Closest representation of power tube-only distortion

[thinkingchicken]

Just wanna share something. We are talking about power tube distortion again...

I'm not intended to compare which sounds better as what is good or bad is pretty subjective. I have no experience in building amps, no background in engineering, etc. but I'm starting to get interested into this stuff. I just wanna hear the distortion characteristics differences between different components such as power tubes like EL34, triodes, diodes, transistors, etc. But so far, I only found an example of power tube distortion.

The other day someone in a different online forum (The Gear Page) posted an audio about how a power tube distortion really sounded like. We can listen to the audio below.

https://soundcloud.com/ilya-v/power-tube-crossover

Then I open the audio file with Audacity and the waveforms are hard-clipped squarish waveforms.

power tube distortion.PNG

power tube crossover distortion.PNG

@katopan shared this picture below in the discussion about the waveforms generated by different stages in the Trainwreck Express amps a while back.

Distorted EL34 waveforms.PNG

If we compare the waveforms to what katopan shared and the waveforms from the audio, the waveforms are exactly the same. So, the audio is the closest thing we can hear about how a power tube distortion really sounds like. We understand we can make a power tube distortion sounds different from that by adding things like phase inverters, speakers, etc. which is basically how a normal amp works.

Thoughts?

[wpaulvogel]

One thing you have to understand is that it’s easy to use several probes and traces on a scope and watch the waveforms running into a dummy load from a signal generator and be able to have only the power tubes clipping. When you play a guitar into the same amp with the speakers, everything changes because the guitar produces multiple frequencies with a single note and the output of the guitar is anything but constant and the speakers are really never at a set impedance. Once all these variables exist, it’s impossible to quantify the results.
You will have to subject yourself to listening to a 1000hz noise clean RMS increasing to clipping while probing the different stages of a amp to hear what you’re asking about. I’ve done it and it’s not pleasant. I just enjoy the guitar overdriving the amp and run with it.

[maxkracht]

You can learn things from looking at the waves, but it is important to be aware of the limitations of a graphical representation. Essentially, those pictures tell you: the frequency (how often a wave repeats), the amplitude (how loud it is), and the envelope (attack, decay, sustain, release). It does not give any indication of the timbre of the sound. So, you could have three identical looking waveforms from three different instruments playing the same note.

[thinkingchicken]

One thing you have to understand is that it’s easy to use several probes and traces on a scope and watch the waveforms running into a dummy load from a signal generator and be able to have only the power tubes clipping. When you play a guitar into the same amp with the speakers, everything changes because the guitar produces multiple frequencies with a single note and the output of the guitar is anything but constant and the speakers are really never at a set impedance. Once all these variables exist, it’s impossible to quantify the results.
You will have to subject yourself to listening to a 1000hz noise clean RMS increasing to clipping while probing the different stages of a amp to hear what you’re asking about. I’ve done it and it’s not pleasant. I just enjoy the guitar overdriving the amp and run with it.

Interesting. Which stages you tested, is it just the power tubes or including the others such as the preamp tubes, etc.? Do they all sound the same or is there any difference?

[thinkingchicken]

You can learn things from looking at the waves, but it is important to be aware of the limitations of a graphical representation. Essentially, those pictures tell you: the frequency (how often a wave repeats), the amplitude (how loud it is), and the envelope (attack, decay, sustain, release). It does not give any indication of the timbre of the sound. So, you could have three identical looking waveforms from three different instruments playing the same note.

I noticed the differences of square wave distortion sounds from a cranked Marshall 18 Watt or TW Express, distorted preamp and typical distortion pedals. The hard-clipped square wave distortion either from distortion pedals or distorted preamp tend to be harsher, fizzier, grittier and sounds more synthier sounding than the cranked Marshall 18 Watt and TW Express. But I understand this is a generalization.

[Stevem]

In reality we don't necessarily like distortion, but the compression that comes along with it makes for sustain, and the harmonic overtones combined with the compression and gain levels needed to drive any section of a amp into distortion provide more touch sensitivity which we all love!

Putting up with the way some types of distortion and the added harmonics of them can bend 2 or more notes when played at the same time out of tune is my biggest peeve with what I hear out of way to many amps and on tons of recordings!