Reforming IMF speakers

[Lawrence001]

I bought these nice 3-way IMF CM3 (Compact Monitors) a while ago but put them to one side as the mid range foams had cracked and hardened and I didn't have time to repair them. I did manage to source the foams from a well known Dutch online supplier ( https://speakerrepairshop.nl/en/ ) so that I would be able to get on with them when I did find the time.

Anyway as the family were away for a few days over the bank holiday weekend I decided to do them. I've put some photos below.

The key advice I have to anyone attempting to do this for the first time is to take your time, be careful about damaging the driver and clean off all trace of the original foam before gluing the new one on.

The company makes a little syringe applicator which was invaluable in getting the glue under the foam rather than applying the glue first and trying to place the surround on top, which risks getting messy glue everywhere as you adjust its position.

To note this is my third time I've done this, I've repaired some Videoton Minimax woofers and Kef B110 speakers before, but not big woofers which are a different kettle of fish and need more care around voice coil centering and can go wrong more easily.

I also had to remove the foam from the front slots as it was crumbling and leaving bits everywhere. I tried cutting some internal foam from a pair of speakers to shape, but the balance of the sound changed. I think the new foam is closed cell and is blocking the air coming from the port (but can just be removed when listening). I need to source something appropriate if anyone has any ideas?

The upshot is that they now sound more balanced as you'd expect with the mid ranges allowed more excursion, I'm very happy with the sound. I'm hoping to take these to the Wam show if anyone wants a listen, but I haven't got the room to keep them after, so if there's any interest I'm happy to sell them on and take something else, or hand them over at the end of the day to someone attending.
https://uploads.tapatalk-cdn.com/20230829/f17667283ff6bf2d827e64348ecb9458.jpghttps://uploads.tapatalk-cdn.com/20230829/848fe1a4f245a70e3835e75704c50080.jpghttps://uploads.tapatalk-cdn.com/20230829/fea4dcba8bf76d7e727b8094213e03ca.jpghttps://uploads.tapatalk-cdn.com/20230829/730fd212d42dcbbedebc7eda79fcc83a.jpghttps://uploads.tapatalk-cdn.com/20230829/e83d16895df11effce4376014d0af04a.jpghttps://uploads.tapatalk-cdn.com/20230829/cf8d84808b336f88207390fe41366c55.jpg

[Lawrence001]

Doh I didn't check the title if a mod could change please, bl00dy autocorrect.

[walpurgis]

Looks a decent job.

Try an ebay search for 'filter foam'. That's where I got the open cell sponge for my TDL speaker ports, it comes in various thicknesses and cell sizes.

[Lawrence001]

That's actually a good tip, if you look at this listing you can pick what density you want and this might allow some tuning of the port.

https://www.ebay.co.uk/itm/284373895257

[Puffin]

Nice job. I did re-foamed the mids on a pair Heybrooks and it was the cleaning of the cones after removal that was the hardest part. They have a sticky (dope?) type stuff on them.

[donmarrese]

It's a difficult speaker to do...I did a pair about 6 years ago...sourced from the same place ...I wouldn't have the patience now...you've done a good job!

Sent from my LE2123 using Tapatalk

[Lawrence001]

Thanks for the kind words guys, it took me several hours until early in the morning to do it but there's a satisfaction at the end which makes it all worthwhile!

@puffin yes there was a sticky gunk underneath the old foam I thought it would have dried out by now but I guess it's a function of the glue used originally. I used wooden and plastic cutlery to help scrape it off but you have to be very careful to avoid damage. Some carefully applied nail polish remover (not the harsh type) and kitchen roll helped on the metal chassis but I didn't use it on the cone to avoid damage to the doped area.