a thread in audio forums (fora) have brought up the question as to the
meaning of the letter 'B' in some Wharfedale speaker model
nomenclatures. Some have claimed it stands for the 'Bakelite' (phenolic)
spider. Bakelite is a trade name referring to a product used for
handles on irons and electrical plug housings, telephones to name
three. It has also been used as pot handles as it is a good heat
insulator. A link is provided below for a good description and history
of the product.
In my collection of alnico Wharfedales, there are six 8" units, some are all original. However, one is designated as a SUPER 8 MODEL and has a woven type spider and the annulus is paper, molded with as part of the cone, also referred to as a corrugated annulus. The Super 8 CS/AL MODEL has an aluminum voice coil with a cloth surround for an annulus. It does have a phenolic (Bakelite) spider, yet there is no 'B' in the model designation for that. Some other units are designated with FS/AL but have woven type spiders and a label stating "This speaker is fitted with an ALUMINIUM VOICE COIL.' (The spelling of aluminum as aluminium is British.)
I realise the above is not conclusive and perhaps confusing but the following will clarify things.
All references following are from the book titled, "A Pair of Wharfedales" by David Briggs, whose grandfather was Gilbert Briggs' first cousin. I bought this book on October 2014 from Amazon for 32 Euros, approx. US$36 and it's worth every penny.
The ISBN (International Standard Book Number) is 978-1-906715-14-4
Here's a link to the page obtained by googling that number. http://www.impublications.com/content/a-pair-of-wharfedales
p.116 It was in 1949 at the National Radio Exhibition where 'a new introduction of the Super 8 using the latest Alcomax III magnet. A feature of its corrugated cone was the bakelised apex." If the dark ring around the cone at the apex is noticed, that's the liquid bakelite, prior to curing.
p.150 "The 10" Bronze chassis was modified with the bakelised cone and cloth suspension treatment to produce the /CSB variant.
p.159 Data Sheet, fig. 7.18 at the bottom, it states: AL = Aluminium Speech Coil, FS = Foam Surround, B = Bakelised Apex.
So, in short, bronze was never used for voice coil wire but rather, the chassis. The odd thing is that on the page accessed by the third link, it is stated that aluminum bronzes tend to have a golden colour. After filing the rear edge of the basket on the speaker shown here, the colour was NOT golden or yellowish in appearance but looked more like aluminum. Perhaps there is or was an early aluminum bronze that had more aluminum in it, thus changing the colour. That may be true since the label, being original along with the speaker itself states BRONZE. That, coupled with the italicised statement above, indicates the existence of a non yellow bronze alloy.
CSB = Cloth Surround, bronze chassis
The bakelised apex may be hidden by the flange of the dust cap. On the W15 series (see4 last photo), it is quite visible.
|The bakelised or otherwise treated cone apex on a new cone and coil assembly for a W15FS, one of 4 purchased and imported from Wharfedale in 1972. The foam annulus is still good indicating a change in the type of foam which, on earlier units was tan in colour.|
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