Hi Fi Takes Over

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After a very successful guitar amplifier project for Richard, I have started on a Hi Fi construction venture, which has an Op Amp preamp, a stereo tube amp and 2.5 cubic foot speakers with tuned bass reflex ports. The ports will be interchangeable to give a variety of resonant frequencies from 35 Hz down to 25 Hz. The change is accomplished by simply slotting in a different length of gutter drainpipe, somewhere between 3.5 and 8.5 inches long. One of the speakers is finished and sounds just spot on. The photos clearly show the 35 Hz port in place. Some people might wonder where the tweeter is. It's cleverly mounted within the cone of the woofer. There are actually two tweeters, side by side, so the assembly can't be called 'dual concentric'. I don't believe in mid-range units. I'm trying to emulate a particular sound that I encountered at the start of my career in radio sound, over 40 years ago. Some of my favourite loudspeakers were designed in the 1950s by the B.B.C. and were in use up to the early Seventies. I have not heard anything to match them since. They were called 'LSU/10s'. It was great to hear the rich tones of top notch announcers like Terry Wogan, Denis Meehan, John Skeehan, David Timlin, Andy O'Mahony, Leo Mc Guire, Lorna Madigan, Una Sheehy, Diane Lonergan and Catherine Hogan emanating from these loudspeakers. They were the days. Link to photo of B.B.C. LSU/10.