This question comes up so often that I have finally put down the answer in a paper. Not that this is going to resolve anything.
http://www.gedlee.com/downloads/What%20is%20a%20Waveguide.pdf
http://www.gedlee.com/downloads/What%20is%20a%20Waveguide.pdf
Baloney!
You guys raised the issue, not me! So enjoy it, busy or not!
It surfaced in my in-box, so I responded, then as well as now.
If marketing BS did not work, it would not be found in most audio ads.
From time to time it even creeps into the AES & ASA Journals.
In any event, it is not science and those that produce it lack veracity.
And guess who buys the products so advertized?
The numbers that do can be counted in the millions.
Regards,
WHG
Blah...Destorying meanings of words used?veracity?
You take the "Horn" and "waveguide" words a little bit to seriously if you really think somehow a lie is created here.
People are not stupid, they can figure out and care about any differences if they do exist. You can keep your strict definitions, the rest of us are too busy just buying, building and enjoying.
You guys raised the issue, not me! So enjoy it, busy or not!
It surfaced in my in-box, so I responded, then as well as now.
If marketing BS did not work, it would not be found in most audio ads.
From time to time it even creeps into the AES & ASA Journals.
In any event, it is not science and those that produce it lack veracity.
And guess who buys the products so advertized?
The numbers that do can be counted in the millions.
Regards,
WHG
I agree with everything you post but its still just a word!
Wether or not people use it properly will not change how anyone designs a great speaker.
Example, anyone that bought QSC HPR-152i "waveguides" over the past 2 years and had succesful builds did not care if it was a waveguide or a horn. Knowing the truth would never have changed the design either so what is really the importance of being pedantic over the terms horn or waveguide??
Getting back to the crux, and the rest of the original question posted.
I myself have been sidetracked, but without being rude, and at this point, the debate about semantics is a little tiresome. Im hardly innocent myself but may i ask again:
and also if anyone has any experience, what compression drivers did you use? or any to recommend with this horn/WG? Im toying with loading a couple of those 1" TBs fullranger things or similar, more as a bit of a laugh to be honest. anything better would be a bonus.
I myself have been sidetracked, but without being rude, and at this point, the debate about semantics is a little tiresome. Im hardly innocent myself but may i ask again:
and also if anyone has any experience, what compression drivers did you use? or any to recommend with this horn/WG? Im toying with loading a couple of those 1" TBs fullranger things or similar, more as a bit of a laugh to be honest. anything better would be a bonus.
Last edited:
Nice write-up. Thanks.
You might add that "horn" is "common parlance" albeit with a large evolution of thought in the audio world.
I suppose those towers holding micro-wave waveguides are intended for aiming the waves to the next tower and so directionality is key to their function.
---------------------------
Well I guess I have a couple of problems with the writeup. "Waveguide" has been used for many decades and not just in relation to RF waves.
The implication that other engineers were simply worried about efficiency and either did not care about or did not exploit the ability of horns to control dispersion is nonsense. There was quite a bit of research and design toward manipulating waveform dispersion long before Dr Geddes's opus in JAES. Does publishing something in JAES give ownership of a pre-existing term?
I will use these horns for small 8"/1" stage monitors with one of the following drivers.
green BMS4524
black Celestion CDX1-1425
Both are usable from around 2 kHz
This is how QSC describes the HPR-152i:
http://media.qscaudio.com/pdfs/Specifications/HPR_spec.pdf
"The bi-amplified 15" 2-way HPR152i is a versatile speaker that is at home in nearly any sound reinforcement setting. A high-power low-frequency driver with a 3" voice coil provides extension down to 48 Hz. The 1.75" (diaphragm) compression driver on a 90° x 60° horn delivers smooth high frequencies up to 20 kHz. The power module includes a 100 Hz low-cut filter for use in subwoofer equipped systems. Three threaded M10 inserts allow for vertical suspension."
Its pristine performance probably has more to do with bi-amping of the drivers than the other design elements of the system which can be found elsewhere in system designs not so powered.
The argument can be made, that attribution of pedagogue may be applied to those that insist on calling a horn a waveguide, not to those that disagree with that marketing driven characterization.
