cubo 12

The horn area's are officially the most important aspects of the design (4.2 cm, 4.5 cm, 9.3 cm and so on). The panel lengths and angles where calculated by a forum member. He isn't around here anymore so why the panel is depicted as 304 mm instead of (the correct length of) 301 mm will remain a mystery. Performance wise it isn't a problem luckily.

Best regards

Cubo

OK cheers Cubo, nice to know.

Presumably the horn area should increase gently.

I'm wondering about changing the triangular braces for an angled cross peace so the horn is more horn shaped. I did that mod to a different type of box many years ago of a similar design and it made a significant difference.

Any thoughts on that?

Thank you for the answer, it gave me some good ideas i will work on. Will try to make it like the "sidebags" and some other setup when i am transporting it.

The RCF units was to expensive, for what i have at the moment. I will go for an upgrade of my Cubo 15 instead.!

@Teknopaul: I quickly calculated it as an triangle with two sides of 8.8 cm (and one side of 8.8 x 2^0.5). This would give horn area's related to 13.9 cm, 15 cm (halfway) and 16 cm.

It would also exclude about 1 litre of effective cabinet volume over the volume excluded by the two triangular bracings. So measurement-wise a few fractions of decibels less somewhere along the frequency response. In exchange a smoother response somewhere outside the usable bandwidth. I'm not saying you're not hearing it but I doubt I could measure it.

From a constructive point of view: I've always liked triangular corner bracings, as long as you're talking close proximity, they are one of the most impressive forms of bracing. Not very effective at the centre of the panels it braces though. The two triangles are more effective at that.

One of my first Cubo drawings had both actually. A panel with 45 degree angles in the corner with the two triangular bracings (with the corner omitted) on top of that. It was only scrapped to uphold the KISS-principle. But if you have the time and skills, I say go for it.

@Ganon: Will be interesting to see how it turns out!

Best regards

Cubo

OK Dokey.

I guess I'll try it out. I tried it on a box similar to the ES18BPH which has one, and a quick scoot round google images indicated other folk had the same idea

I can see why adding both becomes a pain to build. Avoiding angled cuts with the tools I got is important, and with the cheapo ply I used can well believe bracing will be more important.


Sat looking at an empty box right now musicstore.de are taking ages to deliver a driver.

I am planning to build two cubo 12s this weekend and am not sure if I will be able to put a pole mount top hat in it. Looking at the plans, I thought I could make it work by notching the B brace but even with a notch I don't think I will have clearance to install a top hat without hitting the 304mm horn piece (unless I clearance the 304mm panel with a die grinder). The only thing I can think of would be to turn the cubo 90 degrees and put the top hat on one of the "sides". Would performance suffer if the cubo was rotated 90 degrees?

Has anyone had success installing a top hat on the cubo 12?

Also, would the Eminence LA12850 drive be a good candidate for the cubo12?

Following on from the notion that horn shape is not as important as throat volume...

Could one build a wooden box/cover for the cubo12 (a box with internal dimensions same as the cubo's external dimensions and one side open). For storage, the cubo goes inside the box. When you setup, you use the box as an S4 horn segment.



I tried to run this though horn response, but I think my initial measurements of the cubo12 are not reliable, still it seemed to add 3dB. Of course, you cant model the fact that the horn shape is so weird. That was my first attempt at using horn response, I've no real idea which numbers are important.

Problems.
The whole horn segment is a corner.
You can't add any braces.
Driver is quite far back in the horn.
You have to stop the joins rattling.

3dB seems worth having tho, at very little cost to overall storage and transport dimensions.

Is this a silly idea?

What about the Fane Colossus 12XB?
FS Hz 43 Hz
RE Ohms 5.2 Ω
Qms 5.81
Qes 0.254
Qts 0.244
Vas Ltr 78 litres
Vd litres 0.56 litres
CMS (mm/N) 0.196 mm/N
BL T/m 20 T/m
Mms (grms) 70.8 grams
Xmax (mm) 10.5 mm
Sd (cm2) 531.6 cm2
Efficiency % 2.316%
Le (1k Hz) 2.49 mH

@Smart: I think I have, I've used a M20 version like these: www.proaudiostash.com.au/product_images/7797.jpg
It's shallow profile doesn't reach al the way to the 304 mm horn panel.

If you're using something like this: cdn.clubafaceri.ro/clients/24/44060/68/t...05-4193588_thumb.jpg
You could drill a hole in the 304 mm panel (a bit larger than the top hat) and seal it of with some flexible kit.

You could also place the Cubo 12 on it's side without much consequence. Only downside to this that I can think of is that might interfere with handle placement.

The LA12850 seems like the most suitable Eminence driver, for high power apllications I've seen so far. And they've a fair amount of suitable Cubo 12 drivers if I recall correctly.

@Teknopaul: It seems like a feasible idea. Some things I would consider though:

- Wood can expand/ contract due to moisture content in the surrounding air, a too snug fit could end up in a non-fit during some season's.

- In my own search for horn extensions I found I was better of measuring the idea than simulating it. It might actually be better or worse then simulated, which could make the difference between lugging an extra 10 kg for nothing or a great idea.

- Danley has a tapped horn with the (I believe, twin 18") drivers far up the last horn segment. It's doable but too much horn length will bring down performance, creating dips in the frequency response, use with moderation

@Stani: I can't think of a single thing that would be wrong with the Fane Colossus 12XB, as long as you don't cross too high (80 - 110 Hz).

Best regards

Cubo