High Efficiency Speaker Asylum

Need speakers that can rock with just one watt? You found da place.

Return to High Efficiency Speaker Asylum

Message Sort: Post Order or Asylum Reverse Threaded

Constant Directivity Horn Recommendations

148.77.3.2
Posted on June 11, 2025 at 09:05:01
cin5
Audiophile

Posts: 98
Location: Long Island
Joined: August 17, 2015
For a two-way speaker, need a horn that performs like K402 but smaller while having better performance than the K510, though somewhat bigger?

Wide HF coverage pattern (directivity), frequency response down to 400 or 500Hz, no resonance issues (HOMs?), excellent distortion and decay numbers. And overall ~ wide dispersion from ~ 500Hz to > ~ 60 degrees horizontal at 13kHz?

Which such constant directivity horns to cross at ~ 500Hz or lower if cost was no issue and horn could be up to ~ 26" w x 20" d to sit atop my midwoofers?
https://josephcrowe.com/blogs/news/altec-416-8b-in-100l-sealed

 

Hide full thread outline!
    ...
RE: Constant Directivity Horn Recommendations , posted on June 11, 2025 at 12:36:07
Inmate51
Industry Professional

Posts: 3555
Location: Dallas, TX
Joined: August 12, 2022
 What is your application and room size (H/W/D)?

*********

We are inclusive and diverse, but dissent will not be tolerated.

 

Constant Directivity Horn Recommendations, posted on June 11, 2025 at 14:12:07
cin5
Audiophile

Posts: 98
Location: Long Island
Joined: August 17, 2015
 Application? Looking for a CD horn as described to build a two-way speaker system to use with multiple subs. Room size ~ 23 ft x 13 wide. Triangular ceiling peaks at 11 ft. Would attach a sketch and more specs but this site won't accept my pdf.

 

RE: Constant Directivity Horn Recommendations , posted on June 14, 2025 at 14:00:10
tomservo
Manufacturer

Posts: 9301
Joined: July 4, 2002
 Hi
The pattern control loss point is dependent on the horn wall angle and the dimension. Don Keele identified a "thumb rule" for this which is 10^6 / horn wall angle/ mouth dimension (inches). You might want to search his paper called "what's so sacred about exponential horns"

This rule also dictates the largest throat dimensions that the driver will "fill" the horn at the top end.
Constant directivity is very desirable if / when you have an audience plane so that the top end extends to all the seats and the outer limits of the horn.

The complication is that all compression drivers have a power response that rolls off in the 1 to 3KHz range and without the narrowing pattern of a curved wall horn up high, a CD horn requires eq.

 

RE: Constant Directivity Horn Recommendations , posted on June 15, 2025 at 19:20:39
Cask05
Audiophile

Posts: 83
Location: N. Central Texas
Joined: November 11, 2007



I've found an even simpler rule of thumb: the frequency corresponding to one wavelength across the diameter of the horn throat is the frequency that the acoustic waves tend to pull themselves off the horn walls, and you get the beginning of beaming. For a 2" throat, this is ~6800 Hz, for 1.4" throat, this is 9700 Hz, and for 1" throat, it is 13600 Hz, etc.

There is a now-patented device that Klipsch uses in its latest horn throats that looks like a set of concentric rings bound together by crossed stiffening ribs at 90 degrees to each other. This device can delay the onset of acoustic beaming by about one octave higher--if designed appropriately. The patent no. is USPTO 20230069408.
Chris
"As far as the ear can tell, consistently clean and spacious bass can be reproduced only by a driver unit coupled to a horn-type acoustic transformer..."; Jack Dinsdale, May 1974

 

RE: Constant Directivity Horn Recommendations , posted on June 16, 2025 at 04:55:56
tomservo
Manufacturer

Posts: 9301
Joined: July 4, 2002
 Your rule of thumb is sort of consistent with Don Keele's observation. That apples to the throat and mouth both.

Fwiw, another thumb rule is if the source is 1wl across, the pattern is about 90 degrees AND the impedance transformation stops when the source is about 1WL in circumference (often was referred to K=1) Make a horn with a 60 degree flare and a 1 inch driver fills out the horn all the way to the top.

