18 SOUND 21" EXTENDED 4.5" VC 1800W RMS

* 97 dB SPL 1W / 1m average sensitivity
* Dual 115mm (4,5 in) Tetracoil Aluminum Voice coil
* 4000 W program power handling
* Ultra linear suspension behavior for excellent sound clarity
* Symmetric flux density and inductance behaviour
* Low noise forced air cooling design
* Water repellent cone and epoxy coated plates
* Suitable for vented, horn loaded and bandpass applications

The 21NTLW5000 is a 21 inch diameter next generation high performance subwoofer, specifically
designed for high SPL very low frequency applications in either a reflex, bandpass or horn loaded
configuration. For optimum results we recommend the usage of power amplifiers able to deliver
4000W program power without clipping.
The 21NTLW5000 uses Eighteen Sound proprietary Tetracoil technology, where two different, axially
separated magnetic gaps and two inside-outside 4.5" diameter aluminum voice coils are wound on
the same former and suspended evenly in the two magnetic gaps.
The Tetracoil design key advantages are:
1) a symmetric flux density versus displacement behavior, that minimizes the even distortion
products;
2) a very symmetric and flat inductance curve;
3) the equivalent voice coil diameter of a 4.6" Tetracoil speaker is greater than 6". Consequently
heat dissipation occurs over a larger surface area, driving AES power handling up to 1800 W.
21NTLW5000 design features include a large displacement suspension system which, in conjunction
with a fiberglass reinforced, straight ribbed cone allows an ultra-