Cubo 18

Thanks Cubo,

I've picked up some sheets of MDF yesterday and hopefully by the weeknd I will have a Cubo 18 and Cubo 18-580mm version built (Weather Permitting) to test out to see what all the fuss is about :lol: . I'll be trying them out with Musicson Drivers I have loaded in a 2x18 reflex cab Im using and see how they compare in the Cubo.

I understand that the Cubo suits a wide variety of drivers but what drivers have good flat frequency response between about 40-120Hz with high SPL in a Cubo18? And what would be considered the "Best" or favorite drivers for a Cubo 18.

If anyone had Hornsrep or akabak input values where I could try out different drivers for myself that would also be great

Thanks Alot

A few pages back I bragged that if the PD 1850 would be neo-fied, I would bring commercial Cubo 18's in roulation. Personally I like the ratio between Qes and Vas for the PD 1850. The best driver will probably bring you to OEM-country.

The 18NLW9600 is a very nice driver, however the Qes/ Vas ratio seems to suggest it's optimised for front loaded horns mainly. The kind of driver that in a hybrid will begin to show it's benefits at power ratings, where ordinary drivers would beg for mercy (give it plenty).

The RCF mentioned, to me seems to be inbetween the new generation 5" VC + neo drivers and the older top line of 4" VC ferrite drivers just before neo got released (expiring patent IIRC). I'm always a bit worried when power compression figures are not given (or are they?). However if you're into a few kilo's lighter, a couple hundred Watts more power handling -kinda drivers, this would be a good consideration.

I like the Celestion, it's just that I have something against the number 23 (if it's the weight in kilo's). It's just the number, 25 kg's nett weight and I would have loved it. It seems to have what it takes.
@Bee: Anything to aid in this?

Some figures: Lowww Qts, about 10 mm Xmax should do it, using the (Hvc - Hg)/2 + 0.25 Hg method (Hg should be at least 11 mm imho). I would also like to see a gaziljon Watts electrical power handling (the lack of that is what most drivers seem to die from). Vas in the 200 - 300 liter region.

Most low Qts, medium Vas drivers would plot terrible in Hornresp or Akabak, measure decent and sound evil (or so I've heard).

Best regards

Cubo

The PD1850 definitely look like they'd be hard on the spinal column

Whats your take on the 18NLW9400 ?

Fs 33 Hz
Re 5 ohm
Sd 0,1225 sq.mt. (189,88 sq.in.)
Qms 6,10
Qes 0,28
Qts 0,26
Vas 268 lt. (9.47 cuft)
Mms 180 gr. (0.40 lb)
BL 26 Tm
Linear Mathematical Xmax ±9,5 mm (±0,37 in)
Le (1kHz) 1,90 mH
Ref. Efficiency 1W@1m (half space) 97,4 dB

Qts not quite as low as the pd1850 but light and not quite as expensive either
It also has a high reference efficiency compared to alot of drivers

Hi Everybody !

I've just finished (Almost still needs a paint job tho) building a set of these monsters!

I am very impressed with the output and their ability to make a hard punch at a distance

I have made them out of Baltic Birch 11-Ply, and loaded the them with the RCF LF18P300ND woofer and did the extended version, because i read somewhere that it was recommended with that speaker

Everything was re-drawed in SolidWorks and imported into Alphacam at my work where we used CNC to cut out all of the boards where cut out.

Here's a link to the album imgur.com/a/O03QJ#0

very nice work there

The 18NLW9400 is a good choice as it's parameters go a bit below optimum reflex parameters and thus take a step nearer the horn parameter realm. Weight and power handling are plusses too, price three.

Reference SPL in dB/W/m is imho largely marketing material.

Fs^3*Vas/Qes*9.6e-8 is what I use mostly

Best regards

Cubo

Hi Cubo, i've got a Cubo 18 extended and cubo 18extended 570mm wide built using an 18nlw9400. It works great, it is about 1dB more sensitive than my 2x18 reflex, not much difference sonically between the 620mm and the 570mm cubo except the the 570mm wide works much better for transporting.

Before I go and order more 18nlw9400s do you think I could benefit from using a B&C 18SW100. it has a larger xmax of 12.5mm vs the 9.5mm of the 18nlw9400?

Sims show the 18sound reaches xmax at approx 800watts where the B&C hits xmax at about its AES rating 1500Watts.

I realise there is not a massive difference in SPL but the reason I ask is will I benefit from reduced distortion and more cone control in sound quality using the B&C verses the 18sound at higher volumes?

Thomann currently have the 18sw100 listed at 399 which is only 20 euro more than the 18nlw9400. it would mean probably selling the 18 sound though to afford a pair of B&Cs, do you reckon it is worth it?

Thanks

I've seen the measurements on speakerplans.com (at least I assume that was you). It made me wonder if you measured the 18NLW9400 directly or almost directly out of the box (it was shipped in)? Im my experience a driver will tend to loosen up after a few days/ weeks of intensive use, meaning the sensitivty in the lowest region will improve.

If you have been using it for quite a while it's as it is. If not, it would be interesting to see if you're getting an improved low end after a few intensive days of use (a couple of 8 hrs plus raves would do the trick ).

Personally I would likely stick with the 18NLW9400 even though the 18SW100 has more Xmax (and looking at the motor structure the B&C could have a power compression as low as, or slightly lower than the 18NLW9400).

Looking at the EBP and n0 however (all functions of Fs, Qts/Qes and Vas by the way), the 18NLW9400 comes out on top. It has a higher EBP, lower Qts, higher Vas and sensitivty calculated from n0 is 2.5 dB higher (in a Cubo that difference will be smaller).

Any simulating program might tell you that the 18NLW9400 will reach Xmax at 800 Watt but practice is different (without getting into the why-that-is), in fact with a proper 30 Hz - 40 Hz high pass I'll doubt it will reach Xmax at it's AES rating and overall, it will be thermally limited before it's mechanically limitted. You'll burn it before you'll shred it.

That being the case for the 18NLW9400, the 18SW100 might be having serious problems ever getting close to it's rated Xmax in Cubo 18 unless it's extra-ordinary powered. It will shine in the ~ 25 Hz - 40 Hz region but only if put in an enclosure that is tuned accordingly.

I don't reckon it will bring you serious improvemnent in this enclosure.

Best regards

Cubo

Thanks Cubo,

You are right those measurements were done with only about 4 hours light live work (light especially compared to the raves you're suggesting ), I only realised looking back at the photo of the test that i'm about 15-20 meters away from the stone building (Rushed the setup to try keep out of the Irish weather! ) so when I get some more hours into the speaker and some sun I'll get some better measurements done away from boundaries.

I did some 1watt measurements too
Cubo18-570 extended at 2.83V RED
2x18 2V Blue
1/12 smoothing

Considering the Cubo is just over half the size of the Dual 18 I'm pretty damn happy .
The Cubo beats it from about 37Hz, excluding the ~1.5 dB dip at approx 57Hz.
Much Cleaner Bass from it too. I've read about the lower distortion that Tapped horns and horns in general produce but I'm quite surprised by the difference


Thanks for your help Cubo, I will stick with the 18NLW9400 and get myself some Ply and make some sawdust

Cheers

Hello Cubo, I've picked a pair of Beyma 18P80ND, and I need to build a lightweight sub for a small PA system (we have a little musical-theatrical group but no one of us is young enough for a 50-60 Kg sub...). I just need to know which kind of solution make this speaker works better in Cubo 18 configuration: magnet inside or outside the chamber, normal or extended version.
Thank you a lot for your great project and for your efforts to help interested people!