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I’m not completely happy with the Eminence Pro 5w8 as a mid-range driver.

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I was wondering about the distortion peaks and rough frequency response plot.

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I then decided to remove the dust cap and install a DIY phase plug instead.

The phase plug mod was too tempting to not try.

I had good results before on few Fostex units and some DIY’s sellers still sell them today.

Took a few minutes to make two phase plugs of 2" long and 7/8" diameter, out of a bamboo cutting board. (hence the center hole from the hole saw)

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Results:

·         FR is a bit more even, as was widely expected.

·         Distortion is worse below 400 Hz as the speaker loses surface area (SD), and remains similar above this low frequency SD loss.

·         Impulse response is much, much better. Less stored energy inside the voice coil cavity.

·         Lost ~0.25 grams worth of cone weight or ~6%. (FYI, ~0.25g is similar to the weight of a typical 1" textile dome tweeter.​)

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As a 400-3 kHz mid-range, the DIY phase plug modification seemed appears good. Subjective listening seems to confirm this impression, but nothing that really jumps out at you. Equalization is always required.

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I’m wondering if I’ll use a DIY coating on the cone?

 

Perhaps another day.

Remember, I have a French mother tongue, doing my best to express myself in the Shakespeare language.

Thanks to a friend, Bevis, most of my website has been corrected for proper English grammar, much easier read now :)

 

Any suggestion/comments,  feel free to E-mail me.

mapoulin@gmail.com

Update May 2024: this website won't be updated for a while as WIX decided to max storage capacity at 500 Mb unless you pay a monthy fee to obtain more storage (the site is already at 2.4 Go).

I may merge the site to another server or find a solution but in the meantime, I can't add anything but text, Sorry
 

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