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Sansui SP-3500 - An AK'er Gift and Restoration Project

drbiggles said:
I know, right. The ad is still up, now 33 minutes old. I wonder how many emails this person has received so far? I left my phone number too. Said I'd leave immediately and come get them. Cross yer fangers!

Biggles
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Good luck! We used to live in SoCal. Don't miss the state, but do miss all the bargains.
 
doctorolds said:
Good luck on those drbiggles!

Has anyone read post #92 about the surrounds? Thoughts...
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I read it! The only thing I've found so far was a reference to a possibility of polyisobutylene, a synthetic rubber. If I can find out exactly what it is, then I can find a solvent and procedure to remove. And then of course, we'll know what to put back in there. If I had an extra woofer, I could try traditional driver doping. But I'm not going to dare with the only working drivers I have.

Those are the thoughts I have.

And about the Tannoys for free? The guy mis-posted in the free section, he wanted 100 bux for them. They must have been worth it because the post was down within 2 hours. Ah well, moving forward.

Biggles
 
drbiggles said:
I read it! The only thing I've found so far was a reference to a possibility of polyisobutylene, a synthetic rubber. If I can find out exactly what it is, then I can find a solvent and procedure to remove. And then of course, we'll know what to put back in there. If I had an extra woofer, I could try traditional driver doping. But I'm not going to dare with the only working drivers I have.

Those are the thoughts I have.

And about the Tannoys for free? The guy mis-posted in the free section, he wanted 100 bux for them. They must have been worth it because the post was down within 2 hours. Ah well, moving forward.

Biggles
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Butyl rubber is also a synthetic rubber that IIRC was used by KLH. It also remains tacky after drying. Maybe another member has a Sansui woofer they may be able to try it on and let us know the results.

To bad about the Tannoy's, but I am sure that we will stumble on another great deal as you always seem to.
 
doctorolds said:
Butyl rubber is also a synthetic rubber that IIRC was used by KLH. It also remains tacky after drying. Maybe another member has a Sansui woofer they may be able to try it on and let us know the results.

To bad about the Tannoy's, but I am sure that we will stumble on another great deal as you always seem to.
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So far, so good, eh?

I got the information from this thread, which I'm sure you've read to death:

http://www.audiokarma.org/forums/showthread.php?t=479962

And, at the bottom you'll notice I recently asked if there were any updates. No luck, yet. I'm not so concerned with the notion of getting it exact, just close enough. I'm kinda surprised we haven't had a Sansui engineer that worked with these woofers back in the day to shed some light.

But as 427 stated, my woofers have been worked and kept limber. So, I'm not losing any sleep at the moment. But I love to stick my fingers in to places they don't belong, so would love to find out. I don't have any way or knowledge of how to measure what the woofer is up to.

Yes, we need a plucky member to step forward and sacrifice a woofer to the greater good!

Biggles
 
drbiggles said:
So far, so good, eh?

I got the information from this thread, which I'm sure you've read to death:

http://www.audiokarma.org/forums/showthread.php?t=479962

And, at the bottom you'll notice I recently asked if there were any updates. No luck, yet. I'm not so concerned with the notion of getting it exact, just close enough. I'm kinda surprised we haven't had a Sansui engineer that worked with these woofers back in the day to shed some light.

But as 427 stated, my woofers have been worked and kept limber. So, I'm not losing any sleep at the moment. But I love to stick my fingers in to places they don't belong, so would love to find out. I don't have any way or knowledge of how to measure what the woofer is up to.

Yes, we need a plucky member to step forward and sacrifice a woofer to the greater good!

Biggles
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I'm just throwing thoughts out so please bear with me. Re the link...

MEK. I agree with most of what is stated, however, this chemical does in fact change the chemical properties of materials NOT based on MEK or using MEK as a bonding agent. What this means is that it can turn some substances into goo, or make them brittle. Either way you've shortened the useful life greatly or completely.