You can do things with lenses but the real issue is what is the horn wall angle your looking to make?
I have not run into a case where these things don't apply.

 

With what driver? nt, posted on June 16, 2025 at 05:43:37
Bas Horneman
Audiophile

Posts: 4132
Joined: March 28, 2001
 .

 

RE: Constant Directivity Horn Recommendations , posted on June 16, 2025 at 07:37:45
Cask05
Audiophile

Posts: 83
Location: N. Central Texas
Joined: November 11, 2007



You have to look at the throat geometry of all the modern Klipsch horn designs to see the applicability of the throat lens approach (picture above).

Virtually all the Klipsch horns use ~90 degrees of horizontal coverage and ~60 degrees vertically. The main Klipsch horn designer (Delgado) has stated that, in multiple tests over the years, the 90 degrees of horizontal coverage is preferred by most, and the 60 degree is about all what you can squeeze down to without suffering pattern flip (loss of vertical directivity at lower frequencies).

I'd always wondered why you didn't increase the coverage angle in your initial "Synergy" designs to 90 degrees for this reason. I guess I don't have much need for PA (fixed of mobile) applications, only for home hi-fi.

Chris
"As far as the ear can tell, consistently clean and spacious bass can be reproduced only by a driver unit coupled to a horn-type acoustic transformer..."; Jack Dinsdale, May 1974

 

RE: Constant Directivity Horn Recommendations , posted on June 16, 2025 at 10:09:03
tomservo
Manufacturer

Posts: 9301
Joined: July 4, 2002



Hi
In commercial sound, you do not want reflected sound arriving that hit the side walls before the listeners ears. Given the rooms are larger than a living room, most of the horns that "throw" are less than 90 degrees.

Pattern flip happens around where the pattern control is lost (covered in the Don Keele paper). It is a function of the mouth dimensions and angles, around 90x60 (or other angles with a similar difference) is about as asymmetric as one can get without significant flip down low.
The Imax Synergy horns are also of this approach.

I have designed a good number of different lenses that allow for more asymmetric patterns and combine several to many hf drivers BUT these all require a different proportion to avoid PF.
For example a 90H by 45V pattern (with no PF) requires the mouth to be 2 x the height as the width, the opposite of what is easier to make.

One of the more extreme of these is the sbh-10 that has a 10 degree Vertical and 140 degree horizontal. Here the throat is about 5/8 inch wide
allowing the wide dispersion and the height and width suitable proportions for the dispersion pattern. What sales said in the brochure is not quite right, the path length is not 25 feet long but it radiates as if it were a single driver on a 10 degree vertical horn that was 25ft deep

https://www.danleysoundlabs.com/wp-content/uploads/2022/02/SBH-10-Spec-sheet1.pdf

I mostly only use 1 inch and a few 1.4 inch drivers, the Synergy horn concept uses separate mid drivers that are close coupled and drive the horn where the expansion rate has slowed to couple mid ranges and later down the horn, couple low frequency drivers so that they all drive the horn as a single acoustic passage, something like combining signals with resistors and radiate / measure as if they were a single driver.

This single point of radiation even makes a difference in studio monitors as well. Home hifi is my hobby but for the company, it's much easier to sell to musicians as they know that their instruments sound like vs guessing what it should sound like with home speakers.

One of the artists who records with them sent this the other day, a Brian Wilson song. This guy is a great guitar player (super tramp) and nice guy

https://www.facebook.com/CarlVerheyenOfficial/videos/1299909281556960

I love bass horns, they are the most fun to design and play with.
If you have been to the mouse house parks in Orlando, you have heard our speakers and the outdoor projection at the Chinese theater also uses two channels of these bass horns (BC218) for lf and several J-3's for left center right and sh-96's for surround. This was a tough one, the audience starts about 500ft from the loudspeakers so line arrays couldn't do it.

There aren't may Diy'rs left especially ones interested in horns, if you want to make something, i would be glad to help.

