Speaker design based on large woofer

[Audionaut]

BMS 12S330

Overview

bmsspeakers.com

Here are two examples using the BMS.
A 12-inch driver that I really appreciate up to 200 Hz.

MFE Secundo Messungen - FIDELITY online

Das Messlabor Alle Messungen werden mit dem PC-basierten Messsystem „Monkey Forest“ mit einer Auflösung von 1 Hz oder kleiner bei einer Abtastrate von 96 kHz durchgeführt. Als Messmikrofon wird eine B&K-Kondensatorkapsel des Typs 4939 (Membrandurchmesser ¼ Zoll) zusammen mit einem...

www.fidelity-online.de

Paired with a 5-inch BMS coaxial speaker

Neo - genuin audio

www.genuin-audio.de

It is possible to achieve very deep bass in small enclosures.

 

[JohnnyNG]

In my opinion, you haven’t mentioned the most important thing about Sigberg speakers: They all rely on a coaxial driver in the most musically critical frequency range.

Is there something specific you find important about the use of a coax? I really like the 5.5” Sica which Sigberg uses to great effect:

https://www.audiosciencereview.com/...6-5-coaxial-speaker-build.61464/#post-2255210

 

[Audionaut]

Is there something specific you find important about the use of a coax?

I think the most important thing is the harmonious integration of the tweeter into the geometry and dispersion characteristics of the woofer.
The Sica Studio Line is a very good example because it achieves this very well in terms of design. You can see it visually in the very smooth transition from the edge to the surround to the cone, and in the design of the tweeter with its small 'horn' that integrates cleanly into the cone.
I also think it’s very important that the coaxial speaker is ALWAYS relieved of the low-frequency tasks, regardless of whether you’re using a 5.5-inch coaxial speaker or a 12-inch one.

 

[ryanosaur]

I'm not sure which Purifi driver is being discussed, but their 6.5" midrange driver only has +/-2.9mm linear xmax, it has no business reproducing 40hz.

And there are lots of 12" woofers not intended to reproduce 25hz.

@ryanosaur If you're running the 12" to 3-400hz, I'm still not sure why you need another two drivers (with different bands) between that and the tweeter. If you're very focused on the directivity, have you considered a waveguide for the tweeter?

And you should be looking at something that is designed for pure midrange use, with a very light cone.

Here is a good article about what makes a good midrange driver (there's actually not that many out there): https://jrkpost.medium.com/the-true-midrange-speaker-driver-1da12977f854

Maybe it's possible to feed the article to ChatGPT and have it search for compatible drivers for you.

Great article. Thanks for sharing, Thorbjørn!

A part of my struggle is in recognizing where I would be ok crossing to the Tweeter. Some that I’ve looked at can cross fairly low but not in line with where even 5” drivers begin to show signs of beaming.

Then, there is the lack of familiarity I have with horns and waveguides. I don’t usually see either of those paired with very wide dispersion. (Also, enter that bias against, mentioned above, which I’ve learned from others. *blushes)

(But hey, I’m man enough to admit where my shortcomings are… at least in some situations.)

Regardless, I am a fan of simplifying where I can. If I can eliminate a set of drivers then it’s a win. If I can switch from 2 moderate-sensitivity Drivers to a single high-sensitivity Driver with no penalty to SQ, then I will.

 

[ryanosaur]

I do not see a horn-loaded compression driver fitting in with your "wide dispersion" paradigm, so presumably you are exploring a different paradigm?

Correct, indeed. I don't see it working either after I spent an evening digging through Compression Drivers and Horns.

Thing is, like many when I first started looking at gear, I was kind of amazed by the JTR Noesis Reference Towers. Even now, the thought of those 215s kind of triggers that Pavlovian response and I'm reaching for a Kleenex to sop up some drool. [Hyperbole]

But it does make me wonder if 60x60º or even 45x45º would be noticeable in a smaller room. I am not designing this for a palace. Perhaps it may end up in our 'great-room,' though more than likely... a more intimate setting.

I was also reminded of Joseph Crowe having designed a Horn-guide for the Raal 70-20.

Horn No.1155 —- Biradial for RAAL 7020XR

Special Note: We work with RAAL to develop custom horn designs. RAAL provides dimensional drawings for their drivers to ensure proper physical fitment. This means we are able to accommodate other RAAL drivers such as the Lazy 210-10. After ordering, we will change the existing the design to...

josephcrowe.com

Of course, when this was brought up, Dennis Murphy commented something to the effect of: why would anybody want to put a ribbon tweeter like the Raal in a horn and ruin its dispersion characteristics?

I'm also reminded of our conversation briefly about the FaitalPro 8HX210... Again, not that this is the direction I want to go, but that Driver does seem to tick a lot of boxes for performance.

I appreciate everything you shared. It's helpful to me to better understand that aspect of design.

Thanks, @Duke !

 

[kemmler3D]

Not so random side question, if I may beg a little advice from any who care...

FWIW, I am still not ready to make a call on this, yet, but... I need to learn.

I am not well versed in any controlled directivity design. Admittedly, the bias of a few people who were influential during the development of my "taste" for very wide dispersion may be affecting my judgement.

A major concern is in horn loading a compression driver as I have seen countless statements about SQ coloration and "shouty" qualities being inherent in this design.

True, false, or it depends?

If I were to look at a Compression Tweeter, how do I avoid falling into any of the negative territory, or even, can I?

