Welcome to Acoustiwave; all things acoustic.
I was eighteen, in my third year of an honours organic chemistry program at the University of Victoria. I had worked several summers with Tahsis Logging at Gold River, on Vancouver Island, British Columbia, and had a little cash left over after paying my tuition and apartment rent. I decided to build a speaker system.
This was the era of furniture before fidelity; my parents had always bought the top-opening console “hi-fi” with the radio and record player inside, more for how it looked in the living room, rather than how it sounded.
Component stereo was in its infancy, but growing rapidly in popularity with audiophiles. I did my research, devouring books on speaker design, and settled on Wharfedale 15″ woofers, and Empire domed midrange/tweeter units.
Wharfedale (British) had pioneered the roll-surround, which still predominates cone technology today. They also introduced ceramic magnet structures for the voice-coil static field.
I had seen the Empire set in a magazine ad, and decided that it would be simpler to trust the top end to an established designer, than go it alone. I obtained the components by mail order, and began construction of the “box”.
I had read numerous discussions on dampening speaker panels, and the consensus at the time for augmentation of bass response was to eliminate cabinet resonance by 1. eliminating interior parallel-facing surfaces as much as possible, and 2. constructing two-walled panels, with a layer of dry sand in between the panels.
I wrestled with the thought of such complicated construction, and came up with a different solution. While I did construct corner enclosures to eliminate most of the parallel surfaces, instead of double panel walls, I loaded dry sand into slightly thinned auto body undercoat, and applied it up to an inch thick with a trowel to all the panel surfaces in the enclosure. I had to do one panel at a time, allowing time for the mixture to dry and remain in place without sagging. It was a technique that I have used several times since; in fact, my current reference set employs that technique for panel dampening.
It worked beautifully. The bass was clean and tight, and the mids and top end were more accurate and transparent than I had ever experienced, even from “store-bought” component systems.
The amp was a Dynaco Stereo 70, a very popular kit in those days, and now according to many, “the most popular tube amp of all time”. I recall, shortly after getting this system set up, Jimi Hendrix released his second album, Axis: Bold as Love – which got a lot of play in my living room. Interesting the associations brought back by these memories.