Select dispersion pattern

[DanielT]

Which dispersion pattern had you chosen? If we play with the idea that you would use a waveguide. Choose vertical and horizontal dispersion and feel free to justify your choice. For inspiration here you can see different waveguides:

Home

Explore our stock of horns and waveguides. Find the partner for your horn driver to deliver midrange and high frequencies, with reliable range and coverage.

www.parts-express.com

Exit:
So I'm curious if there is a general ideal or if it is for the most part an individual sound ideal. Ignore the practical DIY aspects regarding the waveguides from Parts Express. I pasted them to give the inspiration, in support of a theoretical discussion regardning dispersion.

Dispersion threads, which of course already exist at ASR but now with the opportunity to choose a wavegudie.

Some examples, from some of the waveguide / horns in the link from Parts Express:

Nominal coverage: 90 ° H x 50 ° W •

80 x 60 degree dispersion pattern with excellent directivity control

Nominal dispersion: 100 ° H x 40 ° V

 

[alex-z]

That depends on the woofer, I would only pick a waveguide/horn capable of directivity matching in the crossover region. And if multiple options existed, I would choose whichever has the least diffraction

 

[DanielT]

That depends on the woofer, I would only pick a waveguide/horn capable of directivity matching in the crossover region. And if multiple options existed, I would choose whichever has the least diffraction

It's true it should work as a whole, with the woofer. But if you were to choose freely, hypothetically, that it fits in the crossover region what kind of directivity would you choose? We keep the diffraction parameter constant, equal, in this theoretical example.

Edit:
Speaking of bass elements and directivity:

Polar plots
Off axis cancellation effects are often illustrated through polar response graphs which show the dB level at various angles from 0 to 90 degrees. In the diagram the dimensionless number ka refers to circumference * divided by wavelength. * circumference can be easily calculated as pi or 3.141 multiplied by the diameter.

Speaking of bass elements and directivity:

Polar plots
Off axis cancellation effects are often illustrated through polar response graphs which show the dB level at various angles from 0 to 90 degrees. In the diagram the dimensionless number ka refers to circumference * divided by wavelength. * circumference can be easily calculated as pi or 3.141 multiplied by the diameter.

For example a 15 ″ piston has a circumference of around 4ft, so ka is around 250Hz. Above ka = 1 the piston starts to become directional. Relatively smooth off axis response is maintained to ka = 2 (500Hz for the 15 ″ piston) but by ka = 5 (1250Hz for the 15 ″) the piston is beaming with notable response lobing. A 15 ″ single driver speaker would be a narrow directivity speaker whereas a 2 ″ single driver speaker would be considered relatively wide directivity.

Speaker directivity / off axis response: theory and measurement techniques

This blog article is the first in a mini-series about speaker directivity or off axis frequency response. For us the two most important things in determining sound quality in a home theater or stereo are the speaker and the room. Above the room’s transition frequency the speaker’s directivity...

www.acousticfrontiers.com

And:

Wikiwand - Loudspeaker measurement

Loudspeaker measurement is the practice of determining the behaviour of loudspeakers by measuring various aspects of performance. This measurement is especially important because loudspeakers, being transducers, have a higher level of distortion than other audio system components used in...

www.wikiwand.com

Please note I am not an expert, but willing to learn more. A challenge to do it in a good way, match elements that is. It is obvious.

Edit 2:
I have not even mentioned this with reflections walls, ceilings and floors .... breath ..... But fun to think about.

 

[alex-z]

If I was picking freely, I would do a B&C DE550TN mated to a horn with 35-40 degree directivity (targeting -6dB) paired with a 6.5" mid-range, and additional side mounted drivers to narrow directivity below the crossover region. Basically like the Kii Audio Three but capable of higher SPL and narrower radiation pattern.

 

[voodooless]

narrower radiation pattern.

Why so narrow? 35 to 40 deg is quite narrow and not something one sees a lot done in home environments.

 

[Kvalsvoll]

So I'm curious if there is a general ideal or if it is for the most part an individual sound ideal.

It does look like there is ONE pattern that is ideal for a specific use-case. Which means there is ONE pattern that will satisfy both those who seek pin-point precision, and lots of spacious room-filling sound, in the same speaker. And a speaker for typical rooms in a home will be different from a system intended for larger arenas.

