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Old 7th September 2004, 03:15 PM   #11
sardonx is offline sardonx  Canada
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It's funny that you mention B&W because a few years ago i remember being impressed by one of their paper woofer designs. It was a lower end model - floorstander. I always kick myself for not buying it. It was actually a slit paper woofer and it sounded very dry yet full bodied. I think most people think Scan Speak is the first to use slit paper but they're not. Maybe even B&W was not the first, but that's where i first saw it.
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Old 7th September 2004, 04:30 PM   #12
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Default paper tweeters

I was interested in paper cone tweeters since I saw and heard Sequerra Met 7.7 monitors...

www.sequerra.com/electronics/data/met7.html

They sound very good.
I don´t know what the hell is a Shear Radiator, -as described in the Sequerra´s site- and there´s no much information about it via Google. Worth investigating, I think.
The paper tweeter appears to have a tiny phase plug, but I couldn´t investigate extensively because I was in a hurry when I saw them. Pity.
Lately, I was thinking of modify a cheap open back paper cone tweeter with a chamber or a transmission line stuffed with wool or something alike to see the results. I suppose a very low crossover point with this technique, but still I have not do it.
Paper can be doped indeed -with a variety of compounds-, so there must be fun in the alchemy.
Let´s investigate...
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Old 7th September 2004, 04:45 PM   #13
sardonx is offline sardonx  Canada
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Federico,
Nice looking speaker. I don't know what the hell is a shear radiator either!

I don't see why diy paper slitting isn't possible. Try it with a cheap tweeter or woofer and use an exacto knife to make the slits. Then glue it back using super glue. It would be worth while to try with a cheap driver first. Either way you do it you'll be braking up some resonances for sure.
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Old 8th September 2004, 07:55 PM   #14
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Default CONE MODIFICATIONS

Good idea. I have read something about cone splitting in another thread; the only complaint about it is that I doubt that super glue exists here in Buenos Aires. I´ll investigate.
There must be another options in the adhesives market; maybe epoxi or polyester resins, maybe cyanoacrilate -loctite, or ¨la gotita¨, our local equivalent-.
For paper cone coating I have used a lot of things: ¨goma laca¨ -a javanese natural shellac diluted in 96/99 degrees alcohol, usually destined to wood luster, known as ¨french luster¨. Is incredible resistent and rigid, and dries quickly.
I have heard that a german gentleman is using something akin to coat everything, from cables to opamps, and selling it very well as ¨violin varnish¨...
Well, mine is DIY, and I have used it to coat violins too: my father in law ones. And it´s great to coat loudspeaker cabinets in a somewhat sophisticated process called ¨lustre a muñeca¨ -doll luster-, a craft of the highest standard, fine furniture grade.
Another interesting substance -I have used it to resucitate some very old cones of a friend´s speakers- is the coating used for ceramic floorings embellishment and maintenance: a water based acrylic polymer called ¨durasil¨, sold here as glo-cot brand. Three flavors: red, black, transparent. But please, don´t drink it!

Some water based polymer sealants -could be diluted in some additional water to lighten a bit- are very useful too: like a plastiflex coating. The cones so treated withstand the environmental pollutants a lot better than untreated ones, maybe at the expense of a lower resonant frequency due to higher mass in the cone.
Call me crazy, but I have tried those things and worked in some fashion or another...

Cheers
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Old 8th September 2004, 08:07 PM   #15
sardonx is offline sardonx  Canada
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http://home1.stofanet.dk/troels.grav...dex_b/SP95.htm

This guy coats the expensive SS8531 with DAMAR. It's some sort of resin used for canvas or paintings to preserve them. I could be wrong tho.

Well, even if you don't have super glue in Buenos Aires, the hot weather must make all the troubles go away

The ceramic floor acrylic sounds good. I can probably get that stuff for free.
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Old 8th September 2004, 09:28 PM   #16
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Default chemical treatments...

Cool. And very macho you have to be for coating such expensive drivers without any clue, taking the risk to jeopardize them. But no pain, no gain. And no fun, sayed some masochist!
The post treatment graphic shows a nice midrange performance. The man must be happy.

I remember another modification to a paper coned brazilian so-so 6.5 inch driver that I performed a couple of years ago for a friend of mine.
As you have seen, my friend´s speakers are some kind of laboratory rats for me. They see me as some sort of nigromancer doin´ strange things to their audio. But the results tend to be good sounding, and that´s the reason for what I´m still alive...
Well, the modification consists in a coating of several hands of a very powerful lacquer -usually destined to coat bronze and aluminum objects to avoid rust and lost of shine-; the cone becomes very rigid then, and their sound bettered a lot, mostly in the upper midrange. I don´t know the brand of the product, some generic ítem cheaply bottled and with no markings. And I dont´t know if such coating exists in your country.

Today Buenos Aires is a little cold, but we´re entering spring and most of the time its beatiful. Yes, there´s no need for superglue: if it is not broken, don´t fix it, as you say.
Cheers.
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Old 8th September 2004, 09:37 PM   #17
sardonx is offline sardonx  Canada
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Default "some sort of nigromancer doin´ strange things to their audio"

That's simply hilarious.
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Old 13th April 2009, 11:48 PM   #18
eyoung is offline eyoung  United States
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Hola gang...

The only reason for a paper(cone) tweeter is that the source of the signal is moved back so the time phase alignment is more correct, the reason more high end speakers have dome tweeters recessed so the voice coils are nearly in the same plane. The other reason is that the wave length vs driver diameter can cause "beaming" as the wavelength becomes shorter than the diameter of the driver. Beyond that I will digress to someone that is more versed in physics as I am an amature....

hope it helps...Elwood
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Old 14th April 2009, 12:03 AM   #19
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I tested quite a few paper cone tweeters I had accumulated last year; most were very peaky and I ditched them, but there were a couple of OK ones - a Sansui pair and a pair of Matsushita (Panasonic); no idea about off axis behaviour though.
Most were only good from 4KHz or higher and up, and resonant freq was usually around 2Khz
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Old 14th April 2009, 02:16 AM   #20
ARRAY is offline ARRAY  Canada
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Quote:
Originally posted by PeteMcK
I tested quite a few paper cone tweeters I had accumulated last year; most were very peaky and I ditched them, but there were a couple of OK ones - a Sansui pair and a pair of Matsushita (Panasonic); no idea about off axis behaviour though.
Most were only good from 4KHz or higher and up, and resonant freq was usually around 2Khz

Hi Pete, I find it interesting that many of the cone tweeters you checked out had a resonance higher than many dome tweeters. Usually it's the other way around.

Tha Matsushitas I sell are smooth as glass and have a resonance ~800. I wouldn't have bought the supply if they weren't real good. A blind man with one hand tied to his foot from behind could design a crossover for them. It'll be a sad day when I sell the last pair. (Well, maybe not as I'm going to retain my own stash)

Did you try any phenolic ring tweeters?
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