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Why can't you tune your guitar? (2019)

ethanhein.com

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Re: Why can't you tune your guitar? (2019)

#91

Post by hn_throwaway_99 »

Woah, so cool when a topic I was going into in depth gets to HN.

I'm a relatively new adult beginner on the violin, and one of the fascinating (and extremely difficult) things about un-fretted string instruments is the player has the freedom to shift the tuning around to fit the context. On the violin, we normally play melodies and scales using Pythagorean tuning (which is actually a misnomer as Pythagoras didn't invent it, the ancient Mesopotamians did), which is based on the circle of fifths and leads to wider whole steps and narrower half steps than equal temperment tuning. But then for double stops (i.e. chords), and especially when playing in a string quartet, just intonation, which is based on the harmonic series, is used so the notes sound concordant. This page describes all the different tuning systems a violinist may use, also including 12 TET when trying to match a piano: https://www.violinmasterclass.com/posts/152.

This video shows how challenging it can be when trying to adjust intonation when playing in a string quartet: https://youtu.be/Q7yMAAGeAS4 . Interestingly, the very beginning of that video talks about what TFA discussed that when you tune all your strings as perfect fifths your major thirds will be out of tune.

I'll also put in a plug for light note, an online music theory training tool that was mentioned on HN a decade ago: https://news.ycombinator.com/item?id=12792063 . I'm not related to the owner in any way, I just bought access a few years ago and think it was the first time I really understood Western music theory. The problem with music theory is that the notation is pretty fucked up because it includes all this historical baggage, and lots of music theory courses start with what we've got today and work backwards, while I think it's a lot easier to start with first principles about frequency ratios and go from there.

Other notes (pun intended!): The violin is great for learning music theory because you can actually see on the string how much you're subdividing it - go one third of the way, that's a perfect fifth, go halfway, that's an octave, etc. Harmonics (where you lightly touch a string) are also used all the time in violin repertoire. Finally, the article mentions Harry Patch, but you should also check out Ben Johnston, a composer who worked with Patch and was famous for using just intonation. Here is is Amazing Grace string quartet, and you can really hear the difference using just intonation: https://youtu.be/VJ8Bg9m5l50

Re: Why can't you tune your guitar? (2019)

#92

Post by tadfisher »

_alternator_ wrote: post #41
xcf_seetan wrote: post #14

Actually is not a guitar problem, but all 12-TET tuned instruments have this, it is just a side effect of harmonic math. In the guitar case it is not only the tuning that counts, also the material the string are made and the diameter of the strings count to the final frequency, and we are using parallel frets so applying the same distance to different strings. There are guitars with not parallel frets that try to com…

Another thing that’s not been mentioned here: there is a relationship between volume and pitch. In short, you strike a string hard and it goes a bit sharp. The issue is that the tonal math makes a linearization of the string physics, but the highly activated string is effectively a little tighter than the idealized version.

Humans are also not perfect at fretting with the exact same pressure every time, or without inducing some bend in the strings. This is really noticeable with the G string which always sounds out of tune while playing, because our tuning system gives it a half-step-down intonation as a trade-off to make it easier to form chords.

James Taylor compensates by tuning everything down a few cents, between -12 at the low E and -3 at the high E, with a little break in the pattern with -4 cents at the G to deal with its weirdness. Good electronic tuners have "sweetened" presets which do something similar.

Re: Why can't you tune your guitar? (2019)

#93

Post by actsasbuffoon »

post-it wrote: post #28

> If you watch slow-motion video of a guitar string vibrating, you’ll see a complex, evolving blend of squiggles. These squiggles are the mathematical sum of all of the string’s different harmonics. This is incorrect. If you watch a video like [0], the squiggles aren't real, they're an artifact of a rolling shutter camera. A real slowmo camera will correctly show the entire string vibrating[1]. The rest of the articl…

Not sure if I’m misunderstanding your claim. A string does vibrate as the sum of the string’s harmonics. That’s how pinch harmonics work, and they wouldn’t work if that wasn’t the case.

You poke a spot where a given harmonic doesn’t vibrate, and that takes energy away from the other harmonics that do need to vibrate at that spot.

If we’re just talking about visually being able to see them, I suppose that’s a different question. Maybe on an incredibly low pitched string, or with a strobe light playing at a synced frequency? But in terms of what the string is doing, it is vibrating as the sum of its harmonics.

Re: Why can't you tune your guitar? (2019)

#94

Post by NobodyNada »

PaulDavisThe1st wrote: post #85
JohnMakin wrote: post #39

I was born with something not quite like perfect pitch, but when something is even slightly off tune it caused physical discomfort for me. My cs department had a cool project class where you built what was basically a raspberry pi with a microcontroller by hand, and you had to use the dumb speaker and controller to make your own music firmware to produce notes. the challenge involved, was basically, the processor’s c…

I've been doing audio software for 25-30 years. I have no idea what sort of synthesis you'd be doing where the processor clock played any roll at all. Waveform synthesis is normally done in buffers (8 to 8192 samples), and the "clocking" to convert the sample stream into an analog waveform is done by the audio interface/DAC, not the CPU. If you were basically implementing a DAC, then yes, the clock would matter a lot…

> you built what was basically a raspberry pi with a microcontroller by hand, and you had to use the dumb speaker and controller to make your own music firmware to produce notes

This sounds like they were most likely bit banging square waves into a speaker directly via a GPIO on a microcontroller (or maybe using a PWM output if they were fancy about it). In that case, the audio frequency will be derived directly from the microcontroller's clock speed, and the tolerance of an internal oscillator on a microcontroller can be as bad as 10%.

