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Old 17th June 2013, 01:23 AM   #1
tilroh is offline tilroh  Australia
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Default making driver flush with baffle

I had the router out and was ready to cut down my 35cm round BIB baffles when GM suggested not to be so hasty. So instead I traced the driver outline and routed the shape so the FE166s would fit flush into the baffle.

While I had the baffles off I sanded them and applied a quick coat of Interlux Perfection 2pac paint (red). This is a much harder paint than the satin acrylic the baffles were painted with.

I didn't expect any change but:

The mid range harshness is reduced.

The sound is much more directional. I can move my head a few inches and change which channel sounds louder.

Highs seem to come from different directions and confuses my ears. It's weird.

Do you reckon all this is in my head possibly caused by the visuals of bright read paint?

Can flush fitting drivers make much difference?
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Old 17th June 2013, 01:36 AM   #2
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Flush fitting generally reduces diffraction effects. Some yrs ago I read that a round head of a screw used to attach a tweeter caused an audible effect. I can't quite visualize what you did but if the driver is now recessed further into the baffle then you may have increased the gap/clearance around the frame BEHIND the baffle. i.e. inside the enclosure and this has been known to reduce internal reflections and so reduce colouration......
Re: the paint. May be you were just sniffing the two-pac..ha ha.
Cheers,
Jonathan
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Old 17th June 2013, 01:40 AM   #3
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This is personal opinion and I know others differ. Most Fostex drivers are designed to be surface mounted.The rounded shape of the frame indicates this. Also, the plastic ring around the surround seems to negate any benefit of rabbeting the driver into the baffle. and finally, because of the rounded edge on the frame, once the driver is rabbeted in, there is a sharp edge on the rabbet, again negating the benefit of rabbeting in the first place.

While any number of people have rabbeted in those odd shaped Fostex frames, it seems a lot of effort for perhaps no real gain. I would be happy to proven wrong, but I have never seen hard evidence that there is any benefit.

Bob
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Old 17th June 2013, 01:49 AM   #4
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Zaph did some investigations into this.

Zaph|Audio
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Old 17th June 2013, 01:55 AM   #5
tilroh is offline tilroh  Australia
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Quote:
Originally Posted by Jonathan Bright View Post
--- but if the driver is now recessed further into the baffle then you may have increased the gap/clearance around the frame BEHIND the baffle. ----
Cheers,
Jonathan
I didn't occur to me that moving the driver deeper into the box would lessen the restriction but of course it would.

The drivers holes are routed in a "V" shape but the drivers now extend 3.5mm deeper into the wider part of the V. This makes more sense than even red paint. However just give that glossy paint a few days to burn in.....
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Old 17th June 2013, 02:19 AM   #6
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Zaph's study doesn't apply here. He was looking at the diffraction off of the square edge of a standard tweeter with ~4" round flange. He was also looking at the defraction from the tweeter off of the woofer flange. Neither apply with a 6-8" wide range driver that will most likely be beaming significantly at tweeter frequencies. There is also the issue of the plastic ring around the Fostex drivers. I would like to see someone study the effect of rabbeting/or not a Fostex FE166En or FF165WK.

Bob
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Old 17th June 2013, 09:35 PM   #7
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Hi tilroh how's the high frequencies going today?
Woke up this morning and just had another thought about the red paint...........
does the imaging change if you wear dark glasses? Ha ha......
GO ESSENDON!
Cheers, Jonathan
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Old 17th June 2013, 09:56 PM   #8
tubemax is offline tubemax  Netherlands
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I did flush mount the FE167E in MLTL box, but I think is not worth extra job/time, it took me days to finish them due to strange shape of the speaker basket. On the end, I could not tell the difference between flush or surface mount... maybe a bit more lower-end midrange or upper bass, hard to tell now since I don't have boxes anymore...
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File Type: jpg FE167E MLTL 2 copy.jpg (65.6 KB, 135 views)
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Old 18th June 2013, 09:03 AM   #9
tilroh is offline tilroh  Australia
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Quote:
Originally Posted by tilroh View Post
---- applied a quick coat of Interlux Perfection 2pac paint (red). -----
I didn't expect any change but:

The sound is much more directional. I can move my head a few inches and change which channel sounds louder.

Highs seem to come from different directions and confuses my ears. It's weird.
er, maybe I should mention that I just discovered another small change done after the routing and painting. ..... reversing the plus and minus leads....

With polarity corrected, sound is coherent and the bass is back in the middle not just on sides.

Now I can really enjoy the sonic benefits the bright red paint

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Old 18th June 2013, 03:01 PM   #10
IG81 is offline IG81  Canada
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Quote:
Originally Posted by tilroh View Post
er, maybe I should mention that I just discovered another small change done after the routing and painting. ..... reversing the plus and minus leads....
It never fails to give me that uneasy and dizzy-like feeling whenever I pull this off.

IG
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