A Question That Has Burned In My Mind For Years...

[Gepetto]

More fun:
Sawtooth, sine, and square waves of different frequencies combined! View attachment 50115

Each driver will only see a piece of this after being processed by the crossovers. For example, the woofer will only see a very integrated portion of that complex waveform.

 

[MarkWComer]

Each driver will only see a piece of this after being processed by the crossovers. For example, the woofer will only see a very integrated portion of that complex waveform.

Yes, this is correct! The whole of this waveform is presented to the crossover network prior to reaching the driver voice coils, various frequency ranges are divided and then sent to the appropriate driver. The net result reaches the ears as a recombined complex waveform. A 12" woofer doesn't do well with a 15kHz signal- the mass is too large for such a rapid change in velocity, conversely, a 1" tweeter can't push enough air to make a 35Hz signal audible.

 

[pennysdad]

... & yet a microphone does the whole thing with only one tiny little diaphragm.

 

[George S.]

If you had a driver with zero mass and no reactance (inductance or capacitance) in the voice coil, you would eliminate the mechanical time constant and electrical time constant associated with real world woofers and tweeters. If those zero time constant drivers were operated in a perfect vacuum, you would approach an ideal driver situation. Unfortunately they have to move air to be effective and let you hear anything

Probably why modern drivers are smaller and more compliant then the old ones we grew up with

 

[laatsch55]

... & yet a microphone does the whole thing with only one tiny little diaphragm.

Ahhhh yes ...the initial conundrum..

 

[laatsch55]

Lively discussion there fellers, thanks Mark, you graphs explain things very well.

I find it amazing a driver can do what it does...even the harmonics..

 

[pennysdad]

Ahhhh yes ...the initial conundrum..

I've been asking the same question as your initial post Lee all the years I was a Live Sound guy. Never got it, and after reading all the complicated responses, I know I never will.
I used to sit and stare at a cone for hours wondering 'how are you doing all of that at the same time?'
I guess some of us will never get it, but I thank the powers that be for letting me be one of the best sound guys this planet has ever heard, regardless....

 

[laatsch55]

Bless your heart George..

 

[laatsch55]

I've been asking the same question as your initial post Lee all the years I was a Live Sound guy. Never got it, and after reading all the complicated responses, I know I never will.
I used to sit and stare at a cone for hours wondering 'how are you doing all of that at the same time?'
I guess some of us will never get it, but I thank the powers that be for letting me be one of the best sound guys this planet has ever heard, regardless....

I suppose that's proof you dont need to understand it if you can hear and make adjustments based on what you hear eh??

 

[MarkWComer]

... & yet a microphone does the whole thing with only one tiny little diaphragm.

Oh, but now you’re talking about the beginning of the audio chain! A microphone (or any transducer for that matter- phono pickup, tape head, etc.) is a receiving device, as is the eardrum. All of these are reacting to the composite of all waves of varying frequencies simultaneously.

In a recording studio where separate mics are used, the individual waveforms are combined at the mixing board.

 

[MarkWComer]

I suppose that's proof you dont need to understand it if you can hear and make adjustments based on what you hear eh??

It’s all subjective...

 

[pennysdad]

I suppose that's proof you dont need to understand it if you can hear and make adjustments based on what you hear eh??

Knowing what something does, doesn't necessarily mean you have to understand why it did it.
If I turn up the treble control, I don't have to know how many electrons are involved. As long as the treble increases.
Like being a race car driver. You don't have to be a mechanic. As long as you can 'feel' the road.
Anyway, something like that.

 

[laatsch55]

Absolutely Mark, but alot is quantitative...

I find it amazing after all the electronics, and electromechanical devices a recording goes through that a good system can approach sounding close to a live performance, meaning non amplified instruments..

 

[laatsch55]

Yeah,how does a tiny microphone encode bassnotes..

 

[pennysdad]

Oh, but now you’re talking about the beginning of the audio chain! A microphone (or any transducer for that matter- phono pickup, tape head, etc.) is a receiving device, as is the eardrum. All of these are reacting to the composite of all waves of varying frequencies simultaneously.

In a recording studio where separate mics are used, the individual waveforms are combined at the mixing board.

Microphones can be used as speakers too.
eg Coles 4001G Tweeter. Originally started it's life as a microphone.

 

[MarkWComer]

Absolutely Mark, but alot is quantitative...

I find it amazing after all the electronics, and electromechanical devices a recording goes through that a good system can approach sounding close to a live performance, meaning non amplified instruments..

Edison was amazed at how simple a machine as his phonograph could do something so amazing as to reproduce sound. A needle, a diaphragm, and a moving substrate, nothing more!

 

[pennysdad]

Yeah,how does a tiny microphone encode bassnotes..

At the sort of voltage they operate at, it's not a problem to go down to 20Hz.

 

[pennysdad]

Edison was amazed at how simple a machine as his phonograph could do something so amazing as to reproduce sound. A needle, a diaphragm, and a moving substrate, nothing more!

I love the sound you get out of the old Edisons. Really takes me back.

 

[MarkWComer]

Yeah,how does a tiny microphone encode bassnotes..

The same way your tiny eardrum does. The transducer doesn’t need to be tuned to any specific frequency to react to it, compression and rarefaction of air will have an effect on any receiving surface.

HOWEVER: a receiving surface will have a resonant frequency of its own- rattling windows and doors are a prime example. Ella Fitzgerald is known for shattering drinking glasses on an old television commercial.

 

[laatsch55]

At the sort of voltage they operate at, it's not a problem to go down to 20Hz.

So differences in frequencies are a result of different voltages??