Allison Bass driver repair

[trio leo]

I was scared of doing this repair for about 2 years, why I don't know they were knackered any way, what did I have to lose, so I bought the repair kit and this is how I did it.
this is what they looked like when I started


I made a cone support from a piece of hose pipe


then I used thinners to clean the metal basket and very carefully the edge of the cone, I used a craft knife and cotton bud




next I used a small blade craft knife to cut the central dustcap(scary bit) note the angle of the knife is parallel to the cone to avoid cutting the fine wire beneath.




I then used thin strips of plastic coated paper as shims to centralise the cone before glueing the new foam to the cone




after the glue had dried I then glued the foam to the metal basket with a soft brush


clothes pegs as clamps, taking that the shims centralised the cone I glued the foam to the basket where it lay, I didn't try to centralise that as well.


I used a piece of blutak to lower the dome exactly where it came from, as the cut was a bit wobbbly it was easy to line up where it came from.


I used a small file to weigh it down gently whilst the glue dried


and Voila! the finished Item, once the glue dried they look quite good I thought


back in the Allison 3 cabinet yahoooooo



I hope it has been helpful to anyone wanting to have a go, I missed out on 2 years of my favourite speakers now they are back sounding beautiful.
good luck

regards Al

[Theo]

Well done Al - pleased you've got them up and running again! Have the mid/tweeter units been repaired at any stage?

[keiths]

Nice work Alan.

[realysm42]

Does using glue change the sound of it? As it was never there in the centre to begin with, I'm guessing yes?

[Reid Malenfant]

Does using glue change the sound of it? As it was never there in the centre to begin with, I'm guessing yes?

I doubt it very much indeed. PVA is pretty elastic so it'll just aid in damping the thing, the only difference may well be in a very slight alteration of the driver parameters due to a very slight increase in mass.

It'd take some serious measuring gear to find that difference though

So I reckon they'll sound as good as new

[Tim]

Fantastic little tutorial, thanks very much for sharing Alan - they look great

[trio leo]

Does using glue change the sound of it? As it was never there in the centre to begin with, I'm guessing yes?

I agree with Mr Malenfant, the centre cap is just a dust cover, I laid the glue over the cut line in order not to leave any air holes, as the glue is reasonably pliant when dry and there is only a small amount of it, I don't think it has made any difference, whilst it's hard to remember exactly what they were like when I bought them in the 80s they certainly sound fantastic now and I'm glad I took the plunge.
regards Al

[trio leo]

Well done Al - pleased you've got them up and running again! Have the mid/tweeter units been repaired at any stage?

Hello Theo,
The only thing that seems to go wrong with Allisons are the bass foam surrounds.the tweeters and mid range seem fine, I love the large sound stage Allisons give, and although the 3s are 4ft tall they get lost standing in corners.
recently I was lucky enough to try the new Albarry M1108 Mono-bloc power amps through my 3s, what a beautiful control and delivery, I can't wait to afford a pair.

I hope you are enjoying your LO7D, what a deck eh!

regards Al

[YNWaN]

Strangely enough, I have a pair of Alison Six speakers that need re-foaming; have just ordered the roll-surrounds now .

[Alex_UK]

Top Job Alan (and good luck Mark!)