How about this assertion instead, to take the nonsense even further into the realm of linguistic mush: if a horn is a baffle, then all baffles are horns and waveguides as well.
Regards,
WHG
Isn't that the simple truth, though?
A "baffle" could also be called a "180deg waveguide."
Hi bentoronto,
The waveguide on a microwave tower transfers electromagnetic energy between the RF transmitter/receiver and the antenna. The antenna is made up of a feed horn and a parabolic reflector. Directionality comes from the antenna components (horn and reflector), not from the waveguide. *
The simple difference between a horn and a waveguide is that a horn radiates (and has directivity) whereas a waveguide does not.
In essence, this means that the "oblate spheroidal waveguide" is really just another horn... but with a fancy name
.Kind regards,
David
* I can claim some experience in these matters - Thirty years ago I project-managed the installation, testing and commissioning of the longest solar-powered microwave radio system in the world. Although the system is now decommissioned, it still holds that record
.
The simple difference between a horn and a waveguide is that a horn radiates (and has directivity) whereas a waveguide does not.
In essence, this means that the "oblate spheroidal waveguide" is really just another horn... but with a fancy name
Hi David
I simply do not understand the first sentence (waveguides don;t radiate sound?), and I stated the same thing as the second sentence: "All waveguides are horns, but not all horns are waveguides."
To WithTarragon - nowhere did I say that all engineers ONLY worried about efficiency. I said that the Horn Equation can only analyze loading/impedance, it cannot do directivity. The paper clearly discusses the use of diffraction for directivity control. I don't think that any of your objections are actually valid.
As already said - the term "wave guide" is an oxymoron.
(be it in micro wave or acoustic territory)
Also the claim that an OSWG does anything fundamentally different than any other "horn" with respect to diffraction or loading does not and never did hold.
Quite any "horn" provides "directivity" and "wave guidance" and "loading" (to stay in that (nonsense) terms) - compared to any direct radiator (and even these are usually not completely free from "directivity" and "wave guidance" and "loading")
Aso its a matter of fact that quite any "horn" / "WG" / "diffraction alignment device" suffers from the same "time domain impacts" / "CMP behaviour" / "ASAR patterns" caused by diffraction.
All sonic differences in outcome between "guiding" contours are merely gradual - no big deal at all - beyond that is just sales speak.
As said - diffraction is a must (and besides that basically always of the same amount, not depending on contour selected, just depending on wave front generated and acoustic room to be radiated in) - certainly nothing to be avoided as an ill behavior (as popularized by Earl)
Michael
(be it in micro wave or acoustic territory)
Also the claim that an OSWG does anything fundamentally different than any other "horn" with respect to diffraction or loading does not and never did hold.
Quite any "horn" provides "directivity" and "wave guidance" and "loading" (to stay in that (nonsense) terms) - compared to any direct radiator (and even these are usually not completely free from "directivity" and "wave guidance" and "loading")
Aso its a matter of fact that quite any "horn" / "WG" / "diffraction alignment device" suffers from the same "time domain impacts" / "CMP behaviour" / "ASAR patterns" caused by diffraction.
All sonic differences in outcome between "guiding" contours are merely gradual - no big deal at all - beyond that is just sales speak.
As said - diffraction is a must (and besides that basically always of the same amount, not depending on contour selected, just depending on wave front generated and acoustic room to be radiated in) - certainly nothing to be avoided as an ill behavior (as popularized by Earl)
Michael
Last edited:
Microwave waveguides are used because transmission cables are too complex in behaviour to be problem free in installation. Waveguides can contain and direct the waves in a more predictable fashion.
I also see acoustic waveguides as containing and directing the waves. The fact that they don't enter into the issue of loading, as neither do microwave waveguides, may be coincidental and the source of this disagreement but it is a good distinction.
Dr Geddes chose to coin the specific term 'acoustic waveguide', and since they are analogous to microwave waveguides in my opinion, it is totally appropriate in my opinion. It then becomes a matter of semantics if I choose to drop the 'acoustic' from the name, but I henceforth admit I'll be doing so.
I also see acoustic waveguides as containing and directing the waves. The fact that they don't enter into the issue of loading, as neither do microwave waveguides, may be coincidental and the source of this disagreement but it is a good distinction.
