(danny) "But there was a problem in that there just really wasn't enough insulation. And this is it for the insulation………… And when i did my testing on it, i took a little piece of fiberglass insulation and filled that area there that was pretty empty, and those two issues that we saw in the impedance curve, those two resonances completely went away. It was just a matter of some of that, uh, some of that reflecting around in the box and some of it was exiting the port. So, that was an easy fix."
(danny) "So, I took a little piece of no res which is um as a little damper with a pressure sensitive adhesive on the back and it has a foam layer. I took a little piece of it and stuck it on one side of the cabinet, took another measurement. And lo and behold, that knocked some of that tweeter's roughness out of it, so cut another little piece there picked I picked a piece from scrap stuck it on the other side, took another measurement, and this tweeter's response curve just smooth dried out."
Subjectively, the added stuffing cleaned up Alison Krauss "hundred miles or more: a collection".
I swear she is humming more than singing most of the time.
(danny) "Uh, with the pieces of no-rez stuck to the face of this thing doing away with that diffraction. Right there took away that lumpiness in the tweeter's response and smoothed it right out."
graphs are there.
Is my foam cutout doing the same or better ? don't know.
Is it better than the rounded cabinets of the more expensive revels, I doubt it, but it is free.
But, yes.
Perhaps I could send a foam cutout to someone and they could measure if it smoothed out tweet's response.
I can send different thicknesses also.
The foam is pretty porous, 1 layer thick doesn't know much hf ambient down, but 3" from tweet to edge should make a difference.
45 degrees off axis, I can still see the tweeter.
So it shouldn't narrow the +/- 50 degree measurement that we see here on the front page.
I sit 10' away, although 6' away sounds better.
I'm sure the up and down peak / dip past 5khz is caused by the tweet's sound reradiating after hitting the cabinet edges.
F206 has a similar peak 4-5khz then perhaps dip past.
f208 has peak 5-6khz.
m126be has a bit of a peak 4.5-5.5khz.
Could I do a better x-over ? nope.
but perhaps it can sound better for minimal cost.
Overall I am thrilled with the speaker for what it is, a 6" 2-way.
This article shows an easy way to control baffle diffraction using a stepped baffle example. The author experiments with the use of felt, directly applied to the baffle and measures the results. Each piece of felt and its placement has different results. The article clearly demonstrates the...
audioxpress.com