of distortion, and I wouldn't have been able to hear it.
I may be in the minority, but it's reassuring to know that I'm definitely not the only one (i.e. I'm not just a delusional nutcase). Many of the thousands of guitarists who stubbornly stuck with heavy, expensive, unreliable tube guitar amps, did so because they didn't like the way transistor guitar amps sounded.
It's hard to know exactly what they were hearing that they didn't like. But I'll bet a nice cup of coffee that it comes down to a handful of things, including harsh transients and "too clean" clean tones.
-Gnobuddy
Not sure I follow.
If the pedal is capable of more than 500mVpp output, it will push the amplifiers input stage harder than the representative Rod Elliott guitar signal I've been using, no?
-Gnobuddy
Certainly. But it's a much better starting point than a 20 mV sinewave signal at 300 Hz, which is sort of the de-facto test signal!
I've been thinking about this a little bit.
In order to simulate a signal that looked even somewhat similar to the reference guitar signal Elliott captured, I had to include frequencies up to nearly 1 kHz.
To resolve a 1 kHz waveform, we would ideally like to have 50 - 100 samples within one cycle - a sampling rate of 50 kHz - 100 kHz.
The note lasts for several seconds (Elliott used 3.75 seconds).
Sampling at 100 khz for 3.75 seconds leads to 375,000 sample points.
I don't think my Rigol DS1054Z can store that many data points.
Crappy 8-bit vertical resolution, and crappy low-pixel-count LCD displays factor in, too. It's hard to see any kind of subtle detail in a complicated waveform on my Rigol.
These days there are plenty of cheap microcontrollers that can sample at 100 ksamples/second or more, with better than 8 bit ADC resolution. The Arduino Due is one easy-to-use example. The Due "speaks" USB3, so I think it can feed 12-bit ADC samples at 100 ksamples/second continuously to a connected PC via USB-serial.
I think something like a Due with a suitable high-Z input buffer and overvoltage protection might be a good way to collect enough data points from a guitar signal to really see what's going on, and a PC, with its much bigger and much higher-resolution display, might be a much better way to look at the data, than an affordable DSO.
I'm buried in work and personal DIY projects at the moment, though, so I don't think I'm going to start building an Arduino Due guitar interface any time soon.
(The much newer Raspbery Pi Pico is a lot cheaper, and the ADC is certainly fast enough, but I think it's limited to USB 1.1 speeds; not sure of that, though.)
-Gnobuddy
You're assuming your initial pick attack/ whatever initial transient will get past the pedal clipping. I suggest that the top will get clipped off there before it hits the amp input, unless the pedal stays linear (for some value of linear, obviously )Not sure I follow.
If the pedal is capable of more than 500mVpp output, it will push the amplifiers input stage harder than the representative Rod Elliott guitar signal I've been using, no?
-Gnobuddy
Excellent thread, by the way!
Cheers, and regards,
Ant
We may have misunderstood each other a little, and maybe misunderstood Shanx as well.
But I think we all agree on the essentials of what's going on.
A boost pedal / dirt pedal will certainly clip. As you say, it will clip by design.
Depending on how it's set, its output may also be big enough to clip the amplifier it's plugged into as well.
Are we in agreement now?
As an aside: my favorite solid-state guitar amplifier is now my little Flamma FS06 Preamp pedal. It's nothing like a Tube Screamer or other crude logarithmic clipper - it's actually a collection of digitally modelled tube amps in an FX-pedal enclosure.
The Flamma is powered by only 9 V DC.
I'm betting whatever DSP chip is inside is powered by even fewer volts - most likely 3.3V.
In spite of which, to my ears, the Flamma doesn't suffer from any audible grittiness indicating harsh clipping.
It also doesn't suffer from the usual thin, cold, solid-state clean tones.
Amazingly, it actually manages to sound quite a lot like a collection of good tube amps - a promise that's been repeatedly made (and repeatedly broken) for at least thirty years now.
Thank you!
-Gnobuddy
Attack, sustain , release
Guitar is a complicated waveform controlled by the players hands.
Then depends on pickup type, and playing style.
The initial string attack peak will vary by the players attack strength.
Then of course the actual output the pickup is capable of.
The symmetry of the waveform will usually be asymmetrical.
It can be more positive or negative depending on down picking/plucking
or up picking/plucking
also depends if it is a open string or fretted string.
open strings will be more rooted with initial first harmonic.
and quickly change to second harmonic in sustain stage.
Fretted notes, obviously have to have the initial first harmonic.
but very quickly change to second harmonic in the sustain.
