Speaker refoam advice

RuffzGuts

RuffzGuts

Super Member
I have these old seas drivers I've had stored for a good few years now, they belong to some custom speaker's I'd like to restore but they are down the que a bit. I've been hesitant to do the refoam as I figure I'd leave it a project for someone else to do the whole speaker resto if I decide to sell them.
But look I have some time and the foam so I'm thinking about doing it.
I think these driver's are a bit trickier than some, with a recessed basket flange that the foam sits in snug.
My plan is to glue here first, remove dust cap shim, then flip driver over letting the cone fall down onto new foam to glue. To be honest I think I could probably get away without shimming doing it this way.
I can't see any other way to do this as the cone sits very low without foam.
So, I just thought I'd ask if anyone knows better?
 

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Ditto on redk9258's comment above. Dust cap removal could be rather delicate surgery, and will you reuse the original or replace?
No, I don't know better but just a few thoughts from what you describe:
  • First, I'd check that you have the correct new surrounds for that speaker. They should duplicate the original ones of course in diameter but also depth.
  • As I understand it then, your plan is to glue the o.d. to the basket first, then flip the speaker over so that the cone falls down onto the backside i.d. of the new surround with glue applied. Maybe AK'ers more knowledgeable than I can verify, but will the cone just fall into place and how will you weigh down the inner edge to get a good glue joint as is usually done with the o.d.?
  • Will your "backwards " technique when complete affect the proper cone excursion?
This is all just speculation since my experience is only with the conventional method of gluing the i.d. first (surround to cone) and then surround o.d. to basket. But I get your problem with the recessed design; that's why I'm wondering if your new surrounds are the proper fit for these speakers. I'd check with experts at some of the major re-foam suppliers if you're not certain that these are the best replacements for a re-foam.
btw--Personally I prefer rubber over foam, if available.
Good luck, let us know how it turns out.
 
elnaldo said:
I agree, i use a 30Hz tone to center the VC.

Is the spider OK? I mean flat, not pushed in. I've seen sagged spiders causing the cone to be too low. That can be fixed too. I can link to a video.
Not sure if the link works ( the guy in the video is me, explaining the problem to the speaker owner)

Click to expand...
I think you are right mate, I've just had another look at the one in the cab, there are actually 4 of these, this driver has been sitting out on its back for years though so has sagged I believe. Thanks for that.
 
daybreak2350 said:
Ditto on redk9258's comment above. Dust cap removal could be rather delicate surgery, and will you reuse the original or replace?
No, I don't know better but just a few thoughts from what you describe:
  • First, I'd check that you have the correct new surrounds for that speaker. They should duplicate the original ones of course in diameter but also depth.
  • As I understand it then, your plan is to glue the o.d. to the basket first, then flip the speaker over so that the cone falls down onto the backside i.d. of the new surround with glue applied. Maybe AK'ers more knowledgeable than I can verify, but will the cone just fall into place and how will you weigh down the inner edge to get a good glue joint as is usually done with the o.d.?
  • Will your "backwards " technique when complete affect the proper cone excursion?
This is all just speculation since my experience is only with the conventional method of gluing the i.d. first (surround to cone) and then surround o.d. to basket. But I get your problem with the recessed design; that's why I'm wondering if your new surrounds are the proper fit for these speakers. I'd check with experts at some of the major re-foam suppliers if you're not certain that these are the best replacements for a re-foam.
btw--Personally I prefer rubber over foam, if available.
Good luck, let us know how it turns out.
Click to expand...
Yes I am not keen on taking dust cabs out as they are particularly nice looking I think and I don't want them to look bodged up. But I have had problems with speakers I've re foamed in the past without shimming and have said to myself I wont do it that way again.
From memory sourcing the foams for these wasn't easy, they a probably a fairly standard size but precise measurement's due to the recess in the basket bad it a difficult decision on purchase.
Yes its a backward way of going about it, But the recess could also act as a positive here as you would do it the other way normally but have no way of centring it on the basket until centre is glued.
I am hoping to just try and catch it on the lip with minimal glue to start then flip them to finish.
They to me just seem an awkward driver to re foam, they are also rare, cant find the model number anywhere and they were originally foam unlike most Seas woofers.
I am still thinking how to go about it, I may need to make a wooded spacer ring to prop them off the bench a bit so the foam is sitting right and not inversed when glued.
This is why they have sat for so long, :crazy:
 