Then there are compromises. Cost, size, visual appearance concerns, technology and knowledge available for the designer, brand heritage, will lead to designs that can not fully accomplish this ideal radiation pattern. The result is often a speaker that can do some things well, and other aspects not so well.

A good starting point is to realize that radiation pattern actually is a choice. Like you say - "Which dispersion pattern had you chosen?". Because many speakers designs seems to originate from defining a box, then put in some drivers that will fit inside there, and then try to fix issues after all basic properties of this speaker has been set. The typical center speaker is a good worst-case example of this approach.

 

[peanuts]

the jbl clone on top is pretty good. fairs well with larger woofers. like this example with a 12" crossed at 1250hz: (gainphile s15)

essentially the only eq needed with a cheap selenium d220ti driver:

 

[alex-z]

Why so narrow? 35 to 40 deg is quite narrow and not something one sees a lot done in home environments.

I meant per side, sorry if there was confusion, so a total horizontal radiation pattern of 70-80 degrees at -6dB. I want to maintain some side wall interactions, but at a reduced level so that less treatment is required. I think the precision imaging of a narrow directivity design sounds neat, even though I prefer the overall soundstage width of a wide directivity design.

 

[DanielT]

Okay, but then why not go "all the way" and have omni speakers?

But hm, I can only imagine having such omni if I were to walk around the listening room. Otherwise, the sound should be "smeared" out and not be precise. Hm, if you sit completely still in a listening position, is a very narrow H&V dispersion preferable? That should be the case anyway. So it should depend on how people sit still vs move when listening which determines the choice of dispersion.

Although it seems to be wide horizontal but relatively narrow vertical dispersion which is a popular sound ideal. There are quite many waveguides with 100° horizontal dispersion and different degrees of vertical dispersion. For example waveguide / horn from the link in my start post plus test DIY speakers:

Selenium HC23-25 1 "Exponential Horn 100x40 1-3 / 8" -18 TPI

Selenium HC23-25 horn + Pyle PDB512 – AmpsLab

Or:

Dayton Audio H812 1 "Exponential Horn 100x60 2-Bolt

Dayton H812 horn + Selenium D220Ti – AmpsLab

 

[voodooless]

Usually these wide differences in angle lead to issues like pattern flip. See: https://www.prosoundtraining.com/2010/05/24/understanding-horn-directivity-control/

 

[DanielT]

Usually these wide differences in angle lead to issues like pattern flip. See: https://www.prosoundtraining.com/2010/05/24/understanding-horn-directivity-control/

Interesting.

In any case a waveguide is what it is. Called a guide to direct the sound in a certain direction. How much the sound should be guided is probably a matter of taste.

Edit:
Plus, waveguides make it easier to create good FRs when the tweeter is placed on a smaller baffle. Perhaps possibility of having a lower crossover point. Increased sensitivity and a little more sloping FR. See here, attached photos, Dayton tweeter with and without waveguide.

Dayton Audio - ND25FW-4 1" Soft Dome Neodymium Tweeter with Waveguide 4 Ohm

ND25FW-4 1" Soft Dome Neodymium Tweeter with Waveguide 4 Ohm

www.daytonaudio.com

Dayton Audio - ND25FA-4 1" Soft Dome Neodymium Tweeter 4 Ohm

ND25FA-4 1" Soft Dome Neodymium Tweeter 4 Ohm

www.daytonaudio.com

 

[DanielT]

I think Erin explains the basics of sound radiation, narrow or wide radiation patterns,in a good way.

Watch starting at 16:30 in the video where Erin discusses the pros and cons of different types of radiation patterns plus his personal preference:

 

[D!sco]

I think it would really depend on the use-case. A surround sound setup, or stationary home theater would have narrower horns that just barely envelop the audience. In a more casual setting I would want wider dispersion, up to +/-80 degrees, but with only about 1/3-2/3rds the vertical dispersion to get less floor/ceiling bounce. This way the room is simply accepted as is, with hot spots and interactions. It gives a sense of space and allows people to naturally flow where they feel most comfortable while not being 'cut out' of the sound by the abrupt end of a horn's dispersion pattern.

 

[DanielT]

I think it would really depend on the use-case. A surround sound setup, or stationary home theater would have narrower horns that just barely envelop the audience. In a more casual setting I would want wider dispersion, up to +/-80 degrees, but with only about 1/3-2/3rds the vertical dispersion to get less floor/ceiling bounce. This way the room is simply accepted as is, with hot spots and interactions. It gives a sense of space and allows people to naturally flow where they feel most comfortable while not being 'cut out' of the sound by the abrupt end of a horn's dispersion pattern.