Tom

 

RE:There aren't may Diy'rs left especially ones interested in horns,, posted on June 16, 2025 at 10:37:52
Bill Fitzmaurice
Industry Professional

Posts: 5487
Location: New England
Joined: October 20, 2002
 There are nearly 7,000 members on my forum, and they represent only some 10% of those who've bought my plans. Around 70% of those were for horns. :)

 

RE:There aren't may Diy'rs left especially ones interested in horns,, posted on June 16, 2025 at 10:53:44
tomservo
Manufacturer

Posts: 9301
Joined: July 4, 2002
 Hi Bill
That is most cool and encouraging that there are still so many people interested in them.
If it's ok with you, i might post once in a while but I don't want to intrude.
Best
Tom

 

RE:There aren't may Diy'rs left especially ones interested in horns,, posted on June 16, 2025 at 13:51:42
Bill Fitzmaurice
Industry Professional

Posts: 5487
Location: New England
Joined: October 20, 2002
 You're more than welcome to do so.

 

RE: Constant Directivity Horn Recommendations , posted on June 18, 2025 at 05:34:12
Cask05
Audiophile

Posts: 83
Location: N. Central Texas
Joined: November 11, 2007



Thanks for addressing my question(s), Tom. I agree that there aren't really very many knowledgeable (...truly knowledgeable...) DIY horn loudspeaker designers. And Hornresp isn't enough to produce better horns--so for full-range horn loudspeakers having 90 degree coverage--the list of commercially available horns is pretty short. The ways running BEM sims don't seem to understand what the real requirements are (over focus on throat smoothness, etc.)

A link to my last major creation is attached here. I find that I'm going to need to shift to a dual taper straight-sided horn (like your Synergy and Unity designs) for future designs since it gets a bit difficult and expensive to make the horn shown in the link (3D printers still can't handle it). This particular horn in the linked article is essentially the same size as your SH-96, but molded with a tractrix mouth instead of a secondary straight flair. I would like to produce it, but it really takes a lot of expertise and process control to do it using casting resins (heat buildup and warping).

Single point source really is key in home hi-fi (close listening distances generally inside the critical distance in-room). I think the 1.4/1.5 inch diameter exit compression drivers are a sweet spot for home hi-fi without having to introduce secondary midrange cone drivers of your very high output Synergy series. This results in much more simplified designs (two-way or perhaps three-way with ring radiator dual diaphragm compression driver). I don't need 11 drivers in the cabinet...only three. Price goes down accordingly, and performance is not affected for home hi-fi levels.

You comment about guessing the home hi-fi market is nicer than the way I think of it: irrationality rules in "audiophile-like" circles. You actually produce a loudspeaker that is superior and solves the problems that direct radiating home hi-fi loudspeakers, and suddenly, someone says "well, I'm not sure I like the sound" and the disinformation pipeline gets amplified by others who seemingly have something to lose if the market shifted toward MEHs. To say is another way, the hi-fi geeks should have piled on board when the SH-50/SH-60 came out due to their performance in-room, but the "sizzle factor" (generalized to any non-optimal characteristics of loudspeakers that some say they like) wasn't big enough to climb onboard the MEH bandwagon.

There is also the problem of old horn designs that are not very good (i.e., virtually all of those old designs). Candidly, that's why I rarely show up here to post--nostalgia actually gets in the way of innovating better loudspeakers.

Chris
Chris
"As far as the ear can tell, consistently clean and spacious bass can be reproduced only by a driver unit coupled to a horn-type acoustic transformer..."; Jack Dinsdale, May 1974

 

RE: Constant Directivity Horn Recommendations , posted on June 19, 2025 at 12:25:32
tomservo
Manufacturer

Posts: 9301
Joined: July 4, 2002



Hi
So the reason i went with the mid cone drivers on the first version (Unity horn) was because your ears are the most sensitive to harmonic distortion were your ears are most sensitive. If you consider the general equal loudness curves for ones ears, that curve inverted is like the ear's frequency response.

In that day 2 inch exit drivers were the norm and so was the "ice pick in the forehead" sound, so why was it sound systems sounded bright with increasing loudness??.

So my thought was ok I have to start over in life after the shuttle disaster ended Intersonics. A friend asked me to design a speaker for commercial sound. I had gotten back from Egypt, was hired to measure the acoustics in the GP for a movie and at a Christmas party, my friend said "make me a speaker out of a pyramid" I said yeah it will sharpen the sound haha, and i would grant your if i had a magic wand, funny guy (he was).

