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Old 17th October 2007, 10:16 PM   #1
rjb is offline rjb  New Zealand
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Default Whizzer distortion

I notice in other threads, various comments expressing strong dislike of whizzers, with which I tend to agree. Long-term I find a harshness present, which is probably some form of distortion, rather than a peaky frequency response, which I can tolerate better.

However I came across a comment in E J Jordans book on loudspeakers which is of interest. He spends a page and a half on the design of whizzers, and then the final paragraph contains this, regarding the final design of a production unit, (presumably a Goodmans).

Quote ..."For no apparent reason, concentric free mode resonances were found to be almost non-existent . The radial (or bell) modes were particularly severe, however and resulted in a sharp dip at 7Kc/s. One way of stopping a bell ringing is to insert a radial crack. Three such "cracks" were made in the tweeter (whizzer)coneand damped with sponge plastic."

He then refers to a frequence curve of a 12" unit using this, which shows very smooth on-axis and 15 degree curves, but poor at 30 degrees. Unfortunately there is no comparison between treated and untreated whizzer.

I am not aware of any production unit which has had this applied to the whizzer.

Has anybody tried this?
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Old 17th October 2007, 11:32 PM   #2
soongsc is offline soongsc  Taiwan
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The number of three is right on. The reason for non-existence in concentric modes is that the direction of stiffness is greater in this direction, and the energy is dissipated through the easier path, which is the bell mode.
I wish I could get hold of Ted's book, I can't seem to find it here.
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Old 18th October 2007, 04:20 AM   #3
maxro is offline maxro  Canada
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Default Re: Whizzer distortion

Quote:
Originally posted by rjb
...Three such "cracks" were made in the tweeter (whizzer)coneand damped with sponge plastic."...

I am not aware of any production unit which has had this applied to the whizzer.

Looky here.
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Old 18th October 2007, 07:24 AM   #4
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The Goodmans full-range units that had the 'whizzer' cone treated in this way were the Axiom 201 and Axiom 301 models.
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Old 18th October 2007, 09:22 PM   #5
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Quote:
Originally posted by Ouroboros
The Goodmans full-range units that had the 'whizzer' cone treated in this way were the Axiom 201 and Axiom 301 models.

i have a pair of both, the 301 have these.. but my 201 don't.. they have a large dome that extends to within 1/2 " of the whizzer edge

there is hard or harshness in the sound of some full range drivers

i have heard quite a few fostex full rangers speakers and they can be much more harsh sounding than my lowther ex4.. wich are very smooth in comparison
but the fostex are very good value for money..

201's and 301's don't do the top end so well...

i use ex4 and 301 and goodmans 61 on open baffle
they sound very good together
lesser supporting bass speakers would not keep up with the lowther... and no harshness to my ears..

steve
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Old 18th October 2007, 09:57 PM   #6
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Default you might find this interesting...

US Patent # 7, 146, 021 Inventor Benny I Danovi. Title "Whizzer cone for loudspeaker for producing uniform response.
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Old 18th October 2007, 10:19 PM   #7
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Default This may also be of interest...

US Patent # 6, 334, 505, by Ming-Chaing Li date Jan 01, 2002, Title Optimum edges for speakers and musical instruments.
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