Cubo Sub / Cubo 21

The largest cabinet from the Cubo series stands upon the edge of portabilty; To big to be compact, to compact to be big.

Like it's predecessors Cubo 12, Cubo 15 and Cubo 18 it's a stand-alone bass bin. It will equal or out run an 18" reflex cabinet from 30 Hz and up in terms of sensitivty*. Like all Cubo-designs it excels on the KISS-principle, with a single angled cut** and a cut list from 1 and a 1/2 sheets**** of 244 x 122 cm / 8' x 4'.

Development

Based on Cubo 15 and Cubo 18, Cubo Sub is the 3rd prototype in a series of cabinets aiming at good reproduction down to 30 Hz. Mount the driver with the magnet in the horn for best low frequency reproduction from 30 Hz up to 100 Hz. With the magnet in the chamber for maximum output from 35 Hz up to 110 Hz.

Versions

Cubo Sub comes in 3 versions: One optimized for single 15" and 18" drivers***, one for 21" drivers, nicknamed Cubo 21 and one for 2 x 15" drivers, nicknamed Cubo Sub 215. 

Most 21" drivers will fit in the standard Cubo Sub but in that case care must be taken when pre-drilling the bolt pattern. Plans for Cubo 21 are available through e-mail (questionsaboutcubo at gmail dot com), the Cubo 21 plan incorporates a larger baffle at the cost of an extra angled cut.

*         Measurement against BR18a tuned to 37 Hz and BR18b tuned to 30 Hz.

**       Cubo Sub has a single angled cut. Cubo 21 has 2 angled cuts.

***     Due to reproducing sub frequencies 18" drivers with an Xmax of 7 mm or more are favoured. On average a 15" needs 1.5 times the excursion capabilities to produce the same output as an 18" driver or 2 times that of a 21" driver.

****   Cubo Sub 215 has a cut list from 2 sheets of 244 x 122 cm / 8' x 4'.

Acknowledgements

The designer likes to thank Xoc1 for his aid in the development process.

 Download highest quality: Picture below / right click / save as.

  Download highest quality: Picture below / right click / save as.

Preliminary measurements can be found here: http://www.freespeakerplans.com/index.php?option=com_jfusion&Itemid=64&jfile=viewtopic.php&p=11555#p11555

Measurements will follow.

Plans for Cubo 21 will follow.

Plans might be subject to small change (increasing angles)..