Dr Geddes chose to coin the specific term 'acoustic waveguide', and since they are analogous to microwave waveguides in my opinion, it is totally appropriate in my opinion. It then becomes a matter of semantics if I choose to drop the 'acoustic' from the name, but I henceforth admit I'll be doing so.
Hi Earl,
In the context of the current discussion, by radiation I mean the unguided propagation of energy. A waveguide by definition "guides" energy from one point to another.
Not sure how well the waveguide below would perform as a horn loudspeaker....
Kind regards,
David
In the context of the current discussion, by radiation I mean the unguided propagation of energy. A waveguide by definition "guides" energy from one point to another.
Not sure how well the waveguide below would perform as a horn loudspeaker...
.Kind regards,
David
Attachments
Hi AllenB,
Waveguides are used because conventional transmission cables are too lossy / become radiators at microwave frequencies.
Kind regards,
David
not willing to become embroiled in a semantic blood bath, but judging from the microwave waveguide, i would postulate that a waveguide is designed to have constant 'impedance' whether acoustic or EM, thus constant load resisitance....rather like a transimission line, except without the 'loss'.
therefore the 'throat/chamber' of THAT horn would be a waveguide by that definition, and that is how i think of it also.
suffice it to say, Gedlee is getting a bit of a beating for basically putting a more visually descriptive name to his horn, at least for the majority of folks. For those people the word 'horn' in ref to loudspeakers DOES conjure up images of AWFUL PA horns, something I think even the most business naive DOCTOR would seek to avoid association with.
So not to take away from the absurdity of this (almost) discussion, perhaps the name is inaccurate, wordy, desciptive for the less informed, but then again....wasnt Reflex once a 'marketing' tool/name? and 'acoustic suspension' .....?
therefore the 'throat/chamber' of THAT horn would be a waveguide by that definition, and that is how i think of it also.
suffice it to say, Gedlee is getting a bit of a beating for basically putting a more visually descriptive name to his horn, at least for the majority of folks. For those people the word 'horn' in ref to loudspeakers DOES conjure up images of AWFUL PA horns, something I think even the most business naive DOCTOR would seek to avoid association with.
So not to take away from the absurdity of this (almost) discussion, perhaps the name is inaccurate, wordy, desciptive for the less informed, but then again....wasnt Reflex once a 'marketing' tool/name? and 'acoustic suspension' .....?
Last edited:
As long as we are talking about the proper use of terms, thats a pretty big missuse of the term "radiation"
Not sure how well the waveguide below would perform as a horn loudspeaker...
Kind regards,
David
As an Acoustic Waveguide, it would not work very well.
This type of design does not work very well, I've tried it. The junction of the HF and LF devices is basically a large point of diffraction and reflection.
Yes, It proves my point. Waveguide is just a word to smooth over the usage of Horns to people that cringe when thinking about horns.
When the QSC HPR 152i HORN becomes the hottest Econo-waveguide choice you know waveguide is more important as a marketing term then anything else. (See Zilch and all his great work (RIP!!)). I one time I order 30 HPR-152i to help others knowing QSC will stop selling them at < $25 each. The QSC HPR-152i waveguide (Im mean horn) stopped production and people started scrambling. Some hope Dayton would pick it up but that didnt work out. We now have a SEOS-15 design that will be mass produced hopefully very soon (prototypes shipped and being measured). Its superior to all other offerings in the "Waveguide" realm, Obviously it won't be < $25 shipped but it won't be $400 shipped either
Of course ALL waveguides are horns and why does anyone argue or care if waveguide is simply a better term for a horn these days?? Yes, the word "horn" is nasty, its up there with the word "audiophile"
Horns have controlled directivity so the discussion around waveguides being special at that is silly, just look at the incredible designs Danley has to figure that one out.Arguing in the context of microwaves, etc here just shows how bored and obtuse the online community can be....this isnt rocket science and there is nothing hard to understand about the term "Waveguide". Didn't EV coin that name 30 years ago anyways?
Last edited:
It seems you're saying that a waveguide guides waves from place to place as if there is no other purpose. I think I can see your point, but IIRC some waveguides transition to fill a different shape or area.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.