is this a horn or a waveguide?

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Maybe its just semantics but I always thought that all horns were waveguides. If it uses a compression driver I would definitely call it a horn (as well). If it was just a flare on a dome tweeter, increasing directivity, I would call it a waveguide.

If it is straight exponential it won't be constant directivity, will get progressively narrower at HF.

David S.
 

ScottG

Member
2003-02-04 12:23 am
US
Is this a horn or waveguide?


thanks for any help

..relatively synonymous,

All horns are waveguides, they trade/limit/compress dispersion for gain.

Not all waveguides are horns, some alter dispersion through absorption.


That unit is both a waveguide and a horn.. however it is *primarily* a waveguide, so it would be more "correct" to call it a waveguide.

The 3.5" depth (vs. a 1" exit compression driver) is a giveaway that it's a waveguide.. the designer isn't concerned with gain but rather the specific radiation pattern of 70 by 50 down to about 3 kHz.
 
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That unit is both a waveguide and a horn.. however it is *primarily* a waveguide, so it would be more "correct" to call it a waveguide.


Allow me to disagree...

No absorption. no dispersion due to time line tricks, plain ol' solid boundaries - its a simple horn = its a simple waveguide = its a simple diffraction alignment device ...

Will have its quarter wave honk like most horns / waveguides / diffraction alignment device ...

Some rubber to dampen dominating sonic pattern of pure metal is nice but not exactly a "revolution"
;)

By the way, lets state clear that "waveguide" was popularized (not invented) by Earl Geddes for mere commercial reasons > sales speak, as said ..



Michael
 
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ScottG

Member
2003-02-04 12:23 am
US
Allow me to disagree...

No absorption. no dispersion due to time line tricks, plain ol' solid boundaries - its a simple horn = its a simple waveguide = its a simple diffraction alignment device ...

Will have its quarter wave honk like most horns / waveguides / diffraction alignment device ...

Some rubber to dampen dominating sonic pattern of pure metal is nice but not exactly a "revolution"
;)

By the way, lets state clear that "waveguide" was popularized (not invented) by Earl Geddes for mere commercial reasons > sales speak, as said ..



Michael


Well then allow me to disagree with your disagreement! :p


Waveguide is an express conjunction composed of wave and guide. If you know the definition of wave and guide then you know the definition of waveguide.

Waveguide: to guide waves, or alter their pattern through physical limitation.

It really doesn't matter if Earl popularized it or not.. and in fact he prefers a far more limiting definition of waveguide, which is not supported by its plain meaning.
 
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What waveguide is not a horn?

so called "acoustic lenses" possibly ?
;)

They are definitely a "guidance to waves" but not exactly what one would consider as a horn (though quite often been attached to one) - hence I excluded "no dispersion due to time line tricks"
:rolleyes:


Michael
 
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One that doesn't provide any acoustic gain as it guides waves. ;)

Even a minor felt ring around a tweeter to limit the dispersion pattern and lower cabinet edge diffraction is a "waveguide".. though a very minimal one at that.


I'm SOooo sorry - I'm afraid I have to disagree. :( LOL

With absorption material the waves are not getting guided - as the name says - they get killed !
So - as per definition of the "express conjunction" - such form of dispersion regulation device (felt foam etc) cant be a assumed to be a "wave guide"
:)


What waveguide is not a horn?

One that doesn't provide any acoustic gain as it guides waves. ;)

Besides above - allow me to take exception here too
:(

Any "boundary driven wave guiding" will provide some sort of "gain" - be it positive or negative with respect to a certain bandwidth and with respect to a certain "normal" boundary shape (IB for example).
In the end quite any "diffraction alignment" shape used will result in differences to the variable "gain" - depending on the point of view
;)

"Baffle step" being a nice example, one would not think of in terms of "horn" or "waveguide" - but has exactly the same underlaying principles
:)

Michael
 
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ScottG

Member
2003-02-04 12:23 am
US
I'm SOooo sorry - I'm afraid I have to disagree. :( LOL

With absorption material the waves are not getting guided - as the name says - they get killed !
So - as per definition of the "express conjunction" such form of dispersion regulation device (felt foam etc) cant be a assumed to be a "wave guide"
:)

Michael


Then you need to look at the definition of guide. ;)

Guide: to direct, or exert control over.

