Both units have phenolic spiders but one is marked as 10W and the other as 15W. One shows no evidence of having been used as was claimed by the seller.

The Super 8 FS/AL purchased in 2015.  This one is all original, including the foam annulus.  It's remarkable that the foam lasted all these years. It still springs back after being squeezed.  This unit is dated 3/58 on the back side of the cone and it still works after 63 years.  It has the older phenolic spider.

The sheet under the speaker is a two sided template for all the then current models of Wharfedale speakers.  The black bag is a dust cover to protect the open voice coil from foreign debris.  The wires on the bag are the original solid wires that were factory soldered to the speaker to protect it from inexperienced hands holding a soldering iron.  The cardboard box is the original shipping carton.

A pair of ALTEC 415C BiFlex units can be seen on the chair.  One of a pair of Jensen F12N units is on the floor.

Both units were all original but the one on the right, purchased in May 2020 has a new foam annulus.  It was purchased simply because I couldn't pass up the opportunity.  This one is dated 5/57.

A better view of the difference in the foam annuli.  The new annulus on the right raised Fs to about 76hz  whereas the one on the left has an Fs of 59hz.  This says little as the foam annulus of the original on the left is softer due to age.  These fellas aren't woofers and even if used as such or in a full range single speaker system, that difference wouldn't matter much.

The unit on the left will eventually need a new annulus.  I left it alone simply because it worked and that was a good thing for had that annulus been replaced, this comparison couldn't have been done.

The right speaker annulus was OK when purchased but failure was inevitable as it was very slow to recover from compression.  When looked at recently to get a top plate thickness for a fella in Australia, the annulus was noticed to have deteriorated further when the speaker was jerked by removing it from the carton after which its twin was checked and this page is the result as  another opportunity may not have presented itself.

The test setup.  The device being used is the Pocket CLIO, seen at the front edge of the table.

Impedance curves for EB3(original annulus) BLACK and the 5-1-2020(new annulus) RED.

From 150hz and up, the curves are essentially identical.  Nominal Z is 8W.  This conflicts with that which is shown on their labels.  See the section titled The Conflict  following figure 4.

Keep in mind that these units are intended to be used as a mid-range in a 2 or 3 way system which renders the difference in fs moot.  Also, when the original foam annulus is replaced (black trace), it will be very close to the red one.  The original foam annulus is 63 years old and very likely deteriorated despite it's still seeming good.  It is highly doubtful that the original speaker has such a low fs despite the highly compliant foam.  The phenolic spider is stiffer than any canvas type and the very lightweight cone will not contribute to a low fs.

The vertical scale here is 5W per major division and 2W per minor division.

Frequency response measured at 1w1m in the open. (see photo 6)

The slope below 2khz is due to the 8 inch diameter of the speaker.  Doublet action causes the back wave to cancel front wave at a rate of 6dB/octave when the baffle is smaller than the wavelength.  Here, 8 inches is about 1700hz. 

 In Briggs' up-firing corner design, the top baffle is  trapezoidal but its major dimensions are 20"x22" which is large enough to suppress doublet action to about 700hz.  On the open back SFB design, the smaller vertical dimension is close to 30" which will be good to about 400hz.  This may account for the 400hz/5000hz three way crossover offered by Wharfedale.  the more popular one crossed between woofer and mid-range at 800hz. 

These units do well to about 9khz.

THD EB3 1w1m

Remarkable for such an old paper cone speaker.  The -30dB in THD at 800hz amounts to 3.5% THD and the -40dB between 2khz and 5khz is 1%.

Check this link.  dB to %

THD 5-1-2020 1w1m

This unit, the one with the new annulus, has a more uniform distortion component that the one above, not that that really means anything.  There are many theoretical reasons for this but the one that comes to mind is that this unit supposedly has never been used.  Now, that being true would suggest a stronger magnetic flux as playing a speaker will have an adverse effect on the magnet, albeit very small but cumulative over time. Remember that tape recorder heads are demagnetized and magnetic recording tapes are erased with AC current, the former being at 60hz and the latter at 85khz to 120khz, depending on the recorder.

The unit on the left, (EB3) is marked as 15W and the unit on the right (5-1-2020) is marked as 10W. However, herein lurks the conflict as both speakers impedances measure within half an ohm of each other from just under 200hz to 20khz.

Impedance curves were run on both the CLIO and the LMS with the same results.  See figs 5 & 6.  Ignore the blue traces in each figure; they are from another speaker used as a tertiary point of verification. 

Both systems were also compared using a 12.1W 1% resistor also with identical results.

Assuming identical voice coils and flux densities, one would expect the more compliant speaker, EB3 as having a higher impedance due to its ability to generate a higher back EMF.  The CLIO and the LMS are sensitive to this else their impedance curves would be in error.

The vertical scale in fig.5 is 10W per major division and 2W per minor division.  CLIO doesn't allow manual scaling whereas LMS does.