Horn Speakers - Is it me or.......

[jeffaegrim]

This is the graph you are looking for:

View attachment 424747

It's in this post. If you look further down that thread, you will see a polar plot.

Ah - it was the same post, thanks a bunch, silly of me. Been a while

 

[Sokel]

This is the graph you are looking for:

View attachment 424747

It's in this post. If you look further down that thread, you will see a polar plot.

???
This plot does not look like horns to me,at least horns measured by our amateurish methods.

Edit:scrap the above,I went to the thread and remembered.

(again:take them out the street and measure! )

 

[Sal1950]

(again:take them out the street and measure! )

What if it's raining?

 

[gnarly]

No, there is a fundamental confusion to it. You can't legitimately call something a waveguide if its conception gave no thought to the issue of beam width, just because it inevitably 'did something' to beam width compared to a bare drive unit.

Yeah you can. I call flat baffles waveguides sometimes...like when attaching wings to subs used in live sound, barn doors as they are often called.
Helps narrow the radiation pattern.

Also, if we're nitpicking what thought has to go into a waveguide before it can be called a waveguide, I'd say just as important as beam width is how low in frequency is the waveguide designed to hold target beamwidth. But please, let's leave this definitional bantering alone...

There is no horn that is a sub-class of acoustic waveguide that does not have a specification for beam width, therefore horns are not a sub-class of waveguide.

That logic doesn't make sense to me. Beam width is simply a property of both horns and waveguides.
A common property cannot differentiate a set from a subset. It defines the set.
It takes uncommon properties within the set to define subsets.
In this case, horns have the uncommon property of being acoustic transformers to raise efficiency, that waveguides don't have.
(using my functional definition classification.)

But really? And what does preference have to do with anything here?
Who cares about preferences. I've got mine, you have yours, and all I can say it amen to that....we each get to personally enjoy whatever floats our boat.
And I certainly don't give a rat's ass about the general population's preference. Leave that to manufactures

Of course it's easily measured. We all know that it actually exists physically.

The issue is whether it is indeed easily heard and preferred.

Well, it's been easy to hear for me. And please don't use the blind rigorous testing copout.
I had written all I do for honest evaluations, but I don't think you will acknowledge any validity, so I'm just going to erase say goodbye on this.

But what does preference have to do with anything here? ??
Who cares about preferences.
I've got mine, you have yours, and all I can say is amen, thank you lord to that....we each get to personally enjoy whatever floats our boat.
And I certainly don't give a rat's ass about the general population's preference. Leave that to manufactures and their marketing depts.

Geddes is the only one I am aware of who has based his conclusion, that it matters little below 500 Hz, on psychoacoustics and research. Please don't tell me that the opposition comprises DIY communities doing sighted listening of each other's creations and reporting huge differences, and definitely due to the additional beam width control below 500 Hz. And that the difference due to that factor and that factor alone is so huge that it cannot possibly be anything but a true perception of the attributes of the sound waves themselves, even in casual/sighted listening. Please, not that.

Geddes is known to say music resides 1kHz and up. (Coincidentally, as I understand it, OS waveguides only work down to about 1kHz)
I flat out disagree with anyone who says almost 1/2 of the entire audible spectrum, doesn't matter.
Really, the idea is ludicrous...and I still have yet to see any convincing research that says 500Hz and below is less important than above.
So yes, that

 

[robh36062]

Geddes is known to say music resides 1kHz and up. (Coincidentally, as I understand it, OS waveguides only work down to about 1kHz)
I flat out disagree with anyone who says almost 1/2 of the entire audible spectrum, doesn't matter.
Really, the idea is ludicrous...and I still have yet to see any convincing research that says 500Hz and below is less important than above.
So yes, that

Um no it's the importance of directivity matching at crossover and content above 1K and directivity. Imaging as an example. You are taking a simple statement to the extreme. Hope he is here so he can elaborate.

Rob

 

[Newman]

Okay, so what I get from the recent discussion is that all waveguides are horns, but not all horns are waveguides, unless... you want to believe otherwise. In which case, make it up as you go.

