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If you moved all of the waveform above the zero line, would there be any affect other than a drop in dynamic range?

You would have to scale the waveform or clip it, but if you did scale it, would it cause a problem for amplifiers or speakers? I would expect it not to. I understand the the speakers will be physically trying to stay within half of their normal envelope for excursion, so they're not going to sound as great as they could, but they would probably sound fine?

I'm not seeing a concrete requirement for the signal to have a negative phase. It makes sense but I would say that's mostly due to the design of the dynamic transducer and not even relevant to some other transducer types?

Cheers
 

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I am not sure what it is that you're driving at?

Taking your words literally, if you some how augmented all the waveforms to their zero crossing points, you would have no output amplitude and therefore no sound at all.

Speakers require AC signals to function properly, meaning swings from positive to negative.

The zero crossing point is merely the point of zero amplitude and an AC signal transitions from positive to negative, etc.

DJ's and other sampling artists look for this point to transition samples as the amplitudes and therefore volumes are neutral increasing the potential for a seamless mix, if you will.

In electronic device design, it has many other purposes.
 

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I'm not seeing a concrete requirement for the signal to have a negative phase.
As far as the digital aspect goes, we don't listen to digital signals, we listen to analog. At some point in the signal chain DAC must take place. If the signal to the speaker does not cross through zero it's DC, a pressure wave will not be created, so there will be no sound.
 

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As far as the digital aspect goes, we don't listen to digital signals, we listen to analog. At some point in the signal chain DAC must take place. If the signal to the speaker does not cross through zero it's DC, a pressure wave will not be created, so there will be no sound.
Oh really? :p

 

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If you moved all of the waveform above the zero line, would there be any affect other than a drop in dynamic range?
Yes. Firstly you would have a DC offset of 1/2Vpk being applied to the driver at all times which will reduce it's Xmax to 1/2 and add additional unnecessary heating to the coil. Secondly the transfer function of all drivers is worse with more excursion hence more distortion as you would be concentrating all the excursion requirements on one side of zero (rest) rather than swinging the signal around rest.

In an amplifier it's possible to only use one voltage rail. You'll still have the 1/2 Vee offset in a SS amp, but that can be removed by a capacitor or transformer at the output. Both these solutions have limitations which is why they're seldom used these days. There is no need to do this as complementary devices have been around for decades.

Tube amplifiers generally only have power supply and use the output transformer to remove the DC either by feeding PP output stages through the centre tap of the OPT so the DC flux cancels or by putting a large gap in the core in a SET.
 

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Oh really? :p

What the OP describes wouldn't look like that. It might make a sound, but it wouldn't be one you'd want to listen to.
 

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Actually that is what I was trying to describe. What if you feed that signal into an armature or an electrostatic system, would it sound bad?
Armature?
Yes, it would sound awful. The waveform shoe is simply a fully rectified sine wave so not hard to generate either in hardware or software. Try it yourself.
 

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I was a recording engineer for over 3 decades and a lot of the work I did was on classical music. The methods were different from pop/rock music where the engineer "punched in" on the recorder to fix problems. In classical sessions, the artist would do multiple takes and the editing engineer would "splice" them together (term from days of cutting tape). In a digital audio workstation, we try to do edits at the zero crossing to line up attacks of notes so the transition is seamless and you do not hear the edit. If you do a "butt splice" (no crossfade between the two regions), it can produce a pop or click. In the best case scenario, we use 1 ms equal power crossfade types to avoid the pops. Sometimes longer durations or different types of crossfades are necessary to make the edit imperceptible.

Jady described what you are seeing when you look at a zoomed in waveform. You have zoomed in to the sine wave level and see the transition of the waveform from positive to negative.

When you think of an acoustic sound, it has a positive and a negative pressure or a compression and a rarefaction as the source changes the air pressure and it impinges upon your eardrum.
 

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If you moved all of the waveform above the zero line, would there be any affect other than a drop in dynamic range?