I liked the suggestion of the JBL surround, though with one caveat. I would consider doing what was done with Advent and DQ woofers, using a Fiberboard or Masonite ring to the frame for the surround to be attached to. Yes this likely will change the specs of the woofer, however, that could be better OR worse, and the degree of change may be minute enough that "sonically" it could be irrelevant.

These are just thoughts guys, so please go easy on me. OK?
 
Copa1934 said:
I'm just throwing thoughts out so please bear with me. Re the link...

MEK. I agree with most of what is stated, however, this chemical does in fact change the chemical properties of materials NOT based on MEK or using MEK as a bonding agent. What this means is that it can turn some substances into goo, or make them brittle. Either way you've shortened the useful life greatly or completely.

I liked the suggestion of the JBL surround, though with one caveat. I would consider doing what was done with Advent and DQ woofers, using a Fiberboard or Masonite ring to the frame for the surround to be attached to. Yes this likely will change the specs of the woofer, however, that could be better OR worse, and the degree of change may be minute enough that "sonically" it could be irrelevant.

These are just thoughts guys, so please go easy on me. OK?
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Yup, yup. I said the same thing to myself while reading it. Methyl Ethyl Ketone is an amazingly powerful solvent. It's the only solvent that will clean up 2 component polysulfide rubber (before it's fully cured). Wiping that on to the surround, whatever it is, will most certainly permanently ruin it. The substance will break down and continue to fail, it will NOT "cure" back to an original state.

But that's fine if you want to get it out of the surround so we can apply fresh stuff. Eh?

Biggles
 
Copa1934 said:
I'm just throwing thoughts out so please bear with me. Re the link...

MEK. I agree with most of what is stated, however, this chemical does in fact change the chemical properties of materials NOT based on MEK or using MEK as a bonding agent. What this means is that it can turn some substances into goo, or make them brittle. Either way you've shortened the useful life greatly or completely.

I liked the suggestion of the JBL surround, though with one caveat. I would consider doing what was done with Advent and DQ woofers, using a Fiberboard or Masonite ring to the frame for the surround to be attached to. Yes this likely will change the specs of the woofer, however, that could be better OR worse, and the degree of change may be minute enough that "sonically" it could be irrelevant.

These are just thoughts guys, so please go easy on me. OK?
Click to expand...

How dare you suggest Advent and DQ woofers in a Sansui speaker:D
 
Thanks for the link Biggles. I remember reading that some time ago. Hopefully someone very knowledgeable about the early Sansui drivers will be able to give us more information. I think that I have mine sold, but if not I may experiment with the sealant I referred to from vintage-ar. I would not replace it with foam unless forced to. The question remains. What did Sansui, or the manufacture use?
 
Copa1934 said:
I'm just throwing thoughts out so please bear with me. Re the link...

MEK. I agree with most of what is stated, however, this chemical does in fact change the chemical properties of materials NOT based on MEK or using MEK as a bonding agent. What this means is that it can turn some substances into goo, or make them brittle. Either way you've shortened the useful life greatly or completely.

I liked the suggestion of the JBL surround, though with one caveat. I would consider doing what was done with Advent and DQ woofers, using a Fiberboard or Masonite ring to the frame for the surround to be attached to. Yes this likely will change the specs of the woofer, however, that could be better OR worse, and the degree of change may be minute enough that "sonically" it could be irrelevant.

These are just thoughts guys, so please go easy on me. OK?
Click to expand...

At that point I would first look at finding a modern replacement that would work-before I began experimenting on woofers that are still working.
I guess if I was going to that extreme, I would just have them re coned.
It would be much easier-and in the end perhaps about the same price messing with the old surrounds.
Plus you won't have to mess with MEK-nasty stuff.
Yes-re coning will change the specs of the woofer-but once re coned you can then have it tested, and figure out the correct box tuning/etc.
I would probably look at, if possible fabric surrounds, as they control the cone movement well, and would be close to what you have.
Foam surround also control well, but they eventually rot.
Rubber are the worst for control-unless the spider is actually designed for them in mind-flat spiders- as well as the voice coil-then they are on par with fabric/foam.
If you do happen to research and find a nice modern replacement that fit's you box-you may be surprised how well a modern, low distortion bass driver fits in with vintage mids/high drivers.
 
