Size: 62x62x62cm

Frequency: From 40 Hz up to 110 Hz

Enclosure Type: Hybrid

Recommended DriverKappalite-3015lfKappapro-15lf-2kappa-15lf or  drivers with EBP of 100 or higher; Fs (27-50 Hz), Qts (0.21 - 0.41), Vas (150 - 300 L) / (7.4 - 11.1 ft^3). Where EBP = Fs / Qts (strictly speaking it's Fs / Qes)

Cubo 15: Cubo is a multi purpose, stand alone bass bin that will equal or out run a single 18" BR*, of similar size, from ~ 40 Hz and up in terms of sensitivity. Utilising a non-expensive driver such as the Eminence 3015LF, Kappa 15LF and Kappa 15LF Pro** and a cut list from a single 18 mm*** sheet (244 x 122 cm) / (8' x 4') with a single angled cut, Cubo 15" realizes a cost effective, small and light weight enclosure following the KISS-principle.

Development: In 2007 the first prototype was build and tested. Cubo 15" is the 4th prototype in a line of hybrids aiming at the achievements as stated above.  The measurement below shows the gain over the stated bass reflex (see * for details). Cubo 15 plans are also available in an Imperial version, plan available on request.

Versions: As a rule of thumb:

Qts x Vas > 120, Cubo Standard
Qts x Vas = 100 - 120, Cubo Extended or Standard
Qts x Vas < 100, Cubo Extended
Qts x Vas < 50; Cubo 15 Extra Extended

Magnet orientation:

The driver mounted with the magnet visible (the magnet in the horn) typicall gives the lowest bass response and slightly better cooling of the voice coil. Mount the driver with the magnet inside the chamber for most output around 60 - 80 Hz or the highest possible crossover frequency.

Footnotes:* 18Sound 18LW1400 in a 175 liter bass reflex tuned to 37 Hz. (6,6 ft^3) vs. Cubo 15 ; Eminence Kappa 15LF.          ** Apart from these drivers Cubo will work with a wide variëty of 15" drivers preferably with an EBP of 100 or higher; Fs (27-50 Hz), Qts (0.21 - 0.41), Vas (150 - 300 L) / (5.5 - 11.1 ft^3). Where EBP = Fs / Qts.  If you're uncertain if a driver is suited, PM or mail me at This email address is being protected from spambots. You need JavaScript enabled to view it.         *** If you want to use 15 mm material use 11-ply Baltic birch, nothing less. Plans available on request.

Designer: Cubo15 [view profile]alt


Cubo 15 Standard Plan:

Cutsheet (clearly visible after download):

Cubo 15 Extended Plan:

Cubo 15 Extra Extended Plan:

Only the 2 inner horn panels are different from Cubo 15 Extended, all else equal.



Log in to comment

Cubo15's Avatar
Cubo15 replied the topic: #25008 4 months 2 weeks ago
The high pass is good, I know that some Cuboteers cross Cubo 15 at 120 Hz or higher but I prefer 80 - 100 Hz myself, so I can't personally recommend it. The Turbosound tcx115b looks like a good choice, it won't be as loud as a Cubo 15 but it works better with the amplifier/ processing that you've got. So unless you're able to use additional EQ on the Cubo 15 (to suppress 100 - 150 Hz), I think the Turbosound tcx115 is a good choice. Best regards Cubo
savior's Avatar
savior replied the topic: #25007 4 months 2 weeks ago
thanks cube, my problem is that I would use his original amplifier which has the cuts already set and not settable!
you say they won't do?
the amp delivers 550watt, the cut is from 38hz to 120hz.
however in the diagram I may see that the cut is at 40hz 12db.
I'm ignorant of technical data! i have manufacturing experience with cnc machines, but i have always built cabinets and heads for guitar amps designed by others.
do you think maybe a bandpass like the turbosound tcx115b would be better, which as a frequency range is very similar to my sw540 sub? 
You do not have permissions to access this page.
Cubo15's Avatar
Cubo15 replied the topic: #25006 4 months 2 weeks ago
Those are actually pretty good drivers, I would use them in Cubo 15 Extended or Extra Extended up to about 80 - 100 Hz. The only thing lacking is the Xmax, I would use a high pass at 40 Hz and use about 500 W of amplifier power per driver.

