Trying my hand at re-FOAM-ing some Speakers

Let your stereophile run loose! Talk gear, media, and other electronics that makes music for your ears.

Moderators: MrFireDragon, PrettyPrincess, Bookworm, starkruzr, Wapsi

User avatar
TazManiac
Posts: 2917
Joined: Fri Nov 29, 2013 6:53 pm

Trying my hand at re-FOAM-ing some Speakers

Post by TazManiac » Thu Oct 22, 2015 11:46 pm

http://www.simplyspeakers.com/speaker-r ... tions.html

I seemed to only come across replacement Foam, I've always been a fan of rubber surrounds. (It occurs to me the driver may not tolerate the heavier/stiffer properties of rubber vs foam...)

My victims are a pair of Mini Advents

(Google found me some quick illustrative pix;)
http://images.audioasylum.com/usr/y2011 ... _mini2.jpg
http://www.oaktreevintage.com/web_photo ... rs_web.jpg

I'm thinking of waiting for sunlight tomorrow, if so I'll take some pictures and report back...

User avatar
Dave
Posts: 6525
Joined: Tue Jul 31, 2012 5:58 pm
Location: Mountain View, CA, USA
Contact:

Re: Trying my hand at re-FOAM-ing some Speakers

Post by Dave » Fri Oct 23, 2015 12:11 am

Please do! Should be interesting to see how it goes. I was impressed by Simply Speakers' claim that one can do a good job of re-centering the cone without needing to pull off the dust-cap and shim the voice coil. Their video made it look quite practical.

I agree with your preference for rubber surrounds... the foam ones never seem to last, and I hate buying speakers with foam surrounds for that very reason. Simply Speakers claims that their foam is longer-lived than most, though.

Switching from foam to rubber would probably change the compliance somewhat. In a ported/vented speaker system that might change the alignment enough to affect the bass response. The original (Kloss) Advents are sealed-box systems, which are a good deal less sensitive to small variations in driver parameters (that's one of several reasons I prefer sealed-box designs) but I think what you have are ported.

I have a possible re-foaming job of my own to do, one of these days. Somebody donated a pair of old, foam-rotted EPI speakers to our ham-radio repeater association, for inclusion in our annual fundraising sale. My cohort and I decided that they aren't worth selling in their current state... nobody would pay spit for unplayable speakers... but they're probably worth salvaging via a re-foaming job, and maybe some modest parts replacements in the crossover (a film cap for the tweeter). I might also give them a "stiffen and damp" reworking - glue a few wood braces onto the insides to stiffen the walls, and glop the insides with a couple of coats of Shur-Stik Permanent Patch 100 as a vibration absorber.

Only problem is, if I do that much to rebuild/improve them I probably won't want to see 'em sold... and I have no room/need at home for another pair of speakers. I have these already.

User avatar
TazManiac
Posts: 2917
Joined: Fri Nov 29, 2013 6:53 pm

Re: Trying my hand at re-FOAM-ing some Speakers

Post by TazManiac » Fri Oct 23, 2015 11:08 pm

:D

I took crappy cell-phone pictures along the way, and I going to post them tomorrow or Monday, even though they show a very clumsy lack of glue management. Frack it. I did it on a picnic table out back of a barn, sue me... Ifthey play well I'm going to slap the grills back on and let em run.

btw- I like the level of detail of your web page's speaker build, (I'm actually going to go back and read the whole thing...) :P
(oooooh, Bi-Amped, aaaaaahhh...)

Next on the list is a free-to-me set of AR25s with shot surrounds; (I blew the surrounds on the mini Advents the day I got them, but the AR25s came that way from the get-go...)

Since I just parked them in the converted Chicken Coop storage shed, it'll take me a little while to dig them back out, but when I do so I might as well shoot along a few pictures of the other parts of the menagerie while it's all out in the open...

Including my Brother's scratch built 'Road Warrior' Pro-Audio boxes, complete with the 'grey-fuzzy' (black actually), and metal grills, and a single handle on each one. (It's crazy what you decide to lift when you're in your late teens and early twenties...)