Re: Why can't you tune your guitar? (2019)

#95

Post by tadfisher »

criddell wrote: post #54
52-6F-62 wrote: post #5

Absurd. A guitar within tolerance is in tune. It's a fundamental feature of the instrument. Not a flaw. Music doesn't live in an abstract realm of perfections, it is an expression however formed. The fact that we can measure it is one thing. But the music or instruments do not need conform to discrete measurements to satisfy. I know engineers hate this, but ask any musician. It's like arguing that a sitar and its sca…

Engineers hate it and so they invented the true temperament guitar. It’s like a regular guitar except the frets are a bit funky.

Even those are not "true-temperament" instruments like a piano, they adapt a "well-temperament" tuning system like Bach's keyboard tuning [0]. The end result is closer to true-temperament in some keys, and farther in others.

Oh, and that applies to standard tuning only. YMMV with alternative tunings, especially the open tunings.

0: https://www.guyguitars.com/truetemperament/eng/tt_techdetail...

Re: Why can't you tune your guitar? (2019)

#96

Post by jmkr »

Zuider wrote: post #74
goblin89 wrote: post #45

Earlier quoted context omitted.

With an ordinary fretted guitar, you can sort of perfectly tune it to what you play but not perfectly tune it in a global sense. That’s an issue with tuning instruments in general, and why pianos are generally slightly out of tune as a compromise. As you get used to a particular guitar and strings, as you train your ear, you can also learn to work around the imperfections by adjusting how you hold down the strings (e…

Classical guitarists are used to pushing nylon strings into consonance by compressing the string either towards the nut or the bridge. Not so easy with steel, where players will just preemptively retune to whatever chords are most prominent in the song.

I play with generally lighter strings. 8.5-40 mighty slinky fender scale. I noticed when I switched my fingers pay much more attention to pressure, and being in tune with microbends.

Been thinking of going a bit lighter recently, and also getting a classical.

Re: Why can't you tune your guitar? (2019)

#97

Post by tadfisher »

GRiMe2D wrote: post #36
amelius wrote: post #9

> If thirds and fifths are so out of tune in 12-TET, why do we use it? The advantage is that all the thirds and fifths in all the keys are out of tune by the same amount. None of them sound perfect, but none of them sound terrible, either. Can't we have a system that is optimized for the notes that are actually played in a song rather than the hypothetical set? And what if the optimization is done per small group of…

Actually Bach's Well Tempered Clavier IS a book written in a single set of tuning system that actually lost/forgotten. We still have discussions about how it's constructed. For more information google "Well Tempered Clavier interpretation" You can listen to variations here: https://youtu.be/kRui9apjWAY?t=622

Neither lost nor forgotten! It's the basis for the "Thidell Formula 1" temperament [0], which is what produces those squiggly frets on expensive guitars. It also works well for multiple keys (at the expense of others), making it a compromise for a range of music rather than a single song.

0: https://www.guyguitars.com/truetemperament/eng/tt_techdetail...

Re: Why can't you tune your guitar? (2019)

#98

Post by RealityVoid »

analog31 wrote: post #52
RealityVoid wrote: post #46

Earlier quoted context omitted.

Do say more! What was the problem with the clock, more exactly? I believe you, I've had issues caused by clock skew and CAN bus for example, when you have a small error that is amplified on beach bit enough time, errors add up and you eventually get out of synch. But in the case if sound, I would have expected the skew to be less of a problem. Also surprised how the orof instantly know. It took me a while to figure o…

One simplistic way is to successively add a small constant to a large integer, and generate the waveform from the most significant bits. A "cent," which is 1/100 of a semitone, is a factor of about 580 parts per million, so you can work out the precision needed for the constant. On a microcontroller, you can control the timing with a PWM, which runs independently of the processor and its timing foibles. Proof is left…

> On a microcontroller, you can control the timing with a PWM, which runs independently of the processor and its timing foibles.

That is not really true. You usually have a couple of clock sources on a MCU, but the clock gets propagated down the clock tree and the source, and most of the times, the PWM has the same source clock as the CPU. Indeed, I think if you're before the PLL the clock is more accurate as in you get less jitter but the overall drift is the same. You might have distinct clock sources but you need a specific hw and a specific configuration.

Re: Why can't you tune your guitar? (2019)

#99

Post by fortran77 »

Piano tunings are also "stretched" so that the harmonics are more in tune. This is especially needed on verticals and short "baby" grands. See https://en.wikipedia.org/wiki/Stretched_tuning

I have software I use when I tune my Bosendorfer 290 that calculates the stretch. Of course, the final tweaks are done by ear.

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