Audio Video digital subwoofer by Andrea Ciuffoli - 1 jan. 2004

contact me for any problem or question:


This project born to create a true hi-end subwoofer system  to intergrate in my AV system.

Hi-end components

ADIRE Maelstrom hi-end woofer

A full 18" unit, Maelstrom delivers the highest displacement in a single high efficiency, low frequency driver available for under $300.  

A dual 8 ohm voice coil unit, it's capable of extreme levels of bass in a variety of enclosures.  Essentially, Maelstrom is a full-blown pro sound woofer, optimized to cover the entire first octave.  Most pro-sound woofers roll-off around 30-40 Hz; other high excursion 18s trail off in the 25-30 Hz range, and can't extend beyond a few hundred Hz.  Maelstrom's been designed to offer the same level of dynamics, clarity, and high frequency extension as the best pro-sound woofers, but with the ability to crank out serious SPLs below 20 Hz.

Here's the data on Maelstrom:

Re 3.4 ohms Le 3.5 mH
Qms 19.11 Mms 245 grams
Qes 0.29 Cms 0.24 mm/N
Qts 0.28 Rms 1.76 N*s/m
Fs 20 Hz Sd 1180 cm^2
Vas 460 liters BL 19.8
Xmax 13.0 mm one way EBP 69
SPL 92.9 dB @ 1W/1m No 1.22%
Pmax 550W per voice coil; 1000W total to the driver PRICE $299

Note that all specs are taken with the voice coils in parallel.  This unit is capable of an honest 1 kW of power handling, thanks to its 3" diameter voice coil.

Application note can be download from Adire website.

Digital amplifier

LC Audio  ZAPpulse 2.2 SE modules

ZAPpulse is a series of PWM Amplifiers, with output power of 200 to 290 Watts in 8 Ohms. (And up to 1 kW in 2 Ohms continous power). These modules can also be bridged for powers up to 1100 Watts in 8 Ohms.
The cost per Watt is very low, especially when you consider that these amplifiers are so energy efficient (better than 95%) that no heat sinks are required, even for the highest output power.
This new technology is very environment friendly, as it requires less materials to build and amplifier, than usual, and also has very low power consumption. The modules even being very compact (size of a credit card) are very rugged.
Up to 60 Ampere RMS can be produced without overloading the module. The reason for this ruggedness is that in any situation no power is dissapated in the output devices, so keeping them cool at all times.
Even the heaviest driven speakers run perfectly with ZAPpulse modules.... This is the amplifier technology of the future!


Output Power in 8 Ohms: 200 W RMS
Output Power in 4 Ohms: 400 W RMS
Output Power in 2 Ohms: 600 W RMS

Signal/noise ratio: -105dB (20-20.000Hz).
THD: 0,02% (1 kHz, 10W in 8 Ohms, THD measurement is bandwidth limited at 20-20.000 Hz).
Input signal: Analog 930 mV rms.
Frequency response +0-3 dB: DC-140.000 Hz.
Switchfrequency: 490 kHz.
Consumption Efficiency: approximately 96 % at 400W in 4 Ohms.

Follows the minimalist System

I am using the very beautiful 650VA R-core transformer R600-37 of the series produced for

the rectifier used in my project is the  FWB1 module with Schottky Full Wave Bridge Rectifier from


and the
SSM1 - Mains Supply Soft Start Module


The box simulation

Adire Audio offers a free version of LspCAD Pro software

The box design

- box version 1

- box version 2

the size is in cm

Sonic results

soon !