The Briggs Three-way System

 

The only significance of this system, as mentioned earlier, is that it was my first experience with a high fidelity loudspeaker system. Originally designed by one G. A. Briggs of Wharfedale of England in the 50's, it was probably one of the reference systems of the time.

 

How well I remember the first audition of my rock 'n roll on this thing. But I won't repeat myself on that so allow me to go on about it's technical specifications.

Built of 3/4 inch birch plywood at a cost of $20.16 for a 4 ft. by 8 ft. sheet, the entire 9 cubic foot enclosure could be cut from one sheet. Originally assembled with internal cleats and screwed from the inside and braced with an internal slotted divider separating it into two chambers of about 70:30 ratio. The reflex enclosure measures 36x29x19 inches.

The upper chamber housed the speaker and that supplied the back loading through a dozen or so slots cut into the divider. The lower chamber vented through a 4 or 5 inch hole in front, thus loading the diaphragm to about 30 Hz. Actual measurements made outside about 30 years later showed the -3 dB point to be more like 35 Hz. It was quite efficient; a 30 watt amplifier being capable of driving it to levels that were hazardous to dishes in a china closet and a few other things in the house that weren't "nailed down".

That phenomenon only happened when we teenagers were alone in the house.

 

The unit on top housed the midrange and tweeter as well as the crossover unit. The midrange and tweeter were facing the ceiling, which in those days was adequate for monaural reproduction. Today, however, stereophonic reproduction with such an arrangement would produce unsatisfactory results due to phase differences between the left and right channels which could smear the sonic image. Any further discussion on that topic is well beyond the scope of this page.

 

The 2 or 3 way crossover and two views of the 8 inch midrange and 3 inch tweeter. Both had aluminum voice coils and cast frames. Only the better loudspeakers today have cast frames. Also, another thing not seen anymore due to the high cost of cobalt - Alnico magnets, an alloy of aluminum, nickel and cobalt, hence the name. The diaphragms were made of paper, and thin at that. But it was treated and moulded for rigidity. The annulus, or surround of the cone was foam, but by the time I took these photos, that had been replaced by a more rigid and better damped material. The crossover was a first order Butterworth and switchable between 2 or 3 way. The crossover frequencies are 800 Hz.& 5000 Hz.

 

The woofer. Yes, that device responsible for moving dishes. It also has an alnico magnet, 2 inch voice coil and an excursion of about 3/4 inch; 3/8 inch in either direction. The cone, made of treated paper, is extremely rigid. The annulus is foam, not original and the frame is cast. Although designated as a 15 inch, the diaphragm area is just slightly larger than a 12 inch. The 15 inch was measured across the bolt mounting tabs. And, of course, being made in England, all three drivers had a nominal impedance of 15 ohms.

 

 

 

My Special Mr. Klipsch page

More On Loudspeakers

Briggs' Wharfedale Three Way System

A Few Other Systems

My Room - aka: Chamber of Horrors

Corner Horns - Photos taken during construction

Phonograph Stylus SEM Photos

 

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