Understanding this is more thoroughly needed when designing
wavefolder, triggered envelopes, or root detecting circuits for guitar synths,
envelope generators, triggers or any other basic synth pedal.
and numerous early tracking octave up or octave down pedals
tended to have very poor tracking, and would track the correct note
with the pick attack, then quickly drift and track a octave higher in the sustain portion.
most players would adapt to the effect and you would have to change your picking
style to get the effect to track well. or tighter notes above the 7th or 12th fret would
track better. Since higher notes fretted tend to be more symmetrical at attack and sustain
Roland/Boss very famous for developing better filters and root detector signals
for frequency tracking effects and trigger/ envelope generators
In a nutshell the " average" factory passive pickup will have .5 to .7 volt
peaks at pick attack for single notes. And around .3 to .6 volt peaks for chords.
Hotter humbuckers can have 1 to 1.5 volt peaks for single notes
and .8 to 1.2 volt peaks for chords.
Very hot modern passive pickups can be up to 1.5 to 2.3 volts attack peaks.
if you want no clicks and grit at note attack with a solid state preamp.
You just use typical opamp design methods and typical 30 volt rails
for your opamp.
gain of 5 to 10 is typical for first stage, since it offers enough gain for
very low .3 volt signals and very hot 1.5 volt signals or higher.
as far as " distortion" signals it is the typical diode in feedback
and gain is minimum around 10 to 100 for saturation.
And with " metal" pedals more elaborate filters and gain stages.
first stage same gain of 100 the brought down to unity the a second or even third
gain stage which adds another gain of 100.
stability issues more common with distortion stages. since
pretty standard blues" distortion is already breaking most opamp rules
and using gain of around 100.
Marshall / Roland being smarter used multiple stages. first stage often around
10. then second stage around 10 to 20 to get typical sustain saturation
levels to be around the usual 100 for high gain/sustain.
Guitar is a complicated waveform controlled by the players hands.
Then depends on pickup type, and playing style.
The initial string attack peak will vary by the players attack strength.
Then of course the actual output the pickup is capable of.
The symmetry of the waveform will usually be asymmetrical.
It can be more positive or negative depending on down picking/plucking
or up picking/plucking
also depends if it is a open string or fretted string.
open strings will be more rooted with initial first harmonic.
and quickly change to second harmonic in sustain stage.
Fretted notes, obviously have to have the initial first harmonic.
but very quickly change to second harmonic in the sustain.
Understanding this is more thoroughly needed when designing
wavefolder, triggered envelopes, or root detecting circuits for guitar synths,
envelope generators, triggers or any other basic synth pedal.
and numerous early tracking octave up or octave down pedals
tended to have very poor tracking, and would track the correct note
with the pick attack, then quickly drift and track a octave higher in the sustain portion.
most players would adapt to the effect and you would have to change your picking
style to get the effect to track well. or tighter notes above the 7th or 12th fret would
track better. Since higher notes fretted tend to be more symmetrical at attack and sustain
Roland/Boss very famous for developing better filters and root detector signals
for frequency tracking effects and trigger/ envelope generators
In a nutshell the " average" factory passive pickup will have .5 to .7 volt
peaks at pick attack for single notes. And around .3 to .6 volt peaks for chords.
Hotter humbuckers can have 1 to 1.5 volt peaks for single notes
and .8 to 1.2 volt peaks for chords.
Very hot modern passive pickups can be up to 1.5 to 2.3 volts attack peaks.
if you want no clicks and grit at note attack with a solid state preamp.
You just use typical opamp design methods and typical 30 volt rails
for your opamp.
gain of 5 to 10 is typical for first stage, since it offers enough gain for
very low .3 volt signals and very hot 1.5 volt signals or higher.
as far as " distortion" signals it is the typical diode in feedback
and gain is minimum around 10 to 100 for saturation.
And with " metal" pedals more elaborate filters and gain stages.
first stage same gain of 100 the brought down to unity the a second or even third
gain stage which adds another gain of 100.
stability issues more common with distortion stages. since
pretty standard blues" distortion is already breaking most opamp rules
and using gain of around 100.
Marshall / Roland being smarter used multiple stages. first stage often around
10. then second stage around 10 to 20 to get typical sustain saturation
levels to be around the usual 100 for high gain/sustain.
I don't think we ever disagreed really.
That initial pick / pluck transient is always going to be there, and if the signal chain from guitar output to speaker is to be amplified without distortion, any amplifier will have to be capable of far higher wattage than is required for steady state. Doesn't matter whether that's a tube amplifier, or solid state.
