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In the Forum: Audio Discussions
In the Thread: Natural Remedies for Sick Speakers?
Post Subject: Who knows for sure...Posted by haralanov on: 8/4/2010
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 Paul S wrote:
I took a couple of pictures, but I can't figure out how to upload them, just yet.

Hi, Paul. Take a look here http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=1120

 Paul S wrote:
I took out the phase plug, and the gap is truly tiny!

The very tiny magnetic gaps always have some nonlinearities in order to have high efficiencies.

 Paul S wrote:
The cone surround is soft foam. I presently high-pass my OB-mounted units 1st order at 400 Hz. Frank lists the Qts as .1048 (!)

Wow, that value is really on the very low side. I suppose the voice coil has at least two or may be more layers in order to get more turns in the gap which cause high BL factor (low Qes). As a downside there is a big increase in VC inductance, which can be calculated as the inductance of one layer get multiplied by the number of layers plus the mutual inductance of the layers because they are magnetically coupled. So the inductance modulation will be very high despite the driver does not make high excursions because of the high pass filter you use with it. So that may be part of the reason for the peak, but I cannot be sure about that.
You use a driver with very strong motor designed for horn use in open baffle. Soft foam surrounds never have good midrange reproduction, especially with OBs - you need some not so soft suspension an not so overdamped motor in order to get proper sound but I don't want to exercise my moronity making assumptions based on nothing...

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