Last edited:
RuffzGuts said:
I think you are right mate, I've just had another look at the one in the cab, there are actually 4 of these, this driver has been sitting out on its back for years though so has sagged I believe. Thanks for that.
Click to expand...
If you had look at my video, I'm applying a small voltage (perhaps something like 1 Volt) with a bench power supply to lift the cone to the right level.
 
elnaldo said:
If you had look at my video, I'm applying a small voltage (perhaps something like 1 Volt) with a bench power supply to lift the cone to the right level.
Click to expand...

elnaldo said:
If you had look at my video, I'm applying a small voltage (perhaps something like 1 Volt) with a bench power supply to lift the cone to the right level.
Click to expand...
Maybe I could do this with a battery and resistor I don't have a bench power supply. Is it safe to do this for an extended period to glue a new surround though? Doesn't stress the coil?
elnaldo said:
If you had look at my video, I'm applying a small voltage (perhaps something like 1 Volt) with a bench power supply to lift the cone to the right level.
Click to expand...
Could this be done with a battery and resistor? It would need to hold it for some time to glue.. I am still thinking taking advantage of the recess in basket flange and going about things in reverse face down might be a better idea for this driver.. but this I guess its hoping the cone falls to a centre point when the spider takes the weight.
 
That driver looks a lot like the ones I've refoamed in Snell E series speakers. Are you sure that's the correct foam? The foam I got from audio note iirc was more angled.
 
Yes, Snell is where I ended up researching previously. I have no idea what the original foam looked like, these must be 50 year old, foam was completely gone. Foam I have is just an ebay purchase.
 
RuffzGuts said:
Maybe I could do this with a battery and resistor I don't have a bench power supply. Is it safe to do this for an extended period to glue a new surround though? Doesn't stress the coil?

Could this be done with a battery and resistor? It would need to hold it for some time to glue.. I am still thinking taking advantage of the recess in basket flange and going about things in reverse face down might be a better idea for this driver.. but this I guess its hoping the cone falls to a centre point when the spider takes the weight.
Click to expand...

If you have effectively a sagged spider, you need to fix that first, since the foam edge won't hold the cone and straight the spider. You'll end with a sagged cone if you don't fix the spider first.

To do that (I've done that dozens of times when it doesn't worth to disassemble a woofer to replace the spider), I'd wet the spider with some acetone free nail polish remover (ethyl acetate). Some people down here uses acetone, buy I think it's too aggressive and if you use too much you could soften the glue. So, a bit of ethyl acetate on the spider will soften it, and evaporate quickly. I apply it with a small brush, or a syringe, or a dropper bottle (I keep my ethyl acetate in a dropper bottle). All around, on the accordion like surface, not on the glued edges. Then, find a way to support the cone while it dries, I use pieces of cloth or small towels under the cone to keep it at level or even a bit raised (since the material will tend to go back a bit). You can let the cone facing down, so the cone weight help with this. Let it dry a couple of hours. If you are patient, let it overnight. You completed the 1st step.

Then, next step, similar procedure, I apply a light coat or layer of diluted PVA glue, wood glue, white glue. Diluted, liquid, easy to apply. You should paint the spider with that diluted liquid, just a bit, to restore some of the resistance it has loose. Again, support the cone at the right height or a bit higher, and let dry. This time, one day at least. And you are done. The spider should be at level after this step. Then you can refoam the cone. (If the cone ended a bit raised, don't worry too much , the material has some "memory"and will return a bit to it's position after some time.)

Regarding your foam, I see it's flat and you probably need an angled edge, but again, here in the 3rd world we deal with that every day. If you stretch the inner edge with your fingers, sliding the inner edge between your fingers and stretching it a bit more and more rotating the edge, it will create an angle that will help to set the edge on the cone.