Speaking of broad radiation patterns. This one:

TEBM35C10-4

This Balanced Mode Radiator is an audio drive unit with an extended frequency response and wide directivity. Features Wide bandwidth […]

www.tectonicaudiolabs.com

And here placed in a round ball.

I heard them at the Vintage DIY fair. Sorry for the blurry picture, (I'm useless at taking sharp pictures). It was a fascinating experience to be able to move around the room and it felt like the sound and volume were the same. He, Solhaga who built them (with a 3d printer) has them as rear speakers in his home cinema system. Now, I'm not a home theater person, but I can imagine a number of front, center rear speakers, etc with Tectonic TEBM35C10-4 would work perfectly fine. They are not expensive either. Really good price now, $10! Just take the opportunity to buy some:

Home

Tectonic TEBM35C10-4 BMR 2" Full-Range Speaker 4 OhmBy combining the benefits of bending-wave technology and pistonic modes of operation, Tectonic's TEBM35C10-4 BMR 2" full-range delivers extended frequency response and extremely wide directivity. The small form-factor is ideally suited for...

www.parts-express.com

Tested here:

Tectonic Elements TEBM35C10-4 Miniature BMR® Driver Review

Tectonic Elements TEBM35C10-4 Miniature BMR® Driver

www.erinsaudiocorner.com

Solhagas round ball Tectonic speakers #20 in the thread:

Hifi Vintage DIY fair with pictures

I visited this fair yesterday! DIY & Vintage meeting in Mölnlycke Here is a short report. When: 6 November 2021 Where: Country: Sweden City: Gothenburg I took pictures myself BUT most were so damn blurred so I borrow pictures from this thread, taken by other participants. Pictures taken from...

audiosciencereview.com

 

[D!sco]

I always thought they would be a fun line array or CBT subject. There are just so many good candidates for "best full range" and these probably don't have the best upper range.

 

[DanielT]

I always thought they would be a fun line array or CBT subject. There are just so many good candidates for "best full range" and these probably don't have the best upper range.

There are many candidates, a search on Parts Express : Midrange / Midbass Drivers & Full-Range Speakers gives 558 Products. So there are many to choose from.

In addition to that, there is many threads on DIY pages with the title you mention best full range (or variation on that theme).

 

[Flaesh]

H812

[Almost an] antediluvian model, I don't know who originally designed it. Same as Celestion H1 9040P, P-Audio PH-3220, Ciare PR312 and a lot of local brands\nonames

e. g.
https://www.diyaudio.com/community/threads/asathor-a-jbl-4367-clone.367215/ The clone joke is dubious, but the project is well documented and cheap.

 

[DanielT]

I would have checked the driver below IF I had been interested in a narrow radiation pattern. Quite expensive driver but still.

RCF CX12N351 - 12″ Coaxial

12″ Coaxial, 58 Hz, 180 W, 97 dB, 8 Ω

www.loudspeakerdatabase.com

Here it is thought about the RCF CX12N351 in # 1522. I think it is the RCF driver in any case:

Here is comparison of the 15" non-waveguide coax to the 12" waveguided coax.

There is a huge directivity benefit comparing RCF waveguide with and without the side woofers. The difference is much smaller comparing the 12" cardioid to the 15" non-cardioid. Note I lowered the high pass on the side woofers to 100 Hz for this comparison.

Full range line array for wall or corner placement

Possibly a better 12” coax Eighteen Sound - Professional loudspeakers

www.diyaudio.com

 

[Bjorn]

I find that a broadband constant directivity is more important than the beam width itself. Especially in the area of 400 Hz to 5-7 kHz. Some narrowing above that can be ok.

Apart from Omni (360°), anything between 180° and narrower horizontally can work great if it's sufficiently broadband and treatment can be applied. Vertically, a narrow directivity is always preferable IMO.

The desired horizontal beam width for me will depend on the room size, type of treatment and usage. But generally I prefer something in the area of 70-90° with a lot of diffusion in the rear of the room (with good distance) to create both great imaging and spaciousness.

 

[GXAlan]

https://www.audiosciencereview.com/forum/index.php?attachments/jbl-everest-dd55000-1985-white-paper-english-pdf.72153/

This one!