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Old 17th July 2008, 12:52 AM   #31
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Quote:
Originally posted by graaf


the alu pipe would be relatively heavy

Yes there will be a slight shift in TSP. For a lightweight cone,
you have to get a tiny pipe and measure its mass and
the relative mass increase of the cone, but normally it is not
as serious as one might think.

The cone of an 8incher has no neglegible mass, and parts
of the suspension and surround contribute to mass too.
I would say e.g. 15% mass increase is not dramatic and
will lower fs by approx 7% ...

Maybe your cyanoacrylate is the better choice for stiffening
due to mass increase, but i doubt that it will have the same
effect.

Due to my experience a dampener will show only
significant effect, if the coat has some thickness compared
to the cone material. A foam of the dampener increases
thickness and saves mass.

Does your stiffener and dampener penetrate the paper or
does it make a coat ?

Often simply a wide spreaded impedance plot is quite
informative to identify breakups associated with energy
storage.

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Old 17th July 2008, 08:37 PM   #32
graaf is offline graaf  Poland
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Quote:
Originally posted by LineArray

Does your stiffener and dampener penetrate the paper or
does it make a coat ?
cyanoacrylic glue penetrates the paper, the cone is completely soaked through, it changes its colour, its surface becomes hardened and rough, like a rough crust

as to Stabilon and Vinylfex I haven't tried them yet

best,
graaf
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Old 8th August 2008, 02:11 PM   #33
wlowes is offline wlowes  Canada
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I am intrigued to learn more about the results people have obtained from these procedures.

Back to the original post. If I am correct, the patent lays out a procedure for stiffening the diaphragm with varnish, not the cone. Has anyone experiemented with diaphragm stiffening? If so, with what outcome?
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Old 11th August 2008, 07:24 AM   #34
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Quote:
Originally posted by wlowes
the patent lays out a procedure for stiffening the diaphragm with varnish, not the cone.
diaphram is just another name for the cone

dave
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Old 17th February 2010, 09:47 AM   #35
graaf is offline graaf  Poland
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looks like Stewart Hegeman was developing similar ideas of non-uniform asymmetric diaphragm treatment

on the picture Lowther driver according to Hegeman specification

picture taken from: Citation X and Eico HFS-2 Speaker Systems
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Old 17th February 2010, 09:51 AM   #36
graaf is offline graaf  Poland
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and one more

also take note of unusual asymmetrical whizzers in both drivers
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Old 17th February 2010, 05:20 PM   #37
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Quote:
Originally Posted by graaf View Post
and one more

also take note of unusual asymmetrical whizzers in both drivers
I have a scan of the original Popular Electronics (?) article on those speakers.

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Old 17th February 2010, 07:54 PM   #38
rjb is offline rjb  New Zealand
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In March/April 1965 D J Oglvie wrote in HiFi News about modifications he made to a Fane (I think) paper cone speaker. Unfortunately I cannot lay my hands on the article at the moment, but from memory he glued to the cone a thin aluminium sheet rather like a two leafed clover, but with a broad centre. He called it a differential wave impedance cone. He used maths and lab tests to justify his design and gave before and after results. Again from memory these showed a slightly extended bass and reduced efficency, (due to weight no doubt) but a noticably smoother FR particularly in the mid-range. The unit was not designed to cover treble.He claimed reduced cone resonances and a more realistic sound due to less cone breakup. I tried a rough copy on a cheap unit and it did seem to be better, but at that time I was working with full range, trying to find a better alternative to whizzers, (which offended my hearing at that time). I think it may be worth following up
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Old 18th February 2010, 09:44 AM   #39
graaf is offline graaf  Poland
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Quote:
Originally Posted by rjb View Post
He called it a differential wave impedance cone. He used maths and lab tests to justify his design and gave before and after results.
"a differential wave impedance" sounds like the idea was to make the soundwave reach the surround and reflect not simultaneously along all radiuses but at slightly different times, am I correct?

this can be achieved also by making uneven soundwave path lengths with cone asymmetry, like in JVC's "oblique cone":

オブリコーン 技術情報 |ビクター
2ウェイバスレフ型 スピーカーシステム SX-L33 |ビクター

see also the attached graph

I wondered whether the same effect could be achieved by applying a kind of asymmetrical pattern treatment to a paper cone making the sound wave travel slightly faster/slower along different radiuses?

Hegeman modifications to Lowther and other drivers and Ogilvie's article suggest that the idea is indeed workable
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Old 18th February 2010, 09:55 AM   #40
graaf is offline graaf  Poland
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ps.

I wonder what pattern would be best - perhaps three-leaf clover or rather a yin-yang?
would it be more effective to use two kinds of treatments of opposite kind - partly stiffener and partly dampener?
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