I'd glue the foam to the cone first, as usual, and then to the basket, centering the VC with a test tone. I don see anything unusual in your woofer, perhaps I'm missing something in your picts, but it looks like any of the refoam works I do down here.
 
elnaldo said:
If you have effectively a sagged spider, you need to fix that first, since the foam edge won't hold the cone and straight the spider. You'll end with a sagged cone if you don't fix the spider first.

To do that (I've done that dozens of times when it doesn't worth to disassemble a woofer to replace the spider), I'd wet the spider with some acetone free nail polish remover (ethyl acetate). Some people down here uses acetone, buy I think it's too aggressive and if you use too much you could soften the glue. So, a bit of ethyl acetate on the spider will soften it, and evaporate quickly. I apply it with a small brush, or a syringe, or a dropper bottle (I keep my ethyl acetate in a dropper bottle). All around, on the accordion like surface, not on the glued edges. Then, find a way to support the cone while it dries, I use pieces of cloth or small towels under the cone to keep it at level or even a bit raised (since the material will tend to go back a bit). You can let the cone facing down, so the cone weight help with this. Let it dry a couple of hours. If you are patient, let it overnight. You completed the 1st step.

Then, next step, similar procedure, I apply a light coat or layer of diluted PVA glue, wood glue, white glue. Diluted, liquid, easy to apply. You should paint the spider with that diluted liquid, just a bit, to restore some of the resistance it has loose. Again, support the cone at the right height or a bit higher, and let dry. This time, one day at least. And you are done. The spider should be at level after this step. Then you can refoam the cone. (If the cone ended a bit raised, don't worry too much , the material has some "memory"and will return a bit to it's position after some time.)

Regarding your foam, I see it's flat and you probably need an angled edge, but again, here in the 3rd world we deal with that every day. If you stretch the inner edge with your fingers, sliding the inner edge between your fingers and stretching it a bit more and more rotating the edge, it will create an angle that will help to set the edge on the cone.

I'd glue the foam to the cone first, as usual, and then to the basket, centering the VC with a test tone. I don see anything unusual in your woofer, perhaps I'm missing something in your picts, but it looks like any of the refoam works I do down here.
Click to expand...
Interesting way of going about it, I am giving it some consideration.. ethyl acetate isn't off the shelf around here i'd have to order some. pva on the spider makes me wonder if it would change its flexibility some how. hmm.. The problem with the outside edge of the foam is that its a perfect fit to the recess in the basket so without trimming it there is no play for adjustment. trimming it would make a mess.
 
Ethyl acetate is sold as "acetone free nail polish remover", so I think it should be easier to source than acetone.

If the edge is a perfect fit on the basket, you could set it there, unglued, hold it with some clothe pegs, just 4 or 6, center the cone with a test tone or a low voltage (1.5V battery), it will raise the cone, and glue the edge to the cone with some multi purpose adhesive that adheres fast , something like the UHU multipurpose (no affiliation. It will stick when you raise the cone with the battery or tone, with everything centered. Then, pressing with your fingers, you can finish the job, but the cone-edge will be centered.

Probably the best approach would be to apply the glue to the foam edge (inner part), set the edge in the basket, hold it with the cloth pegs, apply the voltage or tone to the cone to raise it so it touches the foam edge, and lightly pressing with your finger start adhering a bit better, always centered in position.

Of course, cutting the dust caps, fitting shims, and adhere everything as you mentioned is also valid. My ideas are only to avoid cutting the dust caps, and keep the woofer looking original. Shimming the woofer would help to raise it to the right height.

In a case like yours, it would be much easier if the foam edge were glued at the back of the cone.