 

[Sal1950]

Okay, so what I get from the recent discussion is that all waveguides are horns, but not all horns are waveguides, unless... you want to believe otherwise. In which case, make it up as you go.

I thought it was vicey versy ???

 

[Duke]

Beam width is simply a property of both horns and waveguides.

What is the beamwidth of this horn?

The beamwidth changes for pretty much every frequency, doesn't it? Well, that's the difference between a horn and a waveguide: A waveguide has an approximately constant beamwidth across its passband. Hence the name of the device, which implies the deliberate guiding of soundwaves.

Geddes is known to say music resides 1kHz and up.

My understanding from Griesinger is that the ear gets most of its information in the region from about 700 Hz to 7 kHz, but I have also seen him refer to "1 kHz" and "500 Hz", so I think the general principle is supported but the cut-off point is inexact.

My guess is that Earl was saying something to the effect that "it's particularly important to get 1 kHz and above as correct as you can."

Coincidentally, as I understand it, OS waveguides only work down to about 1kHz

The low-end extension depends largely on the size of the waveguide.

The 15" waveguide Earl used in the original Summa was good down to about 1 kHz, and I think he later modified the crossover to 900 Hz. A subsequent revision of the Summa's design used an 18" diameter waveguide (and a more capable compression driver), and his crossover frequency moved down to about 800 Hz as I recall. He engineered a design with a 22" waveguide which would have had a 600 Hz crossover frequency but he never built it.

My point being that the primary limiting factor is the size of the waveguide, a secondary limiting factor being the low-end capability of the compression driver.

I flat out disagree with anyone who says almost 1/2 of the entire audible spectrum, doesn't matter.
Really, the idea is ludicrous...

Did Earl actually say that? If so, can you show us where?

And if not, I invite you to correct your statement so that you are not attributing to Earl something he never said.

 

[Newman]

Okay, so what I get from the recent discussion is that all waveguides are horns, but not all horns are waveguides, unless... you want to believe otherwise. In which case, make it up as you go.

I thought it was vicey versy ???

You did? Why?

 

[Sal1950]

You did? Why?

Just a bit of sarcastic humor.

 

[gnarly]

Did Earl actually say that? If so, can you show us where?

And if not, I invite you to correct your statement so that you are not attributing to Earl something he never said.

Important things first:
Invitation welcomed and accepted
I did not mean to attribute my comments directly towards Earl. My apologies for how they read.
The strenght of my comments were meant to be directed to Newman, who referred to Geddes' research to support his opinion.

I let past conversations on DIY with Earl, where we have had differing opinions at times over the importance of the spectrum below the CD/waveguide range, contaminate my post.
Yes, I do think Dr Geddes has said music resides in the HF/VHF a number of times, but I don't want to try and search old DIY threads to find them.....
mainly because I never should have brought that up in reaction to Newman, to begin with. Besides, old posts would need to be resurrected in full for proper perspective., and why even go there..
My bad, and apologies again.

What is the beamwidth of this horn?

The beamwidth changes for pretty much every frequency, doesn't it? Well, that's the difference between a horn and a waveguide: A waveguide has an approximately constant beamwidth across its passband. Hence the name of the device, which implies the deliberate guiding of soundwaves.

Ok, on to (much) less important, but fun, stuff !

I think the term waveguide is far too broad a term, to have a necessary condition of constant directivity across its passband.
And even if we accepted that condition, how far down in frequency does the waveguide need to hold constant beamwidth? How much of its passband?

I''ve seen very few waveguides or horns that are specified as constant directivity/beamwidth, do so all the way down to xover.
I think beamwidth inevitability varies across its passband for each driver section we tie together (with the trick of course being how to blend beamwidths smoothly thru xover.)

I really believe as stated before, that the property of constant beamwidth is a separate property, and makes for a subset of both waveguides and horns. Not a defining property of either.

The low-end extension depends largely on the size of the waveguide.