You would have to scale the waveform or clip it, but if you did scale it, would it cause a problem for amplifiers or speakers? I would expect it not to. I understand the the speakers will be physically trying to stay within half of their normal envelope for excursion, so they're not going to sound as great as they could, but they would probably sound fine?

I'm not seeing a concrete requirement for the signal to have a negative phase. It makes sense but I would say that's mostly due to the design of the dynamic transducer and not even relevant to some other transducer types?

Cheers
I am not sure what it is that you're driving at?

Taking your words literally, if you some how augmented all the waveforms to their zero crossing points, you would have no output amplitude and therefore no sound at all.

Speakers require AC signals to function properly, meaning swings from positive to negative.

The zero crossing point is merely the point of zero amplitude and an AC signal transitions from positive to negative, etc.

DJ's and other sampling artists look for this point to transition samples as the amplitudes and therefore volumes are neutral increasing the potential for a seamless mix, if you will.

In electronic device design, it has many other purposes.
Oh really? :p

Actually that is what I was trying to describe. What if you feed that signal into an armature or an electrostatic system, would it sound bad?
I was a recording engineer for over 3 decades and a lot of the work I did was on classical music. The methods were different from pop/rock music where the engineer "punched in" on the recorder to fix problems. In classical sessions, the artist would do multiple takes and the editing engineer would "splice" them together (term from days of cutting tape). In a digital audio workstation, we try to do edits at the zero crossing to line up attacks of notes so the transition is seamless and you do not hear the edit. If you do a "butt splice" (no crossfade between the two regions), it can produce a pop or click. In the best case scenario, we use 1 ms equal power crossfade types to avoid the pops. Sometimes longer durations or different types of crossfades are necessary to make the edit imperceptible.

Jady described what you are seeing when you look at a zoomed in waveform. You have zoomed in to the sine wave level and see the transition of the waveform from positive to negative.

When you think of an acoustic sound, it has a positive and a negative pressure or a compression and a rarefaction as the source changes the air pressure and it impinges upon your eardrum.
It appears that I misread part of haroldini's original post.

I would add that the driver would produce some mechanical and therefore electrical overshot to the signal, making it appear not as uniform as the image above, and also making it sound much worse.

Damage wise, the drivers venting wouldn't be as sufficient therefore thermal saturation would be reached faster. One always has to keep a watchful eye out for mechanical limits, which are largely governed by the speakers enclosure.

I wouldn't want to test this out using a tweeter, regardless of bandwidth or input wattage.:)
 

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Actually that is what I was trying to describe. What if you feed that signal into an armature or an electrostatic system, would it sound bad?
Well actually, you have to understand whats going on.
Here is random image of internet.



On left you see normal soundwave which represents all music ever. In laymans terms, that black top and bottom line represents how high and low digital signal can go...you can never get past that point. If you digitally increase signals amplitude too much it will hit those limits and clip...literarly get chopped off like on picture on the right. It basically gets flattened up there and speakers don't really like that, but we will get to that later.

So, basically, you could grab whole soundwave and move it above "zero line" as you say it, however, anything that tries to get past the top "black line" will get clipped off, so while listening to it you will hear nasty amounts of distortion, which will, if you have fun loud enough, really quickly burn through your speakers.

Also, I am not aware of any software in existence that would allow something like that.
HOWEVER, if software allowed it, you could actually "shrink" the signal and place it above zero line without clipping. And, that would actually sound normal...no clipping or distortion. HOWEVER ( :D ). You have now caused a lots of problems that make your speaker work suboptimal. Lets say, for the sake of argument that your speaker driver has 1" excursion in each way. So at -1" cone is maximally backwards, at 0 its resting, and at +1" its maximally forward. And you are playing waveform that only exists above "zero line." Assume you have centered it, your new resting place for driver is now at 0.5" and therefore your maximal excursion for waveform you are playing will be only +0.5" (from 0" to +1").
So you have dramatically limited your speakers headroom, if you are not too careful you could overdrive it, plus its probably not good idea for cone to be offset by +0.5" (someone who actually knows how those damn things work could respond to this, if they didn't already :D)
 
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