User avatar
Dave
Posts: 6525
Joined: Tue Jul 31, 2012 5:58 pm
Location: Mountain View, CA, USA
Contact:

Re: Trying my hand at re-FOAM-ing some Speakers

Post by Dave » Sat Oct 24, 2015 12:04 am

Very nice! Do give them time enough for the glue to dry properly, before you stress 'em - no sense popping the new surrounds off by accident. :?

The AR-25s definitely sound as if they'd be worth fixing... a classic brand and design (acoustic-suspension, -3dB at 50 Hz) and ought to sound pretty good. There's a manual for that series at HiFiEngine.com, if you want or need it.

User avatar
Dave
Posts: 6525
Joined: Tue Jul 31, 2012 5:58 pm
Location: Mountain View, CA, USA
Contact:

Re: Trying my hand at re-FOAM-ing some Speakers

Post by Dave » Sat Oct 24, 2015 10:06 am

I just finished reading a series of articles in Speaker Builder, in which a guy rebuilt an old set of AR-3 speakers, and I do mean "rebuilt". He completely disassembled the individual drivers, modified the magnet assemblies, re-wound the voice coils, treated the tweeter domes and woofer cones wirh damping materials.. I don't think there's any aspect of the system he did not rework. In effect he treated the entire speaker system as a pile of semi-finished raw materials, and built a whole new speaker system almost from the ground up.

Quite amazing, and far more than I would ever dare dream of attempting!

User avatar
TazManiac
Posts: 2917
Joined: Fri Nov 29, 2013 6:53 pm

Re: Trying my hand at re-FOAM-ing some Speakers

Post by TazManiac » Sat Oct 24, 2015 11:26 am

Well, it was cold indoors yesterday and last night so I just let them cure some more while I attended to other stuff.

I'm going to park them outside in some early morning sunshine to kind of get up to 'room temperature' a bit then I'll report back later today.

When I had first picked them up I tried them out, and while demo'ing a movie we heard the one side start distorting. Off came the grill and there was the foam in pieces. The other speaker held up though, right up until yesterday when a casual touch poked a hole clean through the surround.

I suppose the second one felt solidarity w/ the first one and held out as long as it could...

When I'm done I'm going to reawaken the wood end caps w/ some walnut oil...

btw- rewinding coils, either speakers or electrical motors, is about where I draw the line...)
Dave wrote:<snip>
The AR-25s definitely sound as if they'd be worth fixing... a classic brand and design (acoustic-suspension, -3dB at 50 Hz) and ought to sound pretty good. There's a manual for that series at HiFiEngine.com, if you want or need it.

PS, as a matter of fact I found just such .PDFS last night, Thx.

User avatar
TazManiac
Posts: 2917
Joined: Fri Nov 29, 2013 6:53 pm

Re: Trying my hand at re-FOAM-ing some Speakers

Post by TazManiac » Thu Oct 29, 2015 11:00 pm

Update- I got them all back together but I haven't really grouped the pictures into an online-album as of yet.

They work, and sound sort of OK, but I'm concerned I might have hooked something back up out of phase inside.

That and I'm given to understand that new surrounds need to be 'broken in a bit' before they hit their stride.

Trouble is I've been gone a week and they've been lonely.

(click on thumbnails for larger image.)

Side by side with the grills off... (As you can see, only one initially blew it's surround)
Image

Cleaning off the old surround material...
Image

Crappy Glue Job, including Alcohol solvent stains and random cotton fibers left behind. The shame, the shame...
Image

User avatar
DinkyInky
Posts: 2405
Joined: Tue Jul 31, 2012 9:38 am
Location: Where there's more than Corn.
Contact:

Re: Trying my hand at re-FOAM-ing some Speakers

Post by DinkyInky » Fri Oct 30, 2015 9:39 am

Looking grand.

If I had known this, I could have saved my Dad's old quads...stood as tall as my son in their cabinets...

Saving info for later...

Don't worry, as you crank it up later after break in, you'll blow those fibers out... :P
Yanno how some people have Angels/Devils for a conscience? I have a Dark Elf ShadowKnight and a Half Elf Ranger for mine. The really bad part is when they agree on something.

Aphyon chu kissa whol l'jaed.
--Safyr Drathmir

User avatar
TazManiac
Posts: 2917
Joined: Fri Nov 29, 2013 6:53 pm

Re: Trying my hand at re-FOAM-ing some Speakers

Post by TazManiac » Fri Oct 30, 2015 7:03 pm

Image

Yeah, I'm just getting started, next up is these old Acoustic Research jobbies...

