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Almighty Subwoofers
By Stig Erik Tangen
01 Jan 1997
Præludium
My quest for the Almighty Subwoofers really started when I as a teenager heard a rock band play. The band had a huge bass guitar amplifier, and the clean punch from this, far from anything I'd ever heard, made a deep impression on this author. The next shock was to hear a system a freaked-out farmer living nearby had build. He took an old Seas speaker system (type 60, I think is was called) and put it into enormous transmission line enclosures. They had reasonable output down to about 25 Hz, and one of his direct-cut church organ records made me order a pair of his speakers immediately.
Later, when I was studying to become an audio technician, I naturally got into DIY (in DIY audio was successful - computers later became my proffession). My first DIY speakers were a pair of 3-way transmission lines, using KEF B-139 bass drivers (like the KEF Bailey). This system was later replaced by a much simpler and better sounding two-way bass-reflex system with a 6,5-inch woofer. Since then I've used the two-way concept in many different variations, ending up in the main system I use now. Common to them all were a lower cut-off starting at 40 Hz. On the way I began to really miss the 20-25 Hz response I had with my transmission lines, and the search for a dedicated subwoofer soon materialized.
My first attempt at a subwoofer was a single mono sub utilizing a Seas P21REX 8-inch driver in a 130 liter vented box. Of obvious reasons this did not work very well. The cone sure moved, but the 20 Hz tone could not be heard through the noise and distortion.
The disappointment from the first try lasted a while, so it took me some time to heat up the jig-saw again. New experiments were done with two (stereo) subwoofers, using 10-inch drivers (ScanSpeak 25W7564). The audible result was good, but the low sensitivity of the system, only 83 dB at 20 Hz, and limited SPL capacity made me expand the system by using two drivers in each box. This system became the "REAL Subwoofers", also presented on the SBP. I used them for two years, the longest period a speaker system had ever served in my stereo without any modifications on the way.
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