HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

Hope its OK with everyone here at HFS, I've copied and pasted here the latest instalment of a thread I'm doing over on Audio-talk where I'm carrying out some of Richards speaker mods. I know some you have done this process before and thought you might like to see what I'm up to

Doh! It was all going so well this afternoon....

Drivers removed, cabinet vacuumed free of dust...


...in preparation for steel plate template experiments...


180mm x 220mm x 3mm plate 8 off per per speaker will cover the internals almost completely and is 'installable' through the mid/bass driver hole...


So, onwards, lets make sure all the cabinet joints are properly sealed and air tight using a skillfully applied thin bead of silicone sealant all the way round the internals...


In true Blue Peter style, lets put that to one side whilst the Sealant sets and get to work doping the driver with...


Yey, super neat application over the dust cover and nice dribble-age (its a technical word) into the dustcover-meets-cone-groove...


Wait about 30 mins while having a coffee, and hey presto...


...erks! The Bison Kit glue has reacted with the material the dust cover is made from and started distorting and pulling up round the edges eventually removing itself from the and free from the paper cone surface! Double erks!

Hmm, <scratches hairy chin>. I'm very tempted to glue a nice round shaped 'thing' in the dust cover's place. The idea of the doping process is I believe to damp the cone and increase mass, perhaps a nice round coin or suchlike?

The Doc will tell you exactly what to do.

I wonder if the dust cover may have caused more issues than it solves, as earlier versions of my Spendor BC2 drivers have phase issues at the crossover point purely because of the semi-solid dust cap they used and the larger diameter voice coil - apparently a phase plug would cure it, but my drivers wouldn't be original then and later versions like mine have, use a semi-transparent, finer dust cap. Celestion went through a fashion of making their plastic cones fully concave, the so-called dust cap being all one with the cone. Early Epos ES14's were like this and I believe Jamie's MA's are like this too?

Wish I knew more about it. Thanks for sharing and PLEASE come here as well and tell all. Just to add that I'm hugely fond now of the 8" Doc-Mod drivers and heard them this afternoon in Terry's Cubix Pro's. Driven by a pair of stock PSU's, the sound was enchanting and dare I say it, less 'assertive' than the rather smaller Doc-Mod B&W's can be on some music.. Delightful

Keep them coming DTB, while not Doc modded anything....yet,
i have refoamed a few pairs of speakers and each time been very proud of my handywork.

Regarding the exposed centre, could you not fashion a fabric disc to cover it up,
it just serve the purpose of debris falling into he gap or you could leave it open like Royds.

Once the glue dries the dome will go back into shape. The Bison kit should largely peel off the cone. Re-fit the dust cap using superglue, put a trail of superglue in the joint once set in place, or press in a thinnish worm of bluetack. Then you can start on the cone again with Bison. I had this problem on a driver in the past, superglue is what I used, bison doesn't loosen that.

If the dust cap has gone then a small circle of two ply cardboard will do the job I should think. Stop glue going down round the voice coil and drying, use a spirit or isopropyl to dilute and release if it does.

Today's instalment.

So, today the dustcap assumed this shape,...


Erk! I wont be using that again then So, knowing that the I needed to get the other dust cap off to make a matched pair I did some surgery, and hey Tesco...


I found these handy light wooden discs in Hobbycraft, perfect size too. Carefully glueing into position...


Whahey!


And then a very thin layer of Bison Kit applied to most of the cone surface, like a 'basecoat' when you're decorating perhaps...


The surround appears to be made of the same rubber material that the shape-changing Dust cap is made from, I'm trying to keep the Bison Kit away from the surround to avoid any more misshapen antics, good idea? Or chance it?

Ive read the techno info and it says it can be used on rubber. It may be that the dustcaps were a man made fabric which as reacted with the chemicals in the glue.

I don't know if it will be a problem. There are rubber surrounds on the drivers I use and have no problems, but that dust cap looks terminal never seen it do that. Anyway I doped a driver yesterday so this is after a days drying, but I know how much these drivers need - lots! for you it is new but I am used to it I just slop it on, it always leaves bubbles as it dries in the V, no problem.



And finished after plastidip.

Woweee! Your 'lots' is more than my 'lots'. I shall top up my 'lots' quota this week then!

Thanks again for the help and guidance everyone, much appreciated.

Indeedy Dave.

Docs doping is proper doping!

I started like you, by not putting anywhere near enough on, but now my JPW's sing

BTW I like those wooden discs you've got hold of. Makes your drivers look a little like Royd Minstrel drivers.

Alfi.

Quick question, is the final Plasti Dip coating purely for aesthetic purposes or is there another reason its required?