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Wharfedale Sand Filled Baffle SFB/3

Werner said:
Might it be that Gilbert Briggs' own books and publications from that era contain enough details to help restoration?
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I gave Tony my copy of G.A Briggs on Loudspeakers, and I recall there was nothing it about the SBF!

Gilbert Briggs was an old-school Gentleman: his books remain excellent reading, full of observations and detail about the wider world/science extant at time of writing, but acclaim and detail on own achievements = very close to zero.
 
That was ‘More About Loudspeakers’, I’ve also got ‘Loudspeakers’, the preceding volume, and there is a fair bit about the SFB in there. All in his humourous manner. Apparently it weighs 65 lbs as he wasn’t prepared to pick anything more than his age in lbs up (he was 67).

My next step, which I’ll do over the next couple of weeks, is to gently attempt removing the drivers from the baffle. Once I can see exactly what condition they are in the viability of restoration can be assessed. Reading the AudioKarma threads I suspect putting a normal foam surround on the bass and mid won’t be a huge issue, and it seems that is really the only viable option. How close that gets to the original spec I don’t know, but it is doable. The tweeter looks a lot more complex and fiddly. I’m actually quite scared of trying to free that from the baffle. Will obviously keep the thread up to date as I learn more!
 
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I unloaded the baffle last night to get a better look at the drivers with a view to getting them rebuilt:

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Hefty beasts, 12" bass, 10" full-range mid and 3" tweeter.

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The surrounds are obviously shot to hell, but the cones are good, they seem free-moving in the magnet gap and I get a Ohm reading for all three drivers if not quite what I'd expect: tweeter 8 Ohms (meant to be 10), 12" bass 12 Ohms (meant to be 15) and the 10" mid is about 17 and I don't know what that is meant to be as it doesn't have a label.
 
Contrary to what I'd read they do have spiders, at least the 12" bass and 10" mid do:

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12"

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10"

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The tweeter doesn't appear to though. Hard to see in there and it is still plenty dusty, but I can't see any spider. The alnico magnet on this thing is just insane, so heavy and powerful, it was actually a real challenge getting it out as the nuts are hard to get to and my spanner kept sticking to it!
 
Speaker impedance would usually be measured at 1Khz and is dependent on inductance as well as resistance so will always be higher than a simple DC measurement.
I would expect your units are all fine with the readings you have.
 
Some measurements just in an attempt to get something a bit more solid out into the public domain on these - this is my re-foaming data. The way I’ve done it is ‘basket’ is the full with across the green felt, i.e. the outer diameter of the foam. The ‘cone’ is just the cone (i.e. I have not factored any surround overlap, it is just how big the cone actually is). ‘Surround’ is my best guess as to the expanse including what is under the felt and 5mm or so under the cone. ‘Depth’ is the depth of the green felt/card spacer on the tweeter, i.e. space available for a roll-surround and cone excursion.

10” mid

Basket: 241mm
Cone: 186mm
Surround: 35mm
Depth: 5mm

12” bass

Basket: 300 mm
Cone: 245mm
Surround: 35mm
Depth: 5mm

Super 3 tweeter

Basket: 86mm
Cone: 66mm
Surround: 13mm
Depth: 4mm
 
This speaker is absolutely beautiful, I wish you luck restoring it.

To remove all that dust, I find a can of compressed air like you can buy to dust off PC keyboards, in combination with a very soft artist's brush to be the least harmful approach. Just use the brush to loosen it and blow it away with the air.

Before you change those surrounds I suggest strongly to practice on lesser speakers if it's your first time.
 
I have someone lined up who, whilst he has not done a pair of these, is experienced at re-foaming drivers.

Here are a couple more (rather poor) pictures to make a point about the rather odd way the drivers are mounted to the baffle:

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My apologies for the picture quality, it is just my iPhone in electric light, and I hate taking pictures in electric light!

The thing I am trying to show here is the central strut that bisects the baffle holes, thus scuppering any idea of the roll surround protruding into the hole. Secondly, and possibly less evident from the picture as I replaced the mounting nuts and washers so as not to lose them, is there is a captive nut on the bolt which in effect spaces the basket away from the baffle, i.e. the driver basket does not sit hard/flush the way say a Tannoy does. The green felt is pretty much the depth.

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Here we can see the available space for movement or any roll-surround is really only the thickness of the green felt. I’m suspecting the best approach will be to mount the surrounds backwards so the roll is at the back.
 
Was the tweeter designed by Ted Jordan? It bears some of his hallmarks - spiderless, straight-sided cone.
 
Yank said:
Was the tweeter designed by Ted Jordan? It bears some of his hallmarks - spiderless, straight-sided cone.
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No idea. Did he use magnets that could pull a Mersey ferry out of the water, as that would be a clue! It is a Wharfedale Super 3 similar but upgraded from this one on Troels’ site. Mine has a metal centre cap. I gave it a very gentle clean with a damp cotton bud earlier so the cap is now nice and shiny, it was just dead foam, not rust in the earlier pics. I’ve given it a dust as best I can, though I hate to think how much crap is in the magnet gap after 60 years facing upwards with no spider!
 
Tony L said:
No idea. Did he use magnets that could pull a Mersey ferry out of the water, as that would be a clue!
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Yes, he liked plenty of flux. But I don't know if he had any association with Wharfedale before his association with Goodmans?
 
Cookie's right, battleship build!

Other than the surrounds everything looks in remarkably-good condition. Am watching this with much interest.
 
Tony L said:
This would have been 1956-7.
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Well I can find no evidence of Jordan ever associating with Wharfedale, and he started at Goodmans in 1952, so never mind. I guess that sort of design was a sign of the times.
 
Just looking at my pics upthread could that be a date written on the rear of the cones? Kind of looks like 11/57, which is perfectly possible. I’m pretty sure this SFB/3 belongs to the MkI Troughline, Leak Point One Plus and TL/12 Plus I’ve mentioned in other threads as they were all sourced from the same auctioneer and estate sale, albeit at different times. The date for all pieces is viable, in fact I’m pretty sure the Troughline has 1957 written inside. Couldn’t find a date in the TL/12 Plus, which is odd for Leak, they are usually signed and dated inside.
 
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