Why does a square waves sound detuned when in the lower range ?

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goldplate
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Why does a square waves sound detuned when in the lower range ?

Post by goldplate » Mon Mar 23, 2020 4:24 am

Why does a square wave sound detuned when its pitch is in the lower range ? A typical example is with a SH-101 sub oscillator. I initially thought it was an inner flaw, but doing some bassy squary chords on my Novation Peak made me found this seemed to be universal.

Then the next question is how to workaround this to get some better sounding squary basses...?

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Re: Why does a square waves sound detuned when in the lower range ?

Post by Navs » Mon Mar 23, 2020 10:59 am

I've heard this too - on an MC-202. I wonder if it's instrument specific, given the similarity between the two Rolands. Have you measured it with a tuner, is it off or is it just our ears?

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Re: Why does a square waves sound detuned when in the lower range ?

Post by wuff_miggler » Tue Mar 24, 2020 1:51 am

it happens to me all teh time.
i cant find the article to explain it...ffs.

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Re: Why does a square waves sound detuned when in the lower range ?

Post by ersatzplanet » Tue Mar 24, 2020 1:01 pm

Does it happen with a digital VCO? Though square waves are basically only odd harmonics, they may sound off tune, but it should be the same no matter what frequency you are playing. It would be interesting to see if it is really off, with a frequency counter, or just perceptually off.
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Re: Why does a square waves sound detuned when in the lower range ?

Post by wuff_miggler » Tue Mar 24, 2020 2:50 pm

happens to me with VSTs. so yeah prety sure same thing with DCOs. (sorry talking on op's behalf )

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Re: Why does a square waves sound detuned when in the lower range ?

Post by äggmedskägg » Tue Mar 24, 2020 3:24 pm

I checked with a digital oscillator, and it happened to me as well. But when I filtered out the harmonics it stopped happening, and I think it starts happening because the fundamental becomes to week because of either lack of bass in the speakers, or if your system can handle it, because it goes so low that your ears start saying "That's not a note, it's just vibrations". I'm not sure which is the case in my system, but that point is around C1 for me.

C1 with a sinewave doesn't sound out of tune. C1 with a squarewave totally does. An A1 sinewave has no pitch. I don't know if it's my ears or the subwoofer that is to blame. :-) So I'm leaning towards the theory that what you are actually hearing is the first odd harmonic.

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Re: Why does a square waves sound detuned when in the lower range ?

Post by wuff_miggler » Tue Mar 24, 2020 3:29 pm

nice one äggmedskägg that sounds spot on.

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Re: Why does a square waves sound detuned when in the lower range ?

Post by cg_funk » Tue Mar 24, 2020 3:32 pm

äggmedskägg wrote:
Tue Mar 24, 2020 3:24 pm
I checked with a digital oscillator, and it happened to me as well. But when I filtered out the harmonics it stopped happening, and I think it starts happening because the fundamental becomes to week because of either lack of bass in the speakers, or if your system can handle it, because it goes so low that your ears start saying "That's not a note, it's just vibrations". I'm not sure which is the case in my system, but that point is around C1 for me.

C1 with a sinewave doesn't sound out of tune. C1 with a squarewave totally does. An A1 sinewave has no pitch. I don't know if it's my ears or the subwoofer that is to blame. :-) So I'm leaning towards the theory that what you are actually hearing is the first odd harmonic.
Yeah, I think it's the sound of the fundamental dropping out of your hearing-range. When you go below audio-range, you start hearing the just the higher ODD harmonics only, and then it doesn't sound all in-tune. So another strange psycho-acoustic trick you can do on modular.

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Re: Why does a square waves sound detuned when in the lower range ?

Post by Homepage Englisch » Sun Jun 07, 2020 1:36 pm

Perhaps for the same reason piano strings are slightly detuned in the lowest and highest registers. Try googling "Railsback curve".

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Re: Why does a square waves sound detuned when in the lower range ?

