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Old 25th February 2012, 01:43 AM   #1
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Default mass loading vs hf response ......

If we add mass to a FR driver .....
Say to lower Fs and increase Qts ...
Does the resultant driver have less highs
than the original ?

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Old 25th February 2012, 02:45 AM   #2
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There is a French document about this and other full range related myths. In two words, they say you will just loose efficiency, but the Fr will remain the same as the maximal HF extension is function of the coil inductance and not of the mass load. Of course Fs will go down.
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Old 25th February 2012, 04:58 AM   #3
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Fair enough in theory.

In theory a 4" cone can only go up to about 3400hz before output drops. Of course, we know this isn't true. Mostly due to the cone not being a theoretical , perfect piston. The cone breaks up, different sections behave differently at different frequencies, the dustcap can have a pronounced effect on the high frquency response depending on it's shape and make.


Adding mass to a full range driver will certainly change the behaviour of the cone and it's break up nodes. Depending on how the mass is added , the change in frequency response could be subtle or drastic.

If I had a 4" driver and added enough clay, putty, silicone, glue, or whatever all over the surface of the cone, to reduce the drivers Fs from 80hz to 50hz , do you think the mid and high frequency response would be the same as a stock driver (just reduced in spl) ?


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Old 25th February 2012, 05:11 AM   #4
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Right, the paper I was linking speaks of a ponctual mass, say some putty at the junction VC/cone, it's not about global coating where the FR will be changed by the reasons you give.
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Old 25th February 2012, 05:14 AM   #5
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The French Paper of which you spoke :
Google Translate

The translation isn't so good, but it is better than my French





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Old 26th February 2012, 12:53 AM   #6
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Hammer Dynamics Super 12 (Page 2) / FullRangeDriver Forum / Fullrangedriver Forum
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Old 26th February 2012, 03:20 AM   #7
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Perhaps damar and the patterns painted onto cones is relevant to this discussion?
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Old 26th February 2012, 04:11 AM   #8
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I skimmed the French paper, and assume when they discuss fullranges they are including whizzer cones. Those would be separate from a cone-they are making their own kind of acoustic.

There is absolutely a moving mass rolloff...in horn systems (per D.B. Keele). I can't say it applies for sure otherwise, although it seems like it should.

And in real life, whatever goop you put on to drop the resonance a lot will probably absorb HF energy and cause more rolloff.
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Old 26th February 2012, 01:19 PM   #9
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Quote:
Originally Posted by Godzilla View Post
Perhaps damar and the patterns painted onto cones is relevant to this discussion?
That seems to be coming into it......However the original question
(in my mind) was the effect of the added weight only.
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Old 26th February 2012, 08:43 PM   #10
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Hammer Dynamics Super 12 (Page 3) / FullRangeDriver Forum / Fullrangedriver Forum



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