The 15" waveguide Earl used in the original Summa was good down to about 1 kHz, and I think he later modified the crossover to 900 Hz. A subsequent revision of the Summa's design used an 18" diameter waveguide (and a more capable compression driver), and his crossover frequency moved down to about 800 Hz as I recall. He engineered a design with a 22" waveguide which would have had a 600 Hz crossover frequency but he never built it.

My point being that the primary limiting factor is the size of the waveguide, a secondary limiting factor being the low-end capability of the compression driver.

Yes, for sure, as we've both been saying. Size determines how low the waveguide or horn holds its pattern.
Many DIY guys are trying to get horns ever larger, to hold pattern ever lower. I was in that camp for quite a while, until I reached a speakers are "too damn big" breaking point.
For stereo, 48" wide is as big as I'll go. 3 channel LCR needs smaller, 36".
Interestingly, even though my CD's will work easily to below 500Hz, I've found relieving the CDs of excursion duty below about 750Hz, with small mid-range drivers improves mid-range clarity.

How did the Summa's sound as their size was increased? Enough time with them to form a fair opinion?

 

[babadono]

These sound horrible.....NOT
my room, not some show.

 

[olegtern]

These sound horrible.....NOT

These sound good...

 

[Sokel]

I'll say it again,I want these:


(link)

even if they don't play
I just love how they look (and I'll probably get them for the house)

The third inverted horn looks like an odd transmission line to me,I haven't seen the insides though,it may well be a simple horn.

 

[Duke]

I think the term waveguide is far too broad a term, to have a necessary condition of constant directivity across its passband.
And even if we accepted that condition, how far down in frequency does the waveguide need to hold constant beamwidth? How much of its passband?

Imo the characteristic of a waveguide which warrants use of that specific term IS its approximately constant directivity over most of its bandwidth. In practice the directivity widens at the low end and narrows at the top end, so it's not perfect, but it's arguably quite useful.

I see no other reason to use the term "waveguide". For instance, a short horn is not a waveguide unless is has the directivity characteristics of a waveguide.

The following tangent might be of interest:

To a reasonable first approximation, in order to control the radiation pattern we must impose directivity on at least 1/4 of a wavelength. For instance, the familiar "baffle step" wrap-around begins when the baffle edges are less than 1/4 wavelength distance from the center of the woofer. As long as the wavelengths are short enough that the baffle edges are more than 1/4 wavelength away, the baffle in effect behaves sort of like a "180 degree horn".

Many conventional horns are shaped more or less like a short trumpet: Relatively little curvature in the throat region, with the curvature increasing as we get closer to the mouth. The directivity of the short wavelengths is established by the wall angle of the horn in that first 1/4 wavelength, way down in the throat where the wall angle is narrow. Then as the wavelengths get longer the pattern widens because the angle has become wider by the time there's enough horn length (1/4 wavelength) to establish pattern control. So the pattern expands from narrow at high frequencies to wide at low frequencies.

For an Oblate Spheroid waveguide (and others which are similar in concept), most of the curvature happens very close to the throat (like within the first inch or so). Beyond the throat region the walls are virtually straight until we reach the mouth round-over. So the pattern imposed on the short wavelengths is much wider than was the case for the conventional short-trumpet-like horn, and is pretty close to the pattern width over the rest of the passband, with the pattern inevitably widening at the longest wavelengths due to the effective angle widening at the mouth round-over.

In the image below the Oblate Spheroid is the light purple curve, and the mouth round-over is not shown. The Conical, Oblate Spheroid, and Hughes (Peavy) profiles are constant-directivity types, and as you can see they have most of their curvature down near the throat.

My understanding is that the Oblate Spheroid curvature is the one which imposes the least disturbance to the wavefront for a given change in angle, so imo it's arguably the "optimum" for a constant-directivity application.

I''ve seen very few waveguides or horns that are specified as constant directivity/beamwidth, do so all the way down to xover.

Off-the-shelf constant directivity waveguides are not particularly common, and some are no longer on the market, but they do exist.