Or that transient is going to need squashing somehow; either by compression or clipping.
There's a reason I still use 100W heads live: it's so that the clean tones have a chance. It certainly isn't for filth - 100W running flat-out on filth tones would take the back wall down at most places we play!
Yeah, the solid state / digital scene is doing some very interesting things at the moment. I'm currently playing around with a TC IR loader. It does a good job of cab modelling, and can at a push simulate a "clean" tube amplifier too, depending on where you insert the impulse. I don't know what bit depth the processing is in that off the top of my head; but it is sounding pretty good.
I suspect the lack of decent solid-state guitar amps is down to the usual culprits: hard(er) clipping from solid-state pre- and power amplifier stages when compared to their tube counterparts, and less care of the tone-shaping through the circuit stages. I suppose that's a design / cost thing, and in any case it mostly goes out of the window when you smack a distortion pedal in front of it all. Sure, an old non-Master Volume Marshall / Fender did not do much there either, but on more sophisticated amps with dedicated filth channels, the tone-shaping through the filth channel stages is pretty critical. And, of course, subjective! (Example: I've always wanted to like Mesa Boogies, but I've never been able to dial in a filth sound that I liked on any of them that I have tried. Plenty of distortion, but they always seemed a bit ice-picky to my ear, and I find it impossible to dial that out.)
Cheers, and regards,
Ant.
Thanks for posting that image here. I remember seeing it in one of your posts on the HBAC thread.
By the way, stumbling across the HBAC thread via a Google search - after the brass band had left and most of the dust had settled - was the main reason why I joined diyAudio in the first place.
One of the more striking things about the guitar waveform you captured is how very spiky it is. That means lots of high overtones, and very little fundamental frequency.
I think that may be the spikiest guitar waveform I've ever seen.
Something to do with the stiff guitar pick, probably, and maybe the pickup position (very near the bridge?).
-Gnobuddy
Attachments
We've already talked about how the curvature of a triode transfer characteristic tends to round off negative signal peaks from the guitar.
But one thing I've forgotten to mention until now is that a tube input stage almost certainly squashes positive going (input) signal peaks as well.
One way in which this happens is well understood - a positive input signal causes the anode to swing negative, and if it swings far enough, anode-cathode voltage drops low enough for the triode to start to "bottom out".
I think there is a second mechanism as well, and I've never heard anyone else bring it up when talking about tube guitar input stages.
Consider a typical half-12AX7 input stage. Vgk is typicall around -1.5 V. A positive input signal peak of, say, +1.2 V brings the grid within 0.3 volts of the cathode, at which point there is already some grid current flow. The input resistance of the tube drops from near-infinity down to some 50 kilo ohms; given the high source impedance of an electric guitar, this is low enough to start to squash the signal peak.
Obviously even bigger positive-going input signals will bring the input grid close to 0V, maybe even slightly positive, input resistance can drop down to just a few kilo ohms, and that big positive peak will be squashed significantly.
If I'm right, uncomfortably large positive signal peaks from the guitar will be squashed right at the input grid itself, and then squashed once again at the anode as it runs out of voltage.
I've suspected this for a long time, but lacked accurate data showing grid current vs Vgk in the vicinity of Vgk = 0.
Today I spotted some interesting data posted by diyAudio member bmc0 about the input resistance of a half-12AX7 when Vgk is near zero, or slightly positive. See posts #266 and #269 in this thread: https://www.diyaudio.com/community/threads/building-a-ss-guitar-amp.381758/page-14#post-7157552
As we've already discussed, uncomfortably large negative signal peaks will also be squashed, this time because of the curvature of the triode characteristics near the origin. And then squashed some more at the input of the second gain stage, because they've been turned into positive-going signal peaks by the signal inversion in the input stage.
Soft signal limiting right at the input - that may be part of "tube mojo" that's been quite overlooked. Now that we suspect this, can we engineer it into solid-state input preamps? Do we need anti-parallel red LEDs (or a couple of 1N4148s in series in each direction) right at the input of an SS guitar amp?
The two attached images are interesting. I've added a pair of anti-parallel 1N4148 diodes in series with a 10k resistor across the output of the e-guitar, and plugged in a guitar source resistance equivalent to the Thevenin resistance of a 500k volume pot set at half-resistance.
The red trace is the signal straight from point C, the simulated guitar pickup (the stack of voltage sources). The blue trace is the signal at point D, which would then be fed into the op-amp input stage.
