I’m lazy , so there are excerpts from my correspondence on Tannoy Yahoo group; all quotes – Mighty ZM 😉
I’m putting this here as future reference for some other desperate Tanner .
K3809 – cloth surround impregnation solvent ?
as I wrote – pair of K3809
cloth surround , no back cone ribs
Fs is high – around 70Hz on both drivers
I contacted Tannoy Support , but they can’t help – all they can recommend is reconing , which is out of possibility , counting on fact that drivers are in excellent condition and just slightly used (well – same as they aren’t used at all )
so – anyone having real life experience , regarding solvent for surround impregnation ?
whatever , guy at http://www.haslingaudio.com is doing exactly the same for SH Altec’s , so I think same is possible for Tanns
Tnx for reply ;
There is no particular info on Altec related link , but point was that planned procedure was implemented …… I sent e-mail to Danish guy , asking for his recipe , if nothing else , as starting point .
Whatever – K3808 (3809) are having impregnated cloth surround , not paper ;
that’s visible on many pictures on net , and “cloth surround” is having exactly that name in related info
In any case , if I succeed in “operation” , I’ll share my findings
of course – “Danish guy ” wasn’t prepared to share his recipe ; I don’t blame him 😉
that’s why I’m sharing mine
besides Sam R’s problem with teared surround ……… and strictly speaking of hardened cloth surround – I’m stubborn and there is no way I’m going to change them …..
I would go to generic soft (probably acquired from Sonido guys in Hungary ) cloth surround , but will ever never invest money in new cones or – God forbid! – neoprene surrounds 😉
I remember some guys at Diyaudio speaking of http://en.wikipedia.org/wiki/2-Butoxyethanol , so I plan to start with that
Hardened cloth surround problem solved !!
soaking both sides of surround , using small brush , with plain Ethanol 95-96% , brought Fs from 71Hz to 29Hz .
I’m expecting that Fs will rise to spec. 35Hz , when solvent evaporate
That’s what we are calling just Pure Alcohol , and you can buy it in every drugstore.
So much speaking of recone and surround replacement
I’ll keep you informed , of course ;
even in case that Fs start rising again , I’ll just repeat procedure , removing old impregnation as much I can , and brush new tacky layer above it
then it will permanent solution
no damage , certainly ;
I’ll post few pics in few days , after having definitive conclusion about longevity of cure
Update : after 24h rest and solvent evaporated – two steps forward , one step back 😉
steps forward are :
1 – impregnate is not brittle and cracked (inducing noise , especially detectable at Fs)
2 – everything looks just nice , almost as new
step back – Fs is back on 71Hz ;))
whatever , I’ll proceed with more cleaning of old impregnation , and then try to seal it with tacky surround goo , which will (hopefully) prevent repeated hardening
will keep you informed
K3809 – cloth surround impregnation solvent ; hardened cloth surround – high Fs – issue SOLVED
procedure finished and confirmed
after 24h (and more ) of solvents evaporating , Fs is still good : 33-35Hz
what you need :
1.small brush , semi hard m ~8mm wide , same as kids are using for painting in school
2.Ethanol 95% (pure alcohol)
3.Acetone with oil ( nothing else than nail polish remover )
4.mouse glue (yes , that organic everlasting sticky goo)
6.cotton cloth ( old T shirt or whatever)
brush – buy it anywhere , mouse glue – anywhere , everything else – nearest drugstore
important to say – surround was originally threated from upper side , mostly ;
just slight residue of original rubbery impregnate is visible from bottom side of surround
procedure for upper side of surround:
using brush – from upper side – soak surround with ethanol ; it’s best to soak it in parcels of 10cm , then rub it with same brush ; whenever you fill brush with residue , wipe it on cloth
repeat procedure until you make two full circles (so entire surround perimeter is twice treated)
move to second speaker ,same procedure , again two circles ;
repeat same soak-rub-wipe-soak-rub-wipe procedure on both speakers , until you can see clear fabric of cloth , without any trace of rubber
it’s fun , but only if you have some muzak and coffee 😉
after few steps in procedure you’ll see what’s happening ; if you think that you’ll gain anything with another soak-rub-wipe circle , just do it
leave speakers 12h , to let Ethanol to evaporate
now – put some mouse glue on small (coffee cup) plate , add acetone and dissolve it to something liquid as milk using brush – put that mixture on upper side of surround ; if you see that your mixture on plate is going firmer , add acetone and mix ; when you treat entire surround , take just acetone with brush and treat entire ( already impregnated ) area with it , to make it more uniform
leave it for 12h
now – bottom side of surround :
soak brush in acetone , rub it firmly in Vaseline , then put that mixture on entire bottom side area ; goal is to have tiny layer of vaseline on bottom side
leave it 12h
easiest way of measuring Fs – use sine signal generator with 50R output impedance , connect it to bass terminals , put CRO probes on terminals
sweep frequency from 100Hz down ; when you see biggest sine amplitude , there is Fs
another possibility for measuring – instead of sig gene – use Sig Jenny program ( wave gene with counter ) , sound card to small amp , amp to bass terminals , AC voltmeter to terminals
put few volts of sine to bass , sweep from 100Hz down , when you see biggest reading on Vac meter , that is it
mine are at 31 and 33 Hz , I’m not loosing sleep because of using mouse glue and vaseline on piece of cloth
Mouse Glue : http://tinyurl.com/pcqn5pg
then one guy is saying that Mouse Glue is forbidden in some EU countries ; my reply :
in that case – just buy softest surround impregnation goop ; easy to do on line, if living in Europe
unfortunately – Serbia , where I’m living – somehow isn’t in Europe , so I’m Paypal-less 😉
that means that I’m just lazy to chase soft surround impregnation goop from Europe , taking in account that there is no domestic one
then guy asked where to search for surround impregnation goop ;
my reply :
sorry – just google ;
search for something like this : http://tinyurl.com/cw3yc8v
but , it’s wise to buy only after confirmation from seller that really soft thing is in question
then guy asked for difference sound-wise , pre and post procedure ; my reply :
sound-wise – taking in account that my pair is most mint pair I ever had opportunity to even see (except surround condition – most probably as result of no-usage for all long years ), I’m eager to say that they’re sounding just as proper pair of K3809 😉
right now being in stage of preparation of making boxes for them , I’m having fresh experience just listening them in bafle-less iteration ; even like that , there is proper difference in bass , comparing to prior (to surround treatment ) performance
whatever , fact that plain and common Ethanol is sufficiently good as solvent for old impregnation , was nice surprise ….
I hope you enjoyed little story
did I told ya that each cone got 2 layers of Dammar ?
if you’re puzzled – here is a link for SigJenny sig gene proggie : http://www.natch.co.uk/downloads/SigJenny/SigJenny.html
considering that article is originally published on my Blog at Baby Diyaudio , some 10 months ago , I can inform you that my Tanns are still at original Fs ……. so , procedure confirmed 😉
Addendum at June 2014. – posted some further details of process here …..