SPEAKER FOAM
- Thread starter riker1068
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Beosystem10
Member (SA)
If that were foam then no, don't use rubber solution on it because that stuff melts foam. But these appear to be paper surrounds and the easy and permanent way to mend those is to use PVA glue and paper stitches which I think you'd call Steristrips in the USA?
Beosystem10
Member (SA)
Beosystem10
Member (SA)
They can be repaired in the way I mentioned in my earlier post, with PVA and paper stitches/steristrips. This results in an invisible repair that doesn't affect the function of the speakers. 777 speakers aren't the same although they may well fit the cabinet physically.
What I'm saying is that you can't "refoam" these as they have no foam to begin with.
I've repaired many paper cones using pva and paper stitches, it works and not only that, but the PVA gives the edges strength that doesn't compromise their flexibility.
Speakers that have foam suspension are totally different in that the paper doesn't extend to the outside of the basket, like the JVC one in these images:
See the round black thing lying on the bench? That's the foam. See how the paper is a separate part and doesn't fill the space? That's because this speaker can be refoamed, yours are paper and can be repaired but not in any way that involves foam suspension rings because they're all paper to the edges.
What I'm saying is that you can't "refoam" these as they have no foam to begin with.
I've repaired many paper cones using pva and paper stitches, it works and not only that, but the PVA gives the edges strength that doesn't compromise their flexibility.
Speakers that have foam suspension are totally different in that the paper doesn't extend to the outside of the basket, like the JVC one in these images:
See the round black thing lying on the bench? That's the foam. See how the paper is a separate part and doesn't fill the space? That's because this speaker can be refoamed, yours are paper and can be repaired but not in any way that involves foam suspension rings because they're all paper to the edges.
I've done it many times. Cut the original paper surround at the perimeter to separate the cone from the basket flange, then install a new foam as normal. Done it, works, sounds great, looks great.
Reli
Boomus Fidelis
Yeah but seems like the sound would change. Foam surrounds start to "move" earlier than papers do, so they produce more low-volume bass, but can't produce midrange as accurately as paper, IMHO. Personally if someone is a fan of 70's/80's music they should stick with paper IMO. Foam and rubber is for garbage 21st century music with 808 bass and nothing else. 
Yeah but the OP wants to restore his paper surrounded speakers that are no longer available new. If the speakers were hidden behind an opaque screen, then a bandaid fix, that was functional might be the only thing necessary but some equipment has features that serve a functional as well as aesthetic purpose, and the speakers in every sharp triple 7 variant do serve both purposes. The awesome looks are every bit as important as the sound. So given the choice of having ugly bandaged but orig sounding speakers or attractive dope looking but with maybe non-orig sound.... I think the second choice would be very popular option. Also I won't argue that the sound properties might change but since sound is subjective, it's debatable whether the finished converted speaker sound better or worse. I personally like a more brassy sound with tight bass but this is the 21st century after all so I'm sure there are many folks liking deep deep bass too.
Beosystem10
Member (SA)
Who said anything about "ugly bandages"? That repair technique is suitable primarily because it's invisible once the repair is completed, unless of course you use too little spread or put the paper on the outside , in which case then yes, they'd be visible close up. The only other viable way in this case is to replace the complete cones and those too are available in kits that include the shims for the cores as well as replacement dustcaps since they won't tend to stay concentric when there's neither the original cone nor the spring of rubber or foam to help.
Can't see the repairs on the outside of this, can you..
Me neither, and that's been repaired, the gummy area around the perimeter resembles closely the original finish but it's been repaired at 9, 11, 2 and 5 as you look at it from this view, with one of the patched ares having run from the cap to around half an Inch fae the edge. It's since been put back up to the device whence it came and although its opposite number remains unrepaired, the sound is as it was before with balance being bang on, no difference in range - such as it is in this low end mini box - and most significantly (from the POV of being paid) its owner couldn't tell by looking that anything was done.
It helps if the spider is still intact, it helped that these stay behind solid plastic frets which allowed little light through but the thing is; it can be done but I'd love to see - no, seriously, I would - how a foam or rubber suspension medium could go into a paper cone without the cone being removed to make the reduction to its diameter using accurate means. There'd have to be a space at least the width of the raised section of the surround so before trying that at home, best make sure & weld your scalpels together for accuracy and toe them out a little relative to each other.