The next day the reality set in what speaker to make?

And i thought about the upside of CD horns and Don Davis's words about the down side (poor lf loading on the driver).

And what fundamentals have harmonics that fall in the 2-4 KHz ice pick range?


The early TEF systems could plot the harmonics vs frequency and it was easy to measure those drivers being grossly distorted down low at what seemed like modest power.

So the hunch was if i coupled mid drivers into the horn where the expansion rate (the impedance transformation high pass) was suitable for mids (in at 300Hz) that the low compression ratio and large area would be lower in distortion.

It was in fact vastly lower because of the low pass acoustic filter (the port mass and front volume) AND the notch's low pass in the response above the operating band.
The HP3562 had showed about .12% thd at 100dB 1m, about 1/200 of the 2 inch at the same spl. I thought ok this is cool.
An electrical or dsp low pass filter doesn't reduce distortion produced by the driver below crossover but an acoustic low pass does as it is after the distortion was produced but before it enters the horn. If the drivers radiation interact where the distance is less than 1/4 wl, then the radiations combine coherently into one source (like closely spaced subwoofers also have mutual coupling except now inside the horn).

I glanced at the link, they got the patent part wrong, the Unity patent expired but the reason for the improvement patent (Synergy horn) was i was not able to make all the crossover phase shift go away in the 3 way Unity horns. The time order of the drivers was ideally the inverse of the crossover's group delay but it was hard to find the path, can't do it the named slope shapes..

I had read a paper of Dick Heyser's when Doug ran the Heyser library where he describes an imaginary full range loudspeaker that radiated as a single point in space over a broad bandwidth. So far as a single source, it did that but i was really keen on making it work as a single driver the rest of the way to preserve time so it would produce a square wave broad band and over a wide angle too.

What i was missing was a better understanding of the mid ports and that investigation made it easier top make a 3rd and 4th order passive crossover without N order phase shift.
Now all three ranges combined into the radiation of a single full range driver..
The first successful passive filter was the SH-50's.
This is the one I made about 21 years ago now, a living room measurement of that one.
That speaker and the ones that followed launched the company.

 

RE: Constant Directivity Horn Recommendations , posted on June 19, 2025 at 14:01:47
Inmate51
Industry Professional

Posts: 3555
Location: Dallas, TX
Joined: August 12, 2022
 Hi Chris,

As you are getting more into horn systems and design, you might be interested in this.

John Meyer (Meyersound.com) is at the top of the hill. He has been researching and designing horn loudspeakers since the early 1970s, and currently produces some of the finest high-output loudspeakers, and provides sound reinforcement for top tier events worldwide. He's a Fellow of the Audio Engineering Society.

https://meyersound.com/product/bluehorn-system/

fyi.

*********

We are inclusive and diverse, but dissent will not be tolerated.

 

RE: Constant Directivity Horn Recommendations , posted on June 20, 2025 at 10:19:14
claudej1@aol.com
Audiophile

Posts: 1049
Location: Detroit
Joined: August 17, 2007
 Meyer sound produces overpriced products with old technology.

 

RE: Constant Directivity Horn Recommendations , posted on June 20, 2025 at 21:25:48
claudej1@aol.com
Audiophile

Posts: 1049
Location: Detroit
Joined: August 17, 2007
 90 degree coverage for home is only necessary for more than ONE listener.

Otherwise, SH-50's with Spuds, DTS-10, or TH-50 subs are wonderful for a Solo listener.

 

RE: With what driver? nt, posted on July 2, 2025 at 10:00:23
cin5
Audiophile

Posts: 98
Location: Long Island
Joined: August 17, 2015
 Of course, the specific driver would depend on the throat exit of the chosen horn, since I've heard too many horror stories about using adapters. But I have the budget for Radian or most 18Sound beryllium models for a two-way system. I would have considered swapping out TrueExtent Be diaphragms with those in the right JBL driver.
https://www.usspeaker.com/homepage.htm , until I was told that JBL drivers were not designed to use them.

 

Page processed in 0.032 seconds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]