The Design Direct Sound ENG 1-90 and the SEOS waveguides made by DIY Sound Group are sadly no longer available. The Eminence WG10 is currently in production, I've measured it and it's a genuine waveguide. The 18Sound XT1464 and XT1060, along with the Faital HF142, have radiation pattern characteristics which imo put them in the borderlands (or "best of both worlds"?) between "horn" and "waveguide". I'm not familiar with devices smaller than about 10" in diameter but am under the impression that there are off-the-shelf waveguides made for, or included as part of, dome tweeters.

Whether or not pattern control is maintained all the way down to the crossover frequency is a juggling of tradeoffs. Often the crossover frequency is down in the region where the waveguide is losing pattern control because the overall system design benefits from pushing the crossover a bit lower than might be "optimum" for the waveguide.

I really believe as stated before, that the property of constant beamwidth is a separate property, and makes for a subset of both waveguides and horns. Not a defining property of either.

And beating my own dead horse here, imo "approximately constant beamwidth over most of its passband" [without the use of diffractive features or vanes] is THE defining property of a waveguide.

I'll say it again,I want these:

View attachment 425127

even if they don't play
I just love how they look (and I'll probably get them for the house)

The third inverted horn looks like an odd transmission line to me,I haven't seen the insides though,it may well be a simple horn.

My understanding is that the inverted horn is actually just a woofer chamber, with the woofer down-firing. But that is absolutely the most elegant large horn speaker I am aware of.

 

[Sokel]

My understanding is that the inverted horn is actually just a woofer chamber, with the woofer down-firing. But that is absolutely the most elegant large horn speaker I am aware of.

You're probably right about the woofer,probably a BR with the vent on top.
To our taste in this house,they are elegant,period,being speakers or not.Is just like they're made for our living room,they fit with the rest of the stuff too.
That makes things easy

 

[Duke]

To our taste in this house,they are elegant,period,being speakers or not.Is just like they're made for our living room,they fit with the rest of the stuff too.
That makes things easy

May the audio gods find a way to bless you with a pair!

 

[Newman]

Nice post Duke!

Imo the characteristic of a waveguide which warrants use of that specific term IS its approximately constant directivity over most of its bandwidth. In practice the directivity widens at the low end and narrows at the top end, so it's not perfect, but it's arguably quite useful.

Yes, I think that's the nub of it.

I also think it is important that people chatting about a topic use defined terms consistently. Otherwise it's not communication, it's constantly-crossed-purposes miscommunication. That's why I encourage those who use terms in their own unique way (even with their own internal logic), to fall into line, in the name of language!

I see no other reason to use the term "waveguide". For instance, a short horn is not a waveguide unless is has the directivity characteristics of a waveguide.

The following tangent might be of interest:

To a reasonable first approximation, in order to control the radiation pattern we must impose directivity on at least 1/4 of a wavelength. For instance, the familiar "baffle step" wrap-around begins when the baffle edges are less than 1/4 wavelength distance from the center of the woofer. As long as the wavelengths are short enough that the baffle edges are more than 1/4 wavelength away, the baffle in effect behaves sort of like a "180 degree horn".

Many conventional horns are shaped more or less like a short trumpet: Relatively little curvature in the throat region, with the curvature increasing as we get closer to the mouth. The directivity of the short wavelengths is established by the wall angle of the horn in that first 1/4 wavelength, way down in the throat where the wall angle is narrow. Then as the wavelengths get longer the pattern widens because the angle has become wider by the time there's enough horn length (1/4 wavelength) to establish pattern control. So the pattern expands from narrow at high frequencies to wide at low frequencies.

For an Oblate Spheroid waveguide (and others which are similar in concept), most of the curvature happens very close to the throat (like within the first inch or so). Beyond the throat region the walls are virtually straight until we reach the mouth round-over. So the pattern imposed on the short wavelengths is much wider than was the case for the conventional short-trumpet-like horn, and is pretty close to the pattern width over the rest of the passband, with the pattern inevitably widening at the longest wavelengths due to the effective angle widening at the mouth round-over.