savior's Avatar
savior replied the topic: #25005 4 months 3 weeks ago
hi cube, i'm savior from italy. i have a problem with 2 sub montarbo sw540. in practice they have the plastic cabinet and too small, so these subs sound the same way both front and back! I was thinking of building two new cabinets and came across the cube 15 project.
the features of my sw540 sub are:
MOSFET amplifier (class AB)
Max. Output power 550 watts continuous rms 850 max peak
Frequency Response 38Hz ÷ 120Hz ± 1dB
impedance 4ohms
Stereo electronic crossover 24dB / octave Crossover frequency 120hz

I think the woofer is from B&C but you don't know the model! however i found some specifications of this woofer in the manual.
Nominal diameter 15 "
Frequency range 37 ÷ 2000Hz
Sensitivity 99db
Rated impedance 4 ohms
Net weight 8 kg
FS 37hz
RE 3.04 Ohms
Qms 16.93
Qes 0.35
Qts 0.34
Vas 0.1m3
ηo 3.17%
B.l 16.62 T / m
SD 0.085m2
Xmax ± 5.25mm
Cubo15's Avatar
Cubo15 replied the topic: #25003 5 months 3 weeks ago
Both the STX W.38.1200.8.MC and W.38.800.8.MC look good on paper, except one thing, the weight of the drivers doesn't correspond to such T/S-parameters: Normally you wouldn't use the physical weight of a driver to base it's performance on, but since all these drivers have ferrite magnets and from the looks of the photo's also have aluminium baskets, you would expect better overall performance with an increasing physical weight.

The 1508-8 SPS BWX for example, weighs 7.7 kg but it has a high-ish Qes (less magnet needed) and small Xmax (4.7 mm again less magnet needed), so those numbers add up.
The Kappa Pro 15LF, weighs 10 kg, has a medium Qes and Xmax, and a 3" voice coil instead of a 4" voice coil like the Black Widow has. Again those numbers add up.

The STX W.38.1200.8.MC, weighs 7.5 kg, (claims a large voice coil and Xmax, medium Qes) and the T/S-parameters suggest it would would be close in performance to the 15TBX100, however the 15TBX100 (also large voice coil and Xmax, medium Qes) weighs 12.3 kg.

So something is off, as I'm rather safe than sorry, I would exclude the STX drivers from the list.

1) Kappa Pro 15LF
2) Black Widow 1508-8 sps (or the Kappa 15LF, 9 kg but a steel chassis)

nemsik's Avatar
nemsik replied the topic: #25001 5 months 3 weeks ago
Hello Oskar,
I have used two "W.38.800.8.MC" from two different series and I think they are quite weak speakers, so I don't know if the "W-38-1200-8-MC" will be much better.
Currently, I have loaded 15TBX100 and the difference is big.
oskarociak's Avatar
oskarociak replied the topic: #25000 5 months 3 weeks ago
Hello Cubo.
Can you judge which of these speakers is best for the cubo 15?
a) Kappa pro 15 lf2
b) Black Widow 1508-8 sps
c) STX W.38.1200.8.MC
Thank you in advance for your answer
Zambrotta's Avatar
Zambrotta replied the topic: #24992 6 months 2 weeks ago
but the one loaded with the 2226 is the meanest of them all thank you for the design brother
Zambrotta's Avatar
Zambrotta replied the topic: #24991 6 months 2 weeks ago
ok thank you for your feedback Cubo I already have 3 x Cubo 15 extended two of them loaded with bm-15w and one with the p150/2226h and their spl is amazing....
Cubo15's Avatar
Cubo15 replied the topic: #24989 6 months 2 weeks ago
Hi Zambrotta,

