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Tannoy K3809 - hardened cloth surround issue - solved

I'm lazy , so there are excerpts from my correspondence on Tannoy Yahoo group; all quotes - Mighty ZM :smesna:


I'm putting this here as future reference for some other desperate Tanner ; I must admit ( or I'm just boasting ) - I'm always having serius backup for all things speakers - from Aleksandar RAAL ....... even if I'm always stubborn and I'm bugging him only post hoc ..... to be sure that I didn't blew something :rofl:



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 :rofl:



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


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 impregnate , and then try to

seal it with tacky surround goo , which will (hopefully) prevent repeated



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


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


measure Fs


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 ;)




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


Zen Mod


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 (surround treatment )



whatever , fact that plain and common Ethanol is sufficiently good as solvent

for old impregnation , was nice surprise ....


Zen Mod


I hope you enjoyed little story :smesna:


In case that I remember to get cam to my workshop tomorrow , I'll make few pics and put it here , along with few pics of same drivers prior to fun procedure


edit : did I told ya that each cone got 2 layers of Dammar ?


all pics are after treatment , except last 3 ones - sent to me from seller , so prior to procedure ...... months ago


if you're puzzled - here is a link for SigJenny sig gene proggie : http://www.natch.co.uk/downloads/SigJenny/SigJenny.html




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