With an absorptive waveguide the direction of the wave is limited or controlled in a particular manner. It doesn't matter if a portion of that wave is suppressed, what matters is the resulting wave's dispersion pattern.
 
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Where the term really came from.

RF waveguides.

David S.
 

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ScottG

Member
2003-02-04 12:23 am
US
..Any "boundary driven wave guiding" will provide some sort of "gain" - be it positive or negative with respect to a certain bandwidth and with respect to a certain "normal" boundary shape (IB for example).
In the end quite any "diffraction alignment" shape used will result in differences to the variable "gain" - depending on the point of view
;)

"Baffle step" being a nice example, one would not think of in terms of "horn" or "waveguide" - but has exactly the same underlaying principles
:)

Michael

Yes, a baffle (depending on the radiation pattern of the device on a baffle), is technically both a waveguide and a horn. A driver's diaphragm even exhibits this characteristic. The difference is that we just don't commonly use them for this description.
 
Then you need to look at the definition of guide. ;)

Guide: to direct, or exert control over.

With an absorptive waveguide the direction of the wave is limited or controlled in a particular manner. It doesn't matter if a portion of that wave is suppressed, what matters is the resulting wave's dispersion pattern.

I agree "halfway" - halfway allow me to disagree
:D

Let me ask you : what actually is a guide that does not guide ?
Can it be called a "guide out of order (not exerting control over)" ? or should it be assumed to be no guide at all ?

What happens with all that absorptive materials is that we actually create a looot of diffraction at least to the remaining portion of the wave front.
In the extreme (100% absorptive material) its like opening infinite room at this position - much like an abrupt end of any guidance.

So - in the end effect :
absorptive material guides by the absence of a guidance - but should we call that a "wave guide" ? - or should we call it a "non-guiding wave guide" ? - or should we call or not call it ... - thats the question...
:)
My proposal :
we call it what *sells* best !

Michael
 
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Yes, a baffle (depending on the radiation pattern of the device on a baffle), is technically both a waveguide and a horn..

I'd say : it depends...
:crazy:

If you take an IB plus a pistonic direct radiator as the reference point - or - if you take any other arrangement as a reference point
;)

Michael
 

ScottG

Member
2003-02-04 12:23 am
US
I agree "halfway" - halfway allow me to disagree
:D

Let me ask you : what actually is a guide that does not guide ?
Can it be called a "guide out of order (not exerting control over)" ? or should it be assumed to be no guide at all ?

What happens with all that absorptive materials is that we actually create a looot of diffraction at least to the remaining portion of the wave front.
In the extreme (100% absorptive material) its like opening infinite room at this position - much like an abrupt end of any guidance.

So - in the end effect :
absorptive material guides by the absence of a guidance - but should we call that a "wave guide" - thats the question...
:D


Michael


SEEK Professional counseling IMMEDIATELY. :D


Actually I don't get "A equals B" from you (il)logic statement. ;)

Also note that diffraction, reflection, and diffusion, are all effects of wave guidance. Suppression and absorption is relative to the remainder of the wave's path.

When is a waveguide not guiding a wave? - when the wave is suppressed or blocked from ever occurring. :p
 
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doug20

Member
2009-03-22 9:38 pm
One that doesn't provide any acoustic gain as it guides waves. ;)

Even a minor felt ring around a tweeter to limit the dispersion pattern and lower cabinet edge diffraction is a "waveguide".. though a very minimal one at that.


Seems like a lot of semantics and splitting hairs definition stuff that has really no pratical sense to it, I know that gets the discussions going on DIYaudio but can we just be pratical about the term waveguide?.

any other waveguides that are not horns?? Im talking about fabricated moldings of some shape.