User avatar
DinkyInky
Posts: 2405
Joined: Tue Jul 31, 2012 9:38 am
Location: Where there's more than Corn.
Contact:

Re: Trying my hand at re-FOAM-ing some Speakers

Post by DinkyInky » Fri Oct 30, 2015 7:17 pm

Taking notes...
Yanno how some people have Angels/Devils for a conscience? I have a Dark Elf ShadowKnight and a Half Elf Ranger for mine. The really bad part is when they agree on something.

Aphyon chu kissa whol l'jaed.
--Safyr Drathmir

User avatar
Jabberwonky
Posts: 2963
Joined: Sun Aug 12, 2012 8:11 am
Location: Houston, Texas

Re: Trying my hand at re-FOAM-ing some Speakers

Post by Jabberwonky » Fri Oct 30, 2015 7:32 pm

DinkyInky wrote:Taking notes...
Give his notes back until he's through with them...
:P
"The price of perfection is prohibitive." - Anonymous

User avatar
DinkyInky
Posts: 2405
Joined: Tue Jul 31, 2012 9:38 am
Location: Where there's more than Corn.
Contact:

Re: Trying my hand at re-FOAM-ing some Speakers

Post by DinkyInky » Fri Oct 30, 2015 8:53 pm

Jabberwonky wrote:
DinkyInky wrote:Taking notes...
Give his notes back until he's through with them...
:P
Hrmph!
Yanno how some people have Angels/Devils for a conscience? I have a Dark Elf ShadowKnight and a Half Elf Ranger for mine. The really bad part is when they agree on something.

Aphyon chu kissa whol l'jaed.
--Safyr Drathmir

User avatar
TazManiac
Posts: 2917
Joined: Fri Nov 29, 2013 6:53 pm

Re: Trying my hand at re-FOAM-ing some Speakers

Post by TazManiac » Fri Oct 30, 2015 9:04 pm

In a way he's right, (and I'm sorry I can't watch videos at my current location...)

Still, if you like I can write up some steps, really just append the instructions the surrounds came with...

User avatar
DinkyInky
Posts: 2405
Joined: Tue Jul 31, 2012 9:38 am
Location: Where there's more than Corn.
Contact:

Re: Trying my hand at re-FOAM-ing some Speakers

Post by DinkyInky » Fri Oct 30, 2015 10:16 pm

TazManiac wrote:In a way he's right, (and I'm sorry I can't watch videos at my current location...)

Still, if you like I can write up some steps, really just append the instructions the surrounds came with...
I fish slapped him Flying Circus style.
Anyway, I said I was taking notes, not stealing them. I'm a very good nerd...everbody wanted to steal mine because they were well done.
Yanno how some people have Angels/Devils for a conscience? I have a Dark Elf ShadowKnight and a Half Elf Ranger for mine. The really bad part is when they agree on something.

Aphyon chu kissa whol l'jaed.
--Safyr Drathmir

User avatar
TazManiac
Posts: 2917
Joined: Fri Nov 29, 2013 6:53 pm

Re: Trying my hand at re-FOAM-ing some Speakers

Post by TazManiac » Sat Oct 31, 2015 11:29 am

Some random observations;

- The guys at simplyspeakers.com sent along two surrounds, a sheet of instructions, a business card and a small tube of glue. The glue is like a cross between Model & Rubber Cement(s).

- Depending on what type, model, size of cone there may or may not be a need for attention to centering the surround and cone prior to the adhesive setting up; basically once it's pressed one to the other you have a little time to move the cone up and down to make sure things like the coil aren't being touched/ rubbed upon. Its not that big a deal but it is an important thing to keep an eye on.

- Using less glue than I did at first is likely a good thing; its not that a splooged a whole lot on, but once in place the surround squoze out what shows in the pics. The Instructions are explicit in describing 'work the two parts together for a few mins...'.

- I'm thinking, for next time, to place the glue on half the thickness of the circumference than the whole area that the cone and surround touch each other.