That's a good driver for Cubo 15 Extended, only drawback is the short Xmax, therefor a 40 Hz high pass is advised.
Zambrotta's Avatar
Zambrotta replied the topic: #24985 6 months 3 weeks ago
Hello Cubo I would like to try out the Cubo sub 15 but I only have a p150/2226 15inch driver that one with a blue basket at my disposal what are the chances of it doing well in that cabinet
Cubo15's Avatar
Cubo15 replied the topic: #24980 7 months 3 weeks ago

It's 30 Hz vs 40 Hz. I''d go for Qts below ~0.4 and Xmax over 7 mm, if you elaborate your question, you'll get a more sophisticated answer ;)
Zambrotta's Avatar
Zambrotta replied the topic: #24979 7 months 3 weeks ago
Hello Cubo how are you...can you shed some light on the difference between the Cubo sub and Cubo 15....also what kind of drivers would work well inside the Cubo sub
Cubo15's Avatar
Cubo15 replied the topic: #24973 10 months 3 days ago
I do like the old 15PS100 over the newer 15PS100, I would place the old version on par with the 15G450N, while the newer version is on the bottom of the list, below the JBL, which in hindsight is a close second to the 15G450N.
nemsik's Avatar
nemsik replied the topic: #24972 10 months 4 days ago
What do you think about B&C 15PS100 in Cubo15 extended?

Unfortunately but I found two different datasheets:
1) ("new")
2) ("old")

Please tell me if "both" speakers are good for Cubo? Which will be better?

I ask because the "old" 15PS100 has EBP = 100Hz but the "new" has only 82hz. The recommended value for Cubo is 100 or higher. 
The "old" has QTS = 0.31 but "new" has 0.43, where recommended is 0.21 - 0.41
The "old" has VAS = 152 but "new" has only 103, where recommended is 150-300

The "new" 15ps100 is suitable for cubo15?

Thank you
giveortake's Avatar
giveortake replied the topic: #24971 10 months 5 days ago

In the footnotes the email has a mistake.

Thanks for this, I have now corrected the email and profile links.
nemsik's Avatar
nemsik replied the topic: #24966 10 months 5 days ago
Thank you, I've emailed to you
In the footnotes the email has a mistake.
Cubo15's Avatar
Cubo15 replied the topic: #24965 10 months 5 days ago
questionsaboutcubo at gmail dot com
nemsik's Avatar
nemsik replied the topic: #24964 10 months 6 days ago
Hi, Mr. Cubo
Is your email correct? Unfortunately, I can't send the message to you.
BwoySkanky's Avatar
BwoySkanky replied the topic: #24942 11 months 2 weeks ago
Bonjour tout le monde, je suis nouveau dans ce topic déjà et ausi dans le monde de la construction heu Autonome de son sound ? je sais pas si ca se dit mais je suis seul sur mon projet ^^, fin bref..

J'aurais quelques tites question désolé, en faite j'ai pour projet de me faire un ''''mini'''' Sound spécialement pour style: Reggae,Steppa,Dub....

Et donc je me renseigne et je tombe sur le mignon Cubo 15 que je ne connaissais mais alors pas du tout et vraiment avec les retours de certains et autres ca ma carrément donner envie faut dire alors voilà, j'ai acheter un HP
the box Speaker 15-300/8-A
Puissance: 300 Watt RMS, 1200 Watt crête
Impédance: 8 Ohm
Réponse en fréquence: 50 - 4000 Hz
j'ai aussi vu que si on utilise du 15" il serais recommander d'utiliser du Multipli bouleau donc je vais chercher ça demain les planches mais en attendant je me demandais quel filtre utiliser pour les basse et a partir de quelle fréquence ?.. merci beaucoup pour votre temps de pri pour me répondre et désolé du roman....

Derniere chose:
Dans l'avenir j'aimerais bien une tite tour comme ceci vous en pensez quoi ?

1 Cubo 15 ext/1 Cubo kick/T2v et par la suite la doublée alors je voit en grand voir trop grand pour comencer et seul en + ? ou est-ce possible d'un coté sachant que le temps et l'argent n'est pas un probleme ha oui sachant que je me suis renseigner sur cette config car ca me parraisser budget Moyen fin bon c'est vous les pro, je suis juste jeune amateur.

