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Old 9th February 2003, 06:35 PM   #21
Wizard of Kelts
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I saw that page that tvi gave about the Passive Radiator jiggle problem. However, that page mentioned that this only became a problem when the Passive Radiator had to move over 15mm-over haolf an inch.

That is a lot of travel.

I was hoping that if you put enough Passive Radiators in the enclosure, that none of them would have to go near 15mm excursion and the problem.

7V: The speaker you built-did the Passive Radiator have to travel anywhere near half an inch in your setup? Or did it exhibit that wiggling behavior well under that?

I do believe you when you said that you were not aware of the Celestions. It was a case of Independent Invention. It happens. Maing the Passive Radiator long so it doesn't wiggle is a perfectly logical thing to do, and I am not suprised that more than one person has thought of it.

There is a thread on turntables in the Analog section where somebody patented something very similar to what appeared in a magazine several times before, and was apparently unaware of the article.

Bam: The Pioneers were what I had in mind as a model of a Passive Radiator. If they do that, no wonder they are hard to find.
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Old 9th February 2003, 09:16 PM   #22
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I think that mine were wiggling before they got to 15mm - but they were only about 6" diameter. As you say, you might avoid the problem with enough radiators. I guess you're going to have to suck it and see.

Mind you, it's not so difficult to make a dual surround radiator. You could use 1" MDF and cut a hole in it for the radiator - which would also need to be 1" thick. I used expanded polystyrene for lightness, covered it with paper and then doped it. You then put one rubber surround on the inside and the other on the outside.

Interesting about "independent invention" and Celestian. My company, 7th Veil, released its first speaker - the System IV - in 1990. You can check the speaker out at 7th Veil Loudspeakers if you're interested. I believe that there were a number of innovative features, particularly for 1990.

I had spent quite some time testing the transmission line to see whether it was necessary to taper it or whether a straight line would do just as well. I discovered that a straight line worked perfectly - which was just as well as I wanted to use steel, rectangular section tube for the line (see the pic at the link above).

When I sent the speaker for review, Hi Fi Choice magazine was very kind and gave it a "Recommendation". Hi Fi News, on the other hand, were less complimentary and hardly gave it any column inches at all. I'm not sure they really listened to it. A few months later Celestian came out with a TL speaker with, you've guessed it, a straight line. Hi Fi News welcomed this speaker with outstretched arms and treated their "invention" of the straight transmission line as if it were the '2nd coming of sliced bread'.

Oh well, the power of advertising, I guess.

Anyway, I've got to get back to the drawing board. I have to finish the new 7th Veil speaker in time for the Frankfurt High End Show. Best of luck with yours.

Steve
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Old 10th February 2003, 03:27 AM   #23
Wizard of Kelts
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Quote:
Originally posted by 7V
In fact, is the patent even valid?

Quote:
Originally posted by tvi
I think the patent office considers an idea "novel" and therefor patentable if it not in the first 10 hits from Google.

James
I'm no patent attorney, but I would guess that the patentable part would be the fact that there is a ring placed within the diaphragm to weight the thing. I really don't know that you can patent double surrounds. I would be very surprised if that would be defendable. As Ken pointed out, Celestion used it back in the seventies, websites appeared with the recommendation, and that is just the stuff we know about offhand.

Perhaps some attorneys who are also DIYers can enlighten us on that. But it seems almost preposterous.
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Old 10th February 2003, 10:35 AM   #24
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Quote:
Originally posted by 7V

Anyway, I've got to get back to the drawing board. I have to finish the new 7th Veil speaker in time for the Frankfurt High End Show. Best of luck with yours.
Got a link? When is it?

Greetings,

Eric
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Old 10th February 2003, 11:20 AM   #25
7V is offline 7V  United Kingdom
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Join Date: Feb 2003
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29th May-1st June 2003
High End 2003
Hotel Kempinski, Frankfurt-Neu Isenburg.
Trade only 29th May 10am - 8pm Public: 30th May to 1st June 10am - 8pm.
Tel: +49 202 702022

Their web site is: Frankfurt High End 2003 and you can choose German or English.

The 7th Veil speakers will be demonstrated in the Bandor room.

See you there?
Steve
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Old 10th February 2003, 02:30 PM   #26
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I once made a PR from a piece of honeycomb style ply and an 18" pushbike tyre innertube, it was not a great success because of limited excursion, but it was great fun seeing how the response changed with the air pressure in the tube!
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Old 10th February 2003, 06:35 PM   #27
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Originally posted by pinkmouse
I once made a PR from a piece of honeycomb style ply and an 18" pushbike tyre innertube, it was not a great success because of limited excursion, but it was great fun seeing how the response changed with the air pressure in the tube!
Don't just sit there, man, PATENT the damn thing!!

Apparently, drawing up a patent is not so expensive as you might think.

Many years ago, an American inventor patented a circuit which became the basis for Pulse Code Modulation. He did this back in the forties, I think. He didn't even bother to build a protoype wth the tubes that were available then. He just made a drawing and patented it.

A few years ago-I don't know if he is still with us or if it was his estate that sued-the court awarded him several million dollars.

Heck, anything that can change the response of a speaker-you never know.
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Old 10th February 2003, 06:46 PM   #28
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thats awesome !! I had the same idea but never built it.. I was thining about an iner tube from a wheelbarrow as it would be about an 8"diameter, but have a masive surround. I never could think of any method to mount the tube to anything other than adhesives which I didn't think would hold together. If you dont mind me asking, how did you mon the inner tube on both sides?
I was thinkn gopf this more along the lines of a super high excursion driver than a passive radiator.. but its the same general idea.

side not, I also tried the variable resistor idea on a driver. I thought it was neat to see that the un connected driver generated enough current to make small arcs when i was playing around with it.

I need to raw a diagram of the other high excursion idea I had and see what you guys think.
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Old 10th February 2003, 11:02 PM   #29
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Quote:
Originally posted by Jared

side not, I also tried the variable resistor idea on a driver. I thought it was neat to see that the un connected driver generated enough current to make small arcs when i was playing around with it.

I need to raw a diagram of the other high excursion idea I had and see what you guys think.
One of the things I like about this site is that people are free to put up their experimental ideas and the other members don't jump all over them.

Other sites they do.

Some of the amp forums here have some of that, but from what I can gather the amp forums at DIYAudio are still more civil than most other audio forums.
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Old 10th February 2003, 11:08 PM   #30
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Quote:
Originally posted by Jared
thats awesome !! I had the same idea but never built it.. I was thining about an iner tube from a wheelbarrow as it would be about an 8"diameter, but have a masive surround. I never could think of any method to mount the tube to anything other than adhesives which I didn't think would hold together. If you dont mind me asking, how did you mon the inner tube on both sides?
Hi Jared

I stapled and contact cemented strips of rubber from another cut up innertube to the "cone" and the mounting, and when they had set properly I pushed the three parts together, and used the rubber solvent glue used for puncture repair to fix them all together.

As this was a test bed experiment I have no idea how it would stand up to long term use, but it did seem very robust. In fact the box it was made for may well still be in the back of a friend's garage somewhere, I must ask, and see if I can get pics!

The only problem I had was that it took a couple of applications of glue and silicone sealant to get all the joints airtight!
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