Sony ULM Speakers

[Command8]

Howdy Y'all,

I bought a pair of Sony SS-7200 ULM-2 Speakers to replace my not so interesting Klipsch r51m speakers.
I think they are a better match perhaps for my Sony ta-1150 amplifier as they are both from the early '70s (the amp currently needs a recap, it loses a channel but I can get it back by increasing the volume or rapidly clicking the speaker switch on and off a few times, so probably a recap, I already flooded the pushbuttons with contact cleaner).

I noticed a crack on the mid-range woofer, I kept prodding until the surround just started cracking everywhere. It seems these rubber cloth inverted surrounds gave up on me. I bought a replacement 12cm rubber surround.
All the videos I've seen on how to refoam only cover 'normal' surrounds that aren't inverted like these.

If I refoam these inverted, I don't know how I'd keep the cone centred as the foam connecting to the cone doesn't overlay on top the cone but is rather tucked under the cone edge as there is a slight lip on the cone.

Do I need to keep the surrounds inverted or can I just refoam the speakers with the surround sticking out?

Thank you all in advance

 

[MrNegative]

Hey, Command8! Congrats on your new (old) pair of loudspeakers!

I'm assuming that by "inverted" you mean that the foam lip goes under the cone? It's not too difficult refoaming speakers like that. From what I've been working on over the past couple weeks, JBL and Marantz woofers share that same design. I used a video from Simply Speakers where they refoam a JBL 128H woofer, I'd recommend watching that.

For centering, play a tone (that won't break the speaker) through the speaker after gluing the foam surround to the cone. While the speaker is moving, glue the outer edge to the metal basket and make sure that there's no scraping sound. If you hear scraping, then you should adjust the surround until it stops and before the glue sets. Scraping indicates the cone's off center.

 

[Command8]

Hey, Command8! Congrats on your new (old) pair of loudspeakers!

...For centering, play a tone (that won't break the speaker) through the speaker after gluing the foam surround to the cone. While the speaker is moving, glue the outer edge to the metal basket and make sure that there's no scraping sound. If you hear scraping, then you should adjust the surround until it stops and before the glue sets. Scraping indicates the cone's off center.

Thank you for the video, that's almost the kind of speaker I'm dealing with, expect that the surround is inward like this:

Expect that the surround doesn't overlap the cone but is tucked under it.

I wish I knew the tip about rubbing alcohol. I was worried of damaging the corn paper cone so I tried being gentle and using a handheld diamond file, I ended up creating a tear in the cone . Oh well, I just added some wood glue on both sides of the cone and a small torn piece of coffee filter. It's not pretty but it might work, well.... lets hope so.

I'll keep going and post the results

 

[Command8]

I ended up doing a lot more research than I thought I would. Apparently, these cloth surrounds are important for the tonal sound and all that.
Maybe I shouldn't have removed the cracking fabric but it's too late.
I tried to fit the rubber surround like above but it's too much of a hassle to reliably keep it centred, as such the rubber surround midrange driver is going to be bowing outwards.

Should I replace the other speaker mid-range driver fabric surround with rubber or not?
From what I've looked at, fabric surrounds are harder to source and yet many threads are dedicated to users revitalising their cloth surround AR speakers.

Am I missing something here?