The CUBE concrete+wood passive phone amp is both industrial and refined.
The hand crafted shape of the high tech concrete provides a huge boost to your phone's sound with no power.
A beautiful statement piece of functional art for your desk or counter.
Source music affects results. One test resulted in a peak 26 dB increase. Decibels are exponential. a 10 dB increase is 2 times as loud.
Our super dense concrete has proven to be the most effective material for passive amps. 
 
Modern high tech concrete sealed for color enhancement and protection. 
Solid hardwood (walnut, maple, special order) is oiled and waxed for beauty and protection.
Overall dimensions:  4.5" x 4.5" x 5.25".*
Phone slot:  3.5" x .5" x .75" deep. *
*These are handmade with natural materials. Some minor size fluctuation may occure.
Works for phones with bottom right side speakers (iPhone, Samsung, etc.). 
Hand sculpted models. No CNC or 3D printing.
A "green" product. Concrete absorbs CO2 during its life cycle.