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Re: Help Appraising Old Wharfedale Drivers....

Posted by Bald Iggle on May 29, 2001 at 18:58:00

In Reply to: Help Appraising Old Wharfedale Drivers.... posted by blunted-one on May 29, 2001 at 18:22:08:

Wow! I had a Super 12/FS/AL ('55) back in the late 50's. These are even older, but should have similar characteristics. All the full range Warfedales made a big thing of having super good transient response. Their Chief Engineer, G. A. Briggs, wrote several articles about how good their transient response was. See if there are initials next to the dates. GAB would be Briggs himself. THat would make them much more valuable to a collector. To get the good transient response, they used very powerful magnets with very high flux density. Back then they used Alnico (an alloy of Aluminum, nickel, and cobalt) for the magnet, that would be the painted part. THe unfinished iron plates you mentioned were a special very high purity iron used for magnetic circuits called Puron. Much better than the usual transformer steel most companies used. This gave great midrange and pretty good treble response, but they were very bass shy because of the high back EMF from the high flux. As a result the bass is way overdamped. The solution for this was a ported cabinet. Warfedales own plans called for 6 cu ft boxes. I used an EV Baronet design of about 3 cu ft, but it needed a corner. There was a small, uniquely designed box called the RC (I think) which was ported through slots that fed in next to the speaker. They were almost as small as acoustic suspension boxes. Another design that worked well was the Carlson Coupler, a really interesting design that gave very good results with Warfedales. The front of the cabinet was cut in the shape of a pair of exponential curves, leaving a slot in the center that looked like a trumpet bell in profile. If grill cloth were put over the front, you could see ripples in the grill cloth move up and down the "bell" as the frequency went up and down.

By the way, use these things with a good tube amp. They're from the tube era, and optimized for the amps of the day.

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