PVA on the spider will be fine, it's just a thin layer of diluted glue to restore the shape, it's sagged anyway and lost some resistance, and a woofer has a very strong force, the spider will move anyway, it flexes at the edges mainly. You can try with just the ethyl acetate (or acetone) and see if it restores the woofer position without applying the glue layer. Sometimes the PVA glue is not needed.
 
redk9258 said:
I know people have differing opinions on shimming, but I would try to do it without. You can do it by feel or use a tone to center the voice coil. Simply Speakers has a real good video on YT showing how to do without removing the voice coil caps.
Click to expand...
Agree with using a tone for centering the coil in the gap. If shims are used and the cone glued down, the coil could shift in the gap when the shims are removed. With the tone, the cone is adjusted while the adhesive is still soft for best centering, and then when the adhesive sets, you know the cone will stay there. The shim technique can work if done carefully, though.
 
Personally, of the few that I have done I've used a 10-20Hz Sine Wave 1.0V peak to centre the cone and foams from
Audiofriends [repairyourspeakers dot com] - they provide the foam and a flexible glue. YMMV
 
elnaldo said:
Ethyl acetate is sold as "acetone free nail polish remover", so I think it should be easier to source than acetone.

If the edge is a perfect fit on the basket, you could set it there, unglued, hold it with some clothe pegs, just 4 or 6, center the cone with a test tone or a low voltage (1.5V battery), it will raise the cone, and glue the edge to the cone with some multi purpose adhesive that adheres fast , something like the UHU multipurpose (no affiliation. It will stick when you raise the cone with the battery or tone, with everything centered. Then, pressing with your fingers, you can finish the job, but the cone-edge will be centered.

Probably the best approach would be to apply the glue to the foam edge (inner part), set the edge in the basket, hold it with the cloth pegs, apply the voltage or tone to the cone to raise it so it touches the foam edge, and lightly pressing with your finger start adhering a bit better, always centered in position.

Of course, cutting the dust caps, fitting shims, and adhere everything as you mentioned is also valid. My ideas are only to avoid cutting the dust caps, and keep the woofer looking original. Shimming the woofer would help to raise it to the right height.

In a case like yours, it would be much easier if the foam edge were glued at the back of the cone.

PVA on the spider will be fine, it's just a thin layer of diluted glue to restore the shape, it's sagged anyway and lost some resistance, and a woofer has a very strong force, the spider will move anyway, it flexes at the edges mainly. You can try with just the ethyl acetate (or acetone) and see if it restores the woofer position without applying the glue layer. Sometimes the PVA glue is not needed.
Click to expand...
Yes ok, I respect your advice and experience. I think I will gather what is needed and try and mentally prepare myself for this operation :rflmao: just over thinking it all I think.
Thank you. :thumbsup:
 
daybreak2350 said:
Ditto on redk9258's comment above. Dust cap removal could be rather delicate surgery, and will you reuse the original or replace?
No, I don't know better but just a few thoughts from what you describe:
  • First, I'd check that you have the correct new surrounds for that speaker. They should duplicate the original ones of course in diameter but also depth.
  • As I understand it then, your plan is to glue the o.d. to the basket first, then flip the speaker over so that the cone falls down onto the backside i.d. of the new surround with glue applied. Maybe AK'ers more knowledgeable than I can verify, but will the cone just fall into place and how will you weigh down the inner edge to get a good glue joint as is usually done with the o.d.?
  • Will your "backwards " technique when complete affect the proper cone excursion?
This is all just speculation since my experience is only with the conventional method of gluing the i.d. first (surround to cone) and then surround o.d. to basket. But I get your problem with the recessed design; that's why I'm wondering if your new surrounds are the proper fit for these speakers. I'd check with experts at some of the major re-foam suppliers if you're not certain that these are the best replacements for a re-foam.
btw--Personally I prefer rubber over foam, if available.
Good luck, let us know how it turns out.
Click to expand...
I have always glued the surround to the cone first, then center using a tone and finally gluing the surround to the frame. Gluing to the frame first just seems like you're making the job harder. Not that it's a super easy job, but it doesn't need to be made any harder. And only remove the dust caps if they're damaged or there is no other way. My opinion only.
 
I use some dowels or the like and temporarily hold the cone up into a position that makes the job easier. After a few hours remove the dowels to prevent deforming the spider.
 
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