One sided waveforms?

[Arpangel]

I’m regularly getting waveforms in Reaper that are constantly one sided, like I only see the lower part of a waveform, with little above that.
Is this something to do with DC offset issues? I seem to remember reading about this somewhere, but can’t remember.

[Mike Stranks]

Music? Voice? If music which instrument(s)?

An image/screenshot would be useful...

Assymetric waveforms are not at all uncommon and usually nothing to do with DCO... there are regular discussions here - including just last week iirc.

[Arpangel]

Music? Voice? If music which instrument(s)?

An image/screenshot would be useful...

Assymetric waveforms are not at all uncommon and usually nothing to do with DCO... there are regular discussions here - including just last week iirc.

Anything, any sound, sometimes the waveform is entirely in the positive, or negative.
I’m wondering if there’s some sort of phase cancellation going on, somewhere in the signal chain?

[ef37a]

MoooHASSIVE even harmonic distortion Tone!

Dave.

[Hugh Robjohns]

I’m regularly getting waveforms in Reaper that are constantly one sided, like I only see the lower part of a waveform, with little above that.

There are lots of perfectly natural reasons why this can occur, and it's usually to do with the harmonic composition (and the phase relationships of those harmonics) within the signal.

Asymmetry is very common with voices, brass and simple synthesizer sounds, for example.

https://www.soundonsound.com/sound-advi ... lop-sided

Is this something to do with DC offset issues?

DC offset issues are extremely rare and the kind of fault condition today that could cause them would be evident in other, more obvious ways.

But if it was a DC offset you would see a decaying waveform settling away from the centre line, whereas an asymmetrical waveform will settle on the line.

My advice, stop looking at the pretty pictures and concentrate more on the lovely sounds....

[Hugh Robjohns]

I’m wondering if there’s some sort of phase cancellation going on, somewhere in the signal chain?

Some sort of weird phase cancellation that only removes negative half cycles? That's clever!

[Arpangel]

Thanks folks, it’s mainly on accordion, if that helps?

[ef37a]

Thanks folks, it’s mainly on accordion, if that helps?

Vivre la difference!

I agree with Hugh. 'Pictures' can be off putting and in any case the 'waveforms' you get in DAWs are not 'true' in the sense of that which an 'scope would display (and that would be different for various timebase and trigger/delay settings)

Sound 'pictures' have a place in the home studio but mainly as a diagnostic tool. When son was here making music he would 'experiment' with various gear lashups. Once a week or so I would run a Right Mark Anny test and almost always pickup hums above my -93dBFS baseline noise floor. Some re dressing of mains and audio cables usually restored quietitude.

Dave.

Dave.

[Hugh Robjohns]

Thanks folks, it’s mainly on accordion, if that helps?

Think about how the accordion makes its sound, and how that might be conveyed in sound pressure variations....

[Drew Stephenson]

It's almost like physics or something.

[Hugh Robjohns]

There is a difference between a sound engineer and a recording technician. One knows which buttons to press. The other knows what happens when the buttons are pressed!

[Arpangel]

Thanks folks, it’s mainly on accordion, if that helps?

Think about how the accordion makes its sound, and how that might be conveyed in sound pressure variations....

You have got a point there Hugh, my friend explained to me, his accordion has three reeds, which you can switch in and out, that produce different chorusing effects, which may have something to do with it.

[Hugh Robjohns]

No, it doesn't.

[MOF]

There is a difference between a sound engineer and a recording technician. One knows which buttons to press. The other knows what happens when the buttons are pressed!

No one told me anything about pressing buttons.

[shufflebeat]

Thanks folks, it’s mainly on accordion, if that helps?

Think about how the accordion makes its sound, and how that might be conveyed in sound pressure variations....

You have got a point there Hugh, my friend explained to me, his accordion has three reeds, which you can switch and out, that produce different chorusing effects, which may have something to do with it.

Possible idiot question here but they are my specialty:

Taking this from the "moving air = moving diaphragm" end of the process, are we suggesting that the diaphragm gets pushed away from the resting position and doesn't recover properly to zero?

There is a difference between a sound engineer and a recording technician. One knows which buttons to press. The other knows what happens when the buttons are pressed!

No one told me anything about pressing buttons.

i thought that was the difference between an accordion player and an accordion maker.

[Hugh Robjohns]

Certainly not an idiot question, and one that comes up often.

Taking this from the "moving air = moving diaphragm" end of the process, are we suggesting that the diaphragm gets pushed away from the resting position and doesn't recover properly to zero?

No, that would be the acoustic equivalent of a DC offset.

If you think of a plucked acoustic guitar string, or a violin, the string vibrations are equal back and forth, so the compressions and rarefactions in the air pressure are balanced. So the waveform captured by a microphone is more or less symmetrical (harmonic phases permitting)

But in air-blown instruments -- voices, brass, accordions etc, the noise generation requires constant positive air pressure so the vibrating reed (etc) will inevitably create stronger compressions (because they are 'power-assisted') than rarefactions (which have to fight against the causation pressure), hence an asymmetrical waveform is produced.

But when the wind stops blowing the vibrating sound enerator decreases and the waveform decays to normal ambient pressure.

[shufflebeat]

If you think of a plucked acoustic guitar string, or a violin, the string vibrations are equal back and forth, so the compressions and rarefactions in the air pressure are balanced. So the waveform captured by a microphone is more or less symmetrical (harmonic phases permitting)

But in air-blown instruments -- voices, brass, accordions etc, the noise generation requires constant positive air pressure so the vibrating reed (etc) will inevitably create stronger compressions (because they are 'power-assisted') than rarefactions (which have to fight against the causation pressure), hence an asymmetrical waveform is produced.

But when the wind stops blowing the vibrating sound enerator decreases and the waveform decays to normal ambient pressure.

Got it. So if I'm understanding correctly that's a similar situation to that which I was describing but happening at the instrument reed rather than the mic diaphragm. Is that what you're suggesting?

[Hugh Robjohns]

So if I'm understanding correctly that's a similar situation to that which I was describing but happening at the instrument reed rather than the mic diaphragm. Is that what you're suggesting?

Yes, I guess so.

[shufflebeat]

So if I'm understanding correctly that's a similar situation to that which I was describing but happening at the instrument reed rather than the mic diaphragm. Is that what you're suggesting?

Yes, I guess so.

It sometimes seems like numbers and diagrams exist in their own separate reality, particularly when they are describing movement of electrons.

For the relatively innumerate like myself it's reassuring to have a good old imaginary model of wood, metal and air that corresponds clearly with the numbers that represent it.

Much appreciated.

[Arpangel]

I was just curious, it sounds good, so that’s OK.