With this particular input signal (the one modelled off one of Rod Elliott's measured data), LTSpice thinks that even with only 500 mVpp of initial signal, the clamping diodes flow a couple of hundred nano amperes, enough to significantly squash the biggest signal peaks.
LTSpice also thinks the diode clampers produce much softer signal limiting than the harsh clipping of the TL072 in the earlier sims I did.
I've never been a big fan of the sound of diode clippers. But if you must use an op-amp to amplify e-guitar, maybe adding antiparallel clipper diodes at the input is the lesser of the two evils?
Maybe somewhat harsh diode clipping is better than even harsher op-amp clipping?
-Gnobuddy
But one thing I've forgotten to mention until now is that a tube input stage almost certainly squashes positive going (input) signal peaks as well.
One way in which this happens is well understood - a positive input signal causes the anode to swing negative, and if it swings far enough, anode-cathode voltage drops low enough for the triode to start to "bottom out".
I think there is a second mechanism as well, and I've never heard anyone else bring it up when talking about tube guitar input stages.
Consider a typical half-12AX7 input stage. Vgk is typicall around -1.5 V. A positive input signal peak of, say, +1.2 V brings the grid within 0.3 volts of the cathode, at which point there is already some grid current flow. The input resistance of the tube drops from near-infinity down to some 50 kilo ohms; given the high source impedance of an electric guitar, this is low enough to start to squash the signal peak.
Obviously even bigger positive-going input signals will bring the input grid close to 0V, maybe even slightly positive, input resistance can drop down to just a few kilo ohms, and that big positive peak will be squashed significantly.
If I'm right, uncomfortably large positive signal peaks from the guitar will be squashed right at the input grid itself, and then squashed once again at the anode as it runs out of voltage.
I've suspected this for a long time, but lacked accurate data showing grid current vs Vgk in the vicinity of Vgk = 0.
Today I spotted some interesting data posted by diyAudio member bmc0 about the input resistance of a half-12AX7 when Vgk is near zero, or slightly positive. See posts #266 and #269 in this thread: https://www.diyaudio.com/community/threads/building-a-ss-guitar-amp.381758/page-14#post-7157552
As we've already discussed, uncomfortably large negative signal peaks will also be squashed, this time because of the curvature of the triode characteristics near the origin. And then squashed some more at the input of the second gain stage, because they've been turned into positive-going signal peaks by the signal inversion in the input stage.
Soft signal limiting right at the input - that may be part of "tube mojo" that's been quite overlooked. Now that we suspect this, can we engineer it into solid-state input preamps? Do we need anti-parallel red LEDs (or a couple of 1N4148s in series in each direction) right at the input of an SS guitar amp?
The two attached images are interesting. I've added a pair of anti-parallel 1N4148 diodes in series with a 10k resistor across the output of the e-guitar, and plugged in a guitar source resistance equivalent to the Thevenin resistance of a 500k volume pot set at half-resistance.
The red trace is the signal straight from point C, the simulated guitar pickup (the stack of voltage sources). The blue trace is the signal at point D, which would then be fed into the op-amp input stage.
With this particular input signal (the one modelled off one of Rod Elliott's measured data), LTSpice thinks that even with only 500 mVpp of initial signal, the clamping diodes flow a couple of hundred nano amperes, enough to significantly squash the biggest signal peaks.
LTSpice also thinks the diode clampers produce much softer signal limiting than the harsh clipping of the TL072 in the earlier sims I did.
I've never been a big fan of the sound of diode clippers. But if you must use an op-amp to amplify e-guitar, maybe adding antiparallel clipper diodes at the input is the lesser of the two evils?
Maybe somewhat harsh diode clipping is better than even harsher op-amp clipping?
-Gnobuddy
Attachments
Instead of simulating based on vague assumptions a simple real world measurement is setup within 10 minutes. The plot depicts a max hard stroke on the low E-string using the bridge pickup of my strat. To measure this you certrainly do not need 4 seconds record, and 8 bits ADC is enough resolulation as well. To get the abs max peak the only thing you do is increase trigger level as much as possible in the "normal" trigger mode. This was the highest level I could produce, playing "normally" levels are a fraction of this.
Attachments
Last edited:
The next thing to do is use another of the four channels on that scope, to display the output of a sonically approved guitar amplifier made of 100% vacuum tubes, when fed that very same guitar pickup signal. You may be able to discover whether it "clips" or "limits" or "compresses" or "squashes" or "poops out" when amplifying that guitar pickup signal.
Thank you for the plot you posted.
To capture one specific waveform, sure, a ten minute experiment with a DSO might be enough.
