I realise that this post and question is a little outside of the remit of
this group but I'm at a loss as to where else to find this information.
I recently bought a pair of Wharfedale Dovedale III speakers from ~1970 or
so. I'd read reports on-line (including the original 'Gramophone' review
that is no longer available) which praised these for their faithful
reproduction of most of the frequency spectrum but in particular their
'deep, clean bass'. I have a pair of Goodmans Magnum SL speakers that are
similar design (3-way acoustic suspension) and vintage and, after replacing
the x-over capacitors they sound pretty good. I was hoping for a similar
result with the Dovedales which were their (British) competition at the
time.
They had been in storage for a decade before I took possession of them (from
a deceased estate) so, before parting with my money I asked for them to be
connected to an amp and played so I could test that all drivers were working
(as I'd heard of people who'd had their tweeters fail). The only source
available was a lo-fi CD / radio player so I only turned up the volume
enough to hear (through my trusty cardboard tube) that all six drivers
worked. I parted with my money and bought them home.
Alas, on getting them home I discovered that the 'rubber' surrounds of the
12.5" woofers had gone hard - they felt almost like bakelite! Of course they
produced no bass and I didn't dare 'drive' them for fear of damaging the
cones. After some frantic Googling I found that at least one other person
had also had this happen (but no follow-up on how, or if it was fixed). I
then spent quite a bit of time contacting various suppliers of replacement
driver surrounds but am unable to find anything for these. Being 12.5" I
can't just try a generic surround either as nothing fits. I got a couple of
quotes to have them repaired but they're way out of my rather limited
budget.
It seems that these really well-built drivers were previously used in other
Wharfedale cabinets, also acoustic suspension, but fitted with doped cloth
surrounds - and that quite a few of these speakers are still going strong.
It's only the rubber-surround ones that have failed....
So I'm trying to find out how to make my own doped cloth surrounds to
replace the (now cracked and broken) 0.5mm thick hardened 'rubber'. I'm an
invalid on welfare so I have time, just not much money. The only
instructions I've found on the web that come close are for making
'siliconed' cloth surrounds. However apparently no glue will stick them to
paper cones other than silicone - which is a once-only job as the only way
to remove it from paper cones (if the desired result isn't achieved first
try) destroys the cones.
As I'd like to preserve these lovely old speakers I'd like to have a shot at
making something similar to the stuff that used to be used for 'doped cloth'
speaker surrounds - the problem is I don't know what cloth or indeed 'dope'
to use! I can just try to use something I consider might be suitable (maybe
cotton and 'rubber cement' or similar - but how to shape and dry it?) but it
sure would be great if anyone can give me guidance or information as to what
used to be used. I'd love to have pointers on how to do it as well but I'll
settle for *any* information I can get rather than trying to re-invent the
wheel.
Help please? Thanks in advance for any useful input. I've had them nearly
six months now while I tried to find answers and I'd really like to try to
bring them back to life. (The highs and mids sound great for speakers of
this vintage!)
--
/Shaun.
"Humans will have advanced a long, long, way when religious belief has a
cozy little classification in the DSM."
David Melville (in r.a.s.f1)
[Sent from my OrbitalT ocular implant interface.]