Okay.. so I somehow managed to convince my Dad to let me have his pair of Memorex 505's, which are some pretty beefy speakers!

Unfortunately, they are not in as good condition as that one. They still work (or at least, did when they were last powered up and used a couple of years ago) but I'm a little wary to use them as there is significant damage to the foam that holds the bass speaker cone (see attachment). There is a large tear that goes about quarter of the way around but it actually goes further than that as you can see where it would tear if you put it under any more pressure.

Does anyone here have any experience with this issue and fixing it? I've read that I can replace the entire piece of foam (if I can find a 15" one) but was curious if any stopgaps would be sufficient, like glueing some fabric (say, bandage) to the rear side of the foam (if you can you even get to it) as I don't feel particularly comfortable with taking a knife to them..

For reference, I was actually pushing the speaker cone inwards to make that gap show up. When left alone, the foam lines up and everything. And those holes in the cone itself are from when the dog put his paw, and claws, on the cone! :( They don't have covers at the moment, but I will be building some to minimise further damage (by the cat, or something he brings in most likely).

Duct tape should do the trick. It's acted as a bandage for a great many music-related things.

I'm sure you can find surround materials. They look to be in pretty good shape nonetheless. You should power them up and play some music. If the sound is muddy, it might be the surrounds not allowing the speaker to move correctly, or it might be electrical.

From a quick Google Search:

http://www.speakerrepair.com/
http://www.parts-express.com/speakerreplacementguide/speakerreplacementguide.cfm

..and kudos to you mister for repairing things and not following 'throw it away - buy new' path.

Both the bass speakers move very freely if manipulated by hand and the foam surrounds for them are not brittle.. just torn on that one speaker (for all I know, I may have been torn like that for the past 10 years though).

The midrange ones are far more stiff, and not evenly stiff. One is just kind of resistive while the other feels like I am trying to push it through treacle. Might that be something else to look into?

As I said, I am not comfortable with taking a knife to them but will do so if is it significantly better than other fixes (I would have thought duct tape would be too stiff and interfere with the movement?).

Hm...I don't have enough first-hand experience to give you any advice on what they should feel like to the touch, but I am sure the links I put above should at least point you in the right direction!

Though I don't think you should put duct tape on the speakers unless it's on the outside of the enclosure for structural integrity, or possible just to make it look like it's not worth stealing ;)

Currently running a Klipsch GMX-A2.1 'system' from my laptop, so no big box speakers for me! :(.....

Maybe this can help you.

You can also try contacting the manufacturer for replacement conemembranes.

You can try post your question here

Most of the user there have massive experience in audio field, some of them are professional. Though it depend on your luck since the traffic is not really much compared to this site.

Done some more research on this and realised that sticking something to the foam would have been pointless. It's not just torn, it has pretty much lost any structural integrity. Just lightly pushing my finger on the foam and it goes right through it (even on the other one that didn't have the rip).

I've decided to do a refoam of both and I emailed some people who sell them about their 15" replacement being out of stock.. they redirected me to a replacement for these specific speakers that they sell (on Saturday evening.. wasn't expecting that)! Just need to find some replacement dust caps. I'll document the process in case anyone is interested.

The stiff mid-range is probably going to be another matter entirely though.. some further research is needed :)