| Opinions needed: Aluminum or Pascalite? [message #16998] |
Fri, 24 September 2004 16:54  |
Floyd Andrews
Messages: 31
Registered: May 2009
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Baron |
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I just bought a pair of Altec 908 (1") drivers, with Symbiotek diaphragms, for my horns and need some opinions about the "best" diaphragm for them. (I know there is no "best", but i want your opinion anyway) I've read that the Symbiotek diaphragms don't go very high in frequency, and I want to use these horns without a supertweeter. So which way should I go: aluminum (902) or pascalite (909)? Titanium? Unobtanium? What do you think?
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| Re: Opinions needed: Aluminum or Pascalite? [message #16999 is a reply to message #16998] |
Sat, 25 September 2004 08:34  |
spkrman57
Messages: 522
Registered: May 2009
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Illuminati (1st Degree) |
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Floyd, I have 902's and use the aluminum. Great Plains audio can help you on that one. Bill (whanuschak@cox.net) is a great guy and one of the last Altec engineers working for Altec when they closed the doors. He also sells new drivers also. Hope this helps. Ron
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| Re: Opinions needed: Aluminum or Pascalite? [message #17000 is a reply to message #16998] |
Sat, 25 September 2004 08:57 |
Russellc
Messages: 397
Registered: May 2009
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Illuminati (1st Degree) |
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Unless you have availability to NOS, I don't belteve pascalite is still available. I have the 908 with symbiotic and they don't sound as awful as people say. That said, the straight aluminum is the one to go with for home use but it is no longer available either. For PA the pascalite or symbiotic. (if you can find them) Greatplaines audio is the place I have had the best luck with. Bill worked for altec and has most of the manufacturing equip from the day. Others make replacements also, but I have not tried them. Another feature of many drivers with symbiotic diaphrams that can be improved on( for home use) is under the covers. Remove them VERY carefully and look. If you only see shiney metal dome and there is a thick felt pad in the back of the cover, just replace the diaphram and close it up. If you see a plastic looking dome and there is no felt in there, I would suggest the following.( again, for home hifi use) When you order your diaphams from bill, tell him you want the parts to remove the loading caps as well. The loading cap IS NOT a capacitor, it is that plastic thing covering the dome. The parts should be: 2 felts to line the back of your covers, and six short screws. When you remove the old diapram and the plastic thing, do not reinstall the plastic thing. the new short screws will make up the space equal to the thickness of the plastic thing you are leaving out.
These plastic loading caps were used in an effort to make heavy use drivers live longer. These same use drivers were usually equiped with the symbioticdiaprams as well. Both measures increased heavy use reliability, but hampered high frequency transients and extension.
If your use is home stereo try this advice. However, if PA is your use, I would call Bill @ Greatplaines audio and ask. With the loading caps removed and the "regular" aluminum diaprams in stalled, they will be basically a 902- A sonically. Hope this helps. If any is unclear, Bill can explain it better than I. Russellc
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| Re: Opinions needed: Aluminum or Pascalite? [message #17002 is a reply to message #17001] |
Sun, 26 September 2004 06:45 |
Russellc
Messages: 397
Registered: May 2009
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Illuminati (1st Degree) |
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Yes. If it has the loading cap. I will have to open some of my 802s up it has been a long time and I don't remembr if the ones I have had the loading caps or not. But I have removed them from 808s and 908s. Basically as far as the way the diaphram mounts is identical in the 802 or 902. Three screws hold the assembly in place. Some models just have the screws going through the mount of the diapram, and others have this plastic thing put on top, and the screws must also go through this thing. When you remove this cap,you removed thickness that the screw would otherwise have to have gone through, and now the screws are too long. This is why you need the shorter screws. To me, the high end gains both in transient response and extension. Easy to change back. Don't forget the felt pads for the back covers. Cheers,
Russellc
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| Re: Opinions needed: Aluminum or Pascalite? [message #17004 is a reply to message #17002] |
Sun, 26 September 2004 06:53 |
Russellc
Messages: 397
Registered: May 2009
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Illuminati (1st Degree) |
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One other note if you are installing a new diapram in the 802, you will likely need a conversion kit which is also available from great plaines. Most of the 802s use an older connector on their wires, the kit is just wires with different connecters. Bill's web site shows what you need, or just give them a call. Russellc
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| Re: Opinions needed: Aluminum or Pascalite? [message #17006 is a reply to message #17005] |
Sun, 26 September 2004 14:18 |
Russellc
Messages: 397
Registered: May 2009
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Illuminati (1st Degree) |
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I have never messed with the 806. Correct me anyone, but I believe the 806 has a slightly smaller magnet assembly which gives it its lower efficiency. I think the 802/902 diapram fits, but may not be exactly the same as the original 806 diaphram. again, correct me anyone, but I believe the original diaphrams for these were somewhat lighter mass than the traditional 802/902, to compensate for the smaller magnet. hopefully I haven't mis informed. Be vary careful with these diaprams, if I'm correct they may be unobtainium! Again, for the straight skinny call Bill @ Great plaines, he will know for sure. Do your 806's have these loading caps? Russellc
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