automojo said:
At that point I would first look at finding a modern replacement that would work-before I began experimenting on woofers that are still working.
I guess if I was going to that extreme, I would just have them re coned.
It would be much easier-and in the end perhaps about the same price messing with the old surrounds.
Plus you won't have to mess with MEK-nasty stuff.
Yes-re coning will change the specs of the woofer-but once re coned you can then have it tested, and figure out the correct box tuning/etc.
I would probably look at, if possible fabric surrounds, as they control the cone movement well, and would be close to what you have.
Foam surround also control well, but they eventually rot.
Rubber are the worst for control-unless the spider is actually designed for them in mind-flat spiders- as well as the voice coil-then they are on par with fabric/foam.
If you do happen to research and find a nice modern replacement that fit's you box-you may be surprised how well a modern, low distortion bass driver fits in with vintage mids/high drivers.
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I can't and won't speak for others, but I raised the question for my own selfish reasons. I don't have the resources to re-cone or find a modern replacement. I was interested in finding a process that I could do in my workshop late at night with very little money spent. Access to an organic chemist and all the organic solvents I could ever dream of are at my disposal. Even synthetic rubbers I can get a hold of, modify them for application too. But I can't do any of that until I find out what was originally used and find a donor woofer. It'll come in time, I don't doubt that.

So, for now I will keep myself busy with the enclosures. I nearly had the energy today to begin, but it's quickly waning.

Biggles
 
automojo said:
At that point I would first look at finding a modern replacement that would work-before I began experimenting on woofers that are still working.
I guess if I was going to that extreme, I would just have them re coned.
It would be much easier-and in the end perhaps about the same price messing with the old surrounds.
Plus you won't have to mess with MEK-nasty stuff.
Yes-re coning will change the specs of the woofer-but once re coned you can then have it tested, and figure out the correct box tuning/etc.
I would probably look at, if possible fabric surrounds, as they control the cone movement well, and would be close to what you have.
Foam surround also control well, but they eventually rot.
Rubber are the worst for control-unless the spider is actually designed for them in mind-flat spiders- as well as the voice coil-then they are on par with fabric/foam.
If you do happen to research and find a nice modern replacement that fit's you box-you may be surprised how well a modern, low distortion bass driver fits in with vintage mids/high drivers.
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My comments were in regards to the link, where a poster (experienced re-coner) responded with explanations on how they adapted a JBL surround. I was merely pointing out another approach.

These are considered "last ditch" options, after other options have been exhausted. Recone is highly unlikely as it's already been established this cone is "odd" in size. Otherwise your suggestions would likely be a good direction to go, and I believe already discussed here and other threads on this speaker.
 
doctorolds said:
Thanks for the link Biggles. I remember reading that some time ago. Hopefully someone very knowledgeable about the early Sansui drivers will be able to give us more information. I think that I have mine sold, but if not I may experiment with the sealant I referred to from vintage-ar. I would not replace it with foam unless forced to. The question remains. What did Sansui, or the manufacture use?
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I think I will contact vintage-ar to see if he has any information that may help, or see if he has any knowledge of anyone applying the sealant to drivers other than KLH and AR.
 
4-2-7 said:
Can you post contact info regardless.

Thanks
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IIRC he is a member here but forgot his user name. I will have to go to his eBay store and contact him that way. Does that help? If I come across his user name I will let you know, update the thread.
 
Copa1934 said:
LOL. May the speaker gods forgive me.

I think you guys are referring to Carl aka Spkrdtr.
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I think the gentleman at vintage-ar is named Larry. IIRC RoyC is very knowledgeable about the sealant, and I think he may have created it and hooked up with Larry for distribution.

Maybe we should start a new thread about treating or not treating Sansui cloth surrounds since we have taken this thread in another direction.
 
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