What I mean is, from the edge of the cone to the center/dust cap is a certain area. When the surround is placed in position the two parts overlap a bit, this smaller area can be described as a 'ring'. The coverage of the cone's whole ring area w/ glue prior to laying the surround on top will inevitably result in 'splooge'.

I'm pondering applying just a bit less, and concentrating it up on just the ridge of the cone, allowing the resulting contact and hand working to spread the viscous glue further down the cone towards the center, but stopping short of oozing out too much from under the surround.

- The material of the surrounds will get soft in contact with the solvents in that glue, and will further conform as it sets, I'm further pondering a little set time once contact between the two parts is made might be in order, like this for example:

] Press cone up and down a bit to verify centering and no touching of the coil.
] Apply glue to edge of cone.
] Lay surround in place and just lightly confirm contact with wet glue. At this point I'm avoiding pressing things together too much.
] Press cone up and down a few times to allow minor adjustment of surround to cone contact; the glue will get less and less slippery as the mins pass, but there is time to let the assembly find it's center.
] After more than a few mins, work the two parts together more firmly, but gently, going around the circle like tightening lug nuts during the changing of a tire.

(redacked pause during initial post)

- Last random musing, at least for now; the inside of each two element speaker contains a cross-over as well. I feel stupid admitting this but I'm not sure I hooked it all back up the same way; One Drivers has Black and Red wires, the other Driver in the enclosure has a combination of Blue and something Striped. (It's been a few weeks...) I'm going to open them back up again and make sure everybody is in phase.
I expose this to stress the benefit of tedious documentation of a project that you have never seen the insides of yet.

Take pictures, take notes, take your time.

User avatar
Catawampus
Posts: 1980
Joined: Fri Jul 12, 2013 10:47 pm

Re: Trying my hand at re-FOAM-ing some Speakers

Post by Catawampus » Sat Oct 31, 2015 2:57 pm

DinkyInky wrote:I fish slapped him Flying Circus style.
Make sure that it was a bass, at least, to fit the circumstances.

Typeminer
Posts: 586
Joined: Tue Jul 31, 2012 9:34 pm
Location: Pennsylbama, between Philly and Pittsburgh

Re: Trying my hand at re-FOAM-ing some Speakers

Post by Typeminer » Sat Oct 31, 2015 8:09 pm

Catawampus wrote:
DinkyInky wrote:I fish slapped him Flying Circus style.
Make sure that it was a bass, at least, to fit the circumstances.
Save the tuna till he starts rebuilding the receiver.
Saccharomyces cerevisiae is the linchpin of civilization.

User avatar
DinkyInky
Posts: 2405
Joined: Tue Jul 31, 2012 9:38 am
Location: Where there's more than Corn.
Contact:

Re: Trying my hand at re-FOAM-ing some Speakers

Post by DinkyInky » Sun Nov 01, 2015 1:05 pm

Catawampus wrote:
DinkyInky wrote:I fish slapped him Flying Circus style.
Make sure that it was a bass, at least, to fit the circumstances.
Yeah, it's all about that bass...

*sets a well-tuned Wildcat suitcase turntable in the pun vault*
Yanno how some people have Angels/Devils for a conscience? I have a Dark Elf ShadowKnight and a Half Elf Ranger for mine. The really bad part is when they agree on something.

Aphyon chu kissa whol l'jaed.
--Safyr Drathmir

User avatar
scantrontb
Posts: 1005
Joined: Tue Jul 31, 2012 12:44 am

Re: Trying my hand at re-FOAM-ing some Speakers

Post by scantrontb » Mon Nov 02, 2015 2:07 am

DinkyInky wrote:
Catawampus wrote:
DinkyInky wrote:I fish slapped him Flying Circus style.
Make sure that it was a bass, at least, to fit the circumstances.
Yeah, it's all about that bass...

*sets a well-tuned Wildcat suitcase turntable in the pun vault*
No Treble?...
Don't planto mihi adveho illac

User avatar
TazManiac
Posts: 2917
Joined: Fri Nov 29, 2013 6:53 pm

Re: Trying my hand at re-FOAM-ing some Speakers

Post by TazManiac » Mon Nov 02, 2015 4:49 am

Somebody needs to make the rebuttal video; 'Tweak them Tweeters'...

(btw- I was surprisingly delighted by 'All About that Bass' and it's video.)

Post Reply