In the process of upgrading the subs in the play room. The aim was to deliver in the 1kW region into 8 Ohms. Discretion (and common sense - if that ever entered the equation) led me to shoot for something closer to 650 watts (measued 73vrms, or 666 watts on a sine wave into an 8 ohm load, which brought a wry smile to my face).

I chose to use a bridged configuration, as this allowed the use of supply rails at sensible levels (+/-65V) odd. It also allowed me to use a heap of capacitors that I had laying around.

The transformers are ANTEK units, which much to my disgust cost less to buy and ship from the US than to buy locally made. (Sorry about being parochial, but shipping a two 20lb lumps of steel to Australia is expensive - what is with our local businesses???)

No surprise that I was worried about:
- Power supply - needs to be big
- Cooling - an awful lot of heat to get rid of
- Safety - don't want to be melting my speakers,...

Couple of projects of mine - not sure if the photos will load OK.

First is a pair of 25Hz horn subs I used to have - used 18inch p.audio drivers, placed facing one another along a wall to form part of the horn and achieve adequate mouth area for the 25Hz cutoff.

Efficiency was well over 100dB/w/m.

Second photo is one of my digital crossovers I built, 4 way AD1940 based audio DSP with an AD1939 CODEC as A/D and D/A. Works a treat, and makes setting speakers up a snip, as can program in delays, HPF / LPF, parametric etc.

Also included my subwoofer couch - I built this as a challenge from a colleague of mine. The carcass of the couch forms an 800 litre enclosure, the ports exit at the back of the headrest three of them, and I used four fifteen inch drivers. It is tuned to 19Hz, and achieves a -3dB point below 20Hz.