To prove that an input stage op-amp actually does clip, and to provide details of how, when, where, and why it clips, no your ten-minute experiment isn't enough.
But if you're feeling energetic, by all means build my four-op-amp clipping detector, run your guitar through it, and capture the actual clipping behaviour of some typical solid-state input stages.
That would take me a few hours to do properly. I doubt you can do it in ten minutes, either.
While the image you posted does say something specific about your guitar and your picking technique, we still have only what you called "vague assumptions" about the general case. (An assessment I do not agree with, by the way.)
For example, other diyAudio members have posted very different data - one member showed 10 volts peak-to-peak straight from his guitar pickup - more than five times larger than the plot you captured.
There will always be dramatically different results between different guitars, different string gauges, different plectrum (pick) stiffnesses, different picking styles, different types of guitar pickup, et cetera.
-Gnobuddy
Exactly. And that is why my plot is a only one individual example - not relevant to your needs. Relevant to your personal needs are your real measurements. All I wanted to show is how simple it is to capture the real percussion peak.
This is a goal we should definitely strive for - but how do you actually capture and display subtle squashing of a handful of few-millisecond signal peaks buried in several thousand cycles?
The clipping detector circuit I came up with works to show the failings of a hard-clipping op-amp, which reproduces the waveform virtually perfectly except for those instants when it clips.
But I can't think of a way to do the same with a "squashy" input stage that's doing some relatively soft peak limiting. If the signal coming out of the guitar is already being squashed by the tube input, we don't have an un-squashed reference signal to compare it with.
We could certainly detect places where the "squashy" tube circuit was departing from perfect op-amp-like accuracy. But how would we tell (objectively) that the result was better than the harsh-clipping op-amp circuit?
Maybe guitar -> unity-gain op-amp buffer -> series resistor -> squishy tube amp input would work. We could tap off the signal straight from the buffer, and compare with the signal from the tube amp.
But this is not quite the same as "guitar straight into a tube amp". Arguments and disagreements would surely ensue.
Phase-shifts from capacitor coupling would also have to be dealt with to get useful results. I avoided this in my LTSpice simulations by keeping everything DC coupled. But it's not so easy to do that with an actual tube amp.
-Gnobuddy
This is indeed a very real thing.
It gets worse on subsequent stages if they are capacitively coupled. As the grid starts conducting, the cap charges up, effectively shifting the bias more negative until it discharges again. That can cut the tube off completey for a while after a large transient. Blocking distortion.
A suitably large grid stopper mitigates this somewhat (though it might roll off the top end via Miller capacitance if its a common cathode stage) , and smaller capacitors reduce the recovery time.
Power stages are prone to it too.
Cheers, and regards,
Ant
It gets worse on subsequent stages if they are capacitively coupled. As the grid starts conducting, the cap charges up, effectively shifting the bias more negative until it discharges again. That can cut the tube off completey for a while after a large transient. Blocking distortion.
A suitably large grid stopper mitigates this somewhat (though it might roll off the top end via Miller capacitance if its a common cathode stage) , and smaller capacitors reduce the recovery time.
Power stages are prone to it too.
Cheers, and regards,
Ant
On which of my several guitars? Playing which song? Verse or chorus? At the emotional peak of the song, or at the languid introduction? On a day when I'm hyped and excited, or on a day when I'm exhausted after work, and just barely found the energy to drag myself to the music jam?
There simply isn't one "real" measurement to be had, and I don't understand why you seem to think there is.
Newton's equation f = m a is incredibly powerful because it is general, and therefore, applicable to millions of different situations. It is the universality of the equation that made this an incredible advance for humanity.
If Newton had instead measured the force and acceleration on one apple, and said "0.94 Newtons of force applied to this one apple resulted in an acceleration of 9.8 metres per second", that would have been virtually useless to anybody.
In the present case, the best we can do is get a number of individual data points, and draw some generalized conclusions.
The most important conclusions we can draw are the ones which apply generally to most e-guitars. Conclusions about your specific e-guitar, or one of mine, on one particular day, at one particular time, are much less useful.
Several key points have already been made:
One, we can make a usefully realistic guitar signal in LTSpice.
Two, that signal has already revealed clipping in a solid-state input stage.
Three, that revelation is already leading to new ideas to explore.
Nobody here was in doubt about how to capture a trace on a DSO.
But do realize that capturing only a short part of the beginning of a note reveals only one thing - the instantaneous peak voltage.
It doesn't reveal many of the other things that can be seen in Rod Elliott's 3.75 second captures. I discussed several of these in post #2.
-Gnobuddy