VOilà fini désolé encore et merci beaucoup :)
Cubo15's Avatar
Cubo15 replied the topic: #24916 1 year 1 month ago
That's interesting, it's a bit larger than I thought, the difference between Extended and Extra Extended is much smaller, to the point that I wouldn't mention it.


Nugget's Avatar
Nugget replied the topic: #24910 1 year 2 months ago

Extended stands to lose the KISS-principle, 3 angled cuts instead of 1, no backward compatibility between Standard and Extended because of cut sheet differences and construction. All the while I don't think you'll simulate a significant difference let alone measure something.

I am not quite sure how you mean this. Probably you just meant that you wouldn't measure a difference between a cubo extra extended and a cubo extra extended with slightly different first panel.
BUT since i often read in this forum, that Cubo standard and Cubo extended don't differ from tuning because of the longer port / smaller chamber relation, let me just say that i measured totally different. In my measurements (and i have measured at least 5 different Cubos (or extended) from different builders/build periods), Cubo ist tuned at around 47,5 hz, while Cubo extended is Tuned at around 40,5hz when used alone (a stack of four lowers tuning only by 1 hz to 39,5hz). Apart from tuning, there is also lower upper extension for Cubo extended. At cubo extended it's about 138hz, while it's way higher on Cubo standard (i don't have the measurement on hand right now, it's about 170-180hz if i remember correctly).

Don't get me wrong, i like Cubo extended a lot ( i use 4 with RCF LF18N401), but you need special care with the crossover to the midrange driver. I eq out the resonance, set at good LP and time align the 2 sources using a RTA like SMAART and still, there is phase issues above 180hz, because of the bad high frequency exctension. The idea to use them together with normal size horn tops without a kick is not a good one...
Cubo15's Avatar
Cubo15 replied the topic: #24907 1 year 2 months ago
Send an email to questionsaboutcubo @ gmail dot com

oskarociak's Avatar
oskarociak replied the topic: #24906 1 year 2 months ago
Can I get plans for 15mm?
Cubo15's Avatar
Cubo15 replied the topic: #24905 1 year 2 months ago
Your gut feeling is important but you seem to have difficulty substantiating your claim in measurable terms. What exactly is the benefit of the optimization of the flare rate and how would one measure that? I think the reflectors are small compared to the wavelengths involved and thus do not have a significant influence on the frequencies involved.

There's a few things to consider as designing a (bass) cabinet is about compromises, any 'optimization' of the design will lead to at least one 'downgrade' in another field of performance. What you call an optimization of A, someone else will just call B performing worse.

An expanding horn with length X will not tune as low as a non-expanding horn of the same length, based on excursion minima, although this might not necessarily show as such in the frequency response. In other words, increasing the flare rate of the horn will decrease the tuning frequency. Secondly any increase in horn volume, be it by length or horn circumference increase, will lower the volume of the rear chamber which will further increase the tuning frequency, unless the increase in horn length offsets the decrease in rear chamber volume. You could opt to decrease the horn throat but this will increase the compression ratio, which can lead to unpredictable behavior (beyond simulation) and possible damage to the driver on high power levels. To keep the design favorable to a wide range of drivers, with unknown quality within the Qts x Vas range, the compression ratio is best sparingly increased if at all.
Regardless of how you combine these factors, unless you keep the horn volume from increasing, your optimization of the horn flare will decrease the low bass output and increase the peakyness of the lower response. Resulting in worse time behavior below 100 Hz and less low bass output, in return for better time behavior above 100 Hz and a slightly higher allowable crossover frequency.  

If you're interested in the time domain, look at the group delay, phase and impulse response in Hornresp. They're however not always straightforward in their practical meaning and as your suggested changes are small, so are the differences in these graphs, it might be impossible to call one better then the other. For me it's the combination of simulating, building and hearing multiple designs that gives me a feel for how to interpret the combination of these graphs and what is desired, I'm positive I do not understand as much of it as I could or would like to. 

If you're not really sure how this flare rate optimization does improve characteristics to what extend and in what way, I suggest opening a topic about it on, not only will you find more like-minded souls but also the wealth in knowledge currently lacking either of us