JBL C1 woofer re-foaming:

hydrovac

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About 2 months ago, I bought a pair of used JBL C1 bookshelf speakers for my son.
Whenever you buy used speakers, you should check the woofer cone and foam surround, as these are usually the first parts to deteriorate and cause terrible distortion in certain situations. In my case, the speakers must have been stored in someone's garage for a few years, so the foam wouldn't last long.

I looked into my options for re-foaming the speakers (since I was happy with their looks):
I found https://www.ebay.com/itm/Foam-Speaker-Surround-Repair-Kit-For-JBL-Control-1-/150776862757 on eBay, and the kit comes with two foam surrounds, a tube of seriously sticky foam glue (it's almost like superglue!), and some instructions.

The DIY foam replacement route seemed easy enough, things were off to a great start after I had the foam in hand:
The first step in replacing the foam is the removal of the old foam. I used my fingers to grab away the majority of the foam, then I soaked the remaining foam in 91% rubbing alcohol, and carefully scraped off what I could from the metal ring with a sharp wood chisel.

The next step is to put a ring of glue on the edge of the cone, then quickly message the inner part of the foam onto the top surface of the cone. After waiting an hour for the glue to dry on the cone, I went to work quickly getting down some glue on the woofer's metal basket, then squishing the outer part down flat.

So finally... after all glue has dried up, assembled the speaker and hooked it up. Now enjoying the crisp sound of “brand new” C1s!

Damaged foam on both the woofers:
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After replacing the foam:
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Connected the speakers to the amp:
1576436517633.jpeg


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While pasting the surround to the basket, care has to be taken to ensure that the cone is perfectly aligned by repeatedly pressing it down on all sides to ensure mo voice coil rubbing.
 
The control 1's are very under rated.

Used them with a topping amp.

I had to refoam in the past too due to ageing ..

Nice work..
 
While pasting the surround to the basket, care has to be taken to ensure that the cone is perfectly aligned by repeatedly pressing it down on all sides to ensure mo voice coil rubbing.

Shimming the voice coil is another option. No doubt it leads to more precise alignment, but you can get fine results by simply hooking up a battery and popping the cone up and down every few minutes during the first hour of drying, as well as careful eyeballing to begin with.
Remember your spider is in alignment the whole time, with such a low excursion range you don't have to be that precise, unless you mess up big time. Large woofers with big v max numbers, shims a must.

...

The control 1's are very under rated.

Used them with a topping amp.

I had to refoam in the past too due to ageing ..

Nice work..

Thanks Mahesh,
These speakers are small and unobtrusive but they put out quite impressive sound for their size. They are also very efficient designs require little applied amplifier power. I built an amp with 50wpc output and connected a Logitech Bluetooth Audio Adapter as input.
Currently used by my son, where he streams music from android and laptop.

...
 
My kiddos are into Bluetooth Headphones..and spotify.

This seems a nice idea...

can you send PM me more info on the amp you built..
 
I did VC alignment using a 30 hz tone. Installed a signal generator app on my phone to do it.
And in my case my magnet had fallen off, and it was infinitely more complex than a refoam job.
THe speakers have been working fine.
 
My kiddos are into Bluetooth Headphones..and spotify.

This seems a nice idea...

can you send PM me more info on the amp you built..

Noise exposure in kids is a growing concern, every parent should approach noise the same way they would junk food, alcohol or sun exposure.
Explain about the dangers loud sounds can pose to their hearing so they can make smart choices.

Just told my kiddo, "You need to go on a noise diet... you’re using a wireless (“Bluetooth”) headset, and exposing your body to radiation and ears to loud sound.
With great persuasion, could convince him on my proposal of setting up a compact hi-fi system in his room.

...
 
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