What do I look for in a Compression Tweeter for home audio use that will deliver in the most stringent aspects of very high SQ?

Thanks!

I've seen a few horn designs that don't beam too much and don't seem to suffer from diffraction or FR anomalies, at least under 10Khz, (check out xshape) but as @Duke mentions you're probably going to have to forget about a really wide dispersion then.

I think something that opened my eyes about the inherent trade-offs here was some of what Purifi wrote about designing their tweeter. They went for wide dispersion which means the energy is spread thinner which means the tweeter has to work harder to hit the same SPL in a given spot. They were very successful at getting a dome tweeter to play loud and clean, but distortion becomes a problem anyway because the air pressure at the surface of the tweeter starts to make the air itself behave in a non linear way. There's basically a physical limit on how much sound energy you can get from a small diaphragm without distortion.

That limit is pretty high (IIRC it was ~150dB at the dome) but it exists.

I think this also highlights that a wide pattern is not just a matter of choosing the right waveguide or horn, there are real trade-offs on top of that. The spread-out sound has to come from somewhere.

 

[sigbergaudio]

@ryanosaur Have you built many speakers before? I think you would learn a lot by prototyping and measuring something much simpler. Maybe a 3-way with some of the drivers you are contemplating? Then you can re-use the drivers in a more advanced design later?

 

[ryanosaur]

@ryanosaur Have you built many speakers before? I think you would learn a lot by prototyping and measuring something much simpler. Maybe a 3-way with some of the drivers you are contemplating? Then you can re-use the drivers in a more advanced design later?

This isn’t going to be my first attempt. However I have not built anything as of yet. Period.

I will be building my first subwoofer very soon. Like within weeks, soon.

I will also be building some 2-ways using the sica 6.5 coax very shortly thereafter.

I had been waiting too long for affordable material and a local hardware store had 20% off. They used to exclude lumber. Not this time!

My next hurdle will be learning how to get measurements. But I do have REW and a Umik-1 and generally understand the idea behind measuring a single speaker in near-quasi-anechoic setting.

Regardless, I have good woodworking skills and understand basic cabinet making principals. A Router is the only thing I do not regularly use.

This will be fun.

 

[Salt]

The router is the cherry on the cake ... prelimary results, if a concept works coherent, will not need it.

 

[Flaesh]

I like to build from the bottom up: what I do for the Woofer will dictate what stacks above

I haven't read any further yet, but I want to disagree. I would\had build the sound in the room primarily from top to bottom.

ps: A normal tweeter is used from about 800 hertz. But usually it's less wide than you want.

 

[sigbergaudio]

I haven't read any further yet, but I want to disagree. I would\had build the sound in the room primarily from top to bottom.

ps: A normal tweeter is used from about 800 hertz. But usually it's less wide than you want.

Hm, I'd say tweeters are normally crossed over way higher than that. They may have an fs of 800, but that's not where you'd typically do the crossover. More like 2000-3000hz.

 

[Dumdum]

I'd be considering having the large drivers in entirely separate active subwoofers personally, so they can be optimally placed in the room rather than being compromised by where the main speakers need to be for imaging. You would need appropriate DSP upstream for integration though.

Funnily enough I’m about to setup four way active with a Helix dsp ultra S in my front room tuned with Smaart with satori drivers and my twin gz 15” subs in 6 cu ft each I have an 11 channel tonewinner to run fully active

 

[Flaesh]

Hm,

The question here is about defining the norm. I was implying (with a bit of humor) something like this:

For normal 2way like this:

The day before yesterday I found out that the entire MAX series has been discontinued. But horisontal directivity usually is about 90º or less.
JBL M2 claimed wider and available for easy diy assembly from spare parts.

 

[Audionaut]

But horisontal directivity usually is about 90º or less.

No, the Eighteen Sound XT1464 is a 60° × 50° horn.
For me, its beam angle is a bit too narrow for home use.

 

[Flaesh]

the Eighteen Sound XT1464 is a 60° × 50° horn.

Yeah. But there are many other waveguides, including those for 3D printing. The 1464 was used simply as an example, and is available for purchase separately and has been used in home appliances.
I have an XT1464 and JABO KH-53 Kugelwellenhorn, but I use the old SEOS24. I didn't buy M2, fearing (maybe in vain)) that it is too wide for my system and preferences.

The M2’s are a nice way of dipping the toes into the DIY pool because they are relatively simple, cheap and well-supported information-wise on the web, and they sound okay as playstation speakers.

 

[ryanosaur]

OK...

Had to step away for mental clarity and a few other reasons. I'm still here though and working on this.

Came across some posts on one or two of the DIY forums about Pro Drivers losing clarity and detail in "home audio" applications as they are "underpowered" in comparison to their intended purpose. The argument that a trickle of that first watt won't create quality sound at 70-75dB, say, sounds reasonable at first blush, but the more I thought about it the more spurious it seemed to be. Sadly nobody really spoke up with any real fact or countered with any first hand experience. Needless to say, it leaves a kernel of the original claim lying in wait to germinate...

So I ask, please: Any truth to this? Does a highly efficient Pro Driver lose detail and quality at lower drive levels?

 

[levimax]

This was brought up in another thread with the (sort of) conclusion being maybe in some cases it is plausable but it all depends on the driver as "pro driver" covers a huge range different drivers designed for different applications with different parameters and you can't generalize.

My first hand subjective experience with a 18" LaVoce pro driver operating from 15 Hz to 180 Hz is that low level listening is excellent for what that is worth.