In the image below the Oblate Spheroid is the light purple curve, and the mouth round-over is not shown. The Conical, Oblate Spheroid, and Hughes (Peavy) profiles are constant-directivity types, and as you can see they have most of their curvature down near the throat.

View attachment 425128
My understanding is that the Oblate Spheroid curvature is the one which imposes the least disturbance to the wavefront for a given change in angle, so imo it's arguably the "optimum" for a constant-directivity application.

That was a pleasure to read.

Off-the-shelf constant directivity waveguides are not particularly common, and some are no longer on the market, but they do exist.

Although @gnarly also said he has also seen very few CD horns, which surprises me. Whenever I browse a horn catalog, it is dominated by CD horns with their specified '80°H x 60°V' (or whatever) directivity objective. They're everywhere. For example, link.

...Whether or not pattern control is maintained all the way down to the crossover frequency is a juggling of tradeoffs. Often the crossover frequency is down in the region where the waveguide is losing pattern control because the overall system design benefits from pushing the crossover a bit lower than might be "optimum" for the waveguide.

And beating my own dead horse here, imo "approximately constant beamwidth over most of its passband" [without the use of diffractive features or vanes] is THE defining property of a waveguide.

I agree.

I recall the OP, Alan March, mused over his universal experience of (large) horns as sounding unlikable. IMO this is due to two things (and they are still happening):

• Horns, large ones, for high quality home audio are one of the most demanding speakers to get right, and easiest to get wrong. But not impossible.
• The home hobby audio world has done to horns exactly what it has done to some other exotic audio technologies: mythologize all the wrong stuff. Examples: seashell-like spirals; "legendary classics" eg Altec or old JBL or Sato or classic Klipsch; exponential or tractrix flares; long horns; sharp or too tight mouth terminations; old tech compression drivers; truncated backhorns on full range drivers; low order crossovers; no time alignment; no EQ. Frankly, we can add the Unity/Synergy horn to the list: prioritizing point source ideals over diffraction colouration realities, even though research into home audio listening sensitivities would suggest that the opposite prioritization is more realistic.

cheers

 

[Duke]

Nice post Duke!

Thank you!

I recall the OP, Alan March, mused over his universal experience of (large) horns as sounding unlikable. IMO this is due to two things (and they are still happening):

• Horns, large ones, for high quality home audio are one of the most demanding speakers to get right, and easiest to get wrong. But not impossible.
• The home hobby audio world has done to horns exactly what it has done to some other exotic audio technologies: mythologize all the wrong stuff. Examples: seashell-like spirals; "legendary classics" eg Altec or old JBL or Sato or classic Klipsch; exponential or tractrix flares; long horns; sharp or too tight mouth terminations; old tech compression drivers; truncated backhorns on full range drivers; low order crossovers; no time alignment; no EQ. Frankly, we can add the Unity/Synergy horn to the list: prioritizing point source ideals over diffraction colouration realities, even though research into home audio listening sensitivities would suggest that the opposite prioritization is more realistic.

cheers

Whatever "bad things" a big horn does, it starts doing them at a lower frequency, and typically more obtrusively, than a small horn does.

So arguably the bigger the horn, the less compromise you can get away with in things like mouth round-over radius, which in turn makes the horn even bigger for a given low-end extension!

Click on the image of @Sokel's future speaker in post #874. Notice that, proportionately, MORE of the big midrange horn's width is devoted to the mouth round-over than for the small tweeter horn. Imo the designer did some important things right.

 

[Bjorn]

Subjectively, the horns offer better overall playback clarity/coherence - the sound, however, becomes very „in your face“. It demands attention. A conventional design sounds very relaxed to me now in comparison, non-intrusive. The „attack“ is, however, oftentimes missing - especially at larger distances.

The in your face sound demanding attention is likely related to much direct sound.

However, this can be changed with the use of phase grating diffusion. As always: There's a big difference between diffusers, so anything called "a diffuser" might not work well.