Keele, D. (2004) "Maximum efficiency of compression drivers" - diyAudio
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Old 25th October 2007, 11:31 AM   #1
svenr is offline svenr  Guatemala
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Default Keele, D. (2004) "Maximum efficiency of compression drivers"

Hi folks,

Don Keele's probably well known article examines the relationship between driver parameters, nominal and true efficiency for compression driver design. It can be found here:

http://www.xlrtechs.com/dbkeele.com/PDF/Keele%20(2004-10%20AES%20Preprint)%20-%20Maximum%20Efficiency%20of%20Compression%20Drive rs.pdf

It's interesting to observe that Keele stops his talk when it comes to the interesting parts.

When looking at section 6.4.2 equation (40) of the paper, Keele derives the nominal efficiency of a compression driver loaded by an infinite tube while neglecting the influence of voice coil inductance and front chamber compliance. Equation (40) is than simplified by introducing normalization variables and given as equation (41).

When calculating both equations from the same set of given variables I get (surely caused by my math incapability) differing results. Equation (40) involves 5 independent parameters (R1, R2, R3, L2 and C2) as well as the variable w. But the simplified equation (41) shows only 3 independent and 1 interdependent parameter (plus the normalized variable wn). Equation (40) is strongly influenced by inductance L2 representing system compliance, while equation (41) is not influenced by normalization variable wo representing L2.

I've prepared a little spreadsheet (with most of the equations probably transcribed incorrectly):

www.geocities.com/srechenberger

I would appreciate if you could help me out with this; I'm kind of confused...

Greetz
Sven
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Old 25th October 2007, 03:33 PM   #2
GM is offline GM  United States
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Greets!

Wish I could, but my higher math skills are mostly non-existant, so about all I can help with is a valid link: http://www.xlrtechs.com/dbkeele.com/...%20Drivers.pdf

GM
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Old 28th October 2007, 03:14 AM   #3
svenr is offline svenr  Guatemala
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Hi folks,

anybody must be able to give me a hint where the problem is within the transformation...

Cheers
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Old 28th October 2007, 02:03 PM   #4
GM is offline GM  United States
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Greets!

There are, but very few of us on this forum have any interest in compression horns, so try these instead:
http://audioheritage.csdco.com/vbulletin/
http://www.audioasylum.com/forums/hug/bbs.html
http://www.audioroundtable.com/HighEfficiencySpeakers/

GM
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