Post by Michael O. » Sun Jun 07, 2020 1:47 pm

Like the others said, it’s the odd harmonics appearing louder than the fundamental, causing the perceived pitch to appear off. Especially with a sub oscillator like on a Roland, the fundamental may occasionally be so low In pitch that the waveform cycles so slowly that the pitch is imperceptibly low, maybe even just appearing as click sounds, which would be relatively quieter than the harmonics.

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Re: Why does a square waves sound detuned when in the lower range ?

Post by goldplate » Mon Jun 08, 2020 6:00 am

Nice find, thank you for your replies !

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Re: Why does a square waves sound detuned when in the lower range ?

Post by huffnPuff » Mon Jun 08, 2020 6:08 am

You know it's not detuned when you take an oscillator that's pitch-perfect and yet the derived sub-octave square - a mathematically perfect division by 2 (or 4) - sounds off. This alone should lead you to look elsewhere.

Another thing to look for, though it seems not to be the case in this instance, is air-tight earphones. The Sennheiser HD25 are totally useless when it comes to bass reproduction. They may do for mixing DJ sets (just barely, IMO they're good for news reporters in noisy environments and that's it) but certainly not for monitoring while playing an instrument, not even an electric guitar let alone a bass. I think it causes the ear to compress? Anyway this applies to all wave forms, not just square waves.

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Re: Why does a square waves sound detuned when in the lower range ?

Post by bollyhood » Thu Jun 11, 2020 7:26 am

huffnPuff wrote:
Mon Jun 08, 2020 6:08 am
You know it's not detuned when you take an oscillator that's pitch-perfect and yet the derived sub-octave square - a mathematically perfect division by 2 (or 4) - sounds off. This alone should lead you to look elsewhere.

Another thing to look for, though it seems not to be the case in this instance, is air-tight earphones. The Sennheiser HD25 are totally useless when it comes to bass reproduction. They may do for mixing DJ sets (just barely, IMO they're good for news reporters in noisy environments and that's it) but certainly not for monitoring while playing an instrument, not even an electric guitar let alone a bass. I think it causes the ear to compress? Anyway this applies to all wave forms, not just square waves.
Its not as basic as that I belive. Perfect math divisions will not always be perfectly in tune. I think the answer is that our ears are used to equal temperament tuning, and while the overtones/sub osc are mathematically perfect they will not be compensated like what were used to, I think thats the same thing as just intonation tuning.

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Re: Why does a square waves sound detuned when in the lower range ?

Post by huffnPuff » Thu Jun 11, 2020 8:19 am

An octave up is always twice the frequency, that's math (and physiology).

Intonation tuning - based on what I know from playing guitar - adjusts the distance between the saddle and nut per string so that the 12th fret achieves just that - a perfect octave.

You may be referring to the difference between 12-tet temperament and equal temperament; both assume mathematically perfect octaves. How you divide an octave is another issue, and unrelated to this thread.

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Re: Why does a square waves sound detuned when in the lower range ?

Post by bollyhood » Thu Jun 11, 2020 10:43 am

Yeah you're correct of course! But thats the fundamental and would be a sine if it only had a fundamental tone, and were talking about squarewaves, Im no expert in this field so I might be wrong.. Anyways I think this is interesting. I can try to explain what I mean a little deeper

Since a square is built from odd-number harmonics we have a lot more harmonic information compared to a sine. In the case of a squarewave C2 it would be like this: G3, E4, Bb4, D5, F#5, ... Not octave ratios here. Perfect octaves would have been a wavefolded sine, and would not become a square. Its these harmonic partials of the square Im interested in talking about, since these are from the just intonation tuning scale and not equal temperament (if i remember correctly, math and square experts please correct me if Im wrong haha), Im thinking this might be the case why were perceiving its pitch differently in low octaves, since we can hear more of the overtones compared to a higher note. I mean we can barely tell the difference between a sine and a square up in high octaves.

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Re: Why does a square waves sound detuned when in the lower range ?

Post by cornutt » Tue Jun 23, 2020 4:35 pm

How loud were you listening to it? Volume has a little bit of an effect on the perception of pitch. Particularly with bass tone, low volume makes it difficult for the ear to determine pitch.
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