Martin Poulin
Bamboo piece from a 1" holesaw
much much better
Bamboo piece from a 1" holesaw
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.