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Old 29th January 2010, 09:52 PM   #701
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Quote:
Originally Posted by pietschu View Post
OK here's a simple example (although since RF usually means radio frequency, I'll be using Fr)
This being the multi-way forum (aka loudspeakers) radio frequency (RF) should not be a topic for discussion. FR could be mistaken for Full Range

Good example. Add stiffness and you win, and what you lose when you add mass damping doesn't equal what you gain in terms of lowering Q and damping overall panel vibration.

***EDIT: This thread was moved to construction.
Oh well. RF for me and I called it first.

Last edited by MJL21193; 29th January 2010 at 09:56 PM.
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Old 29th January 2010, 11:00 PM   #702
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Originally Posted by MJL21193 View Post
Back up a bit here - I said "add stiffness then add mass".

Increasing stiffness drives the RF up, damping lowers the Q AND shortens the overall decay time for all vibration, not just at the RF.
Thanks Dave for the reference you cited. I would enjoy reading this work. Can you point me in the proper direction? I will do a google search.

Also, Dave I don't exactly follow the terminology you use (I am not very schooled so take it easy). I understand and agree with Johns comments above.
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Old 29th January 2010, 11:16 PM   #703
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FR could be mistaken for Full Range
or frequency response.

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Old 30th January 2010, 12:51 AM   #704
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Originally Posted by planet10 View Post
or frequency response.

dave
That was the one the eluded me for some silly reason. Brain cramp mayhaps.

I built an accelerometer:

NPX_092.JPG

and I did some basic shmit with Arta to display the burst decay:

122.PNG

This is the broadest unbraced panel (the back) of my curved front 3-ways.
This one is from the smallest unbraced panel (the top):

123.png

Quite a difference.
I'm new to the Arta thing so I'll be playing with this for a while.
So much fun, so little time...
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Old 31st January 2010, 04:54 AM   #705
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ok I found the Toole paper and will take a look at it.
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Old 31st January 2010, 05:19 AM   #706
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The papers on the net i've seen aren't nearly as complete as the book.

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Old 31st January 2010, 02:47 PM   #707
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Dave - I see he has a couple of books. Which one do you recommend? I will buy it today.
The paper I am reading is "The modification of Timber of Resonances: Perception and Measurement" circa 1988.

I also understand what you were saying about high and low Q resonance and audibility.

True in the BBC paper they started out on the premise that lowering the resonant Q was desired without testing that idea. However, there is still some good information and can be used as a piece of the puzzle. It does explain a few things they found odd like certain spikes were not as audible as others -perhaps Q related.

This is also consistent with audibility of peaks and dips in driver response. The narrower the aberration in bandwidth the less audible.

Last edited by stephenmarklay; 31st January 2010 at 03:00 PM.
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Old 31st January 2010, 10:02 PM   #708
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Dave - I see he has a couple of books. Which one do you recommend?
I wasn't aware ofmultiple books. His latest "Sound Reproduction" is a summation of his 30-some years of research.

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Old 31st January 2010, 10:06 PM   #709
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The paper I am reading is "The modification of Timber of Resonances: Perception and Measurement" circa 1988.
Is the paper on-line -- be way easier than wading into my (as yet) unsorted library to dig out the AES journal

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Old 1st February 2010, 02:57 AM   #710
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Yep this is online. I am not sure where I found it -google search. If you cannot find it I will send it to you.
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