Then there's the fact that speakers designed to run free edges by foam or rubber must have more coil travel to take advantage of the new suspension and also to avoid bottoming. Loads to work around but probably not impossible. Just a pointless waste of time and cash that would be better spent on more boxes.
, in which case then yes, they'd be visible close up. The only other viable way in this case is to replace the complete cones and those too are available in kits that include the shims for the cores as well as replacement dustcaps since they won't tend to stay concentric when there's neither the original cone nor the spring of rubber or foam to help.Can't see the repairs on the outside of this, can you..
Me neither, and that's been repaired, the gummy area around the perimeter resembles closely the original finish but it's been repaired at 9, 11, 2 and 5 as you look at it from this view, with one of the patched ares having run from the cap to around half an Inch fae the edge. It's since been put back up to the device whence it came and although its opposite number remains unrepaired, the sound is as it was before with balance being bang on, no difference in range - such as it is in this low end mini box - and most significantly (from the POV of being paid) its owner couldn't tell by looking that anything was done.
It helps if the spider is still intact, it helped that these stay behind solid plastic frets which allowed little light through but the thing is; it can be done but I'd love to see - no, seriously, I would - how a foam or rubber suspension medium could go into a paper cone without the cone being removed to make the reduction to its diameter using accurate means. There'd have to be a space at least the width of the raised section of the surround so before trying that at home, best make sure & weld your scalpels together for accuracy and toe them out a little relative to each other.
Then there's the fact that speakers designed to run free edges by foam or rubber must have more coil travel to take advantage of the new suspension and also to avoid bottoming. Loads to work around but probably not impossible. Just a pointless waste of time and cash that would be better spent on more boxes.
Thanks to CPL CHRONIC for the advice. 
I have a question to all. What can I use between the speaker and the placement area to aid in it not rattling? If in fact it would. I would like to put a foam spacer of some sort. I am only as good as turning on the power. lol it will be when I even open this thing up. If I can even do that :unknown:
I have a question to all. What can I use between the speaker and the placement area to aid in it not rattling? If in fact it would. I would like to put a foam spacer of some sort. I am only as good as turning on the power. lol it will be when I even open this thing up. If I can even do that :unknown:
Line Out
Member (SA)
Do remember that a multimeter reads resistance, not impedance. Its not a big deal though. And yes, seems to be connected to series.
Where those Bose woofers are going anyway?
If they are used in a normal 2-way configuration, I recommend connecting a 0,10mH inductor (crossover coil) in series with each woofer (+ lead) and connect the tweeter + lead before the inductor. It will make the higher tones clearer, because then you are adding a 1st order (-6dB) lowpass to the woofer and it wont try to reproduce the higher frequencies, which it isn't designed to. That 0,10mH coil will cut a 2ohm driver from somewhere around 3000hz. I didn't find a lower value coil from parts-express, but I would think there is some. Higher ohm driver needs a higher value coil for the same frequency, for example, 4ohm would need 0,20mH, 8ohm 0,40Mh and so on.
Where those Bose woofers are going anyway?
If they are used in a normal 2-way configuration, I recommend connecting a 0,10mH inductor (crossover coil) in series with each woofer (+ lead) and connect the tweeter + lead before the inductor. It will make the higher tones clearer, because then you are adding a 1st order (-6dB) lowpass to the woofer and it wont try to reproduce the higher frequencies, which it isn't designed to. That 0,10mH coil will cut a 2ohm driver from somewhere around 3000hz. I didn't find a lower value coil from parts-express, but I would think there is some. Higher ohm driver needs a higher value coil for the same frequency, for example, 4ohm would need 0,20mH, 8ohm 0,40Mh and so on.
Cpl-Chronic
Member (SA)
Yes, that is the DC resistance of both in series....that is the seller's pic to show they both are good to go......Mine are all the same & have been running in 2 Sharp 777's for more than a year without any problems at